Internal Regulation

what is the constant molarity of the combined concentration of all the solutes in mammalian body fluids?

0.15 M

what receptors located around the 3rd ventricle of the brain detect osmotic pressure and sodium content in the blood?

OVLT and SFO

(T/F) temperature is high priority biologically

True

what is the necessary condition for life?

a coordinated set of chemical reactions

aldosterone

a hormone released by the adrenal gland when sodium reserves are low that causes kidneys, salivary glands and sweat glands to retain salt and release more watery fluids than usual

sodium specific hunger

a strong craving for salty foods, which develops automatically to restore solute levels in the blood

what happens when there is too much insulin?

all the glucose enters cells, and we experience hunger more

fever

an abnormally high body temperature, produced by the body as a response to fight off infections

vasopressin

an antidiuretic hormone that is released by the posterior pituitary hypothalamus which raises blood pressure and enables the kidneys to preserve water

poikilothermic/ectothermic

animals that depend on external sources for body heat instead of generating it themselves (amphibians, reptiles, most fish)

how does a fever fight off infections?

bacteria cannot survive in high temperatures and the immune systems works more vigorously in higher temperatures

advantage of constant high body temperatures

birds and mammals stay constantly ready for vigorous activity, regardless of the temperature of the air

what does distention of the duodenum do?

cholecystokinin (CCK) gets released and limits meal size by constricting the sphincter muscle, and by stimulating the vagus nerve to hypothalamus

reproductive cells require a hotter or cooler environment?

cooler

what is the main signal to stop eating?

distention of the stomach or intestine

how to restore hypovolemic thirst?

drinking water that contains some salt or other solutes (restores both salts and water that was loss)

where does excess glucose go?

excess glucose is stored in the liver as glycogen or in fat cells

why is our body temperature 37C (98F)?

for muscle activity, we gain advantage by being as warm as possible

arcuate nucleus of hypothalamus

has a set of neurons sensitive to hunger signals and another set sensitive for satiety signals

where does the POA/AH send output to, to do what?

hindbrain and Raphe nucleus, which controls the autonomic responses (shivering, sweating, changes in heart rate, etc)

when is insulin released and what role does it play?

immediately before and after a meal, the pancreas increases insulin, which enables glucose to enter cells (regulates levels of glucose in blood)

what does orexin do?

increases persistence in finding food and increases activity and motivation in general (released from PVN to lateral hypothalamus)

what does the ventromedial hypothalamus do?

inhibits eating

what happens when low blood volume is detected?

kidneys release renin --> proteins on blood form angiotensin 1 --> angiotensin 1 is converted to angiotensin 2 --> angiotensin 2 restricts blood pressure and stimulates SFO to start drinking

output from PVN goes where?

lateral hypothalamus, where it controls secretion of pancreas, alters taste responsiveness, and feeding = stimulation increases drive to eat

why is our body temperature not higher?

maintaining a higher body temperature requires more fuel and energy; proteins will denature when temperatures are higher than 41C

lateral preoptic area

part of the hypothalamus that controls drinking

supraoptic nucleus and PVN

part of the hypothalamus that controls the release rate of vasopressin

what is the primary area for temperature regulation?

preoptic area and anterior hypothalamus (POA/AH); serves as thermosensor

negative feedback

processes that reduce discrepancies from the set point

homeostasis

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

what is the role of leptin?

released by fat cells, leptin monitors fat supples and regulates eating (w/o it, the brain will think we are starving; longterm satiety signal)

what does melanocortins do?

released from axons from satiety cells to PVN, melanocortins limits food intake

what happens when we eat something salty?

sodium ions spread throughout the blood and extracellular fluid doesn't cross the membrane into cells, resulting in osmotic pressure that draws water out of the cell

what does ghrelin do?

stimulates hunger; released by stomach during a period of food deprivation

the POA/AH receives info from where?

temperature receptors (skin, organs, hypothalamus) and receptors in the immune system

allostasis

the adaptive way in which the body anticipates needs depending on the situation, avoiding errors rather than just correcting them

basal metabolism

the energy used to maintain a constant body temperature while at rest (2/3 of our total energy is used for this); occurs in brown adipose cells

set point

the single value that the body works to maintain (like levels of water, oxygen, glucose, calcium, protein, fat, acidity, blood pressure)

osmotic pressure

the tendency of water to flow across a semipermeable membrane from an area of low solute concentration to an area of higher concentration

osmotic thirst

thirst that is a result of eating salty foods

homeothermic/endothermic

use of internal physiological mechanisms to maintain an almost constant body temperature

what cranial nerve is responsible for signaling the end of eating?

vagus nerve (cranial nerve 10) conveys info to brain about the stretching of stomach walls

hypovolemic thirst

when blood volume drops due to bleeding, diarrhea or sweating