Human Physiology. Exam 2
calculate the resting membrane potential using...
GHK equation
endocrine glands
Glands of the endocrine system that release hormones into the bloodstream
what lingers in the synaptic cleft longer: NE or ACh?
NE
difference between NMJ and NEJ
NEJ has varicosities instead of synaptic end bulbs
calculate the ion potential using...
Nernst equation
gaps in the myelin sheath
Nodes of Ranvier
regeneration possible only in...
PNS
2 inhibiting hormones
1. Somatostatin (growth hormone-inhibiting hormone) 2. Prolactin-inhibiting factor (dopamine)
how does regulation of APit secretion by the hypothalamus occur?
1. Specialized neurons of the hypothalamus (neurosecretory cells) synthesize the hypothalamic releasing/inhibiting hormones in their cell bodies and package the hormones inside vesicles; vesicles then moved by axonal transport to the axon terminals for storage 2. When neurosecretory cells are excited, APs trigger exocytosis of vesicles, causing the release of the hormones; hormones then diffuse into the hypothalamic-hypophyseal portal system 3. Once conveyed to APit, hormones then diffuse out of the bloodstream and interact with APit cells; when stimulated by the appropriate releasing hormones, APit cells secrete hormones into the capillaries of the APit, which drain into venous blood 4. APit hormones travels through bloodstream to their target organs
somatic motor pathways consist of ___ motor neuron(s)
1
how does release of hormones occur in the PPit
1. Neurosecretory cells in the paraventricular and supraoptic nuclei synthesize oxytocin and ADH; each hormone is made by a separate cell type and both cell types are present in both the paraventricular nucleus and supraoptic nucleus; hormones produced in the cell bodies and then packaged into vesicles 2. Vesicles move by axon transport along the hypothalamic-hypophyseal tract to the axon terminals in the PPit, where they are stored 3. When appropriate stimulus excites the hypothalamus, APs trigger exocytosis and release of oxytocin and ADH into the bloodstream 4. Released oxytocin and ADH then travels to its target tissues in the body
infundibulum
A stalk that attaches the pituitary gland to the hypothalamus.
what neurotransmitter is released in autonomic ganglions
ACh
somatic motor neurons release ____ at NMJ
ACh that bind to nicotinic receptors
glutamate receptors?
AMPA and NMDA receptors
main difference between PPit and APit
APit synthesizes hormones while PPit implies stores them
in order to contract muscles need high concentration of...
ATP and calcium (near the thin filament)
ANS motor pathways:
CNS to autonomic ganglia (preganglionic) then from autonomic ganglia to visceral effectors (postganglionic)
NE can be released as...
a neurotransmitter or as a hormone (from chromaffin cells)
binding of a hormone to its specific receptor causes
a signaling pathways in that target cell that causes a change in the effector (key) protein
plasticity
ability of neurons to change based on experience, allowingg them to adapt and modify their structure and function to respond to various stimuli
two point discrimination
ability to perceive two points applied to the skin as two separate points
electrical excitability
ability to respond to a stimulus and convert it into an action potential
what are the two binding site of myosin
actin-binding site and atp-binding site
norepinephrine and epinephrine bind to what types of receptors?
adrenergic receptors (metabotropic)
convey sensory input into the CNS
afferent neurons
steroid hormones (9)
aldosteron, cortiosol, adrenal androgen, testostereone, estrogens, calcitriol, T3 and T4
if overlap in receptive field...
all participating neurons will respond to a stimulus that extends into the region of overlap
two types of adrenergic receptors
alpha and beta
water-soluble hormones
amines and peptides and proteins
two lobes of the pituitary gland
anterior and posterior
Four Types of Neuroglia in the CNS
astrocytes, oligodendrocytes, microglia, ependyma cells
convey action potentials to cardiac and smooth muscles and glands
autonomic motor neurons
axon potentials rise at the...
axon hillock
What forms the hypothalamic-hypophyseal tract?
axons of the paraventricular and supraoptic nuclei
what triggers muscle contraction
binding of calcium to troponin
lipid soluble hormones circulate in what form
bound to transport proteins since they are not blood soluble
fascicles
bundles of muscle fibers
what causes conformational change that moves tropomyosin away from binding sites on actin
calcium binding to troponin
5 releasing hormones
Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Prolactin-releasing hormone (PRH) Gonadotropin-releasing hormone (GnRH) Growth hormone-releasing hormone (GHRH)
as stimulus intensity increases, amplitude of he receptor potentials formed ________
increases
larger axon diameter ______ the speed of action potential
increases
myelination...the speed of action potentials
increases
GABA: excitatory or inhibitory
inhibitory
glycine: excitatory or inhibitory
inhibitory
lateral inhibition
input from sensory receptors along the border of a stimulus is substantially inhibited compared to input from sensory receptors at the center of the stimulus
junctional folds
invaginations of the sarcolemma where ACh receptors are especially concentrated
receptors abundant in NMJ on motor end plate where?
