Bio 300 Exam 1 Lecture Flashcards

Question

The Initiation and Awareness of Movement What happens when we decide to move?

Answer 1

The brain makes a commitment to a choice of movement as many as 10 seconds before we become consciously aware of the decision. This delay is needed by higher level systems to prepare for an upcoming movement. Imaging technologies have been used to track the initiation of movement in human volunteers. Participants were asked to carry out movements of the fingers from memory. The first areas to show increased activity were the frontal and parietal lobes planned in SMA and premotor cortex incorporating input from thalamus and BG. Then the primary cortex sends signals via the lateral pathway then lateral pathways carry signals to spinal motor neurons which initiates muscle contractions. These areas might be viewed as the parts of the brain that “think” about the movement and its consequences before the movement is initiated. Theory: interpreter is in left hemisphere

Answer 2

Cholinergic agonists boost acetylcholine activity at the neuromuscular junction - Black widow spider venom Cholinergic antagonists paralyze muscles - Venom of the Taiwanese cobra Sarin gas inhibits acetylcholinesterase (AChE). Muscles are continuously stimulated Rapid fatigue and respiratory failure New messages cannot produce movement

Answer 3

Person’s immune system produces antibodies that bind to the nicotinic ACh receptor and starts in face ACh receptors degenerate Extreme muscle weakness and fatigue Treatments: Immunosuppressants bc autoimmune disease Medications that inhibit AChE

Answer 4

Muscular dystrophy - Group of inherited diseases characterized by muscle degeneration. - Caused by abnormalities involving the protein dystrophin - Sex-linked disorders typically affecting males(XY) bc on X Duchenne muscular dystrophy - No dystrophin at all - Is typically fatal all muscle damaged Becker muscular dystrophy - Faulty dystrophin

Answer 5

Polio: is caused by a contagious virus that specifically targets and destroys spinal alpha motor neurons. Symptoms can include muscle weakness and paralysis, usually of the legs. If the infection affects higher levels of the CNS, breathing can be compromised.

Answer 6

Accidental Spinal Cord Injury (SCI) The spinal cord can be accidentally damaged when the protective vertebrae surrounding the cord are broken and compress or sever the cord itself. If the damage occurs in the cervical, or neck, region of the spinal cord, the person will experience quadriplegia, or the loss of movement in both arms and legs. If the damage occurs in the lumbar region of the lower back, the person will experience paraplegia, the loss of movement in the legs.

Answer 7

ALS results from the degeneration of motor neurons in the spinal cord, brainstem, and motor cortex. The muscles served by these motor neurons degenerate when their input ceases. Patients experience muscle weakness, and about 15 percent experience frontotemporal dementia.

Answer 8

A progressive difficulty in all movements, resting tremors, and frozen facial expressions. Difficulty initiating voluntary movements. Reflexive movements are also impaired. This disease occurs when the dopaminergic neurons of the substantia nigra in the brainstem begin to degenerate. The substantia nigra forms close connections with the basal ganglia. The end result of degeneration is a lack of typical dopaminergic activity in the basal ganglia. Causes remain unknown Genetics play a role in early-onset but not in late-onset Exposure to environmental toxins Head injury Correlation with lack of coffee use Drug treatment of choice: L-dopa (pre curser to dopamine and does cross BBB so it goes all over brain and that can lead to side effects) Surgical treatments: pallidotomy, thalamotomy, electrical stimulation Stem cell transplantation

Answer 9

Genetic disorder that usually strikes in middle age and produces involuntary, jerky movements. will get it or not and when age bc gene. No cure or effective treatments Caused by abnormality in the Huntingtin gene on chromosome 4. Dominant gene, Abnormal proteins accumulate in basal ganglia Huntington’s disease causes degeneration of the caudate nucleus of the Basal Ganglia. Heredity and Presymptomatic Testing: Presymptomatic tests can identify with high accuracy who will develop the disease. The critical area of the gene includes a sequence of bases C-A-G (cytosine, adenine, guanine), which is repeated 11 to 24 times in most people. The higher the number of consecutive repeats of the combination C-A-G, the more certain and earlier the person is to develop the disease. C-A-G Repeats and Huntington: A variety of neurological diseases are related to C-A-G repeats in genes. In each case, people with the greatest number of repeats have the earliest onset of disease . Those with a smaller number will be older, if they get the disease at all. Recall that the genetic contribution is greater for early-onset than for late-onset Parkinson’s disease.

