lec 10: stress response

describe the sympathetic nervous system (fight or flight)

• increase heart rate + breathing

• dilates pupils

• releases glucose

• relax bladder

• produce sweat

describe parasympathetic nervous system

calm and relaxed —> helps body recover / conserve energy

• slows heart rate

• constrict pupil

• contracts bladder

• stimulates saliva

• promotes energy storage

what are some chemical signals that act in either short or long distances in the body

neuron: long distance, short connection

non neural endocrine cell

neurosecretory cell

local paracrine and autocrine cells

explain how neurons send chem signals

neuron send action potential —> trigger release of neurotransmitter —> neurotrans. cross synaptic cleft —> bind to receptor on postsynaptic cell

explain how nonneural endocrine cell sends chem signal

endocrine cell release —→ hormones —> blood stream thru capillaries —> hormones travel —> reach target cells w hormonal receptors

bc it involves blood circulation, it can reach widespread regions of body

explain how neursecretory cells send a signal

hormones released near axon terminal —> enter large blood vessels —> travel thru body

neurosecretory signalling is a link bw what 2 systems

nervous (neurosecretory cell) and endocrine (hormone)

describe local paracrine and autocrine signals

• affect neighboring cells by diffusing short distances —> activating nearby receptors

autocrine:

• cell signals itself releasing hormones that act on receptors of same cells

LOCALIZED DONT TRAVEL LONG DISTANCES

steroid hormones are synthesized by what…

cholesterol

in vertebrates, steroid hormones r produced in the …

gonads (ovaries and testes)

adrenal cortex

skin

testosterone is produced in

gonads

cortisol is produced in the ..

adrenal cortex

steroid hormones are ______ soluble

lipid : diffuse thru cell membranes to reach their target receptors in cells

• no transporters or channels needed

describe process of synthesis of steroid hormone

1. cholesterol side chain cleaved to form pregnenolone in mitochondria

2. pregnenoline travels —> smooth er where it produes various hormones (aldosterone, cortisol, testosterone, estradiol)

when inside the cell, what receptor does steroid hormone bind to

intracellular receptor

what functions as a transcription factor inside the nucleus for steroid hormones

steroid receptor complex

peptide hormones r made up of…

chains of amino acids (3-200)

what/where r peptide hormones synthesized

pineal gland or thyroid

insulin, gonadotropin-releasing hormone(GnRH)

are examples of what type of hormone…

peptide hormones

peptide hormones r _______ soluble meaning…

water soluble: cant cross lipid membranes, require receptors on cell surface to send a signal to let in

GnRH amino acid sequence is…

insulin amino acid sequence is …

amine hormones are modifications of…

basic amino acids

melatonin, epinephrine, norepinephrine,

and dopamine, iodothyronines (T3 and T4)

are ex of…

amine hormones

are amine hormones lipid or water soluble

both it depends!

melatonin and the catecholamines: water soluble

t3 and t4: lipid soluble

dopamine, noepinephine, epinephrine are catecholamines that r derived from what amino acid

tyrosine

thyroxine (t4) and t3 are ___________ that r derived by the amino acid tyrosine

iodothyronines

what amino acid is melatonin derived from

tryptophan

hpa axis purpose

responds to stress

describe how hpa axis works

neural input (percieved by brain or circadian clock) —> hypothalamus recieve stress signal —> secrete corticotropin - releasing hormone / vasopressin —> released into portal system (connect hypothalamus + pituitary gland) —> pituitary gland secretes adrenocorticotropic hormone (ACTH) —> acth reaches adrenocortex —> triggers release of glucocorticoids (prepare body for flight/flight)

