Neuro Exam 2

Neural Communication distance active over

milimeters

Neural Communication speed of action

miliseconds

Neural Communication spatial extent

precise

Neural Communication effect

all or none

Hormonal Communication distance active over

up to meters

Hormonal Communication speed of action

minutes/hours/days

Hormonal Communication spatial extent

diffuse

Hormonal Communication effect

graded

Where is the pituitary gland located?

beneath the hypothalamus

releasing hormones

from hypothalamus control pituitary release of tropic hormone

tropic hormones

from pituitary that affect other endocrine glands

vasopressin

antidiuretic hormone

raises BP

inhibits urine formation

emotions esp fear

oxytocin

maternal bonding and may be linked to autism

steps in hormone release

1) Hypothalamic neurons synthesize releasing hormones

2) Releasing hormones are then secreted into local blood vessels

3) Releasing hormones float to anterior pituitary, which releases a hormone to body

TSH

thyroid hormone

ACTH

cortisol (acronym)

thyroid hormone needs what in the diet

iodine

goiter

- swelling of the thyroid gland, as from iodine deficiency

cushing's disease

results from long-term excess glucocorticoids, with fatigue, depression, psychosis

levels of sex determination

chromosomal sex --> gonadal sex --> internal organs --> external organs --> brain --> gender identity --> gender preference

SRY gene present on Y chromosome

causes development of testes

Testosterone

main organizing hormone of human brains

organizing effects

mostly occur prenatally or shortly after birth

activating effects

occur at any time in life can be reversed

male brains have

greater asymmetry and thicker right hemisphere

women brains have

larger corpus callosum relates to cognitive skills

women have more neurons in

Dorsolateral prefrontal cortex (think before you act)

Superior temporal gyrus (talking/listening)

men are better connected

front and back

women are better connected

left to right

high estrogen level

depressed spatial ability

enhanced speech and manual skill tasks

hypovolemic thirst

stimulated by low extracellular/intravascular volume

osmotic thirst

stimulated by high extracellular solute concentration

hypovolemic thirst process

triggered by loss of water volume

baroreceptors in bv and heart detect the drop

brain activates thirst and salt craving

arteries constrict to raise BP

hypovolemia causes what to release

vasopressin

vasopressin deficiency

chronic thirst

angiotensin cascade

blood volume decreases kidneys release renin which triggers formation of angiotensin 2

angiotensin 2 acts where

in subfornical organ to signal other parts of the brain to say HEYYY lets drink smth

Osmotic Thirst Mechanisms

1.) osmosensory neurons in ant hypothalamus respond to rise in blood osmotic pressure (salt)

causing pituitary to release antidiuretic hormone

2.) cell membranes shrink and mech gated Na+ channels open

Glycogen

glucose stored for short term in the liver

Glycogenesis

converting glucose to glycogen, using pancreas hormone insulin

Lipids

long-term storage, are fat tissue

external factors involved in hunger

emotions, food characteristics, lifestyle behaviors, environmental cues

stimulate hunger

NPY,AGRP,Galanin,Orexin-A,dynorphin

inhibit hunger

GLP-1,CART,NE,5-HT

Glucose

inhibit hunger

Ghrenlin

stimulates appetite, stimulates AgRP neurons

cortisol

stimulates hunger

Defects in leptin production or sensitivity

give a false reporting of body fat, causing animals to overeat

obese people are

leptin resistant

Overnutrition does what to the hypothalamus

inflames

Prader-Willi Syndrome

genetic disease thst causes a sense of never being full or satisfied, ghrelin levels are elevated

lateral hypothalamus lesion

refusal to eat

ventromedial hypothalamus lesion

obesity

NPY/AgRP neurons

produces neuropeptide Y and agouti-related peptide: stimulate appetite and lower metabolism

RESULT weight gain

POMC/CART neurons

produce pro-opiomelanocortin and cocaine- and amphetamine-related transcript (CART): inhibit appetite and raise metabolism

RESULT weight loss

VMH lesions

destroy hunger ending PVN

LH lesions destroy

hunger causing LHA

How does overeating cause brain damage?

Overeating --> hypothalamic inflammation --> inhibits neurogenesis, resets your set point

anorexia nervosa

highest mortality rate of any psych disorder

teen girls with have

larger insula (active when you experience disgust)

larger orbitofrontal cortex (you shouldn't eat that)

adrenal cortex

secretes cortisol

adrenal medulla

releases epinephrine and norepinephrine

Cortisol breaks down what?

glucose and breaks down protein

acute stress

epi and norepi increase output from heart and liberate glucose

immune system is boosted

stress hormones do what

stimulate astrocytes to release fibroblast growth factor 2 which in turn leads to new neurons

at rest

miRNAs balance out DAMPs

acute stress (what's happening)

adrenaline and NE cause immune cells to release DAMPs

after stress (what's happening)

balance restored by cortisol

chronic stress

low grade excess production of DAMPs or block miRNAs

stress how it affects the brain

we revert to our survival

PTSD tx

ecstasy and psilocybin

Stress leads to brain changes and damage

-Frontal cortex and hippocampal volume is reduced in combat veterans with PTSD and in victims of childhood abuse

-Cortical tissue is reduced in torture victims

-Damage due to stress is caused by cortisol - perhaps increased receptor sensitivity

introvert with HIV have higher

virus titers

eCB system

resilience during and/or after stress

chronic stress impairs

2-AG synthesis

reactive agression

impulsive, provoked, and emotional

low prefrontal cortex low activity

proactive aggression

premeditated, unprovoked, emotionless

impaired amygdala function

agressive men and women have small

amygdalae

How can INTENSITY of a stimulus be coded?

coding- pattern of action potentials in a sensory system

3 strategies for coding intensity

1) A single neuron can convey stimulus intensity by changing the frequency of its action potentials

2) Multiple neurons can act in parallel - as the stimulus strengthens, more neurons are recruited

3) Different neurons respond to different ranges (range fractionation)

use the three strats for coding intensity

in vision, hearing, and touch

range fractionation

different cells have different households for firing over a range of stimulus intensities

somatosensory system

detects touch and pain

free nerve endings

respond to pain and temperature

merkels disk

touch

Meissner's corpuscles

touch

Pacinian corpuscles

vibration

ruffini's ending

stretch

small, unmyelinated C fibers

(slow) dull pain

large unmyelinated A-delta fibers

(fast) sharp pain

Capsaicin

in chillies, activates C fibers and is NEUROTOXIC

Capsaicin effect

melts body fat, slows atherosclerosis, lowers blood pressure, fights diabetes, lowers body weight

Innervation of Pacinian Corpuscle

unipolar cell and dorsal root ganglion

tonic receptors (2 parallel touch systems)

slow or no decline in action potential frequency

phasic receptors (2 parallel touch systems)

adapt quickly by decreased frequency

receptive field

part of the world a sensory neuron responds to

most sensory pathways pass through the

the thalamus to end in sensory cortex

spinothalamic pathway

dorsal root axon - lateral spinothalamic tract - spinal cord - medulla - thalamus - cerebral cortex

dorsal column pathway

dorsal root axon - dorsal column - dorsal column nuclei - medial lemniscus- cerebral cortex

pain and temp

spinothalamic