230 - homeostasis and biological rhythms

Thermoregulation is important for protecting proteins and cells how?

Prevents proteins from unraveling when too hot, and chemical reactions from slowing/freezing and destroying cells when two cold

endotherms

generate their own heat through internal processes - metabolism and muscular activity

ectotherms

get heat from environment - behaviorally NOT physiologically

advantages of thermoregulation via endotherms

independence from environment and improved oxygen use capacity sustains greater muscular activity

Negative feedback systems

maintains homeostasis by inhibiting stimulus and bringing systems back to set zoner

Receptors in skin, body core, and hypothalamus detect temperature and send information to what neural regions

spinal cord, brainstem, hypothalamus/POA

preoptic area (POA) of hypothalamus

responsible for physiological responses to cold- shivering and constriction of blood vessels

Lateral hypothalamus

control temperature behaviors such as turning on fans or heat lamps

Three types of behavioral regulation of temperature

Change exposure of body surface, external insulation, or surroundings

T/F- humans store excess water in the body

False!

Intracellular compartment (1/2 water compartments)

Fluid contained within our cells (most water here)

Extracellular Compartment (1/2 water compartments)

fluid outside our cells

What two fluids is the extracellular compartment divided between

Interstitial fluid (between cells) and blood plasma

How does water move in and out of cells

Protein channels called aquaporins via osmosis

Osmosis

passive movement of solvent(liquid) to move through membrane to equalize concentration of solute (molecules)

Osmotic Pressure

physical force that pushes/pulls water across membrane

Osmolality

number of solute particles per unit volume of solvent

Isotonic salt solution

about 90% osmolality, same as mammalian fluids

Hypertonic vs hypotonic solution

Hypertonic has more salt than isotopic, while hypotonic has less

T/F - If cells are surrounded by hypertonic solutions, they will lose water

True!

Osmotic thirst is stimulated by what

high extracellular solute concentrations

Hypervolemic thirst is stimulated by what

reduced extracellular volume

What is usually the cause of us feeling thirsty

osmotic thirst from obligatory water loss from processes like respiration, perspiration, and urination which can also be triggered by eating salty foods

Where are osmosensory neurons and what do they respond to

in hypothalamus and they respond to changes in osmotic pressure as water is drawn out of cells via osmosis

Physiological response to osmotic thirst

aldosterone is released from adrenal gland in response to thirst signals, stimulating kidneys to conserve sodium to aid in water retention

where are circumventricular organs and what do they do

in the walls of ventricles where neurons can monitor salt and hormone levels in the blood

What triggers hypovolemic thirst

a loss of water volume, such as blood loos and diarrhea; concentration unchanged since solutes lost too

baroreceptors

located in major blood vessels and heart to detect drop in blood pressure - hypovolemic thirst

principal sugar used for energy

glucose

complex carbohydrate made by combining glucose molecules and stored in liver and muscles for short periods

glycogen

Process of converting glucose to glycogen which is regulated by insulin

glycogenesis

pancreatic hormone released by beta cells in pancreas

insulin

pancreatic hormone released by alpha cells in pancreas and mediates glycogenolysis

glucagon

process of converting glycogen back into glucose

glycogenolysis

fats stored for long term storage and deposited in adipose tissue

lipids

Process of converting fats and proteins into glucose and ketones under periods of prolonged food deprivation

gluconeogenesis

T/F - the brain requires insulin to get glucose into cells

false!

Glucose transporters span where and work with who to do what

span cell membrane and work with insulin to bring glucose into cell

cephalic phase

sensory stimulus of food evokes insulin release in anticipation of glucose

digestive phase

food causes gut hormone release stimulating pancreas to secrete insulin

absorptive phase

glucodetectors in blood and liver detect glucose and signal pancrease to release insulin

type 1 diabetes

pancreas doesn’t produce insulin

type 2 diabetes

consequence of reduced sensitivity to insulin

How does the brain decide whether to initiate eating

integrates insulin and glucose signals

What is hypothalamus important for regulation of in terms of hunger

metabolic rate, food intake, body weight

1/2 appetite centers in hypothalamus, satiety cener

Ventromedial hypothalamus (VMH)

1/2 appetite centers in hypothalamus, hunger center

Lateral hypothalamus (LH)

system critical for integrating peptide hormone signals from the body

arcuate nucleus

hormone important for appetite control, works as an appetite stimulant that peaks before eating and released by endocrine cells in stomach

ghrelin

hormone important for appetite control, works as an appetite suppressant and peaks after eating and released by intestinal cells

PYY

neuron in arcuate nucleus that inhibits appetite and increases metabolism (satiety)

POMC

neuron in arcuate nucleus that stimulates appetite and reduces metabolism (hunger)

NPY

Where do appetite signals converge?

nucleus of solitary tract (NST) in brainstem

peptide released by gut after feeding and acts on vagus nerve to inhibit appetite

CCK

T/F - leptin inhibits NPY neurons and activates POMC neurons, therefore acting to stimulate hunger

False - it suppresses hunger

Zeitgeber(in reference to rat experiment)

cues animal uses to synchronize with the environment

animal that maintains its own cycle without external cues

free-running

Where is the mammalian biological clock

Suprachiasmatic nucleus (SCN)

how does light information get from the eye to the SCN

retinohypothalamic pathway

Most retinal ganglion cells in the SCN pathway contain this, which makes them sensitive to light

melanopsin

what happened in the experiment when hamsters had a SCN transplant from other hamsters with very short running periods

circadian rhythm matched the shorter period of the donor

if an animal has a shorter period than normal, what is likely the problem

tau mutations

if an animal has a severely arrhythmic period, what is likely the problem

double clock mutation

infradian rhythms

longer than a day (menstrual cycle)

ultradian rhythms

shorter than a day (feeding, hormone release)

being nocturnal or diurnal is part of an animals what

ecological niche

in what stage of sleep are most growth hormones released

slow wave sleep

what type of sleep helps consolidate nondeclarative memories

REM

forebrain system role in mediating sleep

generates SWS

brainstem system role in mediating sleep

activates forebrain into wakefulness (reticular formation)

pons system role in mediating sleep

triggers REM

hypothalamic system role in mediating sleep

coordinates all other systems of sleep mediation

most sleeping pills bind to what kind of receptor

GABA