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SL Review Anatomy. 6.1.1 Explain why digestion of large food molecules is essential. 1. Take in food that is not suitable for use: e.g. starch – not an animal storage molecule. 2. Molecules too large to be absorbed by the villi of small intestine e.g. protein, starch, fats.
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6.1.1 Explain why digestion of large food molecules is essential • 1. Take in food that is not suitable for use: e.g. starch – not an animal storage molecule. • 2. Molecules too large to be absorbed by the villi of small intestine e.g. protein, starch, fats
6.1.2 Explain the need for enzymes in digestion • Digestion happens naturally, but at a very slow rate. • Enzymes necessary to speed up digestion at body temperature (37oC)
6.1.3 Source, substrate, products and optimum pH • Amylase: salivary amylase; salivary glands or pancreas, substrate = starch, products = maltose, pH = 7 • Protease: pepsin; wall of stomach, substrate = proteins, products small polypeptides, pH 1.5-2 • Lipase: pancreatic lipase; pancreas, substrate = triglycerides, products = fatty acids and glycerol, pH 7 - 8
6.1.5 Functions • Stomach: Begins the chemical digestion of proteins, catalyzed by pepsin. Pepsin is activated by HCl. Bacteria are killed by HCl. HCl denatures protein making peptide bonds more accessible to pepsin and other enzymes. Also continues physical breakdown – churning by rugae. • Small Intestine: completes digestion; end products are absorbed by the villi. • Large Intestine: absorption of water, solid feces is egested (eliminated); gut bacteria make B vitamins, vitamin K.
6.1.6 Absorption vs. assimilation • Absorption: • Products of digestion are taken up and passed through a layer of cells called the epithelium of the villi. • Assimilation: • after absorption, molecules become part of the tissues of the body e.g. Amino acids are incorporated into proteins, fatty acids are incorporated into phospholipid bilayers, glucose is broken down during cell respiration for fuel.
6.1.7 Explain how the structure of the villus is related to its role in absorption • 1. villi increase surface area for absorption. • 2. epithelium only 1 cell layer thick- easier for absorption. • 3. plasma membrane modifications, microvilli, also increase surface area for absorption. • 4. protein channels in microvilli for facilitated diffusion. • 5. pumps in microvilli for active transport • 6. blood capillaries inside villus close to epithelium • 7. lacteal in center carries away fats • 8. mitochondria provide ATP
6.2.1 Draw a diagram of the heart showing all 4 chambers, blood vessels and valves. Be sure to put In coronary bv Watch thickness
6.2.2 State that coronary arteries supply heart muscle with oxygen and nutrients
Action of heart: • 1. Atria collect blood and pump it to ventricles. • 2. Ventricles pump blood into arteries. • 3. Direction of flow is controlled by AV and semilunar valves. • Go through cardiac cycle.
6.2.4 Outline control of the heartbeat • Heart muscle beats on its own (myogenic) • Pacemaker (sinoatrial node) sends the signal that begins contraction. • Involuntary control by autonomic nervous system: From the medulla one nerve carries messages from the brain to the pacemaker and speeds up heart rate and one nerve slows it down. • Hormone, adrenalin (epinephrine), carried in bloodstream to pacemaker speeds up beating of heart.
Arteries: thick outer longitudinal collagen and elastic fibers to avoid bulges and leaks. Thick wall – withstand pressure; thick layers of elastic and muscle fibers to help pump. Narrow lumen to help maintain high pressure Thin layers with few circular elastic and muscle fibers – blood does not need to be pumped. Wide lumen Thin wall to be pressed flat by muscle; no danger of bursting. Capillaries: one single layer of thin cells – short diffusion distance; pores between Cells allow plasma to leak and phagocytes to squeeze out; narrow lumen – fit into Small spaces. Many capillaries have large surface area.
6.2.6 and 7. Blood composed of plasma, erythrocytes, leucocytes (phagocytes and lymphocytes) and platelets Blood transports:nutrients oxygen, carbon dioxide, antibodies, urea.
