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THE MCAT-BIO 3

NEURONAL AND ENDOCRINE SYSTEM

QuestionAnswer
neuronal vs. hx communication neuronal - rapid and direct hx - slower and non-specific and long-lasting
Paracrine system local mediators (px a.a. or f.a. derivatives) released into interstitial fluid --> NOT HORMONES
Give example of hx from paracrine system and what does it do prostaglandins - smooth muscle contraction, inflammation
Why is paracrine system different than endocrine system? hx are not produced at discrete site but in many places in body
What are nx dependent upon for energy? Does it depend on insulin to get glucose? -glucose and aerobic respiration (no glycogen) -no
Where does action potential originate? axon hillock
What is sodium / potassium pump? pump 3 Na+ out for 2 K+ in
When do voltage-gated K channels start to open? When Na+ channels start to close
When is the cell at a resting potential? when rate of Na+ passively diffusing back into cell = rate being pumped out
Is the Na/K pump ever NOT working? NO
Is electrical synapse bidirectional / unidirectional and where can it be found? -bidirectional -cardiac muscle and visceral smooth muscle
Is chemical synapse bi/uni directional and where can it be found? -unidirectional -motor end plate (connect nx with muscle)
Brownian motion random motion of molecules
What is slowest step in transferring nervous signal? Ca2+ mediated ntm release
Does ntm enter postsynaptic cell? NO --> ntm attaches to rx and postsynaptic mem becomes more permeable to ions or acts via 2nd messenger
How to get rid of enzyme (3)? 1.) enzyme destroy 2. presynpatic recycling 3. diffuse out
Can a synapse release more than one ntm and both excite/inhibit? NO
Can a single ntm both inhibit and excite? YES
How does AcH act on heart vs. smooth muscle of intestine? inhibitory / excitatory
Neuroglia? capable of cx division and can multiply to fill space caused by brain injury
Microglia & oligodendrocytes -phagocytize microbes and debris in CNS -create myelin sheaths (only found in vertbrates) in CNS
Where are sensory/afferent nx located? Motor/efferent nx? dorsally (back) ventrally (front)
2 divisions of nervous system and what are they? -CNS-brain and spinal cord -PNS-everything outside of brain and spinal cord / connects CNS to limbs and organs
What does PNS break into and what are they controlled by? Where do they receive signal from? -Somatic nervous system (voluntary) -autonomic nervous system (involuntary - controlled by hypothalamus)
What does ANS break into? -parasympathetic (rest and digest) -sympathetic (flight or fight)
Nucleus vs. ganglion cell bodies located in CNS vs. cell bodies located outside CNS
postganglionic sympathetic nx. vs. postsympathetic paras. nx. lie far from effectors vs. lie near effectors
Somatic nervous system 1. Once nerve fibers leave CNS, synapse where? 2. What does it release? 3. What does it innervate? 4. Excitation / inhibition 1. Once nerve fibers leave CNS, don't make synapse till effector organ 2. release AcH 3. innervates skeletal muscle 4. excitation
Autonomic nervous system 1. Once nerve fibers leave CNS, synapse where? 2. What does it release in preganglionic? Postganglionic? 3. What does it innervate? 4. Excitation / inhibition 1. nerve fibers leaving CNS synapse with ganglion before effector organ 2. preganglionic PNS and sympathetic both release AcH ---> postganglionic para. : AcH ---> postganglionic sympathetic: Norepi / epi 3. glands, smooth and cardiac muscle 4. both
AcH is used in? Norepi / epi is used in? -SNS and PNS -SNS only
Where are internx mostly found? Sensory and motor nx? CNS PNS
Path of light once it strikes eye? cornea --> aq. humor--> pupil --> lens --> vitreous humor --> retina
Where does light bend most when it enters eye? Cornea = refractive index of 1.4
How does iris regulate amount of light that enters eye? ciliary muscle
What happens when ciliary muscle contracts? Relaxes? (circle opening, shape of lens, focal point) -circle opening decreases, lens more spherical, bring focal point closer to lens -lens flattens, increase focal distance, circle opening increases
What type of lens is eye? -converging/convex --> real and inverted image -object must be outside focal distance
Fovea and what is it made of? mostly cones and most accurate vision
What are rods made of? What happens when light strikes rods? -rhodopsin -photon strikes retinal in rhodopsin, causes hyperpolarization, transduced into neural signal to brain
What is the precursor for all pigments in rods and cones? vitamin A
Process of sound waves from start --> mvmt of fluid in cochlea. hit pinna - vibrate tympanic ear drum - vibrate middle ear bones (MIS) - vibrate oval window - mvmt fluid in cochlea
What happens once cochlea fluid moved? -vibration of basilar mem -stereocili microvilli "hair" cx bend in organ of corti -influex of K+ --> voltage positive -Ap generated in auditory nerve -AP relayed to brain --> hearing!
