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Describe the structure of human cell with labelled diagram the function of organelles and cellular transportation in 2000 words tell me where to add a structure of what in the answer

I can see your textbook pages covering the human cell structure, organelles, and cellular transport. Let me create a comprehensive ~2000-word answer based directly on your textbook content, with clear guidance on where to place diagrams.

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labelled diagram of human cell organelles nucleus mitochondria

This pathophysiology diagram illustrates the mechanism of action of plant-derived silver (Ag+) and zinc (Zn2+) alloy nanoparticles on human cancerous cells. The flow chart begins with the bimetallic nanoparticles interacting with a depicted human cancerous cell containing labeled organelles, including the nucleus, mitochondria, ribosomes, cytoplasm, and cell membrane. The diagram delineates a three-step cascade of adverse effects: (1) Cell Membrane Disruption, (2) Mitochondria Dysfunction, and (3) DNA Damage. These interconnected cellular stressors lead to a final pathological outcome: Apoptosis (programmed cell death). The visual serves as an educational resource to explain the cytotoxic potential of green-synthesized nanotechnology in oncology, specifically demonstrating how metal-ion combinations induce intracellular damage and systemic cell death in malignant lines.

This medical pathophysiology diagram illustrates the biogenesis of exosomes within a human cell. The schematic depicts key organelles including the nucleus, mitochondria with distinct cristae, and the Golgi apparatus. The process of exosome formation begins at the plasma membrane via endocytosis, leading to the creation of an early endosome. This endosome matures into a multivesicular body (MVB) through inward budding of the endosomal membrane. The MVB is shown encapsulating diverse molecular cargo, specifically DNA, RNA, miRNA, and proteins, which are organized into intraluminal vesicles. The final stage demonstrates the MVB fusing with the cell membrane, releasing these internal vesicles into the extracellular space as exosomes. The diagram serves as an educational tool for understanding cellular signaling pathways, paracrine communication, and the transport of genetic and proteomic material between cells. Key labels and a legend identify the molecular components and structural stages of the endocytic pathway.

This computer-processed optical coherence tomography (OCT) image provides a detailed anatomical diagram of a T lymphocyte. The cell is depicted as a three-dimensional, semi-spherical structure enclosed by a transparent plasma membrane. Small, blue filamentous structures, representing surface receptors or protein chains, extend from the membrane into the dark reddish extracellular environment. Internally, the cytoplasm contains a distinct, centrally located spherical nucleus containing orange-colored tubular chromatin or nucleolar components. Various other organelles are visible within the cytoplasmic space, including yellow bean-shaped structures likely representing mitochondria and smaller vesicular bodies. The visual focus is on the spatial relationship between the intracellular compartments and the surrounding fluid environments, illustrating the biological concept of cellular mechanotransduction and the influence of hydrostatic pressure on cell morphology. This pedagogical material is designed for advanced immunology or cellular biology contexts, specifically highlighting the T cell's structural adaptation to fluidic dynamics.

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phospholipid bilayer plasma membrane structure diagram

A medical educational diagram illustrating the structure and biogenesis of extracellular vesicles (exosomes and microvesicles). The top panel shows a high-magnification cross-section of an individual vesicle, highlighting its phospholipid bilayer membrane containing surface antigens, adhesion molecules, tetraspanins, and lipid rafts. The internal lumen is shown carrying cargo such as nucleic acids, proteins, and lipids. The bottom panel depicts the cellular production pathway. It begins with the internalization of the plasma membrane to form an early endosome (EE), which matures into a multivesicular endosome (MVE) or multivesicular body (MVB) containing intraluminal vesicles (ILV). This maturation step is annotated with the regulatory protein Rab27A. The diagram shows two possible fates for the MVE: fusion with the plasma membrane to release exosomes (30–100 nm) into the extracellular space via exocytosis, or fusion with a lysosome for cargo degradation. The illustration uses standard biomedical iconography to teach cellular signaling and transport mechanisms.

This pathophysiology diagram illustrates the cellular mechanisms of oxidative stress-induced damage in human sperm cells, specifically during cryopreservation processes. The central element is a Reactive Oxygen Species (ROS) starburst indicating the initiation of oxidative stress. The diagram branches into two main pathways of cellular injury. The upper section details 'Plasma membrane damage', showing a phospholipid bilayer undergoing structural disruption. Specific molecular processes highlighted include the reorganization of phospholipids, lipid peroxidation leading to cholesterol efflux, disruption of protein disulfide bonds, and modification of the glycocalyx. These changes result in generalized protein, lipid, and carbohydrate alterations. The lower section illustrates 'Oxidative stress' impacting deeper cellular structures: genomic DNA damage (depicted as a double helix with lesion markers) and protein damage (shown as a misfolded tertiary structure). The functional consequences of protein damage are shown as impaired mitochondrial activity and decreased sperm motility, visually represented by an axoneme/flagellum with a downward arrow. This visual aid is intended for advanced medical education in reproductive physiology and andrology.

