IBDP Biology Chapter 15 Notes

human physiology


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This unit deals with understanding the process of human nutrition, digestion, hormonal secretions and gaseous exchange. Humans need amino acids, fatty acids, minerals and vitamins. Phenylketonuria is a genetically inherited disease in which phenylalanine can not be metabolised. Deficiency of vitamin Causes scurvy,y whereas deficiency of vitamin D causes rickets.

Deposition of cholesterol on the walls of blood vessels causes atherosclerosis. Malnutrition includes both undernutrition and overnutrition. Obesity is a significant risk factor for Type II DM and HTN. Then we discuss Digestion which involves a  variety of enzymes and needs specific pH for these enzymes to occur; e.g. gastric enzymes need an acidic pH which is achieved by secretion of HCl, but this HCl can damage the gastric mucosa leading to Ulcers.

Absorption mainly occurs in the small intestine with the help of the villi. Next, we examine the liver and its functions, including detoxification, nutrient storage and secretion of bile and plasma proteins. Alternatively, we also study the heart valves, which modify the flow through the chambers and vessels. The nodes present in the heart regulate the rhythm by passing impulses. ECG measures the electrical activity of the heart.

Lastly, we discuss the endocrine system, which has two types of hormones: steroid and peptide. The pituitary gland is the master gland that regulates the other endocrine glands. We also discuss the gaseous exchange from alveoli through haemoglobin to peripheral tissues.