Human Physiology IV: Main Exam, 11 November 2025

Mount Kenya University · Department of Dental Sciences · Diploma in Community Oral Health · DMP2104

Human Physiology IV past paper from Mount Kenya University 2024-2025 with model answers. This exam covers epidermis cell types, sensory systems, melanin functions, sebace

Instructions: ANSWER ALL QUESTIONS IN SECTION A AND ANY TWO IN SECTION B

SECTION A (30 marks)

1. Identify the four (4) main types of cells which comprise the epidermis (8 marks)

Model answer
  • Keratinocytes – make up ~90% of epidermis, produce keratin
  • Melanocytes – produce melanin pigment
  • Langerhans cells – immune surveillance, present antigens
  • Merkel cells – touch receptors, sense pressure and texture

2. Explain specialized senses in the human body (8 marks)

Model answer
  • Visual – photoreceptors in retina
  • Auditory – hair cells in cochlea
  • Olfactory – olfactory receptor neurons
  • Gustatory – taste buds on tongue
  • Somatosensory – mechanoreceptors, thermoreceptors, nociceptors
  • Vestibular – semicircular canals, otolith organs
  • Proprioceptive – muscle spindles, Golgi tendon organs

3. Outline biological functions of Melanin in the human body (7 marks)

Model answer
  • UV protection – absorbs harmful ultraviolet radiation
  • Skin pigmentation – determines skin, hair, eye colour
  • Antioxidant – scavenges free radicals
  • Immune modulation – influences immune cell function
  • Thermoregulation – affects heat absorption and loss

4. Give the functions of sebaceous glands (7 marks)

Model answer
  • Lubrication – secretes sebum to keep skin and hair moisturised
  • Barrier formation – sebum creates a hydrophobic layer preventing water loss
  • Antimicrobial – sebum contains fatty acids that inhibit bacterial growth
  • Thermal regulation – sebum reduces heat loss by insulating skin

SECTION B (40 marks)

1. Discuss the mechanism of heat loss from the human body

Model answer
  • Radiation – infrared heat radiated from body surface
  • Conduction – heat transfer through direct contact with cooler objects
  • Convection – heat carried away by moving air or water
  • Evaporation – sweat evaporates, cooling the skin

2. Explain the role of hypothalamus in regulating body temperatures

Model answer
  • Thermoreceptor input – detects core and skin temperature
  • Integration – hypothalamic preoptic area processes signals
  • Effector activation – signals sympathetic/parasympathetic pathways
  • Heat loss mechanisms – vasodilation, sweating, shivering
  • Homeostatic set‑point – maintains body temperature within narrow limits

3. Describe the functions of sensory system

Model answer
  • Detects external stimuli such as light, sound, temperature and pressure and converts them into neural signals.
  • Transmits sensory information via afferent pathways to the central nervous system for processing.
  • Facilitates perception and response by allowing the brain to interpret sensations and coordinate appropriate motor actions.

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