HAP Exam – ER-20-14T | MM: 80

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PART 1 — Attempt any SIX (6 × 5 = 30 Marks)

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A. Discuss the organization of the human body and homeostasis. (5 marks)

1. Chemical level – Atoms (C, H, O, N) combine to form molecules (proteins, lipids, DNA).
2. Cellular level – Molecules form cells, the basic unit of life (e.g., muscle cell, neuron).
3. Tissue level – Similar cells grouped together performing a common function (e.g., epithelial, connective, muscle, nervous tissue).
4. Organ level – Different tissues grouped to form organs (e.g., heart, liver, kidney).
5. Organ system level – Related organs working together (e.g., cardiovascular system, digestive system).
6. Organism level – All systems together form a complete living human being.

• Receptor – Detects changes (stimulus) in the internal environment.
• Control center (brain/hypothalamus) – Processes the information and determines the response.
• Effector – Carries out the response (muscles or glands).

• Negative feedback (most common): Reverses the change back to normal (e.g., regulation of body temperature, blood glucose, blood pressure).
• Positive feedback (amplifies the change): e.g., childbirth contractions, blood clotting cascade.

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B. Explain structure and function of connective tissue. (5 marks)

1. Cells – Fibroblasts (produce fibers), macrophages, mast cells, adipocytes.
2. Ground substance – Gel-like matrix of water, glycoproteins, and proteoglycans.
3. Fibers:
   • Collagen fibers – Strong, flexible; resist tension.
   • Elastic fibers – Stretch and recoil (e.g., skin, lungs).
   • Reticular fibers – Form delicate networks (e.g., lymph nodes, liver).

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C. Describe composition and function of blood and explain blood clotting mechanism. (5 marks)

1. Plasma (55%) – Liquid portion; water (91%), plasma proteins (albumin, globulin, fibrinogen), hormones, electrolytes, nutrients, waste.
2. Formed elements (45%):
   • Erythrocytes (RBC) – 4.5–5.5 million/µL; biconcave disc; contain hemoglobin; transport O₂ and CO₂; no nucleus.
   • Leukocytes (WBC) – 4,000–11,000/µL; defense against infection (granulocytes: neutrophils, eosinophils, basophils; agranulocytes: lymphocytes, monocytes).
   • Thrombocytes (Platelets) – 1.5–4 lakh/µL; cell fragments; essential for clotting.

• Transport of O₂, CO₂, nutrients, hormones, waste
• Regulation of temperature, pH, fluid balance
• Protection via immunity and clotting

Extrinsic pathway: Tissue damage → Tissue factor (Factor III) + Factor VII
                                        ↓
Intrinsic pathway: Contact activation (Factor XII) 
                                        ↓
                        Common pathway: Factor X activated
                                        ↓
                        Prothrombin (II) → Thrombin (IIa)
                                        ↓
                        Fibrinogen (I)  → Fibrin (Ia)
                                        ↓
                      Factor XIIIa crosslinks fibrin → Stable clot

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D. Explain anatomy of heart and regulation of blood pressure. (5 marks)

• Pericardium – Double-layered sac (parietal + visceral); contains pericardial fluid.
• Epicardium – Outermost layer of heart wall.
• Myocardium – Thick middle layer; cardiac muscle.
• Endocardium – Inner lining of chambers.

• Right atrium (RA) – Receives deoxygenated blood from SVC, IVC, and coronary sinus.
• Right ventricle (RV) – Pumps blood to lungs via pulmonary artery.
• Left atrium (LA) – Receives oxygenated blood from 4 pulmonary veins.
• Left ventricle (LV) – Pumps oxygenated blood to body via aorta (thickest walls).

• Tricuspid (RA → RV), Mitral/Bicuspid (LA → LV) – AV valves.
• Pulmonary and Aortic – Semilunar valves.

