Cell Biology, Histology and Animal Physiology
Cell biology, histology and animal physiology links structure to function: organelle roles, tissue identification, and the control of digestion, gas exchange, circulation, excretion, nerve and hormone action, and reproduction.
Core rules
- Cell: mitochondria-ATP; ribosomes-protein synthesis; rough ER-protein processing; Golgi-packaging; lysosomes-intracellular digestion; nucleus-genetic control. Mitosis produces identical somatic cells; meiosis produces haploid gametes with crossing over.
- Tissues: epithelium covers/lines (simple vs stratified; squamous, cuboidal, columnar); connective supports (areolar, adipose, cartilage, bone, blood); muscle contracts (striated skeletal, smooth, cardiac); nervous conducts.
- Digestion: salivary amylase starts starch; pepsin digests protein in acid stomach; bile emulsifies fat; pancreatic amylase, lipase and trypsin act in the small intestine; villi absorb.
- Respiration: haemoglobin forms oxyhaemoglobin in lungs; most CO2 travels as bicarbonate. Circulation is double in mammals; SA node sets heart rhythm.
- Excretion: nephron-glomerular filtration, tubular reabsorption, secretion. Nervous coordination uses resting potential and neurotransmitters; endocrine uses hormones in blood. Reproduction: spermatogenesis and oogenesis.
Worked example
After a starchy meal, starch is not digested in the stomach because salivary amylase is inactivated by acid and pepsin digests protein. Starch resumes digestion in the duodenum by pancreatic amylase, yielding maltose; maltase in the small intestine gives glucose, absorbed by villi into blood.
Traps
Do not say bile digests fat-it emulsifies. Do not confuse mitosis with meiosis. Cardiac muscle is striated but involuntary. Reabsorption occurs in the nephron, not in the ureter.