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Answer to Question #89966 in Human Anatomy and Physiology for laura

Question #89966
Q1) a, Explain the endocrine system is ill-suited to the co-ordination of a reflex such as the withdrawal ?
b1) Using an example (blood glucose), outline the process of hormonal control ?
b2) Describe the features of the endocrine system for control in the example given ?
b3)Using example, explain how major organ systems in the body work together to co-ordinate function ?
Q2) 1, Outline the process of starch breakdown by the digestive systems ?
2, Describe how the alimentary canal is adapted to absorb the products of digestion ?
Q3) 1, Describe the structure of the aveolus within the respiratory system relates to its function ?
2, Describe how the circulatory and respiratory systems work together in providing body cells with oxygenated blood ?
Expert's answer

Q1 a) Endocrine system can not give a quick response what is necessary for regulation of most reflexes, in such case nerve system immediately.

b1)If the blood glucose concentration is too high, the pancreas produces the hormone insulin. Insulin helps the cells absorb glucose, reducing blood sugar and providing the cells with glucose for energy.

When blood sugar levels are too low, the pancreas releases glucagon. Glucagon instructs the liver to release stored glucose, which causes blood sugar to rise.

b2)Insulin is normally secreted by the beta cells (a type of islet cell) of the pancreas.The stimulus for insulin secretion is a HIGH blood glucose.Similarly, as blood glucose falls, the amount of insulin secreted by the pancreatic islets goes down. Đ†nsulin has an effect on a number of cells, including muscle, red blood cells, and fat cells. 

Glucagon is secreted by the alpha cells of the pancreatic islets in much the same manner as insulin...except in the opposite direction. If blood glucose is high, then no glucagon is secreted. When blood glucose goes LOW, however, (such as between meals, and during exercise) more and more glucagon is secreted. Like insulin, glucagon has an effect on many cells of the body, but most notably the liver.

b3)Nervous system and endocrine system in our body function together to integrate all activities.

Example, Brain-Heart-Lungs (In a stressful situation due to sympathetic stimulation from the brain heart rate increases, stimulates perspiration and also widens air passages to facilitate breathing)

Q2) 1The digestion process of polysaccharides such as starch will begin in the mouth where it is hydrolysed by salivary amylase. The amount of starch hydrolysed in this environment is often quite small as most food does not stay in the mouth long. Once the food bolus reaches the stomach the salivary enzymes are denatured. As a result, digestion predominantly occurs in the small intestine with pancreatic amylase hydrolysing the starch to dextrin and maltose.

Enzymes classed as glucosidases on the brush border of the small intestine break down the dextrin and maltase, lactase and sucrase convert the other disaccharides into their two monosaccharide units.

2The small intestine is well adapted for absorbting nutrients during digestion by: being very long, having villi and microvilli that increase surface area, using muscular contractions to move and mix food, and receiving and housing digestive enzymes and bile that help the breakdown of food.

Q3) 1The alveoli are located in the respiratory zone of the lungs, at the ends of the alveolar ducts and alveolar sac, representing the smallest units in the respiratory tract.The wall of each alveolus, lined by thin flat cells (Type I cells) and containing numerous capillaries, is the site of gas exchange, which occurs by diffusion.Among the other cells found in the alveolar walls are a group called granular pneumocytes (Type II cells), which secrete surfactant, a film of fatty substances believed to contribute to the lowering of alveolar surface tension.Another type of cell, known as an alveolar macrophage, resides on the internal surfaces of the air cavities of the alveoli.They are mobile scavengers that serve to engulf foreign particles in the lungs, such as dust, bacteria, carbon particles, and blood cells from injuries.

The function of the alveoli is to get oxygen into the blood stream for transport to the tissues, and to remove carbone dioxide from the blood stream.

2 The interactions between the cardiovascular and respiratory systems are best demonstrated by following the path of a red blood cell starting in the heart and traveling through the lungs.

A red blood cell that has just returned from delivering oxygen and that has brought back carbon dioxide would be in the right upper chamber of the heart or in the right atrium. When the atrium contracts, the cell is pumped into the right lower chamber of the heart, or the right ventricle. When that ventricle contracts, the red blood cell is pumped out of the heart through the pulmonary artery to the lungs.

In the lungs, the red blood cell enters tiny blood vessels that come into close contact with the walls of the alveoli air sacs of the lungs. The carbon dioxide in the red blood cell passes through the walls into the alveoli while the oxygen in the alveoli air passes into the red blood cell. The red blood cell then returns to the heart via the pulmonary vein.

From the pulmonary vein, the red blood cell enters the left atrium of the heart and then the left ventricle. The part of the heart muscle powering the left ventricle is very strong because it has to push the blood out to the whole body. The red blood cell is pumped out of the left ventricle via the aorta artery and eventually reaches the capillaries leading to the individual cells. There the cells absorb the oxygen from the red blood cell and pass on their waste carbon dioxide. The red blood cell returns to the right atrium of the heart via the veins to complete the cycle.

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