Flash Cards
beneficial stress
eustress
anything that disrupts homeostasis
stress
what happens during eustress
there is a deviation and then normal homeostatic mechanisms bring it back into range
detrimental stress that causes further deviation from homeostatic norms
distress
who was Hans Selye?
an Austrian-born physician who noticed that a bunch of his patients who wer experiencing various ailments all had the same blood chemistry, so he said that “stressful events lead to a disease state”. he was laughed out of Europe and came to America where he developed the General Adaptation Syndrome
says that stress occurs through a well-developed sequence of steps
general adaptation syndrome
what are the steps in the general adaptation syndrome
- alarm reactions
- resistance reactions
- physiological exhaustion
when does the alarm reaction stage of the general adaptation syndrome usually occur and what happens during it?
it occurs every time you are presented with a stress. generally takes care of the situation. it is short lived, reverses the stress using the nervous system
what happens if the alarm reactions don’t work during the general adaptation syndrome?
move on to the second stage - resistance reactions
what occurs during the resistance reactions stage of the general adaptation syndrome?
body adapts to longer term stress. this one is slower to respond and often is a hormone response
what happens during the physiological exhaustion stage of the general adaptation syndrome?
body shuts down and without intervention it ends in death
what are the key organs/systems involved in the general adaptation syndrome?
the endocrine and nervous systems
what is the ‘mediator’ of the nervous system, and what is the ‘mediator’ of the endocrine system?
electrical signals/impulses in the nervous system, hormones in the endocrine system
what are the target tissues in the nervous and in the endocrine systems?
muscles, glands, or other neurons in the nervous system, all cells in the human body are targets for at least one hormone of the endocrine system
how quickly do we see a response with the nervous system and how quickly do we see one with the endocrine system?
immediate with the nervous system - from several hours to several days with the endocrine system
how long is the response duration for the nervous and endocrine systems?
the nervous system is short lived while the endocrine system is longer-lived
chemical messengers
hormones
what are hormones produced by?
endocrine glands
do you need a high dose of a hormone?
no, you only need a little bit
what does it mean that hormones are specific?
they only interact with their target cells/tissues
what is a target cell?
specific cell that reacts with a specific hormone. the hormone will bring out some sort of change in that cell
how are hormones classified?
based on how they operate, based on their solubility, and based on their chemistry
what are the two types of hormones based on how they operate?
circulating hormones and local hormones
produced by endocrine gland and circulate in the blood over a distance before they reach their target
circulating hormones
what is an example of a circulating hormone?
the posterior pituitary produces antidiuretic hormone which has to go from the brain to the kidney through the blood
type of hormones that stay in the area near the tissue/gland that produced them. in the interstitial fluid.
local hormones
what are the two types of local hormones?
autocrines and paracrines
hormones that are secreted and affect the cells that produced them - what is an example?
autocrines - endorphins
hormones that affect cells that neighbor the gland that secreted them. what are some examples?
paracrines - prostaglandins and interleukin II
what are the types of hormones that are classified based on their chemistry?
biogenic amines, peptides and proteins, gaseous hormones, steroid hormones, eicosinoids
small hormones that are usually modified amino acids. hormones like T3 and T4.
biogenic amines (NH3)
hormones that consist of chains of amino acid
peptides and proteins
what hormones are peptides and proteins?
human growth hormone, antidiuretic hormone, oxytocin, insulin
what is the only confirmed gaseous hormone in the human body and what cells does it affect?
nitric oxide affects almost every cell
hormones derived from cholesterol. some of the most potent. sex hormones, cortisol, aldosteroid.
steroid hormones
hormones that are derived from arachidonic acid. usually function as a local hormone. typically pull acid from the cell membrane and then convert it into the hormone. prostaglandin
eicosinoids
what dictates the function of the hormone
solubility
how is a lipid hormone able to be transported through the blood?
it must bind to a plasma transport protein, which makes the hormone temporarily soluble in water
do lipid soluble proteins have a hard time passing into the cell?
no
what happens if the lipid soluble hormone is in the target cell?
it will bind to the receptor and form the hormone receptor complex which enters the nucleus, interacts with DNA and activates certain genes. one of the things that is turned on is protein kinases which alter the physiology of the cell.
why do we want hormone reactions inside the cell to be short lived.
because they longer the hormone is affecting the cell, the greater chance of mistakes in DNA that could lead to cancer, since the hormones interact with DNA
what happens if the lipid soluble hormone is not in the target cell?
the hormone will become an inclusion and become recycled
do water soluble hormones have a problem being transported in the blood?
