Biopsychology- Internal Regulation

ghrelin

"hunger hormone" that is released by the stomach during a period of food deprivation; this causes stomach contractions and also acts on the hypothalamus to decrease appetite; acts on the hippocampus to enhance learning

separate populations, different aspects

.... of cells within the POA/AH and a couple other hypothalamic areas regulate .... of temperature regulation

taste, chew

..... and .... are needed for food satiety

what are the four ways the lateral hypothalamus contributes to feeding?

1) axons from the lateral hypothalamus to the NTS to alter taste sensation and salivation response 2) axons from the lateral hypothalamus extend to several parts of the cerebral cortex and facilitate ingestion and swallowing 3) the lateral hypothalamus increases the pituitary gland's secretion of hormones that increase insulin secretion 4) the lateral hypothalamus sends axons to the spinal cord to control autonomic responses like digestive secretions

supraoptic nucleus and the paraventricular nucleus

2 areas of the hypothalamus which control the rate a which the posterior pituitary releases vasopressin

sequence of a fever

Leukocytes (white blood cells) → cytokines (released by immune cells) → stimulate vagus nerve (& attacks invader) → hypothalamus (has receptors for prostaglandins and will cause a fever) → ↑ prostaglandins → fever

neuropeptide Y

a decrease of what inhibitory NT is related to decreased eating

vasopressin

a hormone released from the posterior pituitary that raises blood pressure by constricting blood vessels; this conserves water b/c it is an antidiuretic hormone

set point

a single value/state that the body works to maintain

aldosterone

adrenal glands produce this hormone when the body's sodium reserves are low; causes the kidneys, salivary glands, and sweat glands to retain salt

low sodium, low blood volume

aldostrone indicates .... and angiotensin II indicates ...

generates heat, radiates heat

an animal .... in proportion to its total mass, but it ... in proportion to its surface area

homeothermic

animals who use physiological mechanisms to maintain a nearly constant body temperature despite changes in the temperature of the environment; this is costly energy wise

poikilothermic

animals whose body temperature matches the temperature of their environment (cold-blooded)

subfornical organ (SFO)

area important for detecting osmotic pressure and salt content in the blood; projects info to the supraoptic nucleus and the paraventricular nucleus, and the lateral pre optic area; near third ventricle where BBB is leaky which enables this area to detect what is in the blood stream and notice a lack of tension in cells as a signal that the body is dehydrates

OVLT

area important for detecting osmotic pressure and salt content in the blood; receives input from receptors in the brain and from receptors in the digestive tract, enabling the brain to anticipate an osmotic need before the rest of the body experiences it; projects info to the supraoptic nucleus and the paraventricular nucleus, and the lateral pre optic area; near third ventricle where BBB is leaky which enables this area to detect what is in the blood stream and notice a lack of tension in cells as a signal that the body is dehydrates

lateral hypothalamus

area of the brain that receives input from the PVN; activation of this area will produce: • changes in the nucleus of the solitary tract → perception that food is better tasting • changes in cerebral cortex → facilitating ingestion, response to food cues • activation of pituitary gland → increased insulin secretion • activation of ANS → increased digestive secretions

paraventricular nucleus (PVN)

area of the hypothalamus that releases melanocortin when excited by satiety cells in the accurate nucleus; critical to limit eating

pre optic area/anterior hypothalamus (POA/AH)

areas of the brain that regulate and defend body temperature through shivering, sweating, changing blood flow; send output to hindbrain's raphe nucleus which controls physiological mechanisms

gastric bypass surgery

bypass portion of the stomach and small intestine to create a smaller stomach and less of a chance of absorbing calories in the small intestine; leads to dramatic weight loss •risk of malnourishment (people who have this surgery must eat highly nutritiously) •often feel overly-full/uncomfortable (nimiety) •side effects: infections, bowel obstructions, leakage of food, nutritional deficiencies •best course of action: put person in a program about a year before the procedure to make sure the person is aware of how to handle their condition •risk of dying; highly invasive procedure

