Physiology exam 2

paracrine

autocrine

neurotransmitter

hormone

name the four functional categories of chemical messengers:

amino acid

amine

peptide/ protein

steroid

eicosanoid

name the 5 chemical categories of messengers:

apical membrane

the plasma membrane separating an epithelial cell from the lumen of a body cavity (or externam environment)

transcytosis

transport of macromolecules through a cell (across the membrane)

chemical messenger

a substance with signaling functions

neurohormone

a chemical messenger released from a neuron into the blood (via interstitual fluid)

messenger half-life

the time after a messenger is secreted during which its concentration decreases by 50%

agonist

a chemical which binds to a receptor and causes the same responce as its normal ligand

second messenger

an intracellular messenger molecule produced in response to binding of an extracellular (first) messenger to a receptor

signal transduction

translation of a chemical signal (messafe) to a response in a target cell

catabolism

breakdown of organic molecule (energy-releasing)

exergonic

energy-releasing

enzyme

a catalyst for a biological reaction (usually a protein)-lowers the activation energy for a specific reaction

cofactor

ion or molecule required by an enzyme for the enzyme to be active

ligand

a molecule that binds to a protein (substrate to enzyme, chemical messenger to receptor)

protein kinase

an enzyme that catalyses phoshorylation of a protein substrate

phosphatase

an enzyme that catalyses dephosphorylation of a protein substrate

proteolysis

breakdown of protein to amino acids

ion

charged particle (one or more atoms with unequal total numbers of protons and electrons)

membrane potential

an electrical force due to an unequal distribution of anions and cations between the two sides of a membrane

flux

the number of molecules crossing a membrane per unit time and surface area (or net movement of molecules through any surface)

osmosis

passive transport of water across membranes

hyperosmotic

having a greater concentration of solute particles

hypertonic

causing a cell to shrink

exocytosis

release of material from a cell, achieved by fusion of vesicles with the plasma membrane

autophagosome

a membrane-bound structure containing material sequestered from the interior of a cell

secretion

transport from the internal to external environemnt (from interior of cell or body)

electrical driving force

chemical driving force

name the 2 forces which, in combination, are known as the electrochemical force:

electrical driving force

a separation of charge across a membrane (membrane potential), which causes ions ot move to the side with a net charge opposite to their own (assuming the membrane is permeable)

chemical driving force

is a metaphor for hte net movement of molecules down a concentration gradient (from high to low concentration)

facilitated diffusion

glucose enters a cell passively through a carrier

active transport

a pump uses energy to move a particle across a membrane, in a direction opposite to the direction of the electrochemical driving force

phagocytosis

a cell engulfs solid particles or microorganisms

feedback inhibition

an intermediate in a biochemical pathway decreases the activity of an upstream enzyme in the same pathway

cotransport (symport) - secondary active transport

active transport of glucose into a cell is couple with passive transport of Na+ into the same cell

counter transport

movement of Na+ into a cell drives the flow of H+ out of the same cell

glutamate

neurotransmitter is the chemical messenger and amino acid is the chemical category

epinephrine

neurotransmitters or hormones are the chemical messenger and amine is the chemical category

insulin

neurotransmitters or hormones are the chemical messenger and peptide/protein is the chemical category

estrogen

hormone is the chemical messenger and steroid is the chemical category

lipophobic

are messengers stored in vesicles and released by exocytosis and are transported in dissolved form

lipophilic

are messengers that cross the plasma membrane, usually have receptors in the cytosol or nucleus of the target, and generally have a longer half life

channel-linked

enzyme-linked

G protein-linked

lipophobic ligands have 3 types of receptors (in plasma membrane):

cAMP

cGMP

diacylglycerol

inosito triphosphate

Ca2+

G protein, whcih hydrolyze GTP, have 5 major second messengers:

antidiuretic hormone

promote water reabsorption by the kidneys

melatonin

maintain the circadian cycle (antioxidant)

thyroid hormones

maintain the basal metabolic rate

cortisol

stress response; increase blood glucose concentration

glucagon

elevate blood glucose level

Organ that secetes it: pancreas

pituitary gland

the main function of this is to produce hormones (primary endocrine organ)

heart

the main function of this is to pump blood, but it also secretes a hormone (secondary endocrine organ)

its rate of release by secretory cells

rate of breakdown

storage

binding to carrier proteins

name some factors that affects the level of a hormone in the blood:

PRH

PIH

TRH

CRH

GHRH

GHIH

GnRH

TSH

ACTH

GH

LH

FSH

name the 12 tropic hormones of the hypothalamus:

decrease; decrease; increase

primary hypersecretion of thyroid hormones cause a ___ in TRH, ____ in TSH, and ___ in thyroid hormone

central nervous system

peripheral nervous system

2 main components of the nervous system:

central nervous system

includes the brain and spinal cord

afferent nervous system

efferent nervous system

peripheral nervous system is divided into:

afferent nervous system

receives input from the sense organs

efferent nervous system

delievers output to effector organs

cell body/ soma (contain nucelus)

branches (dendrites and axons)

a neuron consists of:

dendrites

receive input from other neurons at synapses

axons

action potential are initiated at the axon billock and travel to the axon terminals, where neurotransmitters are released

leak channels

the resting membrane potential is maintained by the flow of ions through ___, which are located throughout a neuron and are always open