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cellular transport diffusion osmosis active transport diagram

An anatomical and pathophysiology diagram of the human Neurovascular Unit (NVU) and Blood-Brain Barrier (BBB), illustrating cellular architecture and molecular transport mechanisms. The diagram depicts the specialized endothelial cells with their abluminal surface covered by pericytes and astrocytic endfeet. A cross-sectional inset shows the circumferential arrangement of these cells around the vessel lumen. Key structural features include tight junctions, which restrict paracellular transport. Five primary transport mechanisms are detailed: 1. Active Efflux (P-gp, BCRP, MRPs) moving substances from endothelial cells to the blood; 2. Facilitated Active Transport (GLUT1, LAT1, CAT1,3) for nutrient influx; 3. Ion Transporters (Na+, K+, Cl-); 4. Receptor-Mediated Transport involving vesicle trafficking; and 5. Passive Diffusion across the BBB. The illustration highlights the complex signaling and physical barriers required to maintain cerebral homeostasis and presents significant implications for neuro-oncology and CNS drug delivery pharmacology.

A comparative medical schematic illustrating the cellular uptake and pharmacokinetics of conventional versus nanoparticle-based drug delivery within a cancer cell. The diagram is divided into two sections. The left side depicts 'Conventional drugs' utilizing active transport and passive transport for cellular entry, while also highlighting mechanisms of drug efflux. This delivery method is associated with clinical challenges such as off-target drug diffusion, rapid elimination, and low bioavailability. The right side depicts 'Nanoparticle drugs' entering the cell via endocytosis. The illustration shows a nanoparticle encapsulated within a lysosome, facilitating intracellular release. This method is characterized by therapeutic advantages including targeted drug delivery, prolonged systemic circulation, and high bioavailability. The diagram serves as an educational tool in pharmacology and oncology to demonstrate how nanotechnology can overcome biological barriers and improve drug efficacy while minimizing systemic toxicity.

Here is your full ~2000-word essay on the human cell, based directly on your textbook (Section 1, Chapter 3). I have marked every place where a diagram should be inserted.

Structure of the Human Cell, Functions of Organelles, and Cellular Transportation

1. Introduction to the Human Cell

The human body develops from a single cell called the zygote, formed by the fusion of an ovum (female egg cell) and a spermatozoon (male sex cell). As the fetus grows, cells undergo division and specialisation, producing the wide variety of cell types found in the adult body. All individual cells share the same genetic makeup as the original zygote, yet each is too small to be seen with the naked eye - they are only visible when thin tissue slices are stained and viewed under a microscope.

A cell consists of a plasma membrane enclosing a number of organelles suspended in a watery fluid called the cytosol. Everything inside the cell except the nucleus is collectively called the cytoplasm, which includes both the cytosol and the organelles within it.

[INSERT DIAGRAM HERE - Figure 3.1: The Simple Cell] Draw a labelled diagram of the human cell showing: plasma membrane, cytoplasm, nucleus, nuclear envelope, nucleolus, chromatin, ribosomes, rough endoplasmic reticulum (with ribosomes), smooth endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, centrosome, and centrioles. This should be placed at the start of this section as it provides the reader with an overview of all organelles before they are described individually.

2. The Plasma Membrane

The plasma membrane forms the outer boundary of every cell. Its structure and functions are fundamental to cell survival, as it controls passage of substances into and out of the cell, regulating the intracellular environment.

Structure

The plasma membrane consists of two layers of phospholipids (a phospholipid bilayer) with proteins and sugars embedded in them. The lipid cholesterol is also present. Each phospholipid molecule has:

A head that is electrically charged and hydrophilic (water-loving)
A tail that has no charge and is hydrophobic (water-hating)

The bilayer is arranged like a sandwich: the hydrophilic heads face the outer surfaces of the membrane, while the hydrophobic tails form the central water-repelling layer. This arrangement controls which substances can cross the membrane.

[INSERT DIAGRAM HERE - Figure 3.2A: The Phospholipid Bilayer] Draw a labelled diagram showing: phospholipid bilayer with heads facing outward and tails facing inward, membrane protein molecules spanning the bilayer, cholesterol molecules embedded in the membrane, and carbohydrate chains attached to the outer surface. Place this diagram immediately after explaining the phospholipid bilayer structure above.

Membrane Proteins

Proteins that extend all the way through the membrane provide channels allowing the passage of electrolytes and non-lipid-soluble substances. These membrane proteins perform several important functions:

Some have branched carbohydrate molecules attached to the outside of the cell, giving the cell its immunological identity - these are 'self' markers
They act as receptors (specific recognition sites) for hormones and other chemical messengers
Some are enzymes
Transmembrane proteins form channels filled with water that allow very small, water-soluble ions to cross the membrane
Some are involved in pumps that actively transport substances across the membrane

3. Organelles

Organelles (literally meaning 'small organs') have individual and highly specialised functions. They are often enclosed by their own membrane within the cytosol. The main organelles include: the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and cytoskeleton.

3.1 Nucleus

All body cells have a nucleus, with the exception of mature erythrocytes (red blood cells) and skeletal muscle fibres (which contain several nuclei). The nucleus is the largest organelle and is contained within the nuclear envelope - a membrane similar to the plasma membrane but with tiny pores through which some substances can pass between the nucleus and cytoplasm.

The nucleus contains the body's genetic material in the form of deoxyribonucleic acid (DNA), which directs all metabolic activities. In a non-dividing cell, DNA is present as a fine network of threads called chromatin. When the cell prepares to divide, chromatin forms distinct structures called chromosomes. Ribonucleic acid (RNA) is also found in the nucleus and is involved in protein synthesis. Within the nucleus is a roughly spherical structure called the nucleolus, which synthesises and assembles the components of ribosomes.