no because they are soluble into the plasma
where do water soluble hormones start to encounter a problem?
when trying to enter the cell
how do water soluble proteins enter the target cell?
the target cell will have a receptor outside the plasma membrane which is linked to a special protein called a G protein which links the outside of the cell to the inside.
what happens after the water soluble hormone has bound to the receptor on the outside of the plasma membrane?
the G protein is activated when the hormone binds. it activates adneylate cyclase which catalyzes the conversion of ATP to cyclic adenosine monophosphate (cAMP) which is the second messenger. cAMP diffuses in the cell, activating enzymes that generate change in physiology
control of the endocrine system. floor of the brain. controls the anterior pituitary gland
hypothalamus
in what areas does the hypothalamus have neurons
it has neurons in the ventral hypothalamus, paraventricular nuclei, and syrapoptic nuclei
what does the anterior pituitary gland secrete into and what types of hormones does it secrete?
secretes into the hypothalamic hypophyseal portal system - secretes releasing hormones and inhibiting hormones
produced by the downward growth of embryonic hypothalamic tissue and has a neural connection to the hypothalamus
posterior pituitary gland
what are the neurosecretory cells of the posterior pituitary gland
supraoptic and paraventricular nuclei secrete neurohormones - oxytocin and antidiuretic hormone
hormone made of nine amino acids that is a positive feedback mechanism. causes uterine contractions, milk ejection, and is called the cuddle hormone
oxytocin
what gland produces oxytocin
posterior pituitary gland
hormone made of nine amino acids that inhibits water secretion in the kidney tubules
antidiuretic hormone
what gland produces antidiuretic hormone?
posterior pituitary gland
“master gland”, the truly glandular part of the pituitary gland
anterior pituitary gland
what hormones does the anterior pituitary gland secrete?
human growth hormone, thyroid stimulating hormone, adrenocorticotropic hormone, gonadotropins (follicle stimulating hormone and luteinizing hormone) prolactin
hormone that is used to produce insulin-like growth factors and stimulates body growth in most cells
human growth hormone
what happens when human growth hormone is not produced in proper amounts?
if there is too much, you can get gigantism or acromegaly. if there is not enough you can have pituitary dwarfism
when there are not proper amounts of human growth hormone, does the time of the disorder matter?
yes, if it is before the growth plates close you have gigantism, but if it is after the growth plates close, you get acromegaly
stimulates the release of hormones from the thyroid gland. affects almost every cell in the body - glucose oxidation, heat production, blood pressure, tissue growth
thyroid stimulating hormone
what are characteristics of myxedema (hypothyroid disorder)
low metabolism, cold, puffy eyes, thick, dry skin, goiter, sluggish
what is cretinism?
congenital deficiency that has to do with thyroid stimulating hormone. can cause mental retardation and stunted growth
autoimmune disease in which antibodies attach thyroid stimulating hormone receptors. hyperthyroid disease.
grave’s disease
what are symptoms of grave’s disease?
elevated metabolism, sweating, rapid heart rate, weight loss, antibodies attack protein in the eye muscle causing exphtalamus (bulging eyes)
hormone released to increase protein breakdown, increase gluconeogenesis to produce sugar from non-carbs, increase blood vessel sensitivity to vasocroticosteroids (constrict blood vessels to increase blood pressure) triggers inflammation (decrease immune system), dampens the immune response
adrenocorticotropic hormone
also called corticotropin
adrenocorticotropic hormone
hormone that regulates the function of the gonads
gonadotropins
what are the two types of gonadotropins?
follicle stimulating hormone and luteinizing hormone
hormone that stimulates milk production in humans
prolactin
what does hyper-secretion of prolactin cause?
inappropriate lactation, loss of menstrual cycle, infertility in females, breast enlargement in males
what percent of the adrenal gland does the adrenal medulla make up, and what type of tissue is the adrenal medulla made of?
20-25% of the adrenal gland. it is made up of nervous tissue and contains chromaphin cells
what are chromaphin cells?
modified post-ganglionic neurons of the autonomic nervous system?
what percent of the adrenal gland does the adrenal cortex make up, and what type of tissue is it?
