Exam 2 Flashcards
what does homeostasis require?
communication
cells and tissue must remain intergrated
what are the different types of signals?
electrical - nervous
chemical - endocrine
what are the four methods of cell-to-cell communication?
- gap junctions
- contact-dependent
- local communication
- long distant communication
what is gap junctions?
simplest of communication
has connexins
what are connexins?
allow ions to pass between cells via a channel (Conn exon)
- creates electrical continuity between cells
- ions, small molecules
what is the only way electrical signals are carried between cells?
connexins
where are gap junctions found?
myocardium
intestinal smooth muscle
uterine smooth muscle
what are contact-dependent signals?
require direct contact between surface molecules of 2 cells
CAM can act as receptors
where are contact-dependent signals found?
immune system
growth
development
what is local communication?
chemical reaches target via diffusion through interstitial fluid
ex: cytokines
eicosanoids
what are the three different types of local communication?
autocrine
paracrine
juxtacrine
what is autocrine?
acts on cell of origin
what is paracrine?
acts on adjacent cells
what is juxtacrine?
may act on both cell of origin and adjacent cells
what are some types of long distance communication?
endocrine
nervous
what is endocrine communication?
hormonal signaling
chemical signal carried by circulatory system
what is nervous communication?
very rapid and targeted response
electrical signal through neuron, then chemical secreted at end (neurocrine)
what is a ligand?
a molecule that binds to a receptor
what is a receptor?
a protein that binds a ligand and creates a response
may be membrane bound or floating in cytosol
what are all the parts of a signal pathway?
signal molecule membrane receptor protein intracellular signal molecule target protein response
what are the two categories of chemical signals?
lipophilic
lipophobic
what is a lipophilic chemical signal?
bind to cytosolic or nuclear receptors
activation turns on gene and mRNA is made
very slow process
what is a lipophobic chemical signal?
bind to receptors on cell membrane
fast process
4 receptor types
what are the four different lipophobic receptor types?
receptor-channel
receptor-enzyme
G protein-coupled receptor
integrin receptor
what is a receptor channel?
ligand binding opens or closes the channel
what is a receptor enzyme?
ligand binding to a receptor enzyme activates an intracellular enzyme
what is a G protein coupled receptor?
ligand binding to a G protein-coupled receptor opens an ion channel or alters enzyme activity
what is an integrin receptor?
ligand binding to integrin receptors alter the cytoskeleton
what is signal transduction?
transmission of information from one side of a membrane to the other using a membrane protein
what are the three novel signal molecules?
calcium
NO
CO
what is calcium used for?
most versatile ionic messenger Ca2+ binds to calmodulin bind/alter movement of microtubules trigger exocytosis alter gate state of ion channels enter fertilized eggs
what is NO used for?
- result of synthesis of arginine by NOS
- diffuses into cell, binds to gaunylyl cyclase and forms cGMP
what is CO used for?
similar to NO
what is modulation of signal pathways?
specificity and competition
what are the two classifications of a ligand?
agonist
antagonist
what is an agonist ligand?
molecule binds to a receptor and causes a response
what is an antagonist ligand?
molecule binds to a receptor and results in no response
“blocks”
what are signal pathways?
cells capable of changing the number of available receptors to modulate a response
-deals with saturation of proteins and ligands
what is upregulation?
an increase in the number of available receptors
what is down regulation?
a decrease in the number of available receptors
what is termination of signal pathway?
removes signal molecule
breaks down receptor ligand complex via endocytosis
what are Cannon’s postulates?
- nervous system has role in preserving fitness of the internal environment
- homeostasis - some systems are under tonic control
- blood vessel diameter - some systems are under antagonistic control
- insulin and glucagon - one chemical signal can have different effects in different tissue
- epinephrine
what is the control system?
regulated variables have a set point and normal range
what is a set point?
optimum value
what is local control?
isolated change in vicinity of cell/tissue
paracrine/autocrine response
ex: O2 in tissue
what is reflex control?
long distance
coordination of reaction outside organ of response
-systemic
uses nervous and/or endocrine
what is reflex control?
long distance
coordination of reaction outside organ of response
-systemic
uses nervous and/or endocrine
what are the two parts of physiological reflex?
response loop
feedback loop
for reflex control, what are the two different kinds of input signals?
stimulus
sensor
what is stimulus?
disturbance or change
sets pathway in motion
ex: temperature, O2, blood pressure
what is a sensor?