6.3.1. Pathogens: an organism or virus that causes a disease • Virus: HIV, Influenza • Bacteria: Meningococcal, tuberculosis • Fungi: Thrush (oral and vaginal), ringworm, Candida (yeast infections) • Protozoa: malaria, giardia • Flatworms: schistosomiasis, blood and liver flukes • Roundworms: Hookworms
6.3.2 • Explain why antibiotics are effective against bacteria but not against viruses. • Antibiotics block specific metabolic pathways found in bacteria. (e.g. prontosil blocks folic acid metabolism; tetracycline targets 70s ribosomes). • Viruses reproduce using the host cell’s metabolic pathways, which are not affected by antibiotics.
6.3.3 Outline the role of skin and mucous membranes in defense against pathogens. Skin and mucous membranes a) intact skin is a barrier that cannot normally be penetrated by bacteria or viruses. b) mucous membranes that line the digestive, respiratory genitourinary tracts bar the entry of potentially harmful microbes
c. Secretions from sebaceous and sweat glands give the skin a pH ranging from 3-5, which is acidic enough to prevent colonization of many microbes. d. Microbial colonization is also inhibited by the washing action of saliva, tears, and mucous secretions that continually bathe the surfaces of exposed epithelia. e. All of these secretions contain antimicrobial proteins. One of these is the enzyme lysozyme which digests the cell walls of many bacteria and thus destroys many bacteria entering the upper respiratory tract and the openings around the eyes. f. Normal bacterial flora on skin inhibit the growth of pathogens.
6.3.4 Outline how phagocytic leucocytes ingest pathogens in blood and in body tissues.
6.3.4 • Phagocytes: are leukocytes and identify pathogens and ingest them through endocytosis. • Pathogens are digested by hydrolytic enzymes from lysosome. • This can happen in blood or in tissues. • In tissues, damaged cells produce chemicals that dilate capillaries, allowing phagocytes to squeeze through pores, and attract phagocytes through chemotaxis.
6.3.5 Distinguish between antigens and antibodies • Antigen: any foreign substance that stimulates an antibody reaction. E.g. protein coats of viruses, cell walls of pathogenic bacteria and fungi, pollen. (antibody generator) Antibody: protein that recognize and bind to specific antigens. Stimulates destruction.
6.3.6 Explain antibody production Many different types of lymph- ocytes exist..each one recognizing one specific antigen and responds by dividing to form a clone. clone secretes a specific antibody against the antigen.
6.3.7 Outline the effects of HIV on the immune system. • HIV infects several different cells of the immune system including lymphocytes, phagocytes, and brain cells. The number of active lymphocytes are reduced and there is a loss of the ability to produce antibodies. • As immune system fails, a variety of diseases caused by viruses, bacteria, fungi and protozoa are seen (opportunistic infections). These diseases weaken the body and eventually lead to death.
6.3.8 Cause, transmission, and social implications of AIDS • Acquired Immunodeficiency Syndrome (AIDS) is an immunodeficiency disease caused by a retrovirus (RNA) – the human immunodeficiency virus – HIV 1 and 2 • HIV does not survive long outside the body and cannot easily pass through the skin. Transmission involves the transfer of body fluids from an infected person to an uninfected one through It is transmitted through small cuts or tears in the vagina, penis, mouth or intestines during vaginal, anal or oral sex. In traces of blood on a hypodermic needle that is shared by intravenous drug abusers. Across the placenta from a mother to a baby, or through cuts during childbirth or in milk during breast-feeding. In transfused blood or with blood products such as Factor VIII used to treat hemophiliacs.
6.3.8 continued • Individuals with HIV AIDS, because of these continued diseases, suffer social stigma, and general fear by the public at large, often lose their jobs and become estranged from their families. • It becomes difficult for these individuals to live on their own. • If they are the primary wage earner, families become poorer. May lose life insurance. • Other social implications: families and friends suffer grief. Sexual activity in a population may be reduced because of the fear of AIDS.
Syllabus Statements 5.5.1 List the features of the alveoli that adapt them to gas exchange 5.5.2 State the difference between ventilation, gas exchange and cell respiration 5.5.3 Explain the necessity for a ventilation system 5.5.4 Draw a diagram of the ventilation system including trachea, bronchi, bronchioles and lungs. 5.5.5 Explain the mechanism of ventilation in human lungs including the action of the internal and external intercostal muscles, the diaphragm and the abdominal muscles.
6.4.1 Definitions • Cell respiration: controlled breakdown of organic compounds and release of ATP. Occurs in mitochondria and cytoplasm • Gas Exchange: Swapping of oxygen, which is needed for cell respiration, for carbon dioxide, which is a waste product. • Ventilation: Increasing contact of the respiratory medium with the respiratory surface. The process of bringing fresh air to the alveoli and removing stale air.