70-75% of the adrenal gland - made up of glandular tissue - it is the truly glandular part of the gland
what two hormones does the adrenal medulla secrete?
epinephrin and norepinephrine
what does epinephrin cause
palpitations, white face, sweaty palms, tachycardia, affects sphincters, dilates muscles
what does norepinephrine cause?
increased heart rate, releases glucose, increases blood flow to muscles
what four zones is the adrenal cortex divided into?
the adrenal capsule, zone of glomeriosis, zone of fasiculata, zone of reticularis
zone of the adrenal cortex that is made up of dense irregular connective tissue and is around the whole gland
adrenal capsule
zone of the adrenal cortex where the cells are organized into little balls. they secrete mineralcorticoids which regulate sodium and potassium homeostasis
zone of glomerioisis
what is an example of a mineralcorticoid?
aldosterone - it increases water absorption in the kidney tubules
zone of the adrenal cortex that consists of cells grouped in small bundles and secretes hormones that affect carbohydrates
zone of fasiculata
smallest, innermost zone of the adrenal cortex which seretes gonadocorticoieds
zone of reticularis
what are gonadocorticoieds
hormones that affect reproductive physiology
what are the two different types of cells in the nervous system?
neuroglial cells and neurons
supportive cells of the nervous system
neuroglial cells
functional cells of the nervous system
neurons
what are the different types of neuroglial cells?
astrocytes, microglial cells, ependymal cells and oligodendrocytes in the CNS
neurilemmocytes/schwann cells and satellite cells in the PNS
what are the functions of astrocytes?
interaction is formed between the capillaries, neurons, and them which produces the BBB, can regulate blood flow to the brain because they wrap around capillaries, nourish neurons because they have the ability to convert sugar into lactate which provides some ATP, involved in the production of nerve growth factors - help form synapses, have a role in synaptic signaling, produce sclerosis or astrocytosis - scar tissue in the place of a damaged neuron
function of microglial cells
involved in immune function. they are modified macrophages
function of ependymal cells
line spinal and cranial cavities and produce cerebrospinal fluid
function of oligodendrocytes
form myelin sheath around axons of neurons in the CNS
function of neurilemma cells/schwann cells
form myelin sheath around axons of neurons in the PNS
functions of satellite cells
usually associated with cell bodies of unicellular neurons, involved in the environment of a neuron
short processes that transmit electrical signals towards the soma
dendrites
long extensions that generate electrical signals called impulses away from the soma
axons
axon hillock
cone shaped region where the axon meets the soma
axon terminal
the end of an axon
integral proteins that provide a passageway through the membrane
membrane channel
are gaited channels open or closed most of the time? when do they open?
they are closed most of the time and open in response to a stimulus
what types of channels respond to some type of physical distortion (touch, pressure, stretch)
mechanical gaited channels
type of channel that responds when a chemical interacts with a receptor on a membrane
ligand-gated channels
type of channel that responds to light
photon-gaited channel - found in the pineal gland
type of channel that responds to electrical signals/current flow
voltage-gaited channels
trigger zones
axonal membrane regions with high densities of voltage-gated channels
what is the resting membrane potential
-70 mVolts
when the axon is at rest, which area is more positive?
the outside of the membrane is slightly more positive than the inside, so we say that the membrane is polarized because there is an unequal charge across the membrane
what do membrane pumps do? do they require energy?
they pump 3 Na out for every 2 K pumped in. they are active transport mechanisms and so require ATP
what molecule is the axon membrane more permeable to? why is this and what affect does it have on the membrane?
the membrane is more permeable to K leakage than Na because water tends to follow sodium. this causes potassium to leak out and makes the difference between the membrane worse.
what helps neutralize some of the positively charged particles inside the axonal membrane?
there are large proteins inside the axonal cells which are negatively charged
anything that causes Na and K gates to open
stimulus
which channels open the fastest, and which open the slowest?
sodium-gated channels open very quickly while potassium-gated channels open much more slowly
depolarization
Na rushes into the membrane and for a moment the inside of the membrane is more positive than the outside of the membrane
repolarization
Na gates shut and K gates open slowly - this delay helps reestablish the membrane to where it was
after the K and Na gates have opened and reploarization has occurred, which side of the membrane is more positive? why?
still more positive on the inside because K has left the membrane
what is the refractory period?
below resting potential. charge on the membrane is slightly below resting potential because for a brief moment, Na and K are on the wrong sides of the membrane.
what restores the cell to the resting membrane potential after it has entered the refractory period?
the sodium-potassium pumps open up
what is an action potential.
a stimulus occurs, sodium comes into the membrane and potassium goes out. the membrane is a little more negative, but goes back to the resting membrane potential after the pumps open. the next portion of the axon is stimulated and the same thing occurs there
moving wave of action potentials
impulse
what does it mean that an impulse is a self-propagating electrical signal?
it has the ability to reconstruct itself along the length of the axon
how much will the deviation from resting membrane potential in an action potential always be?