[INSERT DIAGRAM HERE - Nucleus close-up] Draw a labelled close-up of the nucleus showing: nuclear envelope, nuclear pores, chromatin/DNA, nucleolus, and surrounding cytoplasm. Place this diagram within the nucleus section to help the reader visualise the internal structure separately from the whole-cell diagram.

3.2 Mitochondria

Mitochondria are membranous, sausage-shaped structures in the cytoplasm - sometimes described as the 'power house' of the cell. They are central to aerobic respiration, the process by which chemical energy is made available in the cell. This energy is released in the form of ATP (adenosine triphosphate). Synthesis of ATP is most efficient in the final stages of aerobic respiration, a process that requires oxygen. The most active cell types (e.g. liver, muscle, and spermatozoa) have the greatest number of mitochondria.

[INSERT DIAGRAM HERE - Mitochondrion electron micrograph / diagram] Draw or reference a diagram of a mitochondrion showing its double membrane and inner folds (cristae). Your textbook Figure 3.6 is a false-colour electron micrograph showing the mitochondrion (orange) and rough endoplasmic reticulum (turquoise). Place this after the mitochondria description.

3.3 Ribosomes

Ribosomes are tiny granules composed of RNA and protein. They synthesise proteins from amino acids, using RNA as the template. Ribosomes are found:

Free in the cytoplasm (in free units or small clusters) - making proteins for use within the cell, including enzymes required for metabolism
On the outer surface of the nuclear envelope
On the rough endoplasmic reticulum - making proteins for export from the cell

3.4 Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER) is an extensive series of interconnecting membranous canals in the cytoplasm. There are two types:

Smooth ER: synthesises lipids and steroid hormones; associated with detoxification of some drugs. Some of its lipids replace and repair the plasma membrane and membranes of organelles
Rough ER: studded with ribosomes; the site of synthesis of proteins - particularly enzymes and hormones - that are 'exported' from cells by exocytosis

3.5 Golgi Apparatus

The Golgi apparatus consists of stacks of closely folded, flattened membranous sacs. It is present in all cells but is larger in those that synthesise and export proteins. Proteins move from the ER to the Golgi apparatus, where they are 'packaged' into membrane-bound vesicles. These vesicles are stored and, when needed, move to the plasma membrane and fuse with it, expelling their contents from the cell - a process called exocytosis.

[INSERT DIAGRAM HERE - Golgi apparatus electron micrograph] Reference Figure 3.7 from your textbook: the coloured transmission electron micrograph showing the Golgi apparatus in green. Place this image alongside the Golgi apparatus description to show its characteristic stacked, flattened appearance.

3.6 Lysosomes

Lysosomes are small membranous vesicles pinched off from the Golgi apparatus. They contain a variety of enzymes involved in breaking down fragments of organelles and large molecules (e.g. RNA, DNA, carbohydrates, proteins) inside the cell into smaller particles that are either recycled or exported as waste. In white blood cells, lysosomes contain enzymes that digest foreign material such as microbes.

3.7 Cytoskeleton

The cytoskeleton is an extensive network of tiny protein fibres. It provides an internal support system for the cell and guides the movement of materials around the cell interior. It has two main components:

Microfilaments: tiny fibres made of actin, anchored to the inside of the cell membrane, giving the cell support and shape. Actin is also involved in the contractile process in muscle cells
Microtubules: large, rigid proteins that give the cell mechanical support and provide guidance tracks for internal movement of organelles and chromosomes during cell division

3.8 Centrosome

The centrosome directs organisation of microtubules within the cell. It consists of a pair of centrioles (small clusters of microtubules) and plays an important role in cell division.

3.9 Cell Extensions

Some cell types project extensions from the plasma membrane. Their main components are microtubules, which allow movement:

Microvilli: tiny projections containing microfilaments that cover the exposed surface of certain cells (e.g. absorptive cells lining the small intestine). They greatly increase surface area, maximising absorption of nutrients
Cilia: microscopic hair-like projections lying along the free borders of some cells. They beat in unison to move substances along a surface - e.g. moving mucus upwards in the respiratory tract
Flagella: single, long, whip-like projections containing microtubules, forming the 'tail' of spermatozoa to propel them through the female reproductive tract

4. Transport of Substances Across Cell Membranes

Each cell is enclosed by its plasma membrane, which provides a selective barrier to substances entering or leaving. This property - selective permeability - allows the cell to control entry or exit of many substances, thereby regulating the composition of its internal environment.

Particle size determines which substances can cross: small molecules like water can pass freely by simple diffusion, while large molecules cannot and are confined to either the interstitial fluid or the intracellular fluid. Specific pores or channels in the plasma membrane admit certain substances but not others.

[INSERT DIAGRAM HERE - Figure 3.3: Selective Permeability] Draw three panels showing: (A) particle size - large particles excluded, small ones pass; (B) specific pores/channels - only particles matching the channel size allowed through; (C) pumps and carriers - active export of specific particles. Place this diagram at the start of the transport section to visually establish the principle of selective permeability.

4.1 Passive Transport

Passive transport occurs when substances cross the semipermeable membrane and move down their concentration gradient (downhill) without using energy.