Why is oval window smaller than tympanic membrane? -to increase pressure -greater force required to transfer sound from air to perilymph
Semicircular canals -sense position and mvmt of head -balance -3 are perpendicular to each other
endocrine vs. exocrine -endocrine-release hx into env't through ducts -exocrine-release sweat, oil, enzymes directly into body fluids
What do hx ABSOLUTELY need? receptors!
What are 3 basic types of hormones and how do they act? -peptide (2nd messenger) -steroid (nuclear rx) -tyrosine (nuclear rx)
Where are all peptide hx made? -preprohx (rough ER) --> prohx (ER lumen) --> hx (Golgi)
Whether it be ntm or protein hx, what happens when it attaches to rx? 1. opens ion channels 2. activates 2nd messenger
Is 2nd messenger ALWAYS excitatory? no
Where do steroid hx come from? adrenal cortex, gonads, placenta
What are major types of tyrosine derivatives? -T3 and T4 -catecholamines from adrenal medulla
What kind of hx are catecholamines? -px and act through 2nd messenger cAMP
What controls pituitary glands? hypothalamus
What do steroid hx cause? promotes transcription of specific genes
Do a.a. hx or steroid hx have longer-lasting actions? steroid hx
What terminates cAMP action? phosphodiesterase
What hx are ovaries under control of? GNRH --> LH and FSH
Diabetes mellitus vs. diabetes insipidus -mellitus-lack of insulin or resistance to it -insipidus-kidneys unable to conserve water (defect in secretion of ADH)
Diabetics have (2) sx related to insipidus and mellitus. 1. polyuria - increased urination 2. polydipsia - increased thirst
2 types of diabetes mellitus Type I (insulin-dependent) -autoimmune destruction of beta cells Type II (non-insulin dependent) -body resists effects of insulin -most common
Where is somatostatin made? What does it do? stomach, intestines, and pancreas -inhibit GH, insulin, and glucagon -decrease rate of gastric emptying to extend time nutrients are absorbed
How is bile released into duodenum? bile stored in gall bladder joins with common bile duct --> joins pancreatic duct --> duodenum
What are 3 types of cells found in pancreas? -alpha (glucagon) -beta (insulin) -delta (somatostatin)
What else can increase plasma glucose besides insulin? glucocorticoids, epi, and growth hx
Can insulin and glucagon enter cells? NO
Are nx in brain affected by insulin? NO
Where are adrenal glands located and what are they separated into? -top of kidneys -adrenal cortex and adrenal medulla
What does adrenal cortex secrete? -corticosteroids (steroid hx) -sugar, salt, sex -glucocorticoids, mineralocorticoids, cortical sex hx
What does glucocorticoid do and what is major type? -cortisol -increase blood glucose conc and decrease protein synthesis
What does mineralocorticoid do and what is major type? -aldosterone -reabsorbs sodium, secretes K+ and H+ to increase BP by acting on distal convoluted tubuel
What does cortical sex hx do in males and females ? -make androgen -masculanizing effects in female
What does adrenal medulla make? norepinephrine and epinephrine (catecholamines = protein hx) --> tyrosine derivatives (D--> N --> E)
How does (nor)epinephrine act on internal organs and skin? On skeletal muscle? -vasoconstrictors -vasodilators
What stimulates aldosterone and increases BP via vasoconstriction? angiotensin II
What does parathyroid hx do in kidney, gut, and bone? -decrease excretion of calcium through kidney, increase secretion of phosphate -increase absorption of calcium in gut --> activate Vitamin D and excrete K+ -increase bone resorption and recruitment of osteoclasts
How does PTH act on osteoclasts? -PTH acts on osteoblasts which produces RANKL to stimulate osteoclasts
PTH _____ calcium levels, calcitonin ____calcium levels -increase and decrease
2 major roles for thyroid gland -set metabolic rate -calcium homeostasis
What kind of hx are T3 and T4 and what do they do? -nuclear hx -increase basal metabolic rate and increase cx respiration
hypothyroidism and sx -deficiency of iodine and decreased thyroid hx -lethargy and low metabolism
hyperthyroidism and sx -tumor / thyroid over-stimulation -over activity
goiter enlarged thyroid as result of hypo/hyperthyroidsm
calcitonin actions on kidney, gut, bone -increase excretion of calcium from kidneys -decreases absorption from gut -decreases osteoclast activity and increases storage in bone