Answer 10

Homeostasis - Temperature regulation and other biological processes that keep certain body variables within a fixed range. - A precisely defined set point - Mechanisms for detecting deviations away from the set point - Internal and behavioral elements designed to regain the set point Set point - single value body works to maintain - deviation from set point will sweat, shiver, or paint so motivated behavior back Allostasis - adaptive way body anticipates your needs so thirsty not dehydrated just avoid errors so not have to correct later Motivation: Drive (push) theories - Organisms are pushed toward a goal to reduce tension and discomfort (hunger/thirst is not comfortable so motivated to find food or water) Incentive (pull) theories - Organisms are pulled toward a goal by the anticipation of rewards or incentives (chocolate cake not relieve hunger pain or anticipating dopamine for cake)

Answer 11

Where does all that energy go? Basal metabolism Basal metabolism - used to maintain constant body temp when at rest and most energy Surface-to-Volume Ratios: -- The higher an animal’s surface-to-volume ratio, the harder it must work to maintain core temperature so more energy --- Rats have larger surface-to-volume ratios than humans or elephants.

Answer 12

Endothermic (Homeothermic) human warm blood - temp constant Endotherms have automatic internal responses to deviations from the temperature set point. Responses to lower temperatures: Shiver Blood vessels constrict Thyroid hormones increases to boost metabolic rate Responses to higher temperatures: Perspiration, licking, panting Blood vessels dilate near skin surface We also use behavioral mechanisms like ectothermic animals - humans put on sweaters go in shade We spend about two-thirds of our total energy maintaining body temperature (basal metabolism). How warm is too warm? Above 105f proteins break bonds - bird is 105 Tardigrades are indestructible and live in extreme conditions Reproductive cells require a cooler environment than the rest of the body.

Answer 13

Ectothermic (Poikilothermic) - temp is regulated behaviorally and don’t need as many calories - temp not maintained Ectothermic animals: surviving in extreme cold Death will occur if body temperature drops below freezing. If body temperature drops below the freezing point of water, ice crystals form. Ice crystals tear apart blood vessels and cell membranes, killing the animal. Amphibians and reptiles avoid risk of cold using several methods: Withdraw fluid to store in ECF Antifreeze stock blood with at start of winter - chemicals cause ice crystals to form and not chunks no water freeze inside cell bc rip cell membrane so antifreeze makes not sharp crystals makes slush and they will withdraw most into extracellular not inside merbane If damage blood clot which repair An ectothermic animal, with a much lower level of basal metabolism, needs far less fuel. Birds and mammals keep their bodies warm at all times, regardless of air temperature, and stay constantly ready for vigorous activity. Iguana cold day fight predator but hot day run bc dont have energy

Answer 14

Fever - immune system works more but above 103 or 104 is doing more harm than good Hyperthermia (heat stroke)- A life-threatening condition in which core body temperature increases beyond normal limits. Hypothermia is a potentially fatal core body temperature below 95F.

Answer 15

Preoptic area (POA) of the hypothalamus, (along with adjacent areas of the anterior hypothalamus (AH) and septum), coordinate info from thermoreceptors with structures that trigger responses to higher core temps. - informing body to shiver, pant, sweat and damage means no sweat or shiver Posterior hypothalamus responsible for initiating responses to cooler core temps. POA receives input from temperature receptors in the skin, in the organs, and in the brain especially from the POA/AH itself. Immune system delivers prostaglandins and histamines to the POA.

Answer 16

Warm-sensitive neurons 30% (inhibit cold sensitive ones) warmer so send more AP and will inhibit the cold sensitive. These receptors respond directly to changes in the temperature of the brain and blood in their vicinity. Warm-sensitive neurons maintain a background level of activity that increases sharply when core temperatures surpass 98.6 F. - active and when fires inhibits cold from firing so warming the more freq the firing and when cold the firing goes down and the cold can now increase bc less inhibition (cold only active when warm are not) (inhibit the inhibitor than excitation) Cold-sensitive neurons 5% in posterior hypothalamus - as get colder the warm will fire less so the cold will fire more - seesaw. Cold-sensitive neurons receive inhibitory input from the warm-sensitive neurons. As core temperature drops below 98.6 F the reduced activity of the warm-sensitive neurons results in less inhibition of the cold-sensitive neurons, allowing them to increase their activity. Temperature-insensitive neurons 60% are baseline(24/7 control) in the posterior hypothalamus. These neurons maintain a steady rate of responding under all temperature conditions, yet they do have a role to play in thermoregulation. Input from the temperature-insensitive neurons provides a baseline of activity in the cold-sensitive neurons that is modified by the amount of inhibition provided by the warm-sensitive neurons.

