Physiological Psychology Module 4

Homeostasis

the tendency of a system, primarily the physiologicalsystem of higher animals, to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that tends to disturb its normal condition or function

positive feedback loop

to amplify the change

Hormones

are made of proteins

negative feedback loop

to reverse the change of direction in a system

3 parts of maintaining homeostasis

receptor, control center, effector

Walter Cannon

coined the term homeostasis

setpoints

the thermostat of your home's heating system

process of motivation

both activates and directs behavior

drive states

it arises in response to physiological needs and disappear again, usually with a sense of relief when those needs are met.

Temperature regulation

involves all the major features of a homeostatic system: a precisely defined set point, mechanisms for detecting deviations away from the setpoint, and, finally, internal, and behavioral elements designed to regain the set point

endotherms

(mammals and birds) ability to maintain body temperature through internal metabolic activity

ectotherms

(Amphibians, reptiles, and fish) they rely on external factors

Raynaud's disease

This condition produces sudden spasms in arteries, particularly those in fingers and toes, in response to cold.

Deficits in thyroid activity

diagnosed based on the patient's lower-than-normal body temperature

sympathetic nervous system

responds to cold by stimulating more significant metabolic activity in so-called brown fat cells

body's core temperature

refers to the temperature maintained for vital organs within the head and torso.

hot flashes

Disturbances in the body's ability to maintain the average core temperature point

Temperature regulation

results from a structural hierarchy activity, beginning with the spinal cord and extending through the brainstem to the hypothalamus

Lower levels

(spinal cord) do not respond to heat or cold until an animal's core temperature is as much as two to three degrees away from the set point

higher levels

act as much more precise thermostats

hypothalamus

initiates compensation whenever core temperature deviates as little as 0.01 degrees from the ideal set point

solutes

Molecules dissolved in a fluid

solution

fluid that contains solutes

electrolyte

If a solute break into ions and dissolves

Sodium

the most important electrolyte for managing the body's fluid levels

intracellular fluid

• two-thirds of the body's water found within cell

• has higher potassium concentration

extracellular fluid

• into the blood supply (7 percent of the body's water total)

• higher concentrations of sodium and chloride

isotonic

two solutions with equal concentrations of solutes

Intravenous (IV) Fluids

typically, isotonic solutions containing sugars and sodium

nephrons

it removes the impurities and excess water and sodium

Walter Cannon

He proposed that the sensation of a dry mouth was the critical stimulus responsible for feelings of thirst, leading to drinking.

Fluid regulation

Although the feelings of dry, dusty mouth and throat certainly stimulate us to take a drink, these feelings are too quickly relieved to be trusted entirely as a means of .

Claude Bernard

He surgically produced an opening, or fistula, in the esophagus of animals.

osmotic thirst

Occurs in response to cellular dehydration that results from drops in the intracellular fluid volume.

Hypovolemic thirst

Occurs in response to drops in blood volume

double depletion hypothesis

suggests that a combination of these processes contributes to thirst

higher salt content

it makes the blood hypertonic, or more concentrated, relative to the intracellular fluid

Osmotic pressure

moves water out of the cells to regain the balanced, isotonic state

untreaded diabetes

People with __ cannot move sugars out of the blood supply, causing the blood to become hypertonic.

diabetes mellitus

it's early warning signs is the intense sensations of thirst accompanied by frequent urination

osmoreceptors and baroreceptors

stimulate the posterior pituitary gland to release antidiuretic hormone (ADH)

antidiuretic hormone (ADH)

• controls the retention of water

2 effects on kidney:

1. signals the kidneys to reduce urine production

2. stimulates the kidneys to release the hormone renin into the blood supply

renin

released in response to activity in the kidneys' blood-flow receptors

Angiotensin II

Once in the bloodstream, renin triggers angiotensinogen's conversion, a blood protein, into ___

Angiotensin I

Produced as a brief interim step between the blood proteins and angiotensin II

Angiotensin II

constricts blood vessels, helping to maintain blood pressure; triggers the release of the hormone aldosterone from the adrenal glands

Aldosterone

signals the kidneys to retain sodium rather than excrete it in the urine; controls the retention of sodium

Sodium

essential to the maintenance of the extracellular fluid

subfornical organ (SFO)

Angiotensin II appears through its action on the . It's location is below (sub) the fornix, near two lateral the OVLT.

electrical stimulation of the SFO

produces drinking behavior

Median preoptic nucleus

• Unlike the OVLT and the SFO, it is located in the area where the blood-brain barrier is weak

• it does not contain receptors for angiotensin II

• receives input from the solitary tract (NST) nucleus, which is in the medulla

angiotensin

serves as a neurotransmitter in connections between the SFO and median preoptic nucleus

solitary nucleus

receives input from baroreceptors located in the circulatory system and osmoreceptors located in the digestive tract

lateral hypothalamus (LH)

which projects to the midbrain's zona incerta

zona incerta

• sends information to several motor regions, including the basal ganglia, the red nucleus, and the spinal cord

• produces drinking behavior, suggesting that this structure is responsible for initiating the drinking behavior's motor components

brain's septal area

Lesions of the _ generally produce overdrinking, suggesting that this structure plays a role in the cessation of drinking

hyponatremia

condition in which extracellular sodium levels drop 10 percent or more below average

pancreas

• produce glucagon and insulin

• a large gland located behind the stomach

glucagon

converts glycogen back into glucose

insulin

helping glucose circulating in the blood supply to move into cells and stored as glycogen

Type 1 diabetes mellitus

usually occurs when the body's immune system destroys insulin-producing pancreatic cells

high glucose cells

excreted in the excess circulating glucose cause an imbalance of solutes between the intracellular and extracellular compartments, producing enormous thirst

type 2 diabetes mellitus

diagnosed when individuals produce insulin, but their bodies either do not make enough insulin or use insulin efficiency-- a condition knows as insulin resistance

fructose

leads to insulin resistance and other pre-diabetic states

low levels of insulin and glucose

corresponds with fasting and feeling of hunger

high levels of insulin and glucose

corresponds to satiety

leptin

fat cells produce and secrete a substance knowns as __

satiety

fullness, occurs long before sufficient nutrients make their way into cells

peptide cholecystokinin (CCK)

promotes insulin release by the pancreas and contracts the gallbladder to release bile to help break down fats; functions in the brain as a neurotransmitter related to satiety

ventromedial hypothalamus (VH)

satiety center

Alpha-MSH and CART

• cause the pituitary gland to release TSH and ACT, raising body metabolic rates

• activate the autonomic nervous system's sympathetic division, increasing metabolism and body temperature and inhibiting feeding behavior

Sohal and Weindruch

suggested that eating promotes some unknown byproducts and accelerate the cellular level's aging process

Body Maxx Index (BMI)

• system for determining ideal weight

• computed by dividing a person's weight in kg by the square of their height in meters

BMI 18.5 and 24.9

appears to live the longest (BMI)

BMI: 25 to 29.9

overweight BMI

BMI: 30 to 39.9

obese BMI

BMI: 40 or more

morbidly obese BMI

Morbid obesity

limits activity and normal physiological functions and puts a person at high risk for disease and death

anorexia nervosa

"loss of appetite"; individuals maintain 85 percent or less of their average body weight while demonstrating a distorted image of their bodies as obese

Bulimia Nervosa

a cyclical pattern of binge eating followed by purging through vomiting or use of laxatives

Hsu, Chester, and Santhouse

reported a genetic predisposition to eating disorders based on the study of monozygotic and dizygotic twins

Antidepressants

frequently useful in managing Bulimia