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E. Define respiratory volumes and capacities; explain structure and function of nervous system including diagram. (5 marks)

           Nervous System
          /              \
  Central NS (CNS)     Peripheral NS (PNS)
   Brain + Spinal cord    Cranial + Spinal nerves
                               /           \
                      Somatic NS        Autonomic NS
                    (voluntary)        (involuntary)
                                       /         \
                               Sympathetic   Parasympathetic
                              (fight/flight)  (rest/digest)

• Brain: cerebrum (thought, movement, sensation), cerebellum (coordination, balance), brainstem (midbrain, pons, medulla – vital reflexes), hypothalamus (homeostasis).
• Spinal cord: Conducts signals between brain and body; mediates spinal reflexes.

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F. Discuss endocrine glands and their hormones with function. (5 marks)

• Water-soluble hormones (peptide/protein): bind surface receptors → second messengers (cAMP).
• Lipid-soluble hormones (steroids, thyroid): enter cell → bind nuclear receptors → gene expression.

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PART 2 — Attempt any TEN (10 × 3 = 30 Marks)

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i. Explain the scope of anatomy and physiology. (3 marks)

• Gross anatomy: structures visible to the naked eye (e.g., organs, bones).
• Microscopic anatomy: histology (tissues) and cytology (cells).
• Developmental anatomy: changes from conception to old age (embryology).

• Examples: cardiovascular physiology (how the heart pumps), neurophysiology (nerve impulse conduction).

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ii. Describe the structure of a cell membrane. (3 marks)

1. Phospholipid bilayer – Two layers of phospholipids with hydrophilic (water-loving) heads facing outward and hydrophobic (water-fearing) tails facing inward. Provides the basic structural framework.
2. Proteins:
   • Integral (transmembrane) proteins – Span the entire membrane; function as channels, carriers, receptors.
   • Peripheral proteins – Attached to inner/outer surface; function in signaling and structural support.
3. Cholesterol – Interspersed among phospholipids; stabilizes membrane fluidity.
4. Carbohydrates (glycocalyx) – Attached to lipids (glycolipids) or proteins (glycoproteins) on the outer surface; involved in cell recognition, immunity, and adhesion.

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iii. Classify tissues with examples. (3 marks)

• Epithelial tissue: tightly packed cells, no blood supply (avascular), covers surfaces.
• Connective tissue: widely spaced cells, rich extracellular matrix.
• Muscle tissue: contractile, contains actin and myosin filaments.
• Nervous tissue: excitable cells capable of generating and transmitting electrical impulses.

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iv. Explain types of joints. (3 marks)

1. Fibrous joints – Bones joined by fibrous tissue; little/no movement.
   • Sutures (skull), syndesmosis (tibia-fibula), gomphosis (teeth in socket).
2. Cartilaginous joints – Bones joined by cartilage; slightly movable.
   • Synchondrosis (epiphyseal plate), symphysis (pubic symphysis, intervertebral discs).
3. Synovial joints – Most common; freely movable; contain synovial fluid in joint cavity.
   • Ball and socket (hip, shoulder), hinge (elbow, knee), pivot (atlas-axis), gliding (carpals), saddle (thumb CMC), condyloid (wrist).

• Synarthrosis – Immovable (e.g., skull sutures)
• Amphiarthrosis – Slightly movable (e.g., pubic symphysis)
• Diarthrosis – Freely movable (e.g., knee joint)

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v. Describe function of RBC and WBC. (3 marks)

• Normal count: 4.5–5.5 million/µL (men); 4.0–5.0 million/µL (women).
• Biconcave disc shape; no nucleus; lifespan ~120 days; produced in red bone marrow (erythropoiesis).
• Contain hemoglobin (Hb) – each molecule carries 4 O₂ molecules.
• Functions: Transport O₂ from lungs to tissues; carry CO₂ from tissues to lungs; buffer blood pH; determine blood groups (ABO, Rh antigens).

• Normal count: 4,000–11,000/µL; nucleated; shorter lifespan; formed in bone marrow and lymphoid tissue.

