1.Explain energy transduction and receptor potential as they relate to the function of a sensory receptor.
There are many different types of energy used in triggering certain cells to do different things. For example, there is mechanical energy which cause helps with auditory reception and the displacement of hairs. Also there are electromagnetic energy which involves the change in temperature, and chemical energy which can be obtained by smell, hormones, and taste.
The Receptor potential of a cell is the initial response of a receptor cell to a stimulus, consisting of a change in voltage across the receptor membrane proportional to the stimulus strength. The intensity of the receptor potential determines the frequency of action potentials traveling to the nervous system.
2.Select one of the options below and compare and contrast the paired terms:
primary and secondary immune response
The primary immune response is the first line of defense of an animal's body. The very first source of immunity is the skin. The skin cannot be penetrated, but when opened pathogens can easily enter the body. Also, mucous is an important first line of defense, the mucous of one's digestive tract is vital in the prevention of unwanted pathogens entering the blood.
The secondary immune response is usually initiated by the breaking of the primary immune response. The 2ndary response usually involves cells and antibodies. Phagocytes are cells that are found in the bloodstream which can engulf certain pathogens. Also, there are calls that produce antibodies that kill specific pathogens. The antibodies are usually memorized so the next time the same pathogen occurs, the killing process will be much more rapid.
passive and active immunity
artificial and natural immunity
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.
Glucose concentrations in the blood stream are primarily controlled by the action of two antagonistic pancreatic hormones, insulin and glucagon. Glucose is first detected in the bloodstream by glucose transporter receptors expressed on the surface of specialized pancreatic cells known as alpha- and beta-cells. Beta-cells respond to rising levels of blood glucose by secreting the hormone insulin.
Insulin restores normal levels of glucose in the blood when glucose is high by signaling body tissues to take up glucose for energy, or to convert glucose to glycogen and lipids and store it as energy in the liver, muscle and fat cells. When the level of glucose is low, the alpha-cells of the pancreas release the hormone glucagon to stimulate skeletal muscles and the liver to breakdown glycogen into glucose and adipose tissue to digest lipids into fatty acids and glycerol. Glucagon can also stimulate the liver to create glucose from glycerol. These reactions all work together to bring glucose levels back to normal.
4.Briefly describe the sequence of events that take place in muscle contraction.
The sequence of events leading to contraction is initiated somewhere in the central nervous system, either as voluntary activity from the brain or as reflex activity from the spinal cord. When a motor neuron in the ventral area of a spinal cord is activated, an action potential is passed outward in a ventral root of the spinal cord. The axon branches to supply a number of muscle fibers called a motor unit, and the action potential is conveyed to a motor end plate on each muscle fiber.
The motor end plate is where the action potential causes the release of acetylcholineinto thesynaptic cleftson the surface of the muscle fiber. Acetylcholine causes the electricalresting potentialto change, and this initiates an action potential which passes in both directions on the surface of a muscle fiber. The action potential spreads inside the muscle fiber at the opening of transverse tubules onto the muscle fiber surface,.
5.Why is saltatory conduction faster than continuous conduction?
The two different types of conduction of nerve impulses are salutatory and continuous conduction. Saltatory conduction occurs between fibers separated by Nodes of Ranvier. This conduction is much faster because the action potential is not transmitted along nerve fibers one by one. Instead, it is transmitted through only the gaps between the nerve fibers and is quickly sent to the other side of the fiber where it enters a new fiber.
Continuous conduction occurs between axons without myelin, which are one continuous nerve fiber. This process is slower because the action potential needs to send one whole impulse which needs to travel through the entire nerve fiber, and arrive at the final destination. Continuous conduction involves processes like re-polarization and de-polarization to move an action potential through the nerve fibers.
6.What evolutionary advances are demonstrated in the nervous systems of bilaterally symmetrical animals?
Bilateral symmetry gives animals directed movement, which aid when animals are searching for food or escaping from predators. Also, it allows for quicker and accurate responses to stimulation, since the nervous system is cephalized and much more complex than those found in organisms without bilateral symmetry. Bilateral symmetry also allows the nerves to be directed to an increase amount of specific areas. Furthermore, cephalization allows the brain to be much more functional in detecting stimuli and sending responses.