leukocytes (white blood cells)

cells that attack bacteria, viruses, fungi, or other invaders in the body; release cytokines

prostaglandins

chemicals in the hypothalamus that are necessary for producing fever; released as a result of white blood cell mobilization

vagus nerve

cranial nerve that conveys info about the stretching of the stomach walls, providing major basis for satiety

satiety pathway

distention of intestines --> neurons to release CCK (short term signal) -->stimulates satiety cells in the arcuate nucleus --> increased secretion of insulin (also stim. satiety cells)-->PVN (hypothalamus) --> inhibits lateral hypothalamus

process of osmotic thirst

eating salty foods → stomach → small intestines with villi → blood vessels in the villi that will absorb nutrients from the digested food → such a high concentration of salt, water is pulled out from the cells, increasing interstitial fluid and leaving cells "deflated"

angiotensin II

enzyme that constricts the blood vessels when blood volume drops (result of vasopressin release), compensating for a drop in blood pressure; also helps trigger hypovolemic thirst in conjunction with receptors that detect blood pressure in large veins; stimulates neurons in areas near the 3rd ventricle and is released as a NT in the hypothalamus

triglycerides

fats and amino acids that we get from food are stored in the body as...; amino acids may be used to build things within the body as well

glycogen, then triglycerides

glucose that we get from food are stored in the body as...; this is used as energy

fever

higher body temperature that represents an increase set point for body temperature; advantages include being too hot for bacteria to grow and enhancing immune system functioning; disadvantages include dying from too high of a temperature

orexin/hypocretin

hormone released by the lateral hypothalamus that has 2 roles in feeding; 1) increases persistence in seeking food; 2) responds to incentives or reinforcement in general; stimulation to these receptors increase activity and motivation; can override satiety receptors causing you to eat even when you are not hungry

insulin

hormone that enables glucose to enter cells and stimulates glycogenesis (except brain cells b/c they are already able to enter); when levels of this hormone are high, glucose enters cells easily and experience decreased appetite; when levels are low, glucose enters cells more slowly and hunger increases; in people with type I diabetes, the pancreas no longer makes this hormone

antidiuretic hormone

hormone that increases water retention; enables kidneys to reabsorb water from urine and make the urine more concentrated; increased levels during sleep when you cannot drink

cholecystokinin (CCK)

hormone that limits meal size in 2 ways; 1) it constricts the sphincter muscle between the stomach and duodenum, causing the stomach to hold its contents and fill more quickly 2) it stimulates the vagus nerve to send signals to the hypothalamus, causing cells there to release an NT that is similar to the hormone itself; this hormone produces short term effects only

glucagon

hormone that stimulates the liver to convert some of its stored glycogen to glucose to replenish low supplies of glucose in the blood; stimulates glycogenesis, lipolysis, then gluconeogenesis (using proteins)

body monitors swallowing and detects distention of the stomach/small intestine to limit drinking

how do we stop ourselves from drinking too much, even when we are dehydrated?

examining its own temperature and receiving input from temperature receptors in the skin and spinal cord

how does the POA/AH detect external temperature?

receptors around the 3rd ventricle (have leakiest BBB)

how does the brain detect osmotic pressure?

dopamine

many axons containing ... pass through the lateral hypothalamus that contribute to ability to feed

sham-feeding

method of feeding animals by delivering nutrients through tubes inserted in the stomach so the animal cannot taste or chew the food; animals that are fed this way eat and swallow almost continually without becoming satiated

they are desensitized to leptin (this is caused by damage to the endoplasmic reticulum in neurons of the hypothalamus; can only be reversed with exercise)

most obese people produce leptin; why don't they stop overeating?