NOT protein receptors
specialized cells: central or peripheral
must reach threshold: range or limit
what is a central sensor?
head:
eyes, ears, nose, tongue
what are peripheral receptors?
every thing that isn’t a central sensor
ex: pressure, temp, pain, touch
for reflex control, what are input signals?
depends on the type of reflex
- neural: sensory neuron
- endocrine: no pathway
what is special about endocrine input signal?
there is no pathway
gland releases hormone and doesn’t have to send a message
for reflex control, what is the integrator?
the cell that receives information about the change and is programmed to initiate a response
-can have one or multiple stimuli
where does the endocrine reflex take place?
the endocrine cell
where does the neural reflex take place?
within the central nervous system
for reflex control, what are output signals?
efferent pathway
neural vs. endocrine
signal vs. route
for reflex control, what is a target?
cells/tissues that carry out the response
neural: muscle, glands, some adipose
for reflex control, what are the levels of responses?
cellular and systemic
what are the three different types of set points?
acclimatization
acclimation
biological rhythms
what is acclimatization?
adaptation of physiological processes to a given set of natural environmental conditions
what is acclimation?
adaptation of physiological processes to a given set of artificially induced conditions
what are biological rhythms?
regulated variables predictably change
what is a feedback loop?
a way to modulate the response
- information about the response sent back to integrating center
- can be positive or negative
what is a negative feedback loop?
more common
the response opposes and removes the stimulus
occurs in most reflexes
homeostatic
what is a positive feedback loop?
response reinforces the stimulus
not homeostatic
rarely occurs in the body
what is endocrinology?
the study of hormones
what are hormones?
chemical messenger secreted into the body by specialized cells
what makes a chemical hormone?
secreted by cell glands secreted into blood transported to distant target exert effects at low concentrations (nano-pico) act by binding to receptors action must be terminated
what are the three chemical classes of hormones?
proteins/peptides - insulin, oxytocin, ACTH
amines - dopamine, epinephrine
steroids - cortisol, progesterone, vit D
how else can you classify hormones?
source
how their release is controlled
type of receptor they bind to
what is half life?
how long you have until you have half the concentration
what is the most common type of hormone?
peptide
what are steroid hormones?
derived from cholesterol origin: adrenal cortex, gonads, placenta made in ER released via diffusion not soluble in plasma/body fluids
what are amine hormones?
created from tryptophan or tyrosine
tryptophan: melatonin
tyrosine: all others
similar to thyroid
what are catecholamines?
neurohormones
-bind the way peptide hormones do
what is the simple control of hormone release?
endocrine cell senses stimulus and responds by secretion
ex: PTH, insulin, glucagon
what is the complex control of hormone release?
add nervous system
- adrenal medulla: catecholamines
- hypothalamus/pituitary: lots
what is the function of hypothalamus and pituitary glands?
provide major endocrine control
the hypothalamus receives electrical signals from the brain
-causing the release of tropic hormones that will affect the pituitary gland
what is a tropic hormone?
acts on another target (gland) to release more hormones
what is the pituitary considered?
the master gland
what are the two distinct regions of the pituitary gland?
anterior (adenohypophysis)
posterior (neurohypophysis)
what does the anterior region of the pituitary gland do?
production and storage center for these 6 hormones:
- follicle stimulating hormone (FSH)
- luteinizing hormone (LH)
- thyroid-stimulating hormone (TSH)
- somatotropin (GH)
- prolactin (PRL)
- Adrenocorticotrophic (ACTH)
what does the posterior region of the pituitary gland do?
storage center for these two hormones
- oxytocin
- vasopressin/ADH
what is glucagon?
increase in glucose
what is synergism hormone interaction?
the combination of 2 hormones yields a result greater than the additive
ex: glucagon, epinephrine, and cortisol
what is permissive hormone interaction?
one hormone cannot exert effects unless a 2nd hormone is present
ex: thyroid and reproductive system
what is antagonistic hormone interaction?
1 hormone opposes action of another
ex: insulin & glucagon
what is hypersecretion?
hormone present in excessive amounts
ex: graves disease - thyroid hormone (TH)
giantism/acromegaly - somatotropin
cushings disease - ACTH, cortisol
what is hyposecretion?
deficiency of hormone ex: dwarfism - somatotropin hashimoto's disease - thyroid hormone addisons's - ACTH, cortisol diabetes mellitus - insulin
what do most clinical endocrine issues result from?
hypersecretion
hyposecretion
what are the two different divisions of the nervous system?
central
peripheral
what is the central nervous system?
brain and spinal cord
surrounded by the meninges
what are meninges?
layers of protective membranes that are specific the central nervous system
what is the peripheral nervous system?
all outlying neurons
what are the two types of peripheral neurons?
afferent
efferent
what are afferent neurons?
sensory
detect stimuli
what are efferent neurons?
motor
trigger responses
what are the two different types of cells of the nervous system?
neurons
glial cells
what are neurons?
functional unit of nervous system an excitable tissue send electrical signals throughout the body -rapid -direct -uses processes up to 1m
what are glial cells?
support cell
what do neurons release into the ECF?
chemical signals
what doe neurons rely on to send signals?
ion disequilibrium across the cell membrane
what is the structure of a neuron?
specialized structure cell body dendrites dendritic spines axon hillock axon myelin sheaths axon terminus
what does the cell body of a neuron contain?
nucleus and most organelles
what does the dendrites in the neuron do?
receive information
increase surface area
what do the dendritic spines in the neuron do?
increase surface area
what does the axon hillock in the neuron do?
where the axon connects
action potential starts here
what does the axon in the neuron do?
sends signals
what do the myelin sheaths in the neuron do?
helps isolate the signal
what does the axon terminus do?
terminates the signal
goes into the mitochondria
what are the two different types of axonal transport?
slow
fast
what is slow axonal transport?
uses cytoplasmic flow
ex: enzymes, protein
what is fast axonal transport?
uses microtubules
ex: vesicles, microtubules
what are the different structures of a neuron?
pseudounipolar
bipolar
anaxonic
multipolar
what is a pseudounipolar neuron?
axon and dendrites fused together
touch and pain sensory neuron
what is a bipolar neuron?
only one dendrite
retinal and olfactory neuron
what is a anaxonic neuron?
lots of dendrites
no axon
amacrine cell
what is a multipolar neuron?
multiple neurons with and axon
motor neuron
pyramidal neuron
purkinje cell
what are the different types of functions of a neuron?
sensory
interneuron
efferent
what is the sensory neuron function?
input signal
carry information from sensor to CNS (temp, pressure, light)
structures differ in length and organization
somatic senses: psuedounipolar
neurons for smell and vision: bipolar
what is the interneuron neuron function?
integrating center lies entirely within the CNS complex branching - allows easy communication with many neurons quite small structure: anaxonic or multipolar
what is the efferent neuron function?
output signal includes somatic motor and automatic very similar to a model neuron axon bundled with CT = nerves always multipolar
why are glial cells important?
important physical/biochem support for neurons
what is membrane potential?
the difference in energy across a membrane
what causes membrane potential?
diffusion and active transport of ionos
intracellular: negative
extracellular: positive
total body overall is neutral
what is the primary ion that determines resting membrane potential?
K+
creates disequilibrium
how is Na-K-ATPase implicated in membrane potentials?
K+ plus determines membrane potential
for every 2K+ 3Na+ is needed
what are the two factors that influence membrane potential?
- concentration gradient of ions
2. permeability of membrane -gated channel
how many ions does it take to change membrane potential?
a few
what changes when membrane potential changes?
permeability