7.What physiological processes occur in response to an increase in blood pressure?
The nervous system helps maintain blood pressure by stimulating the adjustment of blood vessel sizes, and by influencing the hearts pumping action. The kidneys help in regulating blood pressure by adjusting mechanisms that change blood volume. For example, when blood flow to the kidneys is lowered, like in atherosclerosis, the kidneys set in motion actions that raise blood pressure by expanding the blood volume, and constricting surrounding blood vessels.
The cardiovascular center provides a rapid, neural mechanism for the regulation of blood pressure by managing cardiac output or by adjusting blood vessel diameter. The cardiac center stimulates cardiac output by increasing heart rate and contractility. These nerve impulses are transmitted over sympathetic cardiac nerves. The cardiac center inhibits cardiac output by decreasing heart rate. These nerve impulses are transmitted over nerves.
8.Describe the differences in function of the five immunoglobulin classes.
Immunoglobulin makes up around a lot of the serum antibodies.IgG has a half-life of 7-23 days. Immunoglobulin M is about 13% of the serum antibodies and isthe first antibody produced during an immune response.The half-life of IgM is around 5 days.Some portions of IgM canactivate the classical complement pathway.IgM is also one of the most efficient classes of antibody for activating that pathway. IgA is made primarily in the lymphoid tissues. TheFc portion of IgA binds to components of mucousand contributes to the ability of mucous to trap microbes.
IgD is found on B-lymphocytes as aB-cell receptororon sigwhere it may control of B-lymphocyte activation and suppression. IgD canplay the role in eliminating B-lymphocytes generating self-reactive auto-antibodies. IgE may protect external mucosal surfaces bypromoting irritation, enabling IgG, complement proteins, and leucocytes to enter the tissues. The Fc portion of IgE binds to mast cells and basophilswhere it alleviates manyallergic reactions.
9.Why is it more difficult to obtain sufficient oxygen at higher altitudes?
When people breathe in air at sea level or a low altitude, the atmospheric pressure allows oxygen to easily pass throughthe selectively permeablelung membranes to the blood.At higher altitudes, there is a lower air pressure, which makes it more difficult for oxygen to enter the blood. The result isknown as hypoxia, oxygen deprivation. Hypoxia usually begins with the inability to do normal physical activities, like climbing a stairs without easily being tired.
Other symptomsof "high altitude sickness"are: a lack of appetite, distorted vision, and difficulty memorizing and thinking clearly. On a serious note, pneumonia-like symptoms and a strange increase of fluids around the brain develop; can lead to death within a few days if the air pressure does not return to normal.With the lack of oxygen, there is also an increased risk of heart failure due to the added stress placed on the lungs, heart, and arteries at high altitudes.
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.
The protein called leptin probably acts very similarly to insulin. They both have central and peripheral actions; for some time it has been thought that brain insulin represented a body weight signal with the ability to control appetite. The main effect is increased food intake and decreased physical activity. NPY is secreted by thehypothalamus gland, and, in addition to increasing food intake, it increases the amount of energy stored as fat and blockssignals travelling to the brain.NPY also augments the vasoconstrictor effects of noradrenergicneurons.
MHC molecules show fragments of processed proteins on the surface of a cell. The typical view of MHC is a peptide on cell surfaces allows for pathogen examination by immune cells, and usually aT cellornatural killer cell. If activating T or killer cells' surface receptors can recognize MHC it can activate the immune cell and cause the development of an immune response against presented antigens. The two general classes of MHC molecules are Class I and Class II. Class I MHC molecules are found on nucleated cells and present peptides toT cells. Class II MHC presents these fragments to helper T cells, which stimulate immune reactions from other cells.
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?
In the presence of hormones that increase water permeability, the hypo-osmotic fluid that enters the distal tubule from the ascending limb looses most of the water by osmotic equilibration with the cortical interstitium along the convoluted tubule and cortical collecting duct. It also looses NaCl through re-absorptive transport along the distal tubule, convoluted tubule and collecting duct, until the tubule fluid becomes iso-osmotic with plasma, by the end of the collecting duct. The small amount of fluid that flows into the medullary collecting ducts looses progressively more water to the hyper-osmotic medullary and papillary interstitia and is excreted as highly concentrated urine.