Diffusion Small molecules diffuse down their concentration gradient:

Lipid-soluble materials (e.g. oxygen, carbon dioxide, fatty acids, steroids) cross the membrane by dissolving in the lipid part of the membrane
Water-soluble materials (e.g. sodium, potassium, calcium) cross the membrane by passing through water-filled channels

Facilitated Diffusion This passive process is used by substances unable to diffuse through the semipermeable membrane unaided (e.g. glucose, amino acids). Specialised protein carrier molecules in the membrane have specific sites that attract and bind substances to be transferred - like a lock and key mechanism. The carrier then changes its shape and deposits the substance on the other side of the membrane. The carrier sites are specific (only one substance can use them) and there is a finite number of carriers, so there is a limit to the amount transported at any time - the transport maximum.

Osmosis Osmosis is the passive movement of water down its concentration gradient towards equilibrium across a semipermeable membrane.

[INSERT DIAGRAM HERE - Figure 3.4: Facilitated Diffusion / Active Transport Carrier Proteins] Draw a diagram showing a carrier protein molecule spanning the plasma membrane with extracellular fluid above and intracellular fluid below. Show the molecule changing shape to transport a substance across. Place this here to illustrate facilitated diffusion and then refer to the same diagram again for active transport (below), since the same carrier proteins are used.

4.2 Active Transport

Active transport is the transport of substances up their concentration gradient (uphill) - i.e. from a lower to a higher concentration. This requires chemical energy in the form of ATP to drive specialised protein carrier molecules that transport substances across the membrane in either direction. The carrier sites are specific and can be used by only one substance; therefore the rate of transfer depends on the number of sites available.

The Sodium-Potassium Pump All cells possess this pump. It maintains the unequal concentrations of sodium (Na+) and potassium (K+) ions on either side of the plasma membrane and may use up to 30% of cellular ATP. Potassium levels are much higher inside the cell (principal intracellular cation); sodium levels are much higher outside (principal extracellular cation). These ions tend to diffuse down their concentration gradients - K+ outwards and Na+ inwards. To maintain their concentration gradients, excess Na+ is constantly pumped out across the membrane in exchange for K+. This pump indirectly supports other transport mechanisms such as glucose uptake and is essential in maintaining the electrical gradient needed to generate action potentials in nerve and muscle cells.

4.3 Bulk Transport

Transfer of particles too large to cross cell membranes occurs by:

Pinocytosis ('cell-drinking'): the cell engulfs fluid
Phagocytosis ('cell-eating'): larger particles (e.g. cell fragments, foreign materials, microbes) are taken into the cell. Lysosomes adhere to the vacuole membrane and release enzymes that digest the contents

These particles are engulfed by extensions of the cytoplasm that enclose them, forming a membrane-bound vacuole.

Exocytosis Waste material is extruded by the reverse process. Vesicles formed by the Golgi apparatus (or plasma membrane) leave the cell by fusing with the plasma membrane and expelling their contents - any indigestible residues of phagocytosis leave this way.

[INSERT DIAGRAM HERE - Figure 3.5: Bulk Transport / Phagocytosis and Exocytosis] Draw a 6-step sequence showing: (A) particle outside cell with lysosomes visible; (B) particle engulfed by plasma membrane; (C) formation of a vacuole; (D) fusion of lysosomes with vacuole; (E) digestion of particle by lysosomal enzymes; (F) exocytosis - vesicle fusing with plasma membrane to expel waste. Place this diagram at the end of the bulk transport section.

5. Summary of Diagram Placement

Diagram	Where to Place
Fig 1: Labelled whole cell	Beginning of essay (Section 1) - overview of all structures
Fig 2: Phospholipid bilayer	Section 2 after explaining membrane structure
Fig 3: Nucleus close-up	Section 3.1 to show nuclear envelope, pores, chromatin
Fig 4: Mitochondrion	Section 3.2 to show internal cristae structure
Fig 5: Golgi apparatus micrograph	Section 3.5 to show stacked sac appearance
Fig 6: Selective permeability (3 panels)	Start of Section 4 - establishes transport principles
Fig 7: Carrier protein / active transport	Section 4.1-4.2 - used for both facilitated diffusion and active transport
Fig 8: Bulk transport sequence	End of Section 4.3 - phagocytosis to exocytosis steps

This essay covers all content from your five textbook pages - the cell overview (Fig 3.1), plasma membrane structure, all major organelles (nucleus, mitochondria, ribosomes, ER, Golgi, lysosomes, cytoskeleton, centrosome, cell extensions), and all transport mechanisms (passive transport, diffusion, facilitated diffusion, osmosis, active transport including the sodium-potassium pump, and bulk transport including phagocytosis and exocytosis). The placement guide tells you exactly where each diagram should be inserted for maximum clarity.

Make it point wise answer and make the answer which source i have given to you for bsc nursing 1st sem

Here is your complete point-wise answer based strictly on your textbook pages (the 5 images you shared), written for BSc Nursing 1st Semester level.