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vi. Explain structure of lymph node. (3 marks)

1. Capsule – Outer fibrous connective tissue covering; sends trabeculae inward.
2. Cortex (outer region):
   • Lymphoid follicles – Contain B-lymphocytes; germinal centers form during active immune response.
   • Paracortex – Between cortex and medulla; rich in T-lymphocytes.
3. Medulla (inner region):
   • Medullary cords – Contain B-cells, plasma cells, macrophages.
   • Medullary sinuses – Channels through which lymph flows.
4. Sinuses – Subcapsular sinus → cortical sinuses → medullary sinuses → efferent lymphatic.
5. Hilum – Notched area where blood vessels enter/exit and efferent lymph vessel leaves.

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vii. Describe cardiac cycle briefly. (3 marks)

• Stroke Volume (SV) = ~70 mL
• Cardiac Output (CO) = SV × HR = 70 × 75 = 5250 mL/min (~5 L/min)
• End-Diastolic Volume (EDV) = ~120 mL; End-Systolic Volume (ESV) = ~50 mL
• Ejection Fraction = SV/EDV = 70/120 ≈ 58%

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viii. Explain mechanism of respiration. (3 marks)

• Diaphragm and external intercostals contract → thoracic volume increases → intrapleural pressure drops below atmospheric → air flows in.

• Diaphragm and intercostals relax → thoracic volume decreases → lung recoil → pressure rises above atmospheric → air flows out.
• Forced expiration: internal intercostals and abdominal muscles contract.

• O₂ diffuses from alveoli (high pO₂ ~104 mmHg) into pulmonary capillaries (low pO₂ ~40 mmHg).
• CO₂ diffuses from blood (pCO₂ ~45 mmHg) into alveoli (pCO₂ ~40 mmHg).

• O₂ unloads from Hb to tissues (high O₂ demand, low pO₂).
• CO₂ enters blood from tissues → transported as bicarbonate (HCO₃⁻, 70%), carbaminohemoglobin (23%), dissolved (7%).

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ix. Describe digestion in stomach. (3 marks)

• Stomach wall has three muscle layers (circular, longitudinal, oblique) → powerful peristaltic contractions churn food.
• Food + gastric juice → chyme (semi-liquid).

1. Cephalic phase – Smell/sight/taste of food → vagus nerve → stimulates secretion.
2. Gastric phase – Food in stomach → stretches wall → gastrin release → ↑ HCl and pepsinogen.
3. Intestinal phase – Chyme enters duodenum → inhibitory hormones (secretin, CCK) slow gastric emptying.

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x. Explain reflex action. (3 marks)

Receptor → Afferent (sensory) neuron → Integration center 
        (spinal cord/brain) → Efferent (motor) neuron → Effector (muscle/gland)

• Tap patellar tendon → stretches quadriceps → muscle spindle (receptor) activated → sensory neuron → spinal cord (L2–L4) → motor neuron → quadriceps contracts → leg kicks forward.
• Clinical use: tests integrity of L3–L4 spinal segments.

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xi. Describe function of kidney. (3 marks)

• Glomerular filtration: Blood filtered at ~125 mL/min (GFR); produces 180 L/day of filtrate.
• Tubular reabsorption: ~99% of water, glucose, amino acids, Na⁺, Cl⁻ reabsorbed into blood.
• Tubular secretion: H⁺, K⁺, drugs, toxins secreted into tubule for excretion.

• Controls water/Na⁺ retention under ADH and aldosterone.
• Secretes renin → activates RAAS → raises BP when it falls.

• Excretes H⁺ and reabsorbs HCO₃⁻ to maintain pH 7.35–7.45.

• Adjusts urine concentration (100–1200 mOsm/kg) via countercurrent mechanism.

• Erythropoietin (EPO) – Stimulates RBC production in bone marrow.
• Calcitriol (active vitamin D) – Promotes Ca²⁺ absorption from gut.
• Renin – Regulates blood pressure.

• Urea (protein metabolism), creatinine (muscle metabolism), uric acid (nucleic acid metabolism).