Na+/ K+ATPace (pump)

the flow of ions through leak channels tennds to dissipate sodium and potassium gradients, but this effect is counteracted by active transport through ____

ligand-gated channels; voltage-gated channels

other than Na+/K+ ATPase pump, ions also flow through ____ (mostly in the dendrites and cell body) and _____ (mostly in the axon

interneurons

most neurons belong to the follwoing functional class

multipolar neurons

most nuerons belong to the following strctural class

pseudo-unipolar neurons

most afferent neurons belong to the follwoing structural class

gap junctions

at electrical synapses, messengers (materials) travel from one neuron to another through this

the synaptic cleft

at chemical synapses, messengers travel fron one neuron to another across this

axodendritic

axosomatic

axoaxonic

three types of chemical synapses based on their location on the postsynaptic neuron

axoaxonic synapses

one of the three types of chemical synapses that are responsible for presynaptic facilitation and inhibition

glutamate

aspartate

the follwoing two amino acids cause excitatory postsynaptic potentials:

increase; sodium (into cell) and potassium (out of cell)

when glutamate and aspartate bind to an ionotropic receptor, the flow of ions across the plasma membrane _____. the ions that are affected are ____ and they flow _____

choline derivative (ex. acetylcholine)

biogenic amines (ex. dopamine)

identify two class of neurotransmitters other than amino acids

ras

mutation in a small G protein; are found in about 20% of all tumors

a growth factor; phosphorylates (dimerizes)

Ras participates in a signal transduction pathway which begins with the binding of ____ to a receptor, which ____ itself

GDP; GTP

an adaptor binds to the receptor and the second protein causing ____ to be released from the small G protein and ___ to be bound

Raf

the activated G protein binds to ____, leading to phosphorylation of several proteins

gene expression/ cell division

Ras final outcome is an increase in ___, which does not cause cancer when alll components of the pathway are functioning normally

cAMP; potassium channel protein; decrease

an amino acids binds to a metabotropic receptor and causes an excitatory response, ____ a second messenger activates protein kinase A. ____ is phosphorylated during this response. This process leads to an ____ in the flow of ions across the plasma membrane

Ca²⁺

when an action potential reaches the axon terminal, an influx of which ion triggers the exocytosis of a neurotransmitter

neurotransmitters

hormones

paracrines/ autocrines

among the funcitonal categories of chemical messengers considered in this course, all amino acids are ____, all steroids are ____, and all eicosanoids are _____

autocrines

paracrines

hormones

neurotransmitters

proteins and amines are included in all 4 of these functional categories:

amino acids

amines

peptides/proteins

among the chemical categories of chemical messengers there are 3 that are lipophobic:

steroids

eicosanoids

among the chemical categories of chemical messengers there are 2 that are lipophilic:

gap junction

direct communication between neighboring cells involves the movement of ions through ____

chemical messengers

indirect communication involves ____, which are released from a secretory cell and travel to a target cell, where they bind to receptors

lipophobic ligands; nucleus or cytosol

___have receptors located in the plasma membrnae. the receptors for most of these are located in the ____

fast ligand-gated channel

binding og ligands to a channel-linked receptor leads to the opening of _____

slow lingand-gated channel

binding og ligands to a G protein coupled (linked) receptor might lead to opening or closing of a _____

enzyme-linked

binding of ligands to an ____ receptor causes the receptor to perform a reaction, which is oftern phosphorylation

GTP; GDP

g proteins binds to the nucelotide ____ when they are active, and they become inactive whne they hydrolyze this nucleotide to _____

Ras

activation of the monomeric G protein, ____, by SOS leads to a cascade of phosphorylation and gene expression

second messenger

activation of heterotrimeric G proteins leads to the production of a _____, such as cAMP.

adenylate cyclase; protein kinase A

cAMP is formed from ATP by the enzyme ____, and the usual consequence is activation of _____.

phospholipase C

other G proteins trigger the formation of idacyljlycerol (DAG) and inositol triphosphate (IP3) by ____

protein kinase C; Ca2+

DAG then activates ____ and IP3 stimulates the release of ____ from the endoplasmic reticulum

signal amplification

this phenomenon is known as the number of activated molecules increases at several stages in eahc of these signal transduction pathways

hypothalamus

(anterior/posterior) pituitary

thyroid galnd

adrenal (cortex, medulla)

pancreas

give 5 examples of primary endocrine organs: