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