digestion pathway

mouth (enzymes break down carbohydrates) --> esophagus -->stomach (mixes w/ HCl and enzymes to digest proteins--> thru duodenum --> small intestine (enzymes digest proteins, fats, and carbs, nutrients enter bloodstream)--> large intestine (absorbs water/nutrients)

splanchnic nerves

nerves that convey information about the nutrient contents of the stomach

GABA, neuropeptide Y, agouti-related peptide

neurotransmitters that are released by hunger-sensitive neurons and are inhibitory to the PVN and the satiety cells of the accurate nucleus; NTs block satiety actions of the PVN, causing the person overeat until death

arcurate nucleus

nucleus in the hypothalamus that has one set of neurons that are sensitive to hunger signals and a second set of neurons that are sensitive to satiety signals; hunger-sensitive neurons receive input from the taste pathway and grehlin to produce hunger; satiety sensitive cells deliver an excitatory message to the PVN, which then releases melanocortin

syndromal obesity

obesity that results form a medical condition like Prader-Willi syndrome (too much grehlin)

shivering

one mechanism we can use to increase body heat in a cold environment; muscle contractions generate heat

decreased bloodflow to skin

one mechanism we can use to increase body heat in a cold environment; this prevents the blood from cooling too much

stomach

osmoreceptors in this area of the body monitor how stretchy the cell membranes are to determine whether the body is dehydrated

neural pathway of osmotic thirst

osmotic receptors (osmoreceptors) → hypothalamus (e.g., supraoptic nucleus & paraventricular nucleus) → posterior pituitary (secretes vasopressin, leading to vasoconstriction, retention of sodium & water) → lateral preoptic area (leading to drinking behavior) this makes you want to drink and interested in drinking

ventromedial hypothalamus (VMH)

output from this area inhibits feeding; damage here leads to overeating and weight gain (increased insulin production results in higher storage of fats); to produce a large effect, a lesion must extend outside of this area to invade nearby axons

lateral preoptic area

part of the hypothalamus that controls drinking

duodenum

part of the small intestine adjoining the stomach; first digestive site that absorbs a significant amount of nutrients; fat here releases oleoylethanolamide that stimulates the vagus nerve, which sends a message to the hypothalamus that delays the next meal

leptin

peptide that is only found in vertebrates and acts as a "fat-monitoring" of the body's supplies; this is produced by the body's fat cells; this signals to your brain about your fat reserves, providing a long term indicator of whether you have been overeating or underrating; each meal releases this and when levels of this are high, it means you have plenty of nutrition and will increase activity of your immune system

osmotic pressure

pressure that occurs when solutes are more concentrated on one side of the membrane than on the other; if you eat something salty, sodium ions spread through the blood and the extra cellular fluid but do not cross the membranes into cells- the result is a higher concentration of solutes outside the cells than inside; pressure draws water from the cells into the extracellular fluid resulting in osmotic thirst

negative feedback

processes that reduce discrepancies from the set point; something causes a disturbance, and behavior proceeds to relieve the disturbance

cytokines

proteins released by leukocytes that attack foreign intruders in the body; also stimulate the vagus nerve to send info to the hypothalamus to increase prostaglandins

increased stomach motility and secretions, increased insulin production

rats with damage to their VMH ate normal sized meals, more frequently. Why?

osmoreceptors

receptors that detect the stretch of the cell membrane to determine whether the body is hydrated or not

baroreceptors

receptors that lie in the kidneys and the atria of the heart that detect how stretchy the membrane of the body's cells are to determine blood pressure; if there is low blood pressure this means you are suffering from volumetric thirst

sodium-specific hunger

strong craving for salty tastes; develops automatically as a result of hypovolemic thirst

anterior hypothalamic/preoptic area

structure in the brain that monitors its own temperature via receptors in the skin, spinal cord, and within the structure itself; able to help maintain body temperature based on the neural mechanism of what temperatures it perceives from its receptors

satiety mechanism for osmotic thirst

swallowing & water content of stomach (receptors in throat and stomach relay info that water has been consumed) → anterior cingulate cortex → satiation (OVLT/SFO are still active until they absorb all the water you have ingested) (we need this b/c it takes about 15 min for the water to enter your cells; if we drink too much, our cells will explode)

homeostasis

temperature regulation and other biological processes that keep the body variables within a fixed range

