Physiology Exam 1

equilibrium potential for Na+

+65 mV

Key functions of the Endocrine System

- Regulation of metabolic functions - Regulation of chemical reactions - Regulation of transport of substances through cell membranes

ways to stop G-protein coupled receptor action:

- remove ligand - phosphodiesterase to degrade cAMP -protein phosphatases to dephosphorylate

equilibrium potential for Cl-

-65 mV

Resting Membrane Potential (RMP)

-70 mV

equilibrium potential for K+

-90mV

neurohormones

-produced and released by neurons in the brain -delivered to organs and tissues through the bloodstream

Hormones

-released by endocrine glands or cells into the blood - only target cells with receptors for the specific hormone will respond to it

factors that influence membrane potential

1. The concentration gradients of different ions across the membrane 2. The permeability of the membrane to those ions

gated channel proteins

A protein channel in a cell membrane that opens or closes in response to a particular stimulus (ligand binding, changes in membrane potential, and mechanical stimuli)

G-protein coupled receptors

A special class of membrane receptors with an associated GTP binding protein; activation of a G protein-coupled receptor involves dissociation and GTP hydrolysis

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells

primary active transport

Active transport that relies directly on the hydrolysis of ATP; goes against gradient; ATP binds to carrier proteins

Paracrine

Referring to a secreted molecule that acts on a neighboring cell.

tonic control

Regulates physiological parameters in an up-down fashion. The signal is always present but changes in intensity.

Specificity of receptors

Signals only stimulate cells that have receptors for them.

membrane potential

The voltage across a cell's plasma membrane.

carrier proteins

bind to molecules and change shape to shuttle them across the membrane

active transport uses ____ proteins

carrier

Agonists

chemical substances that mimic or enhance the effects of a neurotransmitter on the receptor sites of the next cell, increasing or decreasing the activity of that cell

feedforward control

control that allows managers to anticipate problems before they arise

how are ligand actions terminated:

degradation

Baroreceptors

detect changes in blood pressure

integrator/control center

determine a set value for the variable, analyzes input from the receptor, commands effector

antagonists

drugs that block the function of a neurotransmitter

secondary active transport

Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport. - uses carrier protein -doesn't use ATP, goes against gradient -no ATP bound to carrier protein

positive feedback

enhances original stimulus; causes rapid change in th variable; ex: childbirth uterus stretching, action potentials

channel proteins

have a hydrophilic channel that certain molecules or ions can use as a tunnel; open vs gated

Physiology is the study of

how the body functions

Upregulation of receptors

increase in receptor number in response to low concentration of hormone

G-protein coupled receptors cascade

ligan binds to G-protein -> activated adynylyl dfghskjf -> converts ATP to cAMP -> binds and activates protein kinase A -> phosphorylation cascade -> cellular response

receptor enzyme

ligand binding to a receptor-enzyme activates an intracellular enzyme

hypotonic

more water inside the cell than out

hypertonic

more water outside of the cell than in

simple diffusion

movement of a solute from an area of high concentration to an area of low concentration

Antiport carrier protein

moves two substrates across the cell membrane in opposite directions

penetrating solutes

solute particles that can enter the cell

osmolarity

solute:water ratio, has units

autocrine

term for hormones that act on same cells that secrete them

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water; impact of osmotic pressure on the shape of cells ; no units

equilibrium potential

the membrane potential at which chemical and electrical forces are balanced for a single ion.

active transport

the movement of materials through a cell membrane using energy (ATP)

passive transport

the movement of substances across a cell membrane without the use of energy by the cell (simple and facilitated diffusion, osmosis)

antagonistic control

two controllers with opposite effects

Competition (receptors)

two ligands competing to bind to the same receptor

Neurotransmitter

-diffuses from the neuron across a narrow extracellular space to a target cell -has a rapid-onset effect

equilibrium potential for Ca++

134mV

Endocytosis

A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.

Downregulation of receptors

Decrease in receptor number in response to high concentration of hormone

intracellular receptors

Ligands move directly across the membrane to bind to the intracellular receptor

facilitated diffusion

Movement of molecules across cell membranes through protein channels and using concentration gradient

Symport Carrier Protein

Moves two substrates across the cell membrane in the same direction

receptor saturation

The maximum intensity that a sensory receptor will respond to stimuli

uniport carrier proteins

Transfer molecules one at a time Driven by concentration gradient Bring molecules from outside to inside Facilitated diffusion Example: glut 1 transporter

membrane receptors

Transmembrane protein molecules that act enzymatically or as ion channels to participate in signal transduction

ligand-gated ion channel

Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.

proprioreceptors

Type of sensory receptor that monitors the body's position in space.

Juxtacrine

a form of cell-cell communication in which a cell releases a substance that binds to receptors on cells directly adjacent to the releasing cell

Stimulus

a signal to which an organism responds

neuromodulator

acts like a neurotransmitter, but slower through an autocrine or paracrine signal

Isotonic

no net water lost

nonpenetrating solutes

particles that cannot cross the cell membrane

Receptor

protein that detects a changes in the variable and send info to the integrator

Gap junctions (communicating junctions)

provide cytoplasmic channels between adjacent cells

effector

receives output from the control center and produces a response

Exocytosis

release of substances out a cell by the fusion of a vesicle with the membrane

Thermoreceptors

respond to changes in temperature

Chemoreceptors

respond to chemicals

Osmoreceptors

respond to the osmolarity of the blood

Mechanoreceptors

respond to touch, pressure, vibration, stretch, and itch

negative feedback

reverses original stimulus, maintains variable in a narrow range, ex: temp, pressure, glucose levels

Regulated variable (homeostasis)

variable which is maintained

saturation of receptors

when all available proteins have bound a substrate