100 mVolts
minimum charge that must be generated before an impulse fires
threshold potential
what is the threshold potential to generate an action potential
-55 mVolts
graded potentials
potentials that are not consistent. there are varying degrees of charge based on ions. they individually will not reach threshold so there will be no effect/feeling. they continue to try and excite the neuron to enough to generate an impulse.
excitatory potential
moves towards the threshold. the graph moves up, but doesn’t reach the threshold.
inhibitory post-synaptic potentials
charges move away from threshold because they inhibit sodium gates and open chloride gates and allow chloride to move through. takes more effort to be able to generate an action potential. used in pain medicines
what is the location/origin of graded potentials and what is it in an action potential?
dendrites or cell bodies depending on the type of gated channel in graded potentials. axons in action potentials
what are the types of gated channels in graded potentials? what are they in action potentials?
mechanically gated, ligand-gated, or photon gated in graded potentials. voltage-gated channels in action potentials
what is the amplitude, or deviation from threshold, in graded potentials and what are they in action potentials
varies for graded potentials, +/- 50 mV. always 100 mV for action potentials
what is the duration of graded potentials and what is it for action potentials?
there is a variation in graded potentials, miliseconds - minutes. action potentials last about two miliseconds
what is the propogation for graded potentials and what is it for action potentials?
graded potentials are decremental, they weaken as they go because they are not self-propagating. action potentials don’t weaken because they are self-propagating.
is there a refractory period in graded potentials and action potentials?
there isn’t for graded-potentials, but there is with action potentials.
what is the difference in polarity with graded potentials, what is it which action potentials?
with graded potentials, it can be summed or strung together to reach threshold potential. with action potentials, they are excitable and polarize first
continuous conductance - what is it, where does it happen, how fast is it, does it require a lot of energy, and where is it good?
must establish action potential continuously down the neuron. it occurs in an un myelinated neuron. it is slow (about 1-4 mph or 2m/second). it requires a lot of energy because of the sodium-potassium pumps, and is good in the autonomic nervous sytem
saltatory conductance - what is it, where does it occur, where does ion exchange occur, is it fast or slow?
comes from the french word “to leap”, occurs on a myelinated axon. ion exchange only occurs at the nodes of ranvier, and it is faster
area between the myelin sheath where action potentials are generated
nodes of ranvier
how much faster is conductance in myelinated fiber vs un-myelinated fibers, why is this?
30x faster in myelinated fibers (30-300 mph or 120 m/sec). this occurs because they myelination insulates the fiber, allowing the signal to slide down that area to the next node of ranvier instead of having to do ion exchange at each little piece of the axon
region of communication between an axon and other structures (neurons, muscles, glands)
synapse
neuron where the terminus (end bulb) releases a transmitter substance in response to a stimulus.
presynaptic neuron
what are the different ways a synapse can be classified?
based on structure, or based on function
what are the ways a synapse can be classified based on structure?
axodendritic synapses, axo-somatic synapse, axo-axonic synapse
communication between a presynaptic axon and a post-synaptic dendrite
axo-dendritic synapse
communication between the axon of one neuron and the cell body of another
axo-somatic synapse
axon of presynaptic cell communicates with axon hillock of post-synaptic cell
axo-axonic synapse
what are the ways that a synapse can be classified functionally?
chemical synapse and electrical synapse
occurs when a chemical substance is released into the synaptic cleft and is received by the responding structure
chemical synapse
what are the fates of a transmitter substance?
enzymes destroy them, diffuse out of the synaptic cleft, recycled
what are the two ways a neurotransmitter can be recycled?
uptake and reuptake
when neuroglial cells uptake reusable neurotransmitters and put them in vesicles in presynaptic neuron
uptake
when the original neuron that released the neurotransmitter reabsorbs it by endocytosis into a vesicle
reuptake
what do serotonin inhibitors do?
reduce the reuptake of serotonin and help with anxiety - medicines like zolaf, prozac, and paxil
type of signal found in rhythmic organs such as the hear, brain, and uterus.
electrical signals
what are gap junctions and in what kind of synapse are they seen?
where cells are close together, but aren’t touching. this is seen in electrical synapses
small protein cords that connect cells through gap junctions and allows them to function as one cell
connexions
what do connexions allow?
electrical signals to go in two directions
what are the advantages to electrical synapses?
there is no synaptic delay, they are very fast. it allows two-way communication, and it allows tissues to synchronize
