Chapter 10 Internal Regulation Flashcards
Agouti-related peptide (AgRP)
inhibitory transmitters that block the satiety actions of the paraventricular nucleus
Aldosterone
adrenal hormone that causes the body to retain salt
Allostasis
the adaptive way in which the body changes its set points depending on the situation
Angiotensin II
hormone that constricts the blood vessels, compensating for the drop in blood pressure; triggers thirst
Antidiuretic hormone (ADH)
hormone that enables the kidneys to reabsorb water from urine; also known as vasopressin
Arcuate nucleus
hypothalamic area with sets of neurons for hunger and satiety
Basal metabolism
energy used to maintain a constant body temperature while at rest. See also Body temperature
Bulimia Nervosa
a condition in which people alternate between binges of overeating and periods of strict dieting
Cholecystokinin CCK
hormone released from the duodenum that constricts the sphincter muscle between the stomach and duodenum, limiting the meal size
Cytokines
small proteins that combat infections and communicate with the brain to elicit appropriate behaviors
Duodenum
part of the small intestine adjoining the stomach; first digestive site that absorbs nutrients
Ghrelin
chemical released by the stomach during a period of food deprivation; also released as a neurotransmitter in the brain, where it stimulates eating
Glucagon
pancreatic hormone that stimulates the liver to convert stored glycogen to glucose
Homeothermic
using physiological mechanisms to maintain a nearly constant body temperature despite changes in the environment’s temperature
Hypovolemic thirst
Thirst based on low blood volume
Insulin
pancreatic hormone that enables glucose to enter the cells
Lactase
intestinal enzyme that metabolizes lactose
Lactose
Sugar in milk
Lateral hypothalamus
area of the hypothalamus that controls insulin secretion, alters taste responsiveness, and facilitates feeding in other ways
Lateral Preoptic Nerve
part of the hypothalamus that controls drinking
Leptin
peptide produced by the body’s fat cells
Melanocortin
type of chemical that promotes satiety
Negative feedback
homeostatic processes that reduce discrepancies from the set point
Nucleus of the tractus solitarius NTS
structure in the medulla that receives input from taste receptors
Osmotic Pressure
tendency of water to flow across a semipermeable membrane from the area of low solute concentration to the area of high solute concentration
Osmotic Thirst
thirst triggered by certain neurons that detect the loss of their own water
OVLT (organum vasculosum laminae terminalis)
brain area that detects osmotic pressure and salt content of the blood
Paraventricular nucleus (PVN)
Paraventricular nucleus (PVN) part of the hypothalamus in which activity tends to limit meal size and damage leads to excessively large meals
Poikilothermic
maintaining the body at the same temperature as the environment
Preoptic area/anterior hypothalamus (POA/AH)
brain area important for temperature regulation, thirst, and sexual behavior
Set Point
a value that the body works to maintain
Sham-feeding
procedure in which everything that an animal swallows leaks out a tube connected to the esophagus or stomach
Sodium specific hunger
an automatic strong craving for salty tastes
Splanchnic nerves
Splanchnic nerves
nerves that convey information about the nutrient contents of the stomach to the brain
Subfornical organs
brain structure adjoining the third ventricle of the brain, where its cells monitor blood volume and relay information to the preoptic area of the hypothalamus
Supraoptic nucleus
part of the hypothalamus that controls the release rate of vasopressin
Vagus nerve
tenth cranial nerve, which has branches to and from stomach and several other organs
Ventral medial hypothalamus
region of the hypothalamus in which damage leads to faster stomach emptying and increased secretion of insulin
What is a homeostatic process?
tendency to maintain a variable such as temp within a fixed range.
resembles a thermostat in a house
What are some physiological processes that are controlled near a set point? What are some homeostatic processes that anticipate future news or that change under various conditions?
Set point: a value that the body works to maintain
eg: ca [ ] of 0.1g/L, blood levels of water, O2, glucose , Na Cl protein fat and acidity.
Changes in set point values-body fat (increase in fall, decrease in spring)
temp increase in day and decrease at night
What does the scrotum of most male mammals hag outside the body? why should pregnant women avoid hot baths
sperm need to be at cooler temp
increase in ten is dangerous for baby
Define the term poikilothermic and homeothermic
Poikilothermic-maintaining the body temp at same temp as environment
Homeothermic-using physiological mechanisms to maintain a nearly content ten despite the changes in the environment.
What is a major advantage of a constant body temp? What is the cost to the animal for maintaining homeothermy?
adv: constantly ready for vigorous activity
homeothermy is costly for small animals
an animal generates heat in proportion to its total mass but ut radiates heat in proportion to its surface area,
Small animals have increased surface to vol ration and therefore requires a lot of fuel.