Main fxns of calcium -bone -muscle contraction -normal blood clotting co-factor -cell mvmt and ntm release
anterior pit hx are ____ and ____ -direct-act directly by binding to rx -tropic - bind to rx and cause release of effector hx
direct hx Prolactin Endorphins Growth hx
where does growth occur in bones? epiphyseal plates of long bones
Tropic Hx FSH LH ACTH TSH
ACTH -adrenocorticotroic hx -stimulates adrenal cortex to release glucocorticoids via cAMP
What stimulates adrenal medulla? sympathetic and parasympathetic activity
Hx of posterior pituitary -oxytocin - milk ejection and uterine contractions -ADH - aka vasopressin and causes collecting ducts of kidney to become permeable to water
What is ADH secreted in response to? (brain receptors) -osmoreceptors - increased blood osmolarity -baroreceptors - decreased blood volume
Prolactin is released in absence of_______ prolactin inhibiting factor
What do coffee and beer affect in renal system? block ADH --> increase urine volume
Why isn't prolactin produced before birth? What does lactation block? -inhibitory effects of P and E -menstrual cycle
Where do most synapses occur? on dendrites
Does the cell body of a neuron have a nucleus and organelles? YES!
Myelin sheath and why is it a good insulator? -covers axon intermittently with nodes of Ranvier gaps -fatty and has no channels
Schwann cells makes myelin sheath in the peripheral nervous system by wrapping around axon
Schwan cx vs. oligodendrocytes -Schwann cx act in peripheral nervous system -oligodendrocytes act in central nervous system
What is benefit of saltatory conduction? speeds up AP conduction in axon
Axodendritic synapse axon terminal --> dendrite
Axosomatic synapse axon terminal --> cx body
Axoaxonic synapse axon terminal --> axon hillock
Brief summary of ntm --> ATP ntm leaves presynaptic through vesicles triggered by calcium, binds to rx, opens up channel on postsynaptic that causes change in mem potential
Examples of ntm ATP, AcH, NE, dopamine
What are synaptic knobs? another name for axon terminal
What causes fatigue in a nx? continous synaptic activity --> depletion of ntm --> fatigue
Defining characteristic of AP all or nothing!
What does the resting mem potential hope to achieve? negative inside, positive outside / sodium outside, potassium inside
How does resting mem potential achieve negative inside? Na/K pump and K channel leakage
What happens during depolarization? sodium channels open and positive sodium rushes inside
What happens during repolarization? potassium channels open and sodium channels close , potassium rushes outside
What happens during hyperpolarization? K channels don't close fast enough so mem potential drops below
When does absolute refractory period occur? Relative refractory period? -depolarization to cx re-establish original resting state -after hyperpolarization till resting state re-established
What does "all-or-none" mean? All AP have the same magnitude NO MATTER WHAT
excitatory synapse ntm binding causes postsynaptic potential to be more positive (depolarization) --> AP
inhibitory synapse ntm binding causes postsynaptic potential to be more negative (hyperpolarization)
Endocrine vs. exocrine -endocrine - hx, no duct, acts long distances -exocrine - non-hx secretion into ducts
What does pineal gland make? melatonin
What does thyroid gland make? thyroid hx and calcitonin
What does adrenal gland make? -medulla - epi and norepi -cortex - mineralocorticoids / glucocorticoids
What does dopamine inhibit? prolactin
Where is aldosterone made? adrenal cortex
Parathyroid vs. calcitonin parathyroid increases bone resorption while calcitonin puts calcium back in
What does thymus do? stimulates T-cx to develop
What is major type of glucocorticoid? cortisol --> increase blood sugar
Does ovary make testosterone? small amount
What is the result of diabetes? -glucose can't enter cx --> high blood sugar -cx starved of sugar --> f.a. metabolism
What does f.a. metabolism in diabetes result in? ketone bodies --> ketoacidosis (acidic blood)
Why do diabetes pee more? sugar in urine leads to more water in urine from osmosis
gigantism too much GH during growing age --> well-proportioned giants
acromegaly too much GH later on in life --> disproportioned growth of certain areas of body that still respond to GH
The major types of hx are ______ and steroids a.a.