In the absence of ADH, the hypo-osmotic fluid that enters the distal tubule from the loop of Henle continues to be diluted by transport of NaCl due to co-transporters into the tubule's cells and via Na channels along the collecting duct. Water re-absorption is limited so that the tubule fluid becomes more and more dilute along the distal tubule, collecting ducts, until it is excreted as a large volume of hypo-osmotic urine.
12.How is a fall in blood pressure counteracted by the secretion of aldosterone?
Aldosterone is a steroid hormone that's created by the adrenal gland. It acts on the kidneys toincrease sodium re-absorption.Having more aldosterone means that more sodium eventually winds up in the blood, thus activating thirst mechanisms that cause one to drink water, which increases ECF volume and increases blood pressure. When blood pressure drops, the kidneys can sense a change in blood flow and start secreting the enzyme renin. Renin works through a pathway system mainly to increase aldosterone secretion in order to return blood pressure to normal.
When blood volume is low, cells in the kidneys secretethe enzyme renin. Renin stimulates the production ofangiotensinI, which is converted to angiotensin II. Angiotensin II causes constriction in blood vessels, resulting in an increased blood pressure. Angiotensin II also stimulates the secretion of aldosteronefrom theadrenal cortex. Aldosterone causes the tubules of the kidneys to increase the re-absorption of sodium and water into the blood. This increases the volume of fluid in the body, which increases blood pressure.
13.Since hormones are present in such small amounts, how can their signals be amplified enough to regulate so many physiological processes?
Theendocrine systemproduces hormones that are key in maintaining homeostasis, regulating reproduction and/or development. Hormones are chemical messengers produced by a cell that causes specific changes in the activity of other cells. The endocrine and nervous systems usually work toward the same goal, but they reach their goals entirely differently. Neurotransmitters act immediately on adjacent muscles, glands, or other nervous cells, and their effect is usually short-lived. On the other hand, hormones take a longer time to produce their effect, can affect any cell, and produce effects that last as long as they are in the bloodstream.
Hormones regulate metabolic activity in different types of tissues. They are one kind of mechanism of signaling amongst cells and tissues. Hormones can be defined as signaling molecules that cells release into the bloodstream, which can change the metabolism of the same or other cells. Hormones are different from communication mechanisms that depend on direct contact through gap junctions. Hormones are also different from neurotransmitters, although this distinction is artificial, since neurotransmitters can act as hormones.
14.Explain how hormone secretion regulates the menstrual phase of the menstrual cycle.
When it comes to hormones and the menstrual cycle, one needs to have an understanding of how the two main hormones at work affect the female body. Estrogen is a feel good hormone. It gives energy and with the help of testosterone, an increase in sex drive. When one's estrogen levels are up, she will probably feel a bit more feminine and maybe sexier than normal.
Progesterone has a tranquilizing effect on the body. It slows your systems down a bit. When progesterone levels are high, you are more likely to feel depressed and will probably have less energy. On day one of your menstrual cycle the hormones estrogen and progesterone are as low as they will be at any other point in your cycle. Prostaglandins are at their highest level at this time. When a woman is pregnant, prostaglandins are released at the time that labor begins to create uterine contractions. You probably do not feel stellar on day one of your menstrual cycle.
15.Discuss how environmental factors can have a negative impact on the development of a fetus. Particulate matter in the air can have an impact on your growing baby, particularly in the very early stages of embryonic development. The air quality of the area was worse during the winter months, man intrauterine growth retardation. Environmental influences on the physiology of a developing fetus can stem from exposures the mother may encounter or can result from changes within the mother. In the case of an exogenous environmental influence, the mother's exposure is transferred to the fetus.
Exogenous environmental factors include certain viruses, medications, exposure to pesticides and/or heavy metals and other factors. Endogenous environmental influences may result from the following effects that stress can lead to in a mother and in the mother's womb. They can also start from factors such as the mother's immune response to infections or foreign proteins or even her immune response to the father's protein, which is expressed in the fetus she is carrying.