IBBiologyTopic 6 Human PhysiologyRevisionSheet
Define the following terms –Absorption
The movement of food from the lumen of the intestines into the bloodstream and lacteal through the wall of the villi
Assimilation
The movement of the materials that have made it into the bloodstream and lacteal into the tissue that requires nutrition.
Explain the need for digestion of large food molecules in order for absorption and assimilation to occur.
Food molecules enter the body in complex form, and often are too large to be absorbed. In order to break them down to a size that can pass through the villi into the mucosa and from the mucosa into the bloodstream, they must be first digested by mechanical and chemical means, in order to reach a small enough size, so that they can be absorbed. / Fill in the chart for each of the following enzymes:
Name / Source / Substrate / Product / Optimum pH
Amylase / Salivary glands, mouth
Pancreas / Starch / Maltose, Sucrose / 7-8
Lipase / Pancreas / Unsaturated and saturated fats / Fatty acids / 7-8
Protease / Stomach
Pancreas / Polypeptides / Amino acids (short chains) / 2-3 (stomach)
7-8 (Small intestine)
/ Draw a small diagram of the Digestive system. Draw a diagram of the Heart.
.
.
.
.
.
.
.
.
.
Explain the flow of blood through the heart.
Blood flows into the heart during diastole, when all chambers are relaxed. The atria fill, and an action potential is sent from the SA node. The action potential causes for the atria to contract, and they expel blood through the atrioventricular valves, into the ventricles. Action potential travels through the nerves of the heart. Action potential causes for the ventricles to simultaneously contract, resulting in blood moving through the bicuspid valves, into the major arteries. Blood is prevented from back flow within the heart, due to the one-way valves that are only open when blood is moving forwards. / Outline the role of the following structure in control of the heartbeat:
Pacemaker
Also known as the SA node, this is a bundle of nerve tissue that initiates the pumping of the heart.
Medulla of the brain
The medulla of the brain senses CO2 levels in the blood, which then can speed up or slow the heartbeat. This is controlled primarily through the Vagus nerve, but hormones can also impact the rate of the heartbeat as well.
Myogenic muscle
The muscle tissue of the heart can beat on its own, although arrythmically.
Contractions are synchronized through the SA node.
Adrenaline
Hormone that can cause heart rate to speed up rapidly. Acts as a fast- acting NT that can take action in less than 1ms / Explain how antibiotics are ineffective against viruses.
Antibiotics are proteins molecules that interact with metabolic pathways found within bacteria. Viruses distinctly lack the metabolic processes that are attacked, and thus, they have no interaction with antibiotics.
Outline antibody production.
Pathogens enter the body, and make it past non-specific forms of immunity. If this is the case, then they have been digested by macrophages into epitopes, and macrophages present the epitopes to the T—Cells. T-cells bind with the epitope, and are activated by it, activating them. B cells also can bind to the epitope and are activated by binding. T-cells will begin helping macrophages on the front lines, and B-cells in the lymph nodes, to keep them activated. B-cells, after being activated, begin cloning themselves into plasma cells and memory cells. Plasma cells then begin to produce TONS of antibodies. These antibodies are specifically tuned to the pathogen that is infecting the body.
Discuss the cause, transmission and social implications of AIDS.
HIV is a retrovirus that infects T cells. These T-cells become infected with HIV when HIV inserts its RNA into the cytoplasm, and reverse transcribes the RNA into cDNA to be inserted into the host cell’s nucleus. The original cell begins to produce viruses as a result of this DNA integration, which results in thousands of HIV virions produced for every infected cells. Eventually the host’s immune system is compromised, due to all the T cells being infected and dying as a result.This leads to AIDS. HIV can be transmitted through any fluid environment that could contain these T cells, such as blood, mucus, or sexual fluids. People with AIDS have severely suppressed immune systems which are incapable of fighting even simple infections, which they eventually die of, if not treated.
Socially, AIDS has had a stigma associated with it, and as such, it causes severe repercussions for those that suffer from it. Treatments are very expensive, and often require a lot of time away from work, which means that patients often cannot pay for treatment for very long.
AIDS can lead to severe ramifications for countries if it reaches an epidemic status, as it can lead to workforce depletion, economic depressions, and impact of trade involving meat and dairy. / Describe the features of the alveoli that make them ideal for gas exchange.
Alveoli have high SA:Vol ratios and are close in interaction with pulmonary capillaries. Alveoli are also coated in a mucus membrane (made by Type II Pneumocytes) to create a wet environment. All of the above facilitate in a more rapid transport of oxygen and carbon dioxide.
Explain the mechanism of ventilation. (including intercostal muscles, diaphragm, abdominal muscles)
Inspiration is performed by the diaphragm contracting along with the external intercostals, while the abdominal muscles relax. Expiration is caused by the contraction if the internal intercostals, the relaxation of the diaphragm, and the contraction of the abdominal muscles. / Draw and label a motor neuron.
Describe the connection between a sensory neuron, a relay neuron, and a motor neuron in passing a nervous impulse.
Sensory neurons relay an impulse from the sensory organ to the CNS. Relay neurons pass impulses from CNS to motor neurons. Motor neurons pass the message back from CNS to motor unit (aka muscles)
The connection between each of these are synaptic, and require the action of neurotransmitters.
Distinguish between resting potential and action potential.
Resting potential is when the neuron is polarized to -70mV, and is held there by sodium/potassium pump proteins. This would be when the neuron is at rest, and not actively sending out an impulse. Action potential is when the potential of the neuron is shifting from negative to positive, in order to convey a message. This is an action potential.
Outline synaptic transmission of neurotransmitters.
Synaptic transmission is accomplished through the exocytosis of neurotransmitters from the presynaptic cell. Upon the receipt of an action potential, calcium influx drives this exocytosis to expel neurotransmitters into the synaptic cleft. The synaptic cleft is flooded with NTs, and NTs then diffuse across the synapse to bind to receptors on the postsynaptic cell. The postsynaptic cell then initiates an action potential if it is an excitatory response, or an action potential is prohibited, if it is an inhibitory NT. / Explain hormonal control via homeostasis.
Blood glucose must be regulated. If levels get too low, then the alpha cells of the pancreas begin to secrete glucagon into the blood stream. Once in the blood stream, glucagon travels to the liver to the liver, and begins to act on tissue, which results in glucose being released into the bloodstream.
If blood glucose gets too high, the pancreas can detect it, and the beta cells of the pancreas secrete insulin. Insulin acts on GLUT receptors on cells to cause for the additional uptake of sugar from the blood into the liver for storage, and into cells for metabolism. This will cause blood glucose to return to homeostatic levels.
Distinguish between type I and type II diabetes.
Type I diabetes is an autoimmune disorder, which results in destroyed pancreatic tissue. The destroyed tissue does not produce insulin, and therefore the person cannot regulate blood sugar.
In type II diabetes, excessive blood sugar levels due to diet, cause insulin receptors to become insensitive to insulin. This results in ineffective blood sugar management, even though insulin is produced. Factors that lead to type II diabetes are inheritable, while Type I diabetes is not very inheritable. / Outline the role of the following hormones in the menstrual cycle:
FSH Stimulating the follicle to begin development to primary oocyte.
LH Stimulating the follicle to develop into secondary oocyte
Estrogen Positive feedback on LH around day 14 of cycle to contribute to LH spike, then negative feedback oh LH and FSH after ovulation.
Progesterone Maintenance of the endometrial lining of the uterus, in order to allow for potential implantation of the embryo. Negative feedback on FSH and LH.
Draw a graph indicating the fluctuations in each of these hormones.