Biology Physiology energy transduction and receptor potential


Problem: answer each question completely in a paragraph, or any other suitable format such as a table

1. Explain energy transduction and receptor potential as they relate to the function of a sensory receptor.

When a sensory receptor receives a stimulus, the stimulus information is converted into electrical signals. This is made possible by energy transduction. The stimulus information is paired with a sensory receptor, which is then opened to let certain ions permeate the neuron membrane. When the membrane potential between the nerve cell and its surrounding area decreases and reaches the threshold, the nerve cell will create an action potential. This change in membrane potential is called a receptor potential.

Energy transduction and receptor potential relate to the function of a sensory receptor.

2. Select one of the options below and compare and contrast the paired terms:


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primary and secondary immune response


passive and active immunity


artificial and natural immunity

A) Primary immune response is when the body faces an antigen for the first time. The body will recognize the antigen and produce antibodies in a matter of three to fourteen days to fight the antigen. After the antigen is destroyed, the antibody specific for that antigen decreases in number. When the antigen comes to the body again, the secondary immune response is triggered. During this response, the body recognizes the antigen faster because memory T-cells that has the antigen's information still exists in the body. The body then produces more antibodies faster than in the primary immune response to destroy the known invader.

Essay: you are required to answer each question as completely as possible- in a minimum of 2 paragraphs

3. Explain how homeostatic mechanisms maintain blood-sugar levels in the body.

The body's blood sugar levels are regulated in the pancreas. When the blood sugar level is too high, the beta cells in the pancreas secrete insulin into the blood. This insulin reduces blood sugar and the production of insulin decreases as the blood sugar falls closer to the normal state.

When the blood concentration in the body starts to fall below normal, the body also does something to return it back to normal. The alpha cells in the pancreas release glucagon which increases the blood glucose levels. As the blood glucose concentration gets closer and closer to the normal range, glucagon production decreases.

4. Briefly describe the sequence of events that take place in muscle contraction.

A sequence of events has to take place in order for a muscle to contract. First, acetylcholine is released by a motor neuron which combines to a muscle fiber. This causes the depolarization of the sarcolemma and transmission of an action potential which spreads through the T tubules. The sarcoplasmic reticulum then releases calcium ions that bind to troponin, present in actin filaments, which changes its shape and pushes tropomyosin away from the binding sites.

ATP binds to and “cocks” the myosin head which then binds to the binding sites of the actin filaments, forming cross bridges. The cross bridge then flexes while the phosphate is released. The actin filament is then pulled towards the center of the sarcomere, and ADP is released. Another ATP binds to the myosin and the myosin is released from the actin filament. This happens over and over to contract a muscle.

5. Why is saltatory conduction faster than continuous conduction?

When a neuron conducts an electrical impulse, there are two different types of conduction. One type of conduction is called the salutatory conduction. In saltatory conduction, the impulse only travels in the node between the Schwann cells which insulate the axon. Saltatory conduction is fast and efficient because the impulse jumps from node to node.

Continuous conduction is slower than saltatory conduction because this conduction travels through the whole entire axon. Continuous conduction also uses more energy then saltatory conduction.

6. What evolutionary advances are demonstrated in the nervous systems of bilaterally symmetrical animals?

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The nervous systems of bilaterally symmetrical animals are different from the nervous systems of radially symmetrical invertebrates. In bilaterally symmetrical animals, nerves, nerve cords, ganglia, and brain are present

The advantages of these features are that the nerves are in large numbers which enable fast responses and extensive connections. Also, a brain helps connect everything together to enable many parts of the body to work with each other in little time.

7. What physiological processes occur in response to an increase in blood pressure?

A one's body regulates one's blood pressure. If there is an increase in blood pressure, the baroreceptors in the heart arteries' walls will stretch and this will send a signal to the medulla in the brain. In the medulla, the signal reaches the cardiac and vasomotor centers.

The cardiac center makes the heart slow down by stimulating parasympathetic nerves that slow the heart. The vasomotor center stops the constrictions of arterioles, lowering the blood pressure and causing vasodilation.