What two kinds of stimuli does the pre optic area monitor for temperature control?
Physioloical changes of shivering etc rely on areas near the hypothamius mainly the anterior hypothalamus and the pre optic area(near the optic chiasm) calle dthe pre optic area/anterior hypothalamus (POA/AH)
Monitors 1. body temp (its ow) POA/AH-if its cold si is the rest of the body
2. temp receptors in skin and spinal cord
What prevents the temperature of fish, amphibians, and reptiles from fluctuating wildly?
remain warm by seeking an appropriate warm location
What are prostaglandins E1 and E2 and what are their roles in producing a fever?
release of prostaglandins, stimulates a specific receptor in nucleus of the hypothalamus is necessary for a fever
Of what benefit is a fever?
defines against viral/ bacterial infections
enhaces immune activity
some bacteria can’t do as well under increase temp
Describe the different mechanisms of maintaining water balance that have been developed by desert animals and by animals with an abundant water supply
beavers drink plenty of water etc. and excrete dilute urine. whereas gerbils don’t need to drink at all-they gain H2O from their food and excrete dry feces and concentrated urine
What are the two functions of vasopressin when body fluids are low? what is its other name?
posterior pituitay releases the hormone vasopressin that raises blood pressure by contracting the blood vessels
- increased bp to compensate for decreased body fluids level
- also known as antidiuretic hormone ADH it enables kidneys to reabsorb water from urine.
What is osmotic pressure?
tendency of water to flow across a semipermeable membrane from an area of low solute concentration to an area of higher concentration
How does the body “know” when its osmotic pressure is low?
- certain neurons detect their own loss of water that triggers osmotic thirst
- brain detects osmotic pressure by getting information from receptors around the third ventricle
What are the roles of the OVLT, the supraoptic and paraventricular nuclei of the hypothalamus and the lateral preoptic area?
organum vasculosum laminae termihalis (OVLT) receives input from receptors in the brain itself and from receptors in the digestive tract enabling the brain to anticipate an osmotic need before the rest of the body experiences it.
Supraoptic nuclei and paraventricular nucleus (PVN) parts of the hypothalamus controls the rate at which the posterior pituitary releases vasopressin lateral pre optic area -controls drinking
Why is hypovolemia dangerous?
eg lose significant vole by bleeding or diarrhoea
heart having trouble pumping blood to head and nutrient does not flow easily
-body reacts with hormones that constrict blood vessels vasopressin and angiotensinII and kidneys release renin
Under what circumstances does hypovolemic thirst occur?
angiotensin II triggers thirst need to replace salt as week as vol.
Will an animal with hypovolemic thirst drink more pure water or more salt water with the same concentration as blood? Why
drink more salt water because it is craving the salt
otherwise it would dilute body fluids too much
What steps lead to the production of angiotensin II? What are its two main effects?
low blood vol=>kidneys release more renin=>portents in blood from angiotensin I=>angiotensin I converted to angiotensin II=> angiotensin II contracting blood vessels and stimulating cells in subfornical organ increases drinking.
Which brain structures seem to mediate hypovolemic thirst?
third ventricle neurons adjacent to third ventricle=>send axons to hypothalamus-where they release angiotensin II as their neurotransmitter.
Neurons close to third ventricle respond to andgiotensin II and release it.
What two effects of aldosterone are beneficial in cases of sodium deficiency? what other hormone contributes to salt hunger?
adrenal glands produce the hormone aldosterone when body’s sodium reserves are low=>kidneys and salivary glands and sweat glands to retain salt
angiotensin II together with aldosterone => increase salt intake.
Enzymes for the digestion of what type of nutrient(s) are present in saliva ? In the stomach? In the small intestine?
saliva-amylase breaks down carbohydrates
stomach-hydrochloric acid and enzymes to break down proteins
small intestine enymes to digest proteins, carbs, and fats
From which structures is digested food absorbed?
small intestine
Why do newborn mammals stop nursing as they grow older?
level of lactase decreases
Discuss the evidence that humans are a partial exception to the principle of lactose intolerance in adults
many humans have enough lactase to consume milk and or other dairy well into adulthood
list the factors that may influence food selection
Leptin produced by bodys fat cells = signals brain about fat reserves
just seeing food makes you want it (seeing a pic of food too)
Summarize the evidence for the importance of oral factors in hunger and satiety. What is the evidence that these factors are not sufficient to end a meal normally?
urge to chew is strong - people want to fast and chew food
Sham feeding -chewed and swallowed by food went out of a tube
They chewed and swallowed continuously
How did Deutsch et al. show the importance of stomach distension in regulating meal size?
inflated a cuff at connection of stomach to small intestine => stomach distention => signals full
Which two nerves convey the stomach’s satiety signals?
vagus nerve (cranial nerve X)-conveys information about the stretching of stomach walls Splanchnic nerves-conveys information about the nutrient contents of the stomach
What is CCK? In what two places is it produced? what is one likely mechanism by which it induces satiety?