junctional folds
four types of ion channels important to neuron function
leak channel, ligand-gated channel, mechanically-gated channel, voltage-gated channel
two classes of hormones
lipid soluble and water soluble
within sarcoplasm is...
mitochondria, glycogen (storage form of glucose), and myoglobin (oxygen binding protein)
dual innervation
most viscera receive nerve fibers from both parasympathetic and sympathetic divisions
muscle cells are known as
muscle fibers
adrenergic receptors/neurons release/bind to
norepinephrine
adrenergic receptors respond to binding of...
norepinephrine and epinephrine
if hormones are present in excess...
number of target-cell receptors may decrease (down regulation)
if hormone is deficient
number of target-cell receptors may increase (up regulation)
hormones with an antagonistic effect
one hormone opposes the action of another hormone
hormones affect...
only target cells for THAT given hormone
why do hormones affect only their target cells
only they have the specific binding sites needed for that hormone
motor end plate
region of the muscle fiber plasma membrane opposite of the synaptic end bulbs
what do regulating and inhibiting hormones do?
regulating - stimulate secretion of hormones from APit cells inhibiting - surpresses secretion of hormones from APit cells
sarcomeres
repeating units of myofibril
nocioreceptors
respond to painful stimuli
parasympathetic nervous system
rest and digest (inhibition)/ conserves energy and facilitates processes like digestion and relaxation
Mechanoreceptors
sensitive to mechanical stimuli; provides sensations of touch, pressure, vibration, etc.
acuity
sharpness of perception
hormone secretion can be caused by...
signals from nervous system, chemical Changes in blood, distension of an organ, other hormones
filaments
single strands of material, usually twisted with other filaments to make a thread or fiber; involved in the contraction process; can be thick or thin
two major factors that affect acuity
size of receptive field (smaller = greater acuity) and measure of tactile acuity
somatic nervous system (SNS) innervates
skeletal muscle of the body
autonomic nervous system innervates...
smooth muscle, cardiac muscle, and glands (visceral effectors)
convey action potentials to skeletal muscle
somatic motor neurons
5 cell types in APit and what do they secrete
somatotrophs, thyrotrophs, corticotrophs, lactotrophs, gonadotrophs
lipid soluble hormones
steroid and thyroid
receptive field
stimulated physical area, specific group of chemicals, etc. that cause a response in that neuron
four steps of sensation
stimulation of the sensory receptor; transduction of the stimulus (energy from stimulus converted into a graded potential); generation of action potentials; integration of sensory input
The ANS consists of two divisions:
sympathetic and parasympathetic
neuroeffector junction
synapse between an autonomic neuron and its target muscle or gland
muscle action potentials enter the cell how
t-tubules
autonomic tone
the balance between sympathetic and parasympathetic activity
perception
the conscious awareness and interpretation of sensations
sensation
the conscious or subconscious awareness of changes in the external or internal environment
myofibrils
contractile elements of skeletal muscle fiber that extend through the sarcoplasm
tendons
cord of connective tissue that attaches the muscle to a bone
Schwann cells function
create myelin sheath in PNS
sarcoplasm
cytoplasm of muscle fiber
parasympathetic responses - 3 decreases
decreased heart rate; decreased diameter of the bronchial tubes of the lungs; decreased diameter of the pupils
most sensory pathways...
decussate (cross over to the opposite side)
thermoreceptors
detect changes in temperature
Chemoreceptors
detect chemicals in the mouth, nose, and body fluids
photoreceptors
detect light that strikes the retina of the eye
three basic functions of nervous system
detection of stimuli, integrative function, motor output
three ways in which a neurotransmitter can be removed from the synaptic cleft
diffusion, enzymatic degradation, uptake by nearby cells
few hormonal regulatory systems work via positive feedback, give an example
during childbirth, stretching of uterine cervix by fetus stimulates oxytocin release; oxytocin then stimulates contractions of the uterus, and the contractions push the fetus farther down, which stretches the cervix more and stimulates more oxytocin release
modality
each unique type of sensation (i.e. touch, pain, vision, taste, etc.)
convey motor output to PNS
efferent neurons
third branch of ANS
enteric nervous system (neurons in the GI tract that regulates digestion, absorption, and movement of food in the digestive tract)
AChe
enzyme that terminates ACh in the synaptic cleft
asparate: excitatory or inhibitory
excitatory
glutamate: excitatory or inhibitory
excitatory
hormones with a permissive effect
exposure to a second hormone causes a greater response in target cells of the first hormone
you can create more muscle cells..true or false, explain
false, you have a set number when you are born because they are unable to undergo cell division
two main advantages of electrical synapses
faster communication, synchronization
sympathetic nervous system
fight or flight (excitation)/ prepares you for emergency or intense physical activities
sarcoplasmic reticulum (terminal cisterna)
fluid filled system of membranous sacs that store calcium and encircles each myofibril
water soluble hormones circulate in what form?