8. Describe the differences in function of the five immunoglobulin classes.

Immunoglobulins combine with antigens and activate processes that destroy the antigens. There are five classes of immunoglobulins. The classes are IgG, IgM, IgA, IgD, and IgE. IgG immunoglobulins are part of the gamma globulin fraction of the plasma and like IgM, activate the complement system, interact with macrophages, and defend against many pathogens in the blood. IgM immunoglobulins are the first antibodies that are processed in an immune response.

IgA is present in bodily fluids like breast milk and tears. IgA prevents bacteria and viruses from attaching to epithelial surfaces. IgD, which has a low concentration in plasma, is an important immunoglobulin on the B-cell surface because it helps B-cells mature and activate them following antigen binding. IgE binds to mast cells and trigger them to release signaling molecules like histamine when an antigen or parasitic worm binds to IgE.

9. Why is it more difficult to obtain sufficient oxygen at higher altitudes?

It is more difficult to obtain sufficient oxygen at higher altitudes. This is because as altitude increases, barometric pressure decreases, which causes less oxygen to enter the blood. This can cause hypoxia, oxygen difficiency which can make a person unconscious or even die.

Also according to Fick's law of diffusion, the greater the difference in pressure on the two sides of a membrane and the larger the surface area, the faster the gas diffuses across the membrane. So as the altitude gets higher, the smaller the difference in pressure on the two sides of the membrane is, which means slower oxygen diffusion.

10. Outline what is currently known about the regulation of food intake and energy homeostasis. Include the roles of leptin, neuropeptide Y, and MHC in your response.

Food intake and energy homeostasis is regulated by signaling molecules and hormones. Leptin is a hormone produced by fat cells in proportion to body fat mass, and it signals the brain about the status of energy stores.

Neuropeptide Y is a neurotransmitter that is produced in the hypothalamus. It increases the appetite and slows the metabolism of animals when leptin levels and food intake are low. MHC is a protein that can change shapes to instruct and activate T cells and natural killer T cells to create an immune response to the certain antigen with the exact shaped protein.

11. What is meant by the counterflow of fluid through the limbs of the loop of Henle and what is its role in the normal function of a human kidney?

The counterflow of fluid through the limbs of the loop of Henle concentrates filtrate as it moves down the descending loop and dilutes it up the ascending loop. The loop of Henle is an elongated hair-shaped portion of the renal tubule.

The loop of Henle in a kidney works in the filtration of urea and wastes from the blood. It separates these wastes by taking out the water and ions from the plasma.

12. How is a fall in blood pressure counteracted by the secretion of aldosterone?

When there is low blood pressure, the kidney releases renin. Renin triggers the production of angiotensinII which increases the release of the hormone aldosterone.

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Aldosterone increases blood pressure by increasing blood volume. It does this by increasing the retination of sodium ions by the kidneys.

13. Since hormones are present in such small amounts, how can their signals be amplified enough to regulate so many physiological processes?

Hormones are present in small amounts, but their signals can be amplified enough to regulate many physiological processes. They are amplified by signal transduction.

When a signal for the hormone is receives by a receptor protein, many G protein molecules are activated. Each activated G protein molecule activates an adenylyl cyclase molecule which then cataylzes the production of cAMP molecules. These cAMP molecules activate protein kinases that catalyze the phosphorylation of many proteins. These proteins activate other enzymes or catalyze reactions of other proteins resulting in a mass of activated molecules and responses.

14. Explain how hormone secretion regulates the menstrual phase of the menstrual cycle.

Hormones secretion regulates the menstrual phase of menstrual cycle. In the menstrual phase, the old cells and damaged arteries die, rupture, and bleed. During this phase, estrogen and progesterone levels, drop because they are not needed for the preparation of pregnancy and the development of the endometrium yet.

As a result of low levels of estrogen and progesterone, LH and FSH levels increase. LH stimulates theca cells to produce androgens which are converted to estrogen. FSH stimulates a new follicle to begin to develop for another pregnancy.

15. Discuss how environmental factors can have a negative impact on the development of a fetus

Environmental factors can have a negative impact on the development of a fetus. This is because life before birth is very sensitive to the environment. Many drugs, nutrients, pathogens, and gases can travel from the mother to the child through the placenta.

Tetradotoxins can cause malformations in the development of a baby. These drugs may stop the cell movements or divisions, which may cause the baby to not develop normal shape or size.