Answer 17

Once in the POA, pyrogens stimulate the release of prostaglandin E2, which in turn inhibits the firing rate of warm-sensitive neurons (warm slow not inhibiting cold so now body thinks it is cold, not true the body is not actually cold caused by pyrogens) Reduced activity in the warm-sensitive neurons disinhibits the cold-sensitive neurons, increasing their activity, which fools the system into thinking the body is too cold. The hypothalamus responds by raising the temperature set point. Pyrogens Reset the Temperature Set Point in Fever

Answer 18

Intracellular fluid: cytoplasm Extracellular fluid contains body fluids in several compartments: Interstitial fluid Blood supply Cerebral spinal fluid Isotonic solutions have equal concentrations of solutes for osmotic thirst Example: Some intravenous (IV) fluids We typically stop drinking long before water levels in either the intracellular or extracellular compartments return to normal.

Answer 19

Osmosis- Water moves from an area of lower solute concentration to an area of higher solute concentration. Osmosis Causes Water to Move. Hypotonic solutions have a lower concentration of solutes compared to a reference solution. Hypertonic solutions have a higher concentration of solutes compared to a reference solution. Any excess sodium or water is excreted by the two kidneys, located in the lower back. The Sensation of Thirst - do not need 8 glasses of water a day will get from foods and other stuff Animals vary in their need to take in water. Drop in fluid levels initiates two processes: Sensation of thirst Conservation of remaining fluids

Answer 20

Blood enters the kidneys, where it is filtered through a complex system made up of more than a million structures known as nephrons. Impurities and excess water and sodium are removed by the nephrons and sent to the bladder for excretion as urine. The filtered blood returns to the circulation. We lose water through several other normal body processes.

Answer 21

The higher salt content makes the blood hypertonic, or more concentrated, relative to the intracellular fluid. Osmotic pressure will move water out of the cells to regain the balanced, isotonic state. Receptors sense the lower volume of water in the cells, and you begin to feel thirsty. Cellular dehydration is detected by specialized osmoreceptors in the brain. An area located around the third ventricle, the organum vasculosum of the lamina terminalis (OVLT), along with surrounding areas of the hypothalamus, detect cellular dehydration. The OVLT is a good place to detect blood solute levels because the blood–brain barrier is weak in this area. Animals with osmotic thirst have a preference for pure water.

Answer 22

Lower blood volume is sensed by receptors in the heart and kidneys. As blood volume decreases, blood pressure decreases as well. The wall of the heart muscle contains baroreceptors that measure blood pressure. The kidneys contain blood flow receptors that also respond to changes in blood volume. When low blood volume is perceived, thirst is initiated, and the kidneys act to conserve remaining fluids. Animals with hypovolemic thirst have a preference for slightly salty water (sodium-specific hunger).

Answer 23

When either cellular dehydration or hypovolemia is sensed, a sequence of hormone actions helps return fluid levels to their set point. Both osmoreceptors and baroreceptors stimulate release of antidiuretic hormone (ADH), also known as vasopressin, by the posterior pituitary gland located just below the hypothalamus. ADH signals the kidneys to reduce urine production to conserve fluid. Stimulates kidneys to release hormone renin into the blood supply. Once in the bloodstream, renin triggers the conversion of angiotensinogen, a blood protein, into angiotensin II. Angiotensin II constricts blood vessels, helping to maintain blood pressure. Angiotensin II also triggers the release of the hormone aldosterone from the adrenal glands, located above the kidneys. Aldosterone signals the kidneys to retain sodium rather than excrete it in the urine.

Answer 24

Animals vary in their eating strategies. Predators have large digestive systems adapted to huge, infrequent meals. Small birds eat only what is needed at the moment - so they can fly

Answer 25

Mouth digestion begins - salavea chewing Stomach hydrochloric acid to digest proteins and breakdown Small intestine - digest first place into blood stream abosrb Large intestine - water and minerals absorb leftover from small Large small extract into blood if not leave stomach The hormone cholecystokinin (CCK) is released when large quantities of fat are consumed. Also signal fullness Proteins are broken down into amino acids and used by muscles and other tissues for growth and protein synthesis. Carbohydrates are broken into simple sugars, including glucose. Excess glucose is stored as glycogen in the liver. Excess fat is stored in adipose tissue. If the body requires more energy than can be supplied by the glucose circulating in the blood, such as during a period of fasting, the liver converts stored glycogen back into readily available glucose. If continued fasting depletes stores of glycogen, all body structures except the brain begin to use fatty acids from adipose tissue for energy. Energy for the brain can be supplied by ketones, chemicals produced from stored fat by the liver. In addition, fasting causes muscle tissue to break down, and the liver converts the resulting amino acids into glucose.

