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TOPIC 6: HUMAN HEALTH and PHYSIOLOGY 6.1 DIGESTION 6.1.1: Necessity for digestion 6.1.2: Enzyme action 6.1.3: Various enzymes 6.1.4: Digestive System 6.1.5: Stomach 6.1.5: Small and Large Intestine 6.1.5: Small intestine (x-section) 6.1.7: Villus 6.1.6: Absorption and Assimilation 6.2 THE TRANSPORT SYSTEM 6.2.1: Heart Pulmonary artery Aorta s. vena cava Pulmonary Vein Left Atrium i.vena cava Left Atrio-ventricular valve Right Atrium Right Atrioventricular valve Right ventricle Left ventricle Semi-lunar valves Coronary artery 6.2.3: Heartbeat 6.2.4: Heartbeat 6.2.5: Blood Vessels 6.2.5: Blood Vessels 6.2.6: Blood 6.2.7: Transported by Blood 6.3: DEFENCE AGAINST INFECTIOUS DISEASE Pathogen: an organism or virus that causes a disease. 6.3.1: Antibiotics Antibiotics block specific metabolic pathways found in bacteria. Viruses reproduce using the host cell’s metabolic pathways, which are not affected by antibiotics. 6.3.1: Skin and Mucus membranes Mucous membranes line cavities that are exposed to the external. They are at several places continuous with skin: at the nostrils, the mouth, the lips, the eyelids, the ears, the genital area, and the anus. The sticky, thick fluid secreted by the mucous membranes and glands is termed mucus Skin The outer layer of skin is dead and difficult for pathogens to grow on or penetrate. The best way to prevent disease is to prevent pathogens from entering the body. Skin forms a physical barrier that prevents most pathogens from entering the body. Glands in the skin secrete lactic acid and fatty acid, which make the skin surface acidic, preventing bacterial growth. The outer layer of skin flakes off, which removes bacteria. Cuts allow pathogens to gain entry to the body. 6.3.4: Phagocytic leucocytes 6.3.5: Antigen and Antibody An antigen is a substance or molecule that when introduced into the body triggers the production of an antibody by the immune system which will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. Antibody: A protein produced by Blymphocytes (specialised type of white blood cell) that binds to a specific antigen 6.3.6: Production of Antibodies a-f represent only 6 (of the millions) of different lymphocytes 6.3.7: HIV HIV reduces the number of active lymphocytes and therefore a loss of the ability to produce antibodies Transmission of HIV AIDS is a major social problem in all countries, especially in Africa and Asia. It presently infects an estimated 40 million people including men, women and children. Families & friends suffer grief when a loved one is sick with AIDS. Families become poorer if the victim becomes unable to work, and individuals with AIDS may be stigmatized by society making it difficult to find employment, housing, and partners. In countries with high rates of HIV, people may avoid sex or live in fear if sexually active. The AIDS epidemic is so severe in some African countries that the majority of the workforce has died, thus destroying economies and eroding cultures. 6.4.1: GAS EXCHANGE 6.4.1: • Ventilation • Gas exchange • Cell respiration 6.4.3: Alveoli 6.4.3: Alveoli 6.4.3: Alveoli 6.4.4: Respiratory System trachea Right lung Right bronchus Left lung Left bronchus bronchioles diaphragm alveoli 6.4.5: Mechanism of Breathing 6.4.5: Mechanism of Breathing 6.4.5: Mechanism of Breathing 6.5: NERVES, HORMONES and HOMEOSTASIS STATE: The NERVOUS SYSTEM consists of the CENTRAL NERVOUS SYSTEM (CNS) and PERIPHERAL NERVES, and is composed of cells called NEURONS that can carry rapid ELECTRICAL IMPULSES. 6.5.1: Nervous System 6.5.2: Motor Neuron 6.5.3: Nerve impulse STATE: Nerve impulses are conducted from receptors to the CNS by sensory neurons, within the CNS by relay neurons, and from the CNS to effectors by motor neurons. Na+ channel K+ channel K+ Na+ Na+ K+ pump 6.5.4: Resting and Action Potential 6.5.5: Nerve Impulse 6.5.6: Synaptic Transmission 6.5.7: Endocrine System The endocrine system consists of glands that release hormones that are transported in the blood and affect target organs. Homeostasis involves maintaining the internal environment between limits, including blood pH, carbon dioxide concentration, blood glucose concentration, body temperature and water balance. 6.5.8 and 6.5.9: Homeostasis STATE: homeostasis involves maintaining the internal environment between limits, including blood pH, carbon dioxide concentration, blood glucose concentration, body temperature and water balance. 6.5.10: Control of Body Temperature 6.5.10: Arterioles in skin. 6.5.110: Shivering 6.5.10: Sweating STATE: The endocrine system consists of glands that release hormones that are transported in the blood. 6.5.11: Control of blood glucose 6.5.10: Islets of Langerhans 6.5.10: Control of Blood Glucose 5.6.11: Type I Diabetes 6.5.11: Type II Diabetes Type I diabetes (early or juvenile onset): Auto-immune disease in which the beta-cells pancreatic are destroyed. Unable to produce insulin. Responds well to regular injection of insulin probably manufactured as the genetically engineered humulin. Type II diabetes (Adult onset): Reduced sensitivity of the liver cells to insulin. Reduced number of receptors on the liver cell membrane 6.6: REPRODUCTION 6.6.1: Male Reproductive System 6.6.1: Female Reproductive System 6.6.2: Menstrual Cycle FSH: follicle stimulating hormone LH: lutenising hormone 6.6.3: Menstrual Cycle 8 Start of cycle FSH levels rise 8 FSH causes follicles to develop and estrogen to be secreted by follicle which causes more FSH to be released Lining of uterus (endometrium) breaks down (due to low levels of progesterone and estrogen) Rising estrogen levels cause an LH surge 8 Estrogen stimulates repair of the endometrium LH surge causes ovulation High LH causes less estrogen to be secreted (an example of negative feedback) High LH levels also allows progesterone levels to rise 8 After ovulation follicle develops into the corpus luteum which secretes progesterone which maintain the endometrium High levels of progesterone inhibit FSH and LH secretion (negative feedback) 8 If no embryo is formed the corpus luteum breaks down then progesterone and estrogen levels fall and endometrium will break down Low levels of progesterone and estrogen allow levels of FSH to rise 8 6.6.4: Testosterone Testosterone: Prenatal development of male genitalia Development of secondary sexual characteristics Maintenance of sex drive 6.6.5: IVF 6.6.6: Ethical Issues with IVF • FOR: • AGAINST