Chapter 13: Homeostasis, Active Regulation of the Internal Environment

Aldosterone

"salt-retaining hormone" which promotes the retention of Na+ by the kidneys. na+ retention promotes water retention, which promotes a higher blood volume and pressure

obesity treatments (7)

1. epigenetic transmission 2. apetite control 3. increased metabolism 4. inhibit fat tissue 5. reduced absorption 6. reduced reward 7. anti-obesity surgery

leptin

A hormone produced by adipose (fat) cells that acts as a satiety factor in regulating appetite.

Atrial natriuretic peptide (ANP)

A hormone, secreted by the heart, that normally reduces blood pressure, inhibits drinking, and promotes the excretion of water and salt at the kidneys.

ghrelin

A hunger-arousing hormone secreted by an empty stomach

hypothalamus

A neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.

negative feedback

A primary mechanism of homeostasis, whereby a change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation.

subfornical organ

A small organ located in the confluence of the lateral ventricles, attached to the underside of the fornix; contains neurons that detect the presence of angiotensin in the blood and excite neural circuits that initiate drinking.

homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

aquaporins

A transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane

ectotherms

An animals that warms itself mainly by absorbing heat from its surroundings

endocannabinoid

An endogenous ligand of cannabinoid receptors; thus, an analog of marijuana that is produced by the brain.

endotherms

Animals (such as birds or mammals) that can regulate their body temperature.

nutrient

Compounds in food that the body requires for proper growth, maintenance, and functioning

osmosis

Diffusion of water through a selectively permeable membrane

lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.

ketones

Fragments formed by the tissues during incomplete use of fat for energy, and released into the blood.

hypotonic

Having a lower concentration of solute than another solution

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

osmality

Osmotic concentration of a solution; the number of moles of solute in 1 kg of water times the number of particles into which the solute dissociates

trophic factors

Small proteins in the brain that are necessary for the development, function, and survival of specific groups of neurons.

glycogen

Storage form of glucose

adipose tissue

Tissue that stores fat.

binge eating

a disorder in which a person repeatedly eats too much food at one time

nucleus of the solitary tract

a nucleus of the medulla that receives information from visceral organs and from the gustatory system

PYY3-36

a peptide hormone, secreted by the intestines, that probably acts on hypothalamic appetite control mechanisms to suppress appetite

osmosensory neurons

a specialized neuron that monitors the concentration of the extracellular fluid by measuring the movement of water into and out of the intracellular compartment

glucodetector

a specialized type of liver cell that detects and informs the nervous system about levels of circulating glucose

hypovolemic thirst

a thirst resulting from loss of fluids due to bleeding or sweating (low blood volume)

basal metabolism

amount of energy required to carry out involuntary activities of the body at rest

arcuate nucleus

an arc-shaped hypothalamic nucleus implicated in appetite control

bulimia

an eating disorder characterized by episodes of overeating, usually of high-calorie foods, followed by vomiting, laxative use, fasting, or excessive exercise

anorexia nervosa

an eating disorder in which an irrational fear of weight gain leads people to starve themselves

vasopressin

antidiuretic hormone

hypothalamus plays special role in ____

appetite regulation

appetite controller in ____ in hypothalamus --> responds to ____ (fat levels), ____ --> release ___ which activates ____ to decrease appetite. leptin inhibits ____ --> appetite suppressant. ____ stimulates appetite control + ____ inhibits

arcuate nucleus / leptin / POMC/CART neurons / OCMSTI / MC4R / NPY/AgRP neurons / ghrelin

____ only long-lasting medical intervention in obesite

bariatric surgery

drop in blood volume --> 1. ___ in blood vessels signal the brain 2. ___ reduces urination, 3. kidneys release renin --> ___ reduce blood vessel volume

baroreceptors / vasopressin / angiontensin

baroreceptors

detect changes in blood pressure

motivation

drive state that prompts homeostatic behaviors (e.g. having a drink to intake water)

_____ and _____ regulate body temperature by generating body heat through ____ and capturing heat from external environment

endotherms / ectotherms / metabolism

digestin

enzymatic action that breaks larger organic molecules down into smaller components

obligatory losses

essential fluid losses required to maintain body functioning

hyperphagia

excessive eating

satiety

feeling of fullness

Gluconeogenesis

formation of glucose from noncarbohydrate sources

glycogenesis

formation of glycogen from glucose

brain cells use ____ directly, which is imported with ____, which also stores as ___, ____ converts glycogen back to glucose

glucose / insulin / glycogen / glucagon

nervous system crucial in _____ of temperature, fluid balance, chemical energy, nutrients, and feature ______

homeostasis / negative feedback

orexin

hunger-triggering hormone secreted by hypothalamus

LH

hypothalamic region, lesion --> aphagia

____ from drop in extracellular compartment volume, ___ from increase in osmality

hypovolemic thirst / osmotic thirst

aphagia

inability to eat

Angiotensin II

increases blood pressure by stimulating kidneys to reabsorb more water and by releasing aldosterone

diabetes mellitus

insulin is not secreted adequately or tissues are resistant to its effects

cells function when ____ has correct ratio of salts and ions via ____, ____ is buffer between _____ and outside world

intracellular fluid / osmosis / intracellular compartment

circumventricular organs

lacks a blood-brain barrier; can monitor chemical changes in the blood

anorexigenic neurons

neurons of the hypothalamic appetite system that inhibit feeding behavior

orexigenic neurons

neurons of the hypothalamic appetite system that promote feeding behavior

____ detect extracellular fluid concentration, increase ____ concentration --> water intake

osmosensory neurons / solute

body temperature regulated by ____, ____, and _____

preoptic hypothalamus / brainstem / spinal cord monitor

osmotic pressure

pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

CCK

produced by the small intestine when you eat and tells brain you're full, suppressing appetite

glucose transporters

proteins that assist in the transport of glucose molecules across cell membranes

insulin is crucial for ____

regulation of body metabolism

bariatric surgery

surgical reduction of gastric capacity to treat morbid obesity

extracellular compartment

the fluid space of the body that exists outside the cells

intracellular compartment

the fluid space of the body that is contained within cells

glucose

the form of sugar that circulates in the blood and provides the major source of energy for body tissues. When its level is low, we feel hunger.

thermoregulation

the maintenance of body temperature within a range that enables cells to function efficiently.

hunger

the natural physical drive to eat, prompted by the body's need for food

VMH

the part of the hypothalamus that can cause one to stop eating, lesion --> hyperphagia

set point

the point at which your "weight thermostat" is supposedly set. When your body falls below this weight, increased hunger and a lowered metabolic rate may combine to restore the lost weight

vagus nerve

the tenth cranial nerve that innervates digestive organs, heart and other areas

osmotic thirst

thirst triggered by certain neurons that detect the loss of their own water

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

isotonic

when the concentration of two solutions is the same

POMC/CART

when these neurons are stimulated they decrease appetite, make POMC & CART

NPY/AgRP

when these neurons are stimulated they increase appetite by making neuropeptide Y and agouti-related peptide