Answer 26

The body’s supply of energy from glucose is regulated by hormones, glucagon and insulin, made by the pancreas. Glucagon converts stored glycogen back into glucose. Insulin assists in moving glucose from the blood supply into body cells and helps store glucose as glycogen. Need insulin to get nutrients into cells Type 1 diabetes mellitus occurs when insulin-producing pancreatic cells are attacked and destroyed by the body’s immune system. - remain hungry even though ur eating cells are starving - autoimmune Type 2 diabetes mellitus is when individuals produce insulin but their bodies either do not make enough insulin or do not use insulin efficiently—a condition known as insulin resistance. Produce insulin but body just ignores it - lifestyle choice difference and what happens if give leptin they ignore it who does it - more fat more lepitn Without normal insulin function, glucose from food circulates through the bloodstream without being absorbed or stored by the body’s tissues. Effects of Steady High Insulin Levels on Feeding: eating - blood glucose increases and insulin level is high - insulin helps glucose enter cells and hunger temporarily decrease - blood glcuose levels decline but insulin levels do not - rapid return of hunger - then eating again

Answer 27

Glucose hypothesis: Hunger can occur as a function of blood glucose levels. Glucose levels in the blood are high just following a meal. As glucose levels drop, a person begins to feel hungry again. Glucose levels are intimately tied to insulin levels. Lipostatic theory Receptors in liver monitor fatty acids If hunger results from low levels of available glucose and fats, receptors must assess nutrient levels and communicate with areas of the brain that initiate feeding behavior. Glucoreceptors in the liver influence the release of insulin from the pancreas. Find in hindbrain the medulla and liver Rats with lesions in the lateral hypothalamus (LH) would starve to death in the presence of food because they would not initiate eating.

Answer 28

After identifying the responsible gene, researchers found the peptide it makes, leptin. - the more leptin the less hungry and the more fat cells the more leptin, high levels of leptin say eat less, high levels leptin increase activity bc u have enough fat, hibernation and when pregnant ha slow leptin sensitivity bc need to eat more Long-term hunger regulation is accomplished by the monitoring of fat supplies by the body. The body’s fat cells produce the peptide leptin. The hormone ghrelin is produced primarily by the pancreas and the lining of the stomach. Receptors for ghrelin are found in the arcuate nucleus and the ventromedial hypothalamus. Levels of ghrelin are highest during fasting and decrease following a meal. Orexins (hypocretins) are produced in the lateral hypothalamus. Injection of orexins into the hypothalamus results in increased eating in rats. Levels of orexins are higher following food deprivation. Orexin cells are also stimulated by ghrelin, which again should lead to feeding. leptin levels are high vs low: When leptin levels are high, indicating sufficient fat is stored, the orexin cells are inhibited, and feeding is reduced. When leptin levels are low, indicating fat stores are low, the orexin cells are active, orexins are released, and feeding is stimulated.

Answer 29

Main signal to stop eating is the distention of the stomach. The arrival of foods containing fats and proteins at the duodenum signals the release of the peptide CCK. CCK promotes the release of insulin by the pancreas and contracts the gallbladder to release bile to help break down fats. CCK clearly contributes to feelings of satiety and injection with CCK antagonists increases eating. Stress combined with a high fat diet increases release of NPY and increases appetite. Sleep deprivation leads to overeating

Answer 30

The most successful treatments require a change of lifestyle, including increased exercise as well as decreased eating. Exercise helpful not strianous just constant like walking Reduce or eliminate the intake of soft drinks. Even if diet soda (intuitive eating ruined with diet soda or zero calorie) why bc body doesn't know how to deal with fake stuff Fructose is sweeter than common table sugar, the hope was that people could satisfy their craving for sweets without as many calories. Fructose increase people's problem stored in fatty liver but glucose stimulates release of leptin and glucrion to make hungry - fructose gain calories without feeling satisfied In one study, rats mostly ate the usual laboratory diet, but sometimes one group ate naturally sweetened yogurt while the other group ate yogurt sweetened with saccharin (noncaloric) they gained more weight