cAMP path a.a. binds mem rx, G-px, adenylate cyclase activated, cAMP made, protein kinase cascade
What types of hx can go directly into cx? Where does it bind? -steroid and thyroid hx -binds rx in cytoplasm or nucleus
Phospholipid path a.a. binds mem rx, G-px, phospholipase C activated, mem phospholipid split into DAG and IP3 -DAG triggers px kinase cascade -IP3 releases Ca from the ER
What creates specificity of hx for target cx? whether or not there are rx for hx
Humoral control of hx glands directly respond to chemical levels in the blood -parathyroid and low Ca
Neural control of hx glands release hx when stimulated by nerves -flight or fight
Hormonal control of hx glands release hx when stimulated by other hx -tropic hx
Sensory = __________. Motor = ___________. -afferent to CNS -efferent away from CNS
Sympathetic is ________. Parasympathetic is ______. -flight or fight -rest and digest
Examples of positive feedback. -LH and estrogen surge -oxytocin and contractions -blood clotting platelets
What is reflex arc? receptor - sensory nx - integration center - motor nx - effector
Why do reflexes bypass the brain? creates faster response -brain still aware of what is happening
monosynaptic vs. polysynaptic -monosynaptic - no internx / direct synapse of sensory to motor -polysynaptic - internx present
During knee jerk, the ____ is contracted and the ______ is relaxed. -extensor -flexor
What does the golgi tendon reflex protect? protects muscle from heavy loads by causing muscle to relax and drop the load
What happens during the golgi tendon reflex? nx from golgi tendon organ fires, motor nx inhibited, muscle relaxes, load dropped
What is role of spinal cord in reflex arc? provides synapse(s) for reflex arc
What does efferent control refer to in reflex arc? brain can still override spinal reflexes
Where in the skin are the touch, heat, and pain rx located? Pressure rx? -close to surface near dermis-epidermis boundary -deeper in dermis
Proprioreceptor -senses position of a body part -controlled by cerebellum
What do thermoreceptors detect? A CHANGE in temperature
Olfaction process chemicals enter nose, trapped in mucus, picked up by mem rx on cilia, cx depolarization
Taste process Chemical dissolve in saliva, carried inside taste bud, microvilli pick up chemicals, release ntm to brain
What are inner ear bones? malleus(hammer) , incus (anvil) , stapes (stirrup)
What is the ear drum? tympanic membrane
What is vestibule in hear? contacts oval window and continuous with semicircular canals --> balance
What is main fxn of cochlea? propagates sound pressure waves in fluid and transduces them into nerve impulses sent to brain
Which is more sensitive: rods or cones? rods
What is importance of rhodopsin and what is it made of? -chemical responsible for light reception -retinal + opsin
Light converts ____(cis/trans) retinal --> _____(cis/trans) retinal cis --> trans
What is blind spot? Where bundle of nerves exist in back of retina that sends signal to brain
How does brain create 3D image? combines 2 images from each eye (also to get rid of blind spot)
How many nx do the sympathetic and parasympathetic system rely on? 2
Describe the nx in a sympathetic nervous system. short preganglionic and long postganglionic
Describe nx in a parasympathetic n.s. long preganglionic and short postganglionic
Where is oxytocin and ADH produced? hypothalamus
What is aldosterone produced in response to? low sodium or elevated potassium
Which division of autonomic nervous system has dominant effect on heart? parasympathetic nervous system
How is the GI tract an endocrine gland? secretes secretin, CCK, gastrin
How are kidneys an endocrine gland? secrete erythropoietin to stimulate bone marrow to make RBC
How is heart an endocrine gland? secretes ANP to regulate salt and water balance
How is thymus an endocrine gland? secretes thymosin to regulate proper T-cx differentiation