Structure of the Human Cell, Functions of Organelles & Cellular Transportation

(BSc Nursing 1st Semester - Anatomy & Physiology)

PART 1 - INTRODUCTION TO THE HUMAN CELL

The human body develops from a single cell called the zygote
The zygote results from fusion of the ovum (female egg cell) and the spermatozoon (male sex cell)
Cell division follows and cells with different structural and functional specialisations develop
All individual cells carry the same genetic make-up as the zygote
Individual cells are too small to be seen with the naked eye
They can be seen when thin slices of tissue are stained in the laboratory and magnified using a microscope

Basic composition of a cell:

A cell consists of a plasma membrane enclosing a number of organelles
Organelles are suspended in a watery fluid called the cytosol
Cell contents excluding the nucleus = cytoplasm (cytosol + organelles)

📌 [INSERT DIAGRAM HERE - Fig 3.1: The Simple Cell] A labelled diagram of the whole cell showing all organelles - place this here as an overview before reading further Label: Plasma membrane, Cytoplasm, Nucleus, Nuclear envelope, Nucleolus, Chromatin, Ribosomes, Rough ER (with ribosomes), Smooth ER, Golgi apparatus, Mitochondria, Lysosomes, Centrosome, Centrioles

PART 2 - THE PLASMA MEMBRANE

Structure:

Consists of two layers of phospholipids (phospholipid bilayer)
Proteins and sugars are embedded in the bilayer
Cholesterol (a lipid) is also present

Phospholipid molecule has two parts:

Head - electrically charged and hydrophilic (water-loving)
Tail - has no charge and is hydrophobic (water-hating)

Arrangement:

Arranged like a sandwich
Hydrophilic heads are aligned on the outer surfaces of the membrane
Hydrophobic tails form a central water-repelling layer
These differences influence the transfer of substances across the membrane

📌 [INSERT DIAGRAM HERE - Fig 3.2A: Phospholipid Bilayer] Draw the bilayer sandwich structure showing heads outward, tails inward Label: Head (hydrophilic), Tail (hydrophobic), Membrane protein molecules, Cholesterol molecule, Carbohydrate chains

Membrane Proteins - Functions:

Proteins that extend all the way through the membrane provide channels that allow passage of electrolytes and non-lipid soluble substances
Some membrane proteins have branched carbohydrate molecules attached to the outside - these give the cell its immunological identity ('self' markers)
They act as receptors (specific recognition sites) for hormones and other chemical messengers
Some are enzymes
Transmembrane proteins form channels filled with water - allow very small water-soluble ions to cross the membrane
Some are involved in pumps that transport substances across the membrane

PART 3 - ORGANELLES

Organelles literally mean 'small organs'
They have individual and highly specialised functions
Often enclosed by their own membrane within the cytosol
Main organelles: nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, cytoskeleton

3.1 NUCLEUS

All body cells have a nucleus - except mature erythrocytes (red blood cells)
Skeletal muscle fibres contain several nuclei
The nucleus is the largest organelle in the cell
Contained within the nuclear envelope - a membrane similar to the plasma membrane but with tiny pores through which some substances can pass between it and the cytoplasm

Contents of the nucleus:

Contains the body's genetic material in the form of DNA (deoxyribonucleic acid)
DNA directs all metabolic activities of the cell
In a non-dividing cell, DNA is present as a fine network of threads called chromatin
When the cell prepares to divide, chromatin forms distinct structures called chromosomes
RNA (ribonucleic acid) is also found in the nucleus - involved in protein synthesis
Within the nucleus is the nucleolus - a roughly spherical structure involved in synthesis and assembly of ribosome components

📌 [INSERT DIAGRAM HERE - Nucleus close-up] Draw a magnified diagram of the nucleus Label: Nuclear envelope, Nuclear pores, Chromatin (DNA), Nucleolus, Cytoplasm surrounding

3.2 MITOCHONDRIA

Membranous, sausage-shaped structures in the cytoplasm
Described as the 'power house' of the cell
Central to aerobic respiration - the process by which chemical energy is made available in the cell
Energy is released in the form of ATP (adenosine triphosphate)
Synthesis of ATP is most efficient in the final stages of aerobic respiration
This process requires oxygen
The most active cell types have the greatest number of mitochondria - e.g. liver cells, muscle cells, spermatozoa

📌 [INSERT DIAGRAM HERE - Fig 3.6: Mitochondrion] Draw or reference the electron micrograph showing the sausage-shaped mitochondrion with its internal folds (cristae) Label: Outer membrane, Inner membrane, Cristae (inner folds)

3.3 RIBOSOMES

Tiny granules composed of RNA and protein
Synthesise proteins from amino acids using RNA as the template
Found in two locations:
- Free in the cytoplasm (free units or small clusters) - make proteins for use within the cell, including enzymes for metabolism
- On the outer surface of nuclear envelope and on rough endoplasmic reticulum - manufacture proteins for export from the cell
Metabolic pathways consist of a series of steps, each driven by a specific enzyme

3.4 ENDOPLASMIC RETICULUM (ER)

An extensive series of interconnecting membranous canals in the cytoplasm
Two types:

Smooth ER:

Synthesises lipids and steroid hormones
Associated with detoxification of some drugs
Some lipids produced are used to replace and repair the plasma membrane and organelle membranes

Rough ER:

Studded with ribosomes (giving it a rough appearance)
Site of synthesis of proteins to be exported from cells - e.g. enzymes and hormones
These proteins leave the parent cell by exocytosis

3.5 GOLGI APPARATUS

Consists of stacks of closely folded, flattened membranous sacs
Present in all cells but larger in cells that synthesise and export proteins
Proteins move from the ER to the Golgi apparatus
Proteins are 'packaged' into membrane-bound vesicles
Vesicles are stored and when needed they move to the plasma membrane and fuse with it
Contents are then expelled from the cell - this process is called exocytosis

