Unit 7 - Nervous System & Endocrine System Flashcards

Question

Resting Potential

Answer 1

most ion channels are closed in a neuron at rest - channels are selectively permeable to K+ or Na+ - ions move from high to low concentration inside of cell = more negative outside of cell = more positive - usually all of the ion channels are closed - the potassium channel is leaky so some potassium will leave the cell so the inside of the neuron keeps its negative charge - the sodium potassium pump is open **the concentration gradient pressures Na to enter the cell and pressures K to exit the cell

Answer 2

active transport of ions helps keep the resting potential - moves Sodium ions out of the cell and potassium into the cell (3:2) ratio

Answer 3

the channels open when there is an action potential - they don't open for graded potentials unless enough of them build up, causing it to exceed the threshold

Answer 4

signals from other neurons change the membrane potential and cause ion channels to open a change in the voltage opens the gate ex: sodium ions now pass thru via passive transport

Answer 5

an increase in the membrane potential **the inside is more negative - happens when a potassium channel opens - K+ moves out of the neuron, so the inside becomes more negative (takes it's + change with it)

Answer 6

they come in different sizes - small and brief

Answer 7

opposite of hyperpolarization - a reduction in the membrane potential ***the inside more positive - sodium moves into the neuron so the positive comes into the neuron - it comes closer to the threshold bc it's more positive

Answer 8

a stimulus that is strong enough to make a depolarization that reaches the threshold = an action potential - not a graded response - the size and shape of each action potential is the same - action potentials are the type of signal that carries info along axons **a stronger stimulus makes more action potentials

Answer 9

1. first at resting potential - voltage gated channels are closed (Na+ and K+ channels are closed) 2. deploarization = Na+ channels open - sodium diffuses into the cell 3. Rising Phase = many Na+ channels open - the threshold is crossed triggering the rising phase - Na+ rushes into the cell - K+ channels still closed - positive feedback: - bc more sodium keeps flooding in over and over (it stops once the action potential makes it to the end) 4. Falling Phase = K+ channels open - sodium channels close - K+ leaves the cell (and brings its charge with it so inside is more negative) - membrane potential = more negative 5. Undershoot = K+ channels close slowly - Na+ inactivated (gates are shut) Refractory Period: - period where can't make an action potential - makes sure that the action potential can't go backwards - it dips below the resting potential and then comes back up to the resting potential

Answer 10

1. K+ channels close sodium-potassium pump = - moves sodium out and potassium in - always puts more sodium in and less potassium

Answer 11

- the depolarization of one region of axon stimulates depolarization of the next region - action potentials can't move backwards bc Na+ channels become inactivated

Answer 12

1. Axon diameter = the bigger the diameter of the axon, the signal travels faster 2. Myelin Sheath - the myelin allow for the action potential to travel faster -

Answer 13

- the gaps on the neuron where the sodium channels are so lots of action potentials made - the action potentials jump from each node of ranvier ***if you have an unmyelinated neuron, it would be slower bc the action potentials wouldn't jump **that process is called Saltatory Conduction

Answer 14

site of communication between the synaptic terminal and the other cell presynaptic cell = sends the signal - releases a chemical (the signal) postsynaptic cell = receieves the signal - will receive the chemical (signal) **chemical synapses are more common than electrical synapses

Answer 15

neurotransmitters bind to their own receptors ex: dopamine binds to dopamine receptors

Answer 16

type of receptor - ion channel opens when a receptor binds to it - a neurotransmitter binds which opens the ion channel

Answer 17

when a neurotransmitter binds and sodium goes thru - closer to sending an action potential - depolarization

Answer 18

brings it away from an action potential - Potassium channels open - potassium leaves the neuron so the inside is more negative

Answer 19

one input alone is usually too weak to create an action potential synaptic integration (summation): - in the axon hillock, the EPSPs and the IPSPs are added together the neuron will make an action potential if you have enough (need more EPSPs than IPSPs)

Answer 20

GABA regulates how excited the neurons get all over the CNS - most effects inhibit things - many GABA receptors are on ion channels **drugs that act as GABA receptors are used to treat anxiety (xanax, valium) - IPSPs slow things down so less likely to make an action potential

