Thursday, August 19, 1999

Structure and Function of the Human Body week 5

Explain how adaptation relates to our thermoreceptors and touch receptors. What is referred pain and how could it be dangerous?
Thermoreceptors and touch receptors are both nerves. The thermoreceptors Referred pain is when the perception of pain coming from parts of the body that aren't actually stimulated. It's dangerous, because you don't know where the real dangerious areas really point too. If you didn't have touch receptors, you wouldn't know what information like location, shape, size, texture and movement. (pg 309)
Explain why olfaction and gustastion are considered “chemical” special senses (think of how these two senses work). Explain the importance of hair cells with the sense of hearing and equilibrium. Lastly, compare and contrast rod and cone cells' location, function, and overall amount.
Both olfaction and gustastion occurs as dissolved chemicals stimulate olfactory receptors. The hiding of an odorant changes the permeability of the receptor membrane, producing action potentials. The gustatory are actually chemically based tasted receptors of the tongue which tastes chemicals. Taste buds have gustatory cells which tends to slither microvilli to the taste poor. The poors are more sensitive to acids. (pg 313- 315)
Hair cells are simple mechanoreceptors which are complex structure of the inner ear and the different arrangements of accessory structures of the inner ear and the different arrangements of accessory structures. (pg 329)
Rod cells do not discriminate among colors of light. They help us see in dim light. Cone c ells provide color vision. Cones give humans sharper colors. Rod cells are found on the side while cones are found on the bottom (pg 320)
Explain how the body maintains homeostasis of serum (blood calcium) levels through the use of the thyroid and parathyroid glands.
Fibrin is large insoluble strands. The fibrin fibers interact and provide framework for blood clots. The steps not taken to prevent clotting in a plasma sample, fibrinogen will convert to fibrin. The fluid left over is called serum. The liver synthesizes more than 90% of the plasma proteins including albumins and fibrinogen and globulins. Antibodies are produced by the plasma cells and fibrinogen and plasma proteins clot the blood preserving homeostasis of serum (pg 384)
Explain the role the hypothalamus and pituitary gland have in the regulation of the endocrine system. What would happen if there were no negative feedback control on growth hormone and thyroid hormone?
The hormonal secretion is controlled by negative feedback mechanisms. The stimulus triggers the production of hormone worse direct or indirect effects that reduce the intensity of the stimulus. The simplest case, endocrine activity may be controlled by humoral stimuli - changes in the composition of the exetracelluar fluid. The control of blood calcium levels are controlled by two hormones, parathyroid hormone and calcitinin. The calcium levels are the blood decline, parathyroid hormone is released and the response of target cells elevate blood calcium levels. The blood rise, calcitonin is released and the response of target cells lower blood calcium levels. The endocrine activity is also controlled by hormonal stimuli or changes in the levels of circulating stimuli. The hypothalamus provides the highest level of endocrine control by acting as an important link between the nervous and endocrine systems. (pg 350).
The control of the calcitonin secretion is independent of the hypothalamus gland and pituitary gland. C cells produce hormone calcitonin. Physiologic effects of growth hormone are direct effects and indirect effects. The glands within the endocrine system simulate release of a hormone from thyroid glands are shut off. If too much negative feedback occurred there would be hormone imbalance , because too much of the hormone would be. The hypothalamus secretes TRH. This causes the tituitary to release THS. THS will cause the thyroid hormone to secrete T4. In many parts of the world, inadequate dietary iodine intake leads to the inability to synthesize thyroid hormones. The calcitonin inhabits osteoclasts and stimulates calcium excretion in at the kidneys. C-cells are endocrine cells sandwiched between the follicle cells and their basement membrane. If there was too much negative feedback, the kidneys would fail. If negative feedback occurs, there could be a loss of bone mass. Calcitonin is most important during childhood in controlling muscle cells and nerve cell activities. Thyroid hormones are stored in the colloid of follicle. There would be too much energy utilization, oxygen consumption, growth and development for most cells. There would be more calcium concentration in body fluids in the bones and kidneys.
Explain how the nervous system, general senses, and endocrine system work together to maintain homeostasis. Remember the 3 steps of the nervous system function: afferent (input/sensory) information, analysis, and efferent (output/motor) information. This will be helpful along with remembering what homeostasis is.
The nervous system regulates the breathing, urinary, and digestive systems. The heart rate and breathing are controlled by the nervous system. Hormones are less energetically expensive, the lymphatic system ability to fight infection. Second, the respiratory system maintains oxygen and pH levels. The exposure to drugs, alcohol and toxins kick the excretory functions and test these substances to accumulate damage of the body's cells. A body that lacks nutrients will induce the body to compensate or become sick.
Make sure you provide citations and references for your answers!

Read chapters 9 - 10 ys/endocrine/hypopit/gh.html

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