📌 [INSERT DIAGRAM HERE - Fig 3.7: Golgi Apparatus] Reference the electron micrograph showing the Golgi apparatus (green, stacked sac appearance) Label: Stacked flattened sacs, Vesicles budding off, Direction of protein movement from ER

3.6 LYSOSOMES

Small membranous vesicles pinched off from the Golgi apparatus
Contain a variety of enzymes
Break down fragments of organelles and large molecules - e.g. RNA, DNA, carbohydrates, proteins - inside the cell into smaller particles
These smaller particles are either recycled or exported as waste
In white blood cells, lysosomes contain enzymes that digest foreign material such as microbes

3.7 CYTOSKELETON

An extensive network of tiny protein fibres
Provides an internal support system for the cell
Also guides the movement of materials around the cell interior

Two main components:

Microfilaments:

Tiny fibres made of actin
Anchored to the inside of the cell membrane
Give the cell support and shape
Also involved in the contractile process in muscle cells

Microtubules:

Large, rigid proteins
Give the cell mechanical support
Provide guidance tracks for internal movement of:
- Organelles
- Chromosomes during cell division

3.8 CENTROSOME

Directs organisation of microtubules within the cell
Consists of a pair of centrioles (small clusters of microtubules)
Plays an important role in cell division

3.9 CELL EXTENSIONS

These project from the plasma membrane in some types of cell. Their main components are microtubules:

Microvilli:

Tiny projections containing microfilaments
Cover the exposed surface of certain cell types
e.g. absorptive cells lining the small intestine
Greatly increase the surface area - maximising absorption of nutrients

Cilia:

Microscopic hair-like projections containing microtubules
Lie along the free borders of some cells
Beat in unison to move substances along the surface
e.g. move mucus upwards in the respiratory tract

Flagella:

Single, long, whip-like projections containing microtubules
Form the 'tails' of spermatozoa
Propel spermatozoa through the female reproductive tract

PART 4 - TRANSPORT OF SUBSTANCES ACROSS CELL MEMBRANES

Each cell is enclosed by its plasma membrane - provides a selective barrier
This property is called selective permeability
Allows the cell to control entry or exit of many substances
Regulates the composition of its internal environment

Role of particle size:

Small molecules (e.g. water) can pass freely across the membrane by simple diffusion
Large molecules cannot cross and are confined to interstitial or intracellular fluid

Role of pores and channels:

Specific pores or channels admit certain substances but not others

Role of pumps and carriers:

The membrane is also studded with specialised pumps or carriers that import or export specific substances

📌 [INSERT DIAGRAM HERE - Fig 3.3: Selective Permeability (3 panels)] Draw 3 panels side by side: Panel A - Particle size: large particles excluded, small ones pass through Panel B - Specific pores/channels: only matching particles allowed through Panel C - Pumps/carriers: active import and export of specific particles Place at start of the transport section

4.1 PASSIVE TRANSPORT

Occurs when substances cross the semipermeable membrane and move down their concentration gradient (downhill)
No energy required

4.2 DIFFUSION

Small molecules diffuse down their concentration gradient
Two pathways:
- Lipid-soluble materials (e.g. oxygen, carbon dioxide, fatty acids, steroids) - cross by dissolving in the lipid part of the membrane
- Water-soluble materials (e.g. sodium, potassium, calcium) - cross by passing through water-filled channels

4.3 FACILITATED DIFFUSION

A passive process - no energy required
Used by substances unable to diffuse unaided through the membrane - e.g. glucose, amino acids
Specialised protein carrier molecules in the membrane have specific sites that attract and bind the substance
Works like a lock and key mechanism
Carrier changes its shape and deposits the substance on the other side of the membrane
Carrier sites are specific - can be used by only one substance
There are a finite number of carriers - so there is a limit to the amount transported at any time
This limit is known as the transport maximum

📌 [INSERT DIAGRAM HERE - Fig 3.4: Carrier Protein Molecule] Draw a diagram showing: carrier protein spanning the plasma membrane, substance binding on extracellular side, carrier changing shape, substance released on intracellular side Label: Extracellular fluid, Plasma membrane, Intracellular fluid, Carrier protein molecule Use this same diagram for Active Transport in the next section

4.4 OSMOSIS

Passive movement of water down its concentration gradient
Movement is towards equilibrium
Occurs across a semipermeable membrane
No energy required

4.5 ACTIVE TRANSPORT

Transport of substances up their concentration gradient (uphill)
i.e. from a lower to a higher concentration
Requires chemical energy in the form of ATP (adenosine triphosphate)
ATP drives specialised protein carrier molecules that transport substances across the membrane
Carrier sites are specific - only one substance can use each carrier
Rate of transfer depends on the number of sites available

The Sodium-Potassium Pump:

All cells possess this pump
Maintains unequal concentrations of Na+ and K+ on either side of the plasma membrane
May use up to 30% of cellular ATP
Potassium (K+) - levels are much higher inside the cell (principal intracellular cation)
Sodium (Na+) - levels are much higher outside the cell (principal extracellular cation)
These ions tend to diffuse down their concentration gradients - K+ outwards, Na+ inwards
To maintain their gradients: excess Na+ is constantly pumped out across the membrane in exchange for K+
This pump indirectly supports other transport mechanisms such as glucose uptake
It is essential in maintaining the electrical gradient needed to generate action potentials in nerve and muscle cells