what r the target tissues of the hpa axis

· Protein catabolism in muscle and bone

· Gluconeogenesis in liver

· Fat catabolism in adipose tissue

· Decreased immune system functions

· Permissive to catecholamine action on

vasoconstriction

wheres hypothalamus located

wheres adrenal gland

whats thyrotropin hormone purpose

• whats the purpose of the hormones it helps secrete

stimulates thyroid gland to release t3 and t4

• regulate metabolism + growth

purpose of Adrenocorticotropin (ACTH) hormone

• whats effect of what it releases

• send signal to adrenal cortex to release glucocorticoids

• involved in stress response + metabolic actions

what dies prolactin do

• acts on mammary glands

• helps w growth during pregnancy + milk production

• roles in water ion balance, reproduction

growth hormone purpose

targets tissues like liver n muscle

• helps release insulin ike growth factors

gonadotropins purpose

LH and FSH regulate sex hormone production

MSH purpose

skin darkening in reptiles n amphibians

negative feedback loops in the hpa stress axis suppress the secretion of ______ and _________

• if these 2 things were not regulated, what would happen

CRH and ACTH

if not regulated —> constant anxiety

what r the hormones involved in mammalian nutrient metabolism

insulin (beta cells of pancreas)

glucagon (alpha cells of pancreas)

epinephrine (andrenal medulla)

glucocorticoids (adrenal cortex)

insulin main stimulus for secretion + action on nutrient metabolism

secreted when glucose high, high blood amino acids, parasympathetic stimulation

whats glycogenesis

converting glucose from sugar to fat —> done by insulin

glucagon is stimulated when + effect on nutrient metabolism

when blood sugar low, high blood amino acid, sympathetic stimulation

glucagon increases glucose levels by stimulating glycogen breakdown in ______ cells

liver

epinephrine stimulus for secretion + effect on nutrient metabolism

sympatheitc stim during stress n exercise

epinephinr increases blood glucose levels by glycogen breakgon in _____ and _______ cells

liver

muscle

__________ inhibits insulin release

epinephrine under stress conditions

glucocorticoids are stimulated for secretion when…

stress

• enhance glucagon (increase blood sugar by)

describe how both the sympathetic NS and hpa axis play a role in mammalian sress response

1. SNS is activated to prepare for immediate defense (flgith or flight)

• OCCUR WITHIN LESS THAN 1 MIN OF EXPOSURE TO STRESSOR

early <1 min physiological effects

• increase heart rate

• increase breathing

• increase vasoconstriction of regions like skin

• increase glucagon

• decrease digestion

HPA axis deactivation:

CRH released by hypothalamus

CRH —> activates ACTH

ACTH —> stimulate adrenal glands which release glucocorticoids like cortisol to pronlong stress response

____ links the sympathetic nervous system to HPA axis to coordinate response to stress

CRH

what r psychological effects of stress

• Memory formation: promote memories of emotionally charged events in regions like the amygdala and hippocampus.

• Arousal and alertness

• Analgesia: release of β-endorphins relieve pain during stress response

whats synergism

one hormone amplifies the action of another

glucagon + epinephrine have a ________ effect and they do what

synergism

• amplify effect of oppose the action of insulin

whats antagonism

one hormone weakens the action of another

Epinephrine alone and glucagon alone both work to increase blood glucose levels, counteracting the action of insulin

is an ex of

antagonism

the rough skinned newt is special bc

• has courtship behavior but disengages if danger arises

• corticosterone targets clasp controlling neurons in hind brain using g protein coupled receptors —> fast action —> endocannabinoirds r released to reduce activity of clasp controlling neurons = disnegage

describe how the HPA axis interacts with the immunse system during stress response

low concentration glucocorticoids stimulate the immunse sysrem helping it right infections

high concentrations, glucocorticoids inhibit the immune system. They prevent excessive inflammation by suppressing the production of prostaglandins, which are involved in inflammation.

review this diagram if have time

chronic stress cal lead to …

cardiovascular disease

diabetes

muscle wasting n bone thinning

suppresed immune response (infection)

suppresion of rep. system

long term effects thru epigenetic mechanisms

do hyenes have more glucorotcioids in their feces when living apart from humans

have less meaning interaction w humans increases their stress