lecture 1 homeostasis/introduction

optimal value range for a particular biological parameter

set points

optimal blood oxygen level range

75-100 mmHg

optimal body temp

37 degrees c 

temporary maintenance of internal physiological conditions outside the normal range to respond to an immediate threat to survival. example would be a fever

allostasis 

term used for responses made in anticipation of a change. example=mouthwatering prior to eating

feedfoward

refers to responses made after change has been detected

feedback

sweating when hot

example of negative feedback

increasing labor contractions

example of postive feedback

less common type of homeostatic control. anticipates upcoming change. for example, u produce more saliva and stomach acid when u anticipate eating soon. can be likened to learned anticipatory respones to known cues=predictive coding

feed foward

environmental change, sensor, control center, effector, response, homeostasis restored

negative feedback loop

sensory cells detect changes in homeostatic factors. sensory signals are integrated in neural control centers=brain stem and hypothalamus 

homeostatic feedback loops

effector systems that produce a response to maintain homeostasis

autonomic nervous system=changes activity of organs throughout body. 2. hypothalamus-pituitary axis (release of hormones that affect target organs throughout the body). 3. change in behavior—neural systems in the brain orchestrate a change in animal behavior and motivation to correct homeostatic deficit

True or false: increasing heat capacity slows attainment of new steady state but does not affect the steady state.

true

neural control of blood oxygenation levels: respiratory rate

low O2 in blood, high Co2, blood more acidic. MRCC senses increased blood acidity. MRCC integrates signals, increasing firing frequency. phrenic nerve firing rate increases. breathing rate increases. blood O2 levels increase, shuts off the response 

neural control of blood oxygen levels: heart rate

low O2, high CO2, increased blood acidity. MCCC senses increased blood acidity, integrates signals. increases firing frequency of sympathetic neurons=heart ventricles contracting with greater intensity, arterioles constricting, heart rate increasing.

TRP ion channels open in response to different ranges of temperature

sensing temp

controlling temp when it’s cold

thermosensory periphrial neurons send info to spinal cord and then to POA of hypothalamus. sympathetic tone=increased. increased BAT thermogenesis. vasoconstriction. behavioral changes=warm seeking, closed posture, shivering

anorexigenic hormones: amylin, CCK, Peptide YY, leptin 

signal satiety, reduce eating

orexigenic hormones: ghrelin

signal hunger

true or false: blood amylin peaks right before a meal

true

true or false: ghrelin peaks right before a meal, declines rapidly after eating

true

True or false: blood leptin responds more gradually, increasing over the course of the day as meals are consumed

true

Controlling feeding: hypothalamus and hormones

Digestive system hormones, AgRP/POMC neurons=hunger circuits/satiety circuits in hypothalamus, response

Controlling feeding: brainstem and neural signals

food consumed. stomach stretch. brainstem satiety centers. limbic circuits, feel full. 

the diffusion of water across a membrane from regions of low solute concentration to regions of high solute concentration

osmosis

hypotonic solution

low solute concentration.

hypertonic solution

high solute concentration