4.6 BULK TRANSPORT

Transfer of particles too large to cross cell membranes by other means
Occurs by pinocytosis or phagocytosis
Particles are engulfed by extensions of the cytoplasm, enclosing them in a membrane-bound vacuole

Pinocytosis ('cell-drinking'):

Allows the cell to bring in fluid

Phagocytosis ('cell-eating'):

Larger particles (e.g. cell fragments, foreign materials, microbes) are taken into the cell
Lysosomes adhere to the vacuole membrane
Lysosomes release enzymes that digest the contents

Exocytosis:

Extrusion of waste material by the reverse process
Vesicles formed by the Golgi apparatus move to the plasma membrane
Fuse with plasma membrane and expel their contents
Any indigestible residues of phagocytosis leave the cell this way

📌 [INSERT DIAGRAM HERE - Fig 3.5: Bulk Transport Sequence] Draw a 6-step sequence (A to F): A - Particle outside cell near lysosomes B - Particle being engulfed by plasma membrane C - Formation of a vacuole D - Fusion of lysosomes with vacuole E - Digestion of the particle by lysosomal enzymes F - Exocytosis - vesicle fusing with plasma membrane, waste expelled Place at end of bulk transport section

QUICK REFERENCE: DIAGRAM PLACEMENT GUIDE

Diagram No.	What to Draw	Where to Place
Diagram 1	Whole cell - all organelles labelled	Part 1 - Introduction
Diagram 2	Phospholipid bilayer structure	Part 2 - Plasma Membrane
Diagram 3	Nucleus close-up (envelope, pores, chromatin)	Part 3.1 - Nucleus
Diagram 4	Mitochondrion with cristae	Part 3.2 - Mitochondria
Diagram 5	Golgi apparatus stacked sacs	Part 3.5 - Golgi Apparatus
Diagram 6	3-panel selective permeability	Part 4 - Introduction to Transport
Diagram 7	Carrier protein / facilitated diffusion	Part 4.3 - Facilitated Diffusion
Diagram 8	Bulk transport A-F sequence	Part 4.6 - Bulk Transport

Source: All content is based directly on your textbook - Section 1: The Body and Its Constituents, Chapter 3: Cells and Tissues, pages 42-45 (as shown in the 5 images you provided). This is the standard recommended textbook (Ross and Wilson - Anatomy and Physiology in Health and Illness) used in BSc Nursing 1st Semester.

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Structure of the Human Cell, Functions of Organelles & Cellular Transportation

(BSc Nursing 1st Semester)

PART 1 - INTRODUCTION

The human body develops from a single cell called the zygote (fusion of ovum + spermatozoon)
All cells carry the same genetic make-up as the zygote
Cells are too small to see with the naked eye - visible only under microscope after staining
A cell = plasma membrane + organelles suspended in cytosol
Everything inside the cell excluding the nucleus = cytoplasm (cytosol + organelles)

📌 [DIAGRAM 1 HERE - Whole Cell] Label: Plasma membrane, Nucleus, Nuclear envelope, Nucleolus, Chromatin, Ribosomes, Rough ER, Smooth ER, Golgi apparatus, Mitochondria, Lysosomes, Centrosome, Centrioles, Cytoplasm

PART 2 - PLASMA MEMBRANE

Structure:

Made of two layers of phospholipids (phospholipid bilayer)
Contains embedded proteins, sugars, and cholesterol
Each phospholipid has:
- Head - hydrophilic (water-loving), electrically charged
- Tail - hydrophobic (water-hating), no charge
Arranged like a sandwich - heads face outward, tails face inward (central water-repelling layer)

📌 [DIAGRAM 2 HERE - Phospholipid Bilayer] Label: Hydrophilic head, Hydrophobic tail, Membrane proteins, Cholesterol, Carbohydrate chains

Membrane Proteins - Functions:

Form channels for passage of electrolytes and non-lipid-soluble substances
Carry carbohydrate molecules on outer surface - give cell its immunological identity ('self' markers)
Act as receptors for hormones and chemical messengers
Some are enzymes
Some involved in pumps that transport substances across the membrane

PART 3 - ORGANELLES

Organelles = 'small organs' - individually specialised, often enclosed by their own membrane

3.1 NUCLEUS

Largest organelle; absent in mature RBCs; skeletal muscle has several nuclei
Enclosed in nuclear envelope with tiny pores for substance exchange
Contains DNA - directs all metabolic activities
In non-dividing cells, DNA exists as chromatin; before division forms chromosomes
Contains RNA - involved in protein synthesis
Nucleolus - synthesises and assembles ribosome components

📌 [DIAGRAM 3 HERE - Nucleus Close-up] Label: Nuclear envelope, Nuclear pores, Chromatin, Nucleolus

3.2 MITOCHONDRIA

Sausage-shaped structures; 'power house' of the cell
Central to aerobic respiration - produce energy as ATP
Require oxygen for ATP synthesis
Most numerous in highly active cells - e.g. liver, muscle, spermatozoa

📌 [DIAGRAM 4 HERE - Mitochondrion] Label: Outer membrane, Inner membrane, Cristae (inner folds)