Totipotent cx any one of these cx could make complete organism
What is special about a morula? has totipotent cx
blastula vs. blastocyst blastocyst is mammalian blastula type
blastocoel hollow, fluid-filled cavity
trophoblast surrounds blastocoel and makes chorion and placenta
inner cx mass makes actual organism
Which occurs first, determination or differentiation? determination
Where is the adrenal cortex formed from? mesoderm
Where is the adrenal medulla formed from? ectoderm
Deuterosome vs. protosome -deuterosome = human -protosome = everything else
What does the blastopore become in deuterosomes vs. protosomes? -deuterosome = anus -protosome = mouth
What does archenteron develop into? gut
What do neural crest cx form? peripheral nervous system
umbilical arteries carry deoxygenated blood away from fetus
umbilical veins carry oxygeanted blood towards fetus
ductus venosus -shunts 1/2 of oxygenated blood from umbilical vein to inferior vena cava -bypass nonfxnal liver -preferentially give oxygenated blood to brain
foramen ovale connects right and left atria
ductus arteriosus connects pulmonary artery --> aorta -bypasses nonfxnal lungs
Why does sympathetic system produce more whole-body response? ganglia are connected to each other
What are trophic hx? stimulate other glands to secrete hx
When Na/K pump is blocked, what will be intracx conditions? -increase in intracx sodium -decrease in intracx K
When Na/K pump is blocked, what also is blocked? ATP consumption
What are 3 major px in plasm? albumin, gammaglobulins (antibodies, fibrinogen
Secondary px structure alpha helix or beta sheet
What are the 2 major systems that maintain homeostasis? endocrine and nervous system
What are the parts of a pancreas? head, neck, body, tail
What does low Ca cause? increases nx permeability to sodium --> hyperexcitability
What stimulates osteoblasts? calcitonin
Small intestine: parathyroid vs. calcitonin -parathyroid increases Ca absorption -calcitonin decreases Ca absorption
How does Vit D act on intestine? increases Ca absorption
What does shortage of insulin crease? cause blood glucose level to increase and glycolysis to decrease
What happens if there is a decrease in rate of glycolysis in relation to ketone bodies? -forces body to metabolize fat --> ATP -fat metabolism = ketone bodies
What stimulates the release of estrogen? LH
Where are gap junctions found? heart and smooth muscle
What does thyroid hx stimulate? px synthesis and activity of Na/K ATP ase
What does atrial natiuretic peptide do? decrease blood volume
2 characteristics of cancer -abnormal cell growth -abnormally high conc. of product
Calcitonin actions with Ca and P 1. blocks bone resorption 2. inhibits renal absorption of Ca and P
Parathyroid actions with Ca and P on bone, kidney, and s. intestine -bone = releases Ca and P -kidney = decreases excretion of Ca, increases P -s. intestine = increases reabsorption of Ca and P
Overall what does PTH do? increases blood calcium, and decreases blood phosphate
What hx is in excess with someone with high sugar level and muscle wasting? excess cortisol
What are the 4 hx that increase blood glucose levels? glucagon, cortisol, GH and epi
facilitated diffusion relies on a channel px to move down a concentration gradient
Does endocytosis depend on ATP? yes
What kind of gland is the salivary? exocrine gland
Which is stronger: ionic or covalent bond ionic
What are the tyrosin-deriv a.a.? thyroid hx, epi, and norepi
What are the steroid hx? cortisol, aldo, progesterone, testosterone
Where is AcH used? -parasympathetic NS -neuromuscular jxns to stimulate voluntary muscles
What does the PNS and SNS both release? acetylcholine at preganglionic nerve
Does calcitonin increase phosphate reabsorption in kidneys? NO
If the Na/K pump was not working, what would be the conditions? built up of Na inside, built up of K outside
Created by: 507935299