free-form (not attached to other molecules) since blood soluble
stimulus intensity is encoded by two main factors
frequency of action potentials generated in response to a stimulus; number of sensory receptors activated by the stimulus
signaling pathways caused by lipid soluble hormones usually alters
gene expression
6 hormones released from anterior pituitary
growth hormones (somatotropin), thyroid-stimulating hormone (thyrotropin), adrenocorticotropic hormone (corticotropin), prolactin, follicle-stimulating hormone, luteinizing hormone
hormone secreting organs (12)
heart, hypothalamus, skin, thymus, liver, stomach, pancreas, kidneys, small intestines, ovaries/testes, adipose tissue, placenta
Responsiveness of a target cell to a hormone depends on
hormones concentration (responds better when concentration rises/falls), number of hormone receptors (responds better when higher number of), influences exerted by other hormones
tropic hormones
hormones that stimulate other glands to release their hormones
master of the pituitary gland
hypothalamus
biofeedback
the use of an external monitoring device to obtain information about a bodily function and possibly gain control over that function
sliding filament theory
theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still
transverse (t) tubules
tiny invaginations of the sarcolemma that are open to the outside of the cell so are filled with ECF
What blocks the myosin binding site on actin?
tropomyosin
two small regulatory proteins that are part of the thin filament
tropomyosin and troponin
hormones with a synergistic effect
two hormones acting together is greater than the sum of their individual effects
portal system
type of vascular arrangement in which blood flows from one capillary network through a portal vein and then into a second capillary network before returning to the heart
sympathetic responses
various emotions (fear, embarrassment, rage, etc.), exercise, emergency, excitement, and embarrassment
nongenomic effects
when lipid-soluble hormones activate signaling pathways that change activity of the protein but do not alter gene expression
flexible hinge
where the myosin heads join the myosin tail (allows myosin head to pivot)
modality is encoded by...
which sensory receptor and neural pathway are activated by the stimulus
SNS operates usually _______ conscious control
with
ANS operates ________ conscious control
without
sarcomeres are separated by what?
z-discs
Five Parasympathetic Responses
∙ S - salivation(digestion) ∙ L - lacrimation, tear production ∙ U - urination(digestion) ∙ D - digestion(digestion) ∙ D - defacation(digestion)
four steps of muscle contraction:
1. myosin hydrolyzes ATP, energizing the myosin heads 2. myosin binds to its binding-site on actin and releases previously hydrolyzed phosphate group 3. myosin head pivots pulling the thin filament past the thick and towards the center of the sarcomere, generating tension and ADP is released from the myosin head 4. cross bridge remains firmly attached to actin until it binds to another molecule of ATP, which detaches It from actin
four steps of how muscle contraction begins:
1. sarcoplasmic reticulum releases calcium ions into the sarcoplasm 2. calcium bind to troponin 3. troponin move tropomyosin away from binding site 4. contraction cycle begins now that binding sites are "free"
ANS motor pathways consist of ____ autonomic motor neurons
2 (preganglionic and postganglionic)
Neuroglia found in PNS
Schwann cells
temporal summation
Summation of postsynaptic potentials in response to stimuli that occur at the same location in the membrane of the postsynaptic cell but at different times
spatial summation
Summation of postsynaptic potentials in response to stimuli that occur at different locations in the membrane of a postsynaptic cell at the same time
three types of muscles
cardiac, smooth, and skeletal
hormones
chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues
ACh binds to what kind of receptor
cholinergic
muscle fibers are surrounded by sheaths of...
connective tissue
two types of cholinergic receptors
nicotinic (inotropic) and muscarinic (metabotropic)
each actin molecule contains what
myosin - binding site
what two proteins are the main components of thick and thin filaments
myosin-thick; actin;thin
APit is regulated by...
negative feedback
most hormonal regulatory systems work via... and give an example of this
negative feedback; after parathyroid glands release PTH in response to low blood calcium concentration, PTH acts on its target cells to increase blood calcium level; once blood calcium level is back to normal, PTH secretion is inhibited
labelled lines
neural pathways that convey information about modality to specific region of the cerebral cortex
support neurons
neuroglia
cholinergic neurons
neurons that release ACh
two hormones in PPit
oxytocin and antidiuretic hormone
muscle fibers are arranged...
parallel to one another
two clusters of the neurosecretory cells in the hypothalamus:
paraventricular nucleus and supraoptic nucleus
what kind of chemical modification is usually associated with the activation of an effector protein
phosphorylation (the addition of a phosphoric group to a molecule (PO3))
enodcrine glands include (5)
pituitary, thyroid, parathyroid, adrenal, and pineal glands
receptors for hormones may be present either in...
plasma membrane (water soluble since cannot move through plasma membrane) of inside the cell (lipid soluble since can move through plasma membrane)
sarcolemma
plasma membrane of muscle fibers
hypothalamic-hypophyseal tract
portal system in which blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries in the APit, allowing hormones to act immediately on APit cells