Cholecystokinin-a hormone that limits meal size in two ways
- constricts sphincter muscles between stomach and duodenum => signal satiety
- 2nd stimulates the vagus nerves to send signals to the hypothalamus causing cells to release chemical shorter than CCK
What evidence suggests blood glucose is or is not impt in the regulation of appetite?
Blood glucose stays fairly steady because Increase in gluc=>storage as glycogen in liver and vice versa
What is the effect of insulin on blood glucose? In what ways does insulin affect hunger? Compare the effects of glucagon with those of insulin
insulin enables glucose to enter cells except brain cells
Insulin levels rise in prep for meal
in general increased insulin levels lead to decreased hunger
decreased insulin = less glucose entering cells => hunger
glucagon stimulates liver to convert some of its stores to glucose
Why do people with untreated diabetes eat a lot but gain little weight? How is this similar to and how is it different from the effects of high levels of insulin?
untreated diabetes their insulin level is constantly low and glucose is hight but none of it can enter cells=> eating
=> prolonged increase in insulin also => more eating
What is the result of damage to lateral hypothalamic cell bodies?
Many axons containing dopamine pass thru the lateral hypothalamus so damage to the lateral hypothalamus inter ups these fibers
- major loss of feeding without loss of arousal and activity
- refuse to eat or drink
By what four mechanisms may the lateral hypothalamus contribute to feeding?-
-axons from the lateral hypothalamus alter taste sensation and salivation in response to tastes (makes food taste better)
-axons form lateral hypothalamus extend into several parts of the cerebral cortex facilitating injection and swallowing and causing cortical cells to increase their response to the tastes
increase pituitary glands secretion of hormones that increases insulin secretion
describe the various behavioural chafes produced by lesions of the ventromedial hypothalamus, ventral norandrengeric bundle and surrounding areas. Can we say that animals with such lesions show an overall increase in hunger of pact of satiety?
ventromedial hypothalmus-inhibits feeding
therefore damage to the is area leads to increased eating
To what factories can we attribute the obesity induced by ventromedial hypothalamus lesions?
Damage must extend beyond ventromedial hypothalamus into axons in surrounding area
store lots of fat and eat very frequently but normal sized meals
However damage to PVN=large meals
What are the effects of damage to the paraventricular nucleus (PVN) How are these effects different from those of ventromedial hypothalamus damage?
Paraventricular nucleus inhibits that lateral hypothalamus
therefore the paraventricular nucleus is impt for satiety-sensitive cells of the arculate nucleus of the hypothalamus.
What type of cells produce leptin? What message does leptin convey? Is there any evident hat oversight humans produce too little leptin?
bodies fat cells produce leptin
More fat = more leptin
Leptin signals your brain about your fat reserves
-a mouse that overeats gets injected with leptin stops eating as much
-overweight people however have enough but have become desensitized
What brain area is inhibited by neuropeptide Y (NPY)? what are the effects of NPY on feeding? What chemical inhibits the release of NPY?
neuropeptide Y and agouti related peptide block the satiety actions of the paraventricular nucleus in some cases causes extreme overeating
What are two means by which CCK inhibits feeding? What are the effects of glucagon and GLP-I?
Distension of the intestines triggers neurotransmitter CCK to be released=> be full
insulin, CCK, and leptin increase satiety
Ghrelin increases hunger
Give one example a group of people who demonstrate the relationship of genetic and environmental factors in the control of weight. How important are exercise and restraint of eating?
thin people have thin children
melanocortin-mutated gene for one of the neuropeptides responsible for hunger
variant gent FTO-overeating
genetics and environmental-native american pima of arizona and mexico-seriously overt evolved a tendency to conserve wt.
Compare symptoms of anorexia nervosa with those of bulimia nervosa
anorexia-font eat at all
Bulimia-perios of eating binges and starving.
Describe the personality characteristics of many people with anorexia and their relatives
don’t find pleasure in eating
don’t eat food too much
What chemical differences are seen in bulimia, compared to other people. Can we determine cause and effect relationships between these chemicals and their disorder?
Increased Ghrelin-hormone associated with Increased appetite but may be due to byproduct of binging etc rather than cause