6.4.2 Necessity for ventilation system • Need to create and maintain concentration gradients of gases: • In the lungs, oxygen must be high so that it diffuses into the lungs. • Carbon dioxide must be low so that it diffuses from the circulatory system and is exhaled.
6.4.3 List the features of alveoli that adapt them to gas exchange • 1. Large total surface area for gas exchange – each lung contains 100s of millions of alveoli • 2. Wall is single layer of thin cells. • 3. Capillary wall is single layer of thin cells so short distance for gas diffusion • 4. Alveolus covered with capillaries with low oxygen and high carbon dioxide concentrations. Diffusion gradient. • 5. Cells in alveolus wall secrete fluid, making inner surface moist to dissolve gases; natural detergent to prevent side sticking together.
6.4.4 Draw ventilation system. Insert ribs, intercostals in this diagram (alveoli as an inset at higher magnification)
6.4.5 Explain mechanism of ventilation in human lungs Inhalation: external intercostals and diaphragm contract. Increased volume of thorax – decreased pressure. Exhalation: internal intercostals and abdominal mus- cles contract. Decreased volume of thorax – increased pressure.
Syllabus statements • 6.5.1 State that 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 • 6.5.2 Draw and label a diagram of the structure of a motor neuron (include dendrites, cell body with nucleus, axon, myelin sheath, Nodes of Ranvier and motor end plates) • 6.5.3 state that nerve impulses are conducted from receptors to the CNS by sensory neurons, with in the CNS by relay neurons, and from the CNS to effectors by motor neurons • 6.5.4 Define resting potential and action potential (depolarization and repolarization) • 6.5.5 Explain how nerve impulses are passed along a nonmyelinated neuron • 6.5.6 Explain the principles of synaptic transmission
Syllabus Statements 6.5.7 State that the endocrine system consists of glands which release hormones that are transported in the blood. 6.5.8 State that homeostasis involves maintaining the internal environment at a constant level or between narrow limits, including blood pH, oxygen and carbon dioxide concentrations, blood glucose, body temperature and water balance. 6.5.9 Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms. 6.5.10 Describe the control of body temperature including the transfer of heat in blood, the role of the hypopthalamus, sweat glands skin arterioles, and shivering. 6.5.11 Explain the control of blood glucose concentration, including the roles of glucagon, insulin and alpha and beta cells in the pancreatic islets. 6.5.12 Distinguish between type 1 and type 2 diabetes
5.6.1 Homeostasis involves maintaining internal environment (blood and tissue fluid) at constant level or between narrow limits: • Regulate pH, oxygen and carbon dioxide concentrations, blood glucose, body temperature and water balance.
6.5 Nerves, Hormones and Homeostasis • State that the nervous system consists of the central nervous system and peripheralnerves, and is composed of cells called neurons that can carry rapid electrical impulses.
6.5.2 Draw and label a diagram of the structure of a motor neuron
6.5.3 • State that 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.
6.5.4 a)The membrane potential of an unstimulated neuron (or excitable cell) is called the resting potential. b)Usually this is about -70mV (millivolts) or 5% of the voltage in a flashlight battery. c)Inside of cell is more negative than outside. Ionic differences are maintained by the selective permeability of the plasma membrane.
6.5.4 Action Potential • An action potential is a rapid change in the membrane potential of an excitable cell, caused by stimulus-triggered, selective opening and closing of voltage-sensitive gates in sodium and potassium ion channels.
6.5.7 Endocrine System involved in homeostasis • Endocrine: consists of glands which release hormones that are transported in the blood. E.g. Regulation of glucose levels with insulin and glucagon produced by the pancreas.
6.5.8 Homeostasis involves • Maintaining the internal environment between limits: • Blood pH • Carbon dioxide concentration • Blood glucose concentration • Body temperature • Water balance
6.5.9 Homeostasis: monitoring and correcting • In feedback – level of product feeds back to control rate of its own production. • Negative feedback – stabilizing effect because a change in levels always causes the opposite change. • E.g. a rise causes a decrease or reduction • A decrease causes an increase or rise in level. • Monitor a set point. Little fluctuations are not allowed to become large fluctuations.
