Human Anatomy IV: Main Exam, 24 March 2025
Mount Kenya University · Department of Dental Sciences · Diploma in Dental Technology · DHA1301
Human Anatomy IV past paper from Mount Kenya University 2024-2025 with model answers for embryology, osteoporosis, cell cycle, pulmonary circulation, nervous system, cart
Instructions: ANSWER ALL QUESTIONS
SECTION A (30 marks)
1.
- a) List the principles of development in experimental embryology. (9 marks)Model answer
- Induction – interaction between tissues that directs development
- Competence – ability of cells to respond to inductive signals
- Specification – commitment of cells to a particular fate
- Determination – irreversible commitment to a developmental pathway
- Differentiation – process by which cells acquire specialized structure and function
- Morphogenesis – shaping of tissues and organs
- Growth – increase in size and number of cells
- Pattern formation – spatial arrangement of structures
- Regulation – feedback mechanisms that ensure proper development
- b) State the process of fertilization. (4 marks)Model answer
- Approach of sperm to oocyte – chemotactic movement toward the zona pellucida
- Acrosome reaction – release of enzymes to penetrate zona pellucida
- Fusion of membranes – sperm plasma membrane fuses with oocyte membrane
- Activation of oocyte – cortical granule release, completion of meiosis II and formation of the zygote
2.
- a) Give factors that are likely to cause osteoporosis. (6 marks)Model answer
- Low calcium intake
- Vitamin D deficiency
- Sedentary lifestyle
- Smoking
- Chronic glucocorticoid use
- Post‑menopausal estrogen deficiency
- b) Identify four (4) stages of a cell division cycle. (4 marks)Model answer
- G1 phase – cell growth and preparation for DNA synthesis
- S phase – DNA replication
- G2 phase – further growth and preparation for mitosis
- M phase – mitosis (nuclear division) and cytokinesis
3. Write notes on pulmonary circulation. (5 marks)
Model answer
- Pulmonary circulation transports deoxygenated blood from the right ventricle to the lungs via the pulmonary artery, where gas exchange occurs, and returns oxygen‑rich blood to the left atrium through the pulmonary veins.
- Key points:
- Low‑pressure, high‑capacity circuit
- Pulmonary artery carries deoxygenated blood; pulmonary veins carry oxygenated blood
- Gas exchange in alveolar capillaries
- Increases blood oxygen saturation and removes CO₂
- Provides a site for removal of metabolic waste and temperature regulation
4. Identify two (2) basic types of cells present in the nervous system (2 marks)
Model answer
- Neurons – excitable cells that transmit electrical signals
- Neuroglial (glial) cells – support, protect and nourish neurons
SECTION B (40 marks)
5. Explain the four (4) major divisions of the nervous system.
Model answer
- Central Nervous System (CNS): brain and spinal cord; integrates sensory information and coordinates motor output.
- Peripheral Nervous System (PNS): all nerves outside CNS; transmits signals between CNS and the rest of the body.
- Somatic Nervous System: voluntary control of skeletal muscles; conveys sensory information from skin, joints and skeletal muscles.
- Autonomic Nervous System: involuntary control of smooth muscle, cardiac muscle and glands; divided into sympathetic and parasympathetic divisions.
6.
- a) State the structure and functions of the cartilage.Model answer
- Structure: composed of cells (chondrocytes) embedded in a dense extracellular matrix of collagen fibres, elastic fibres and proteoglycan-rich ground substance; avascular, aneural, and covered by perichondrium.
- Support: provides flexible yet strong framework for ears, nose, trachea and articular surfaces.
- Growth: allows longitudinal growth of long bones via epiphyseal plates.
- Shock absorption: cushions joints and reduces friction during movement.
- Attachment: serves as attachment sites for tendons and ligaments.
- More answers:
- Protection of delicate structures (e.g., vertebral cartilage protects spinal cord).
- b) Elaborate on the eukaryotic cells replication process via mitosis.Model answer
- Prophase: chromatin condenses into visible chromosomes; nuclear envelope breaks down; spindle fibers form; kinetochores appear on centromeres.
- Metaphase: chromosomes align at the cell’s equatorial plate (metaphase plate) attached to spindle fibres.
- Anaphase: sister chromatids separate at centromeres and are pulled toward opposite poles by shortening spindle fibres.
- Telophase: chromosomes de‑condense back into chromatin; nuclear envelopes re‑form around each set of chromosomes; spindle disassembles.
- Cytokinesis: division of the cytoplasm; in animal cells a contractile ring forms a cleavage furrow, in plant cells a cell plate develops.
- Regulation: checkpoints (G1, G2, metaphase) ensure DNA integrity before progression to the next phase.