Answer 21

depression usually treated with SSRIs (prozac, zoloft) - serotonin are metabotropic receptors bc they don't bind to ion channels - SSRIs block the reuptake of serotonin only so serotonin lingers longer which alleviates symptoms of depression **bc it's not an ionotropic receptor, the effects take longer to develop reuptake: - mechanism where serotonin is recycles - taken from synapse and packed back into vesicles ***SSRIs block the natural reuptake process

Answer 22

ions wouldn't be able to move across the axon membrane - there wouldn't be an action potential made

Answer 23

secretes chemical mesengers (hormones) into the blood stream

Answer 24

- neurotransmitters are released by neurons into the synapse and they travel a short distance - rapid effects, short lasting - voluntary control ex: you can lift your arm and put it back down when you want to **endocrine and nervous system interact with each other

Answer 25

- hormones usually travel long distances - slow, long lasting effects - not much voluntary control ex: you can't volunatrily increase your thyroid levels ***endocrine and nervous system interact with each other

Answer 26

group 1: removed testes - not masculanized male group 2: removed and replaced testes - typical male group 3: remove and transplant testes - typical male conclusion: - testosterone flows thru the body to affect male development - testosterone = hormone

Answer 27

- chemical messangers - released into bloodstream (neurotransmitters are chemical messangers released in the synapse) - act on distant target cells (and target cells that are close) pathway: - stimulus happens - endocrine system releases hormone into blood stream - binds to target cells - get a response

Answer 28

ex: glucose levels are low - pancreas releases glucagon - glucagon flows thru blood and binds to specific target cells - acts on liver (glucagon receptors in liver) result: glucose made

Answer 29

cells that have receptors for the specific hormone ex: testosterone only binds to target cells (testosterone specific receptors)

Answer 30

amines = bind to receptors in plasma membrane proteins/peptides = hormones bind to receptors in plasma membrane steroids = hormones bind to receptors in nucleus or cytoplasm

Answer 31

water soluable (hydrophilic) - travels easily thru water - lipid insoluable - can't travel thru lipids

Answer 32

water insoluable (hydrophobic) - can't travel easily thru bloodstream without help - lipid soluble - pass thru cell membranes (made of lipids)

Answer 33

hormone is stored in the vesicle and secreted thru exocytosis - now the hormones are in the bloodstream - the hormone then binds to a signal receptor - the signal receptor is outside of the membrane bc the hormone is lipid insoluable (so it wouldn't be able to get to the receptor) - now there's a cystoplasmic response (fast effect) - can also start gene transcription (slow) glucose ex: - released from pancreas, binds to liver, releases glucose

Answer 34

no vesicles used - they go to bloodstream but have to be carried thru by a transport protein (bc not water soluble) - then it leaves the bloodstream and it slips into cell (bc lipid soluble) - steroid binds to receptors in cytoplasm or nucleus - receptor hormone complex forms and enters nucleus - causes slow gene transcription or rapid cytoplasmic effects **steroids aren't stored, they're made on demand when you need them

Answer 35

the "master" of the endocrine system - produces and releases a lot of hormones anterior pituitary = at front of head - connected to brain by vessels posterior pituitary = at back of head - directly connected to the brain

Answer 36

neurons that release hormones into blood vessels

Answer 37

makes 2 hormones: ADH -- target is kidney tubules Oxytocin --- target is mammary glands, uterine muscles

Answer 38

1. stimulates uterine contractions before birth - oxytocin receptors appear in the uterus during birth receptor upregulation = makes tissue more sensitive to a signalining molecule (oxytocin) receptor downregulation = makes tissue less sensitive to oxytocin ex: after birth, receptors downregulate so the tissue is no longer sensitive ------ 2. stimulates milk ejection (let down) - milk released from mammary glands positive feedback loop: sensory input to hypothalamus: kitten suckling oxytocin releases: into general bloodstream receptors: oxytocin - oxytocin binds and causes glands to contract - glands that release milk contract the kittens keep suckling which sends more oxytocin and more milk until the kitten stops suckling

Answer 39

synthetic form of oxytocin - moms are given this if you don't have contractions - causes contractions ***uterus isn't sensitive to pitocin until right before birth