allostasis

the adaptive way in which the body changes its set points depending on the situation

basal metabolism

the energy used to maintain a constant body temperature while at rest; requires about 2/3 of your energy

evaporation

the main mechanism we have of cooling ourselves; could occur through sweating, panting, licking

stomach distension

the main signal to stop eating

hypovolemic thirst

thirst based on low blood volume; shows increased preference for slightly salty water instead of pure water (will dilute body fluids)

satiety arcurate nucleus

this area activates alpha-melanocyte stimulating hormone (alpha-MSH) which activates the paraventricular nucleus in the hypothalamus, resulting in the inhibition of the lateral hypothalamus (hunger) and orexin release; this area also inhibits the hunger arcurate nucleus resulting in satiation

hunger arcurate nucleus

this area activates the lateral hypothalamus and stimulates release of orexin, while inhibiting the paraventricular nucleus and the satiety arcurate nucleus using chemicals such as GABA, AgRP, and NPY; this results in hunger and feeding behavior

melanocortin

type of chemical that is released by nuclei in the PVN; important for limiting food intake; deficiencies in receptors lead to overeating

neural mechanism for volumetric thirst

volumetric receptors (baroreceptors) → renin (from kidneys) → interacts with angiotensinogen to create angiotensin I → angiotensin II (interacts with 3 areas) • & → area adjoining 3rd ventricle → hypothalamus → angtiotensin II (in brain) → drinking behavior • & → (with aldosterone) → modulate receptors on tongue & nucleus of solitary tract → salt appetite • & → (with vasopressin) → vasoconstriction

putting on/taking off clothing, becoming more active, huddling

what are some behavioral mechanisms that help us with temperature regulation

warm (ready to use) muscles (less fatigue)

what are some of the advantages of maintaining high body temperature?

it eats as much as possible, tries not to move much, and cannot enter puberty (this can be relieved with leptin injections)

what happens if an animal does not have the gene that produces leptin?

can only regulate temperature by seeking warmer/colder locations

what happens when mammals sustain full damage to POA/AH?

.15 M

what is the combined concentration of all solutes in mammalian body fluids? (this is a set point)

aldostrone and angiotensin II

what two hormones together will change the properties of taste receptors on the tongue, neurons on the tractus solitarius, and neurons in the brain to increase salt intake

reproductive cells (this is why your balls hang low)

what type of cells require a cooler environment than the rest of the body?

posterior hypothalamus, norepinephrine

when the AH/POA senses that the body is cold, it activates the....; this stimulates the brainstem's motor area resulting in involuntary contraction in muscles (shivering), and the NT .... is increased in order to cause vasoconstriction

norepinephrine, cholinergic activity

when the AH/POA senses that the body is hot, it inhibits the NT ....; this causes the receptors to increase vasodilation and reduce the metabolism, heat escapes through the skin, and increased ..... increases sweating

insulin and glucagon, pancreas

which hormones control the flow of glucose? where are they being secreted from?

sequence of digestion

• Mouth (carbohydrates) • Esophagus to stomach (proteins) • round sphincter muscle (i.e., pylorus) • small intestine (duodenum**, proteins, fats, carbohydrates, then jejunum) • bloodstream • large intestine (wastes, absorbs minerals, water)

anorexia nervosa

•Body image distortion: you believe you are fatter than you actually are (body dysmorphia) •< 85% of normal weight (must be at least 15% underweight) •prominent symptom: intense fear of getting fat •amenorrhea •restricting vs. binge/purge subtype o restricting-highly restrictive of food intake o binging and purging but still severely underweight • purging: vomiting, excessive exercise

bulimia nervosa

•recurrent binge (highly impulsive, no control) o prominent symptom: sense of lack of control •recurrent compensatory behavior (vomiting, excessive exercising, laxatives) •2X/week for at least 3 mos. •self-evaluation is unduly influenced by body weight/shape o not AN b/c they can accurately perceive their own weight o but they do think that they are horrible person when they engage in binging and purging(self-evaluative meaning) •purging vs. non-purging subtype