Human Physiology IV: Main Exam, 21 July 2026

Mount Kenya University · Department of Clinical Sciences · Diploma in Community Oral Health, Diploma in Dental Technology · DDS2111/DMP2104

Human Physiology IV (dds2111) Mount Kenya University 2025-2026 past paper with model answers.

SECTION A: SHORT ANSWER ESSAY QUESTIONS (30 MARKS) (30 marks)

ANSWER ALL QUESTIONS. EACH QUESTION CARRIES 6 MARKS.

1. State six functions of the epidermis and dermis that are important in maintaining body integrity. (6 marks)

Model answer
  • Protection: Acts as a barrier against mechanical injury, pathogens and chemicals.
  • Prevention of water loss: Stratum corneum reduces transepidermal water evaporation.
  • Thermoregulation: Dermal blood vessels dilate or constrict to control heat loss.
  • Sensory perception: Contains mechanoreceptors for touch, pressure and vibration.
  • Vitamin D synthesis: Epidermal keratinocytes convert 7‑dehydrocholesterol to vitamin D3 upon UV exposure.
  • Wound healing: Dermal fibroblasts produce collagen and extracellular matrix for tissue repair.

2. Highlight six roles of sweat glands in maintaining normal body temperature and skin health. (6 marks)

Model answer
  • Evaporation cooling: Sweat evaporates, removing heat from the skin surface.
  • Heat dissipation via conduction: Liquid sweat conducts heat away from the body.
  • Regulation of skin hydration: Moisture maintains skin elasticity and barrier function.
  • Excretion of waste: Eliminates small amounts of urea, salts and metabolites.
  • Antimicrobial activity: Contains lysozyme and dermcidin that inhibit bacterial growth.
  • pH balance: Sweat helps maintain slightly acidic skin surface, protecting against pathogens.

3. Outline six physiological processes involved in heat production within the human body. (6 marks)

Model answer
  • Basal metabolic rate: Cellular respiration in organs continuously generates heat.
  • Muscle activity: Shivering and voluntary contraction produce heat through ATP hydrolysis.
  • Hormonal thermogenesis: Thyroid hormones increase mitochondrial activity and heat output.
  • Brown adipose tissue: Uncoupling protein‑1 (UCP‑1) in mitochondria releases energy as heat.
  • Diet‑induced thermogenesis: Metabolism of food, especially proteins, generates heat.
  • Catecholamine‑driven lipolysis: Epinephrine stimulates fat breakdown, releasing heat.

4. Identify six causes of abnormal body temperature. (6 marks)

Model answer
  • Infection – bacterial, viral, fungal or parasitic.
  • Inflammation – tissue injury or immune response.
  • Endocrine disorders – hyperthyroidism, adrenal insufficiency.
  • Neoplastic disease – cancers producing pyrogens.
  • Autoimmune conditions – lupus, rheumatoid arthritis.
  • Environmental exposure – heat stress, chemical toxins.

5. State six types of sensations that can be felt in the oral and facial regions. (6 marks)

Model answer
  • Pain – sharp, dull, throbbing.
  • Tingling – pins‑and‑needles sensation.
  • Prickling – light, superficial irritation.
  • Burning – heat‑like or chemical irritation.
  • Pressure – deep, aching sensation.
  • Paresthesia – abnormal, often numb or electric shock feeling.

SECTION B: LONG ANSWER ESSAY QUESTIONS (40 MARKS) (40 marks)

Answer Question ONE and any other ONE question (Each question carries 20 Marks.)

1.

  1. a) State the normal body temperature and explain the role of the hypothalamus in regulating body temperature.
    Model answer
    • Normal body temperature is 36.5–37.5 °C.
    • The hypothalamus acts as the thermostat, receiving signals from peripheral and central thermoreceptors.
    • It integrates these signals and initiates heat‑producing or heat‑loss mechanisms (shivering, vasodilation, sweating) to maintain homeostasis.
  2. b) Define fever and describe any four signs or changes that occur during fever.
    Model answer
    • Fever – a rise in core body temperature above the normal range (typically >38 °C).
    • Increased heart rate – tachycardia as the body attempts to dissipate heat.
    • Sweating – diaphoresis to cool the skin.
    • Flushed skin – vasodilation leading to reddening of the face and neck.
  3. c) Explain the effects of:
    1. i) Excessive heat on the body.
    2. ii) Excessive cold on the body.
    Model answer
    • i) Excessive heat
    • Sweating increases, leading to evaporative cooling.
    • Vasodilation of skin vessels raises skin temperature.
    • Metabolic rate may rise, producing more heat.
    • If heat load exceeds loss, core temperature rises, causing heat‑stroke.
    • ii) Excessive cold
    • Vasoconstriction reduces skin blood flow, conserving core heat.
    • Shivering generates heat via muscle activity.
    • Metabolic rate increases to produce more heat.
    • Prolonged exposure can lead to hypothermia.

2.

  1. a) Describe how the eye enables a person to see.
    Model answer
    • The eye contains the cornea and lens that focus light onto the retina.
    • Photoreceptor cells (rods and cones) in the retina convert light into electrical signals.
    • Signals travel via the optic nerve to the visual cortex where they are interpreted as images.
  2. b) Explain how sound is transmitted from the ear to the brain for hearing to occur.
    Model answer
    • Sound waves enter the ear canal and vibrate the tympanic membrane.
    • Vibrations are transmitted via ossicles (malleus, incus, stapes) to the oval window.
    • The stapes pushes on the perilymph in the cochlea, creating fluid waves.
    • Hair cells in the organ of Corti convert mechanical waves into electrical impulses.
    • Signals travel through the auditory nerve to the brainstem, then to the auditory cortex for perception.

3.

  1. a) Describe the physiology of taste and smell.
    Model answer
    • Taste: Taste buds on the tongue contain gustatory cells that detect sweet, salty, sour, bitter, and umami.
    • Chemical stimuli bind to receptors, triggering ion channels and generating action potentials.
    • Signals travel via facial, glossopharyngeal, and vagus nerves to the gustatory cortex.
    • Smell: Olfactory receptor neurons in the nasal epithelium bind odorants.
    • Binding opens ion channels, depolarising neurons.
    • Axons project to the olfactory bulb, then to the piriform cortex and limbic system for identification and memory.
  2. b) Explain the importance of the following sensory receptors in the oral cavity:
    1. i) Pressure receptors
    2. ii) Temperature receptors
    3. iii) Pain receptors
    4. iv) Tooth sensory receptors
    Model answer
    • i) Pressure receptors
    • Detect mechanical deformation of oral tissues.
    • Provide feedback for chewing, swallowing, and oral proprioception.
    • ii) Temperature receptors
    • Sense heat and cold, protecting against thermal injury.
    • Contribute to the perception of food temperature.
    • iii) Pain receptors
    • Detect noxious stimuli (mechanical, thermal, chemical).
    • Protect oral tissues from damage.
    • iv) Tooth sensory receptors
    • Located in periodontal ligament and pulp.
    • Detect pressure, temperature, and pain from dental structures.
    • Essential for tooth function and protective reflexes.

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