Answer 40

promotes bonding between mom and offspring - bonding between mated pairs

Answer 41

ADH conserves water by reducing water loss in urine - sweating/dehydration increases blood osmolarity (blood is saltier) - this causes the hypothalamus to release ADH into bloodstream - ADH goes into the distal tubule so water is now back in bloodstream bc of the aquaporins - the target tissue for ADH = Kidney **now water is in the blood so it's less salty - back to normal blood osmorlarity **now signal for ADH to be released other way to reduce blood osmolarity: - neurons in hypothalamus make you thirsty - you start drinking more water - drinking water brings you to normal blood osmolarity **ADH not released in this way **alcohol and caffeine disrupt ADH --- they're diuretics

Answer 42

***the neurosecretory cells don't leave the hypothalamus - the releasing or inhibiting hormones released into portal vessels - the releasing hormones then release anterior pituitary hormones ***they make 2 hormones: TSH and ACTH

Answer 43

has 2 layers: adrenal cortex: cortex layer - releases steroid hormones (glucocorticoids) Adrenal medulla: inner core - releases amine hormones (epinephrine and norepinephrine) **hormones from the adrenal glands prepare your body for stress **everyone has 2 adrenal glands: left and right one

Answer 44

**uses adrenal cortex ex: a zebra is in a drought and they have few resources - hormones help - the adrenal cortex has steroids that are slow but have longer-lasting effects process: - stress enters the hypothalamus - releasing hormone (CRH) is released by the neurosecretory cells in hypothalamus thru the portal veins - anterior pituitary secretes ACTH (happens when CRH binds to receptors) - adrenal cortex releases of glucocorticoids

Answer 45

- break down proteins and fats and convert them to glucose (energy) - supress immune system - stop reproduction and growth (takes a lot of energy to reproduce)

Answer 46

you want a certain level of glucocortidcoids - after the stress goes away, you don't want a high level of them - glucocorticoids go up to the hypothalamus and block the release of CRH and go to the pituitary to block the release of ACTH **increased levels of corisol tell the hypothalamus to stop releasing CRH and tells the anterior pituitary gland to stop making ACTH result: less ACTH and less CRH

Answer 47

**uses adrenal medulla ex: a zebra and lion get into a fight - adrenal medulla has rapid responses - fight or flight response the adrenal medulla secretes norepinephrine and epinephrine - pituitary gland isn't involved process: - stress is detected by hypothalamus - nerve signals --> neurotransmitter released - nerve cell releases epinephrine and norepinephrine - hormones released in general blood supply

Answer 48

- when there's a stressor, you don't know if it's long or short - so norepinephrine and epinephrine and glucocorticoids are all released

Answer 49

- increases blood glucose immediately - increases blood pressure - increases breathing rate - increases blow flow to brain, heart, and muscles - decreases digestive processes

Answer 50

exam = stressor days before exam: pretty low - right before the test and when you start the test the norepinephrine levels skyrocket days after exam: stress response decreases - norepinephrine levels decrease

Answer 51

- making glucose available and moving it to critical regions (brain, muscles) - increases alertness - pauses the immune system bc you don't want an autoimmune response - decreases investing in energy costly processes (stops growth, stops sperm and egg production) adaptive = happens when you need it to but the hormones go back down when you don't need them

Answer 52

no energy for immediate use (you get tired) - problems with reproduction - suppresses your immune system (so you can get sick) - can affect memory

Answer 53

ex: kid is cold TRH releases from neurosecretory cells in the hypothalamus to the portal vessels - thyroid stimulating hormone goes into thyroid gland - thyroid hormones (T3 and T4) bind which warms you up

Answer 54

high levels of thyroid hormones tell the hypothalamus to stop secreting TRH - also tells the anterior pituitary gland to stop making TSH

Answer 55

hyperthyroidism = too much thyroid hormone symptoms: feel hot, lose weight, irritable Grave's Disease: immune system stimulates TSH receptors (causes thyroid hormone to be released) - the immune system stimulates TSH receptors, not TSH - TSH is low now treatment= remove thyroid and then take thyroid hormones

Answer 56

hypothyroidism = not enough thyroid hormone symptoms = feel cold, gain weight, tired - lack of iodine in diet can cause this - thyroid hormones contain iodine which is obtained from diet - ppl put iodine in slat to make enough thyroid hormone goiter = growth in neck treatment = thyroid hormone in diet - keep producing TSH (a lot of TSH)