3.3 RIBOSOMES

Tiny granules of RNA + protein
Synthesise proteins from amino acids using RNA as template
Free in cytoplasm - make proteins for use within the cell (e.g. enzymes)
On rough ER and nuclear envelope - make proteins for export from the cell

3.4 ENDOPLASMIC RETICULUM (ER)

Interconnecting membranous canals in the cytoplasm; two types:

Type	Function
Smooth ER	Synthesises lipids and steroid hormones; drug detoxification; repairs membranes
Rough ER	Studded with ribosomes; synthesises proteins for export (e.g. enzymes, hormones) via exocytosis

3.5 GOLGI APPARATUS

Stacks of flattened membranous sacs; present in all cells
Receives proteins from ER, packages them into vesicles
Vesicles move to plasma membrane, fuse with it, and expel contents = exocytosis

📌 [DIAGRAM 5 HERE - Golgi Apparatus] Label: Stacked sacs, Vesicles, Direction of protein flow from ER

3.6 LYSOSOMES

Small membranous vesicles from Golgi apparatus
Contain digestive enzymes that break down large molecules (DNA, RNA, proteins, carbohydrates)
Broken particles are either recycled or expelled as waste
In white blood cells - digest foreign material (microbes)

3.7 CYTOSKELETON

Network of protein fibres; gives cell support and guides movement of materials

Component	Structure	Function
Microfilaments	Actin fibres	Support, cell shape, muscle contraction
Microtubules	Large rigid proteins	Mechanical support, guides organelles + chromosomes during division

3.8 CENTROSOME

Pair of centrioles (clusters of microtubules)
Directs organisation of microtubules; key role in cell division

3.9 CELL EXTENSIONS

Type	Description	Function
Microvilli	Tiny projections with microfilaments	Increase surface area - maximise nutrient absorption (small intestine)
Cilia	Hair-like projections with microtubules	Beat in unison to move substances (e.g. mucus up respiratory tract)
Flagella	Long whip-like projections	Propel spermatozoa through female reproductive tract

PART 4 - TRANSPORT ACROSS CELL MEMBRANES

Plasma membrane = selectively permeable barrier
Controls entry and exit of substances, regulating internal environment
Small molecules (e.g. water) pass freely; large molecules cannot cross

📌 [DIAGRAM 6 HERE - Selective Permeability, 3 panels] Panel A: Particle size | Panel B: Specific channels | Panel C: Pumps and carriers

4.1 PASSIVE TRANSPORT (no energy needed)

Diffusion:

Movement down concentration gradient
Lipid-soluble substances (O₂, CO₂, fatty acids) - dissolve through lipid part of membrane
Water-soluble substances (Na+, K+, Ca2+) - pass through water-filled channels

Facilitated Diffusion:

For substances that cannot diffuse unaided (e.g. glucose, amino acids)
Uses protein carrier molecules - lock and key mechanism
Carrier changes shape and deposits substance on the other side
Carrier is specific to one substance only
Has a transport maximum (finite number of carriers)

Osmosis:

Passive movement of water only, down its concentration gradient across a semipermeable membrane

📌 [DIAGRAM 7 HERE - Carrier Protein] Label: Extracellular fluid, Carrier protein, Plasma membrane, Intracellular fluid - show shape change

4.2 ACTIVE TRANSPORT (energy required)

Movement up concentration gradient (low to high concentration)
Requires ATP energy
Uses protein carrier molecules specific to one substance

Sodium-Potassium Pump:

Present in all cells
Pumps Na+ out and K+ in against their concentration gradients
Uses up to 30% of cellular ATP
Maintains electrical gradient needed for nerve and muscle action potentials
Also supports glucose uptake

4.3 BULK TRANSPORT

For particles too large to cross by other methods:

Process	Meaning	How it works
Pinocytosis	'Cell-drinking'	Cell engulfs fluid into a vacuole
Phagocytosis	'Cell-eating'	Large particles (microbes, cell fragments) engulfed; lysosomes digest contents
Exocytosis	Reverse process	Vesicles fuse with plasma membrane and expel waste/secretions out of cell

📌 [DIAGRAM 8 HERE - Bulk Transport Sequence A to F] A: Particle outside cell → B: Engulfed by membrane → C: Vacuole formed → D: Lysosomes fuse → E: Enzymes digest contents → F: Exocytosis - waste expelled

DIAGRAM PLACEMENT SUMMARY

Diagram	Topic	Location in Answer
1 - Whole Cell	All organelles labelled	Part 1 - Introduction
2 - Phospholipid Bilayer	Membrane structure	Part 2 - Plasma Membrane
3 - Nucleus Close-up	Nuclear contents	Part 3.1 - Nucleus
4 - Mitochondrion	Cristae structure	Part 3.2 - Mitochondria
5 - Golgi Apparatus	Stacked sacs	Part 3.5 - Golgi Apparatus
6 - Selective Permeability	3-panel transport intro	Part 4 - Transport Introduction
7 - Carrier Protein	Facilitated diffusion	Part 4.1 - Facilitated Diffusion
8 - Bulk Transport	Phagocytosis to Exocytosis	Part 4.3 - Bulk Transport

Source: Directly based on your textbook - Ross & Wilson: Anatomy and Physiology in Health and Illness, Chapter 3: Cells and Tissues, Pages 42-45 - standard BSc Nursing 1st Semester reference.

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