Communication, Integration, and Homeostasis Flashcards by Julia Jupille

What are the 2 key control systems for coordinating body function

Endocrine and nervous

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What are the different kinds of signals utilized in the body

Local and long distance, and chemical and electrical

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What are the characteristics of intercellular communication

Cell-to-cell, local, utilizes gap junctions (channels from cytoplasm to cytoplasm), and can be juxtacrine, autocrine, or paracrine

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What does juxtacrine mean

Secretes alongside, i.e. contact-dependent communication (interaction between membrane molecules on each cell)

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What does autocrine mean

Self-secreting, i.e. cell sends a signal back to itself

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What does paracrine mean

Secreting nearby, i.e. the cell sends a signal to another nearby cell

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What is a hormone

A substance secreted by an endocrine cell into the blood

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What is an example of long distance communication via endocrine cells

Hormones

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What is a neurocrine

A substance secreted by a hormone

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What are the 3 types of neurocrines

Neurohormones (secreted into the blood), neurotransmitters (released onto neighboring cells - paracrine), and neuromodulators (modify the response of cells)

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What are excitable cells

Cells that use electrical signals to communicate with other cells in the body (Neurons, endocrine cells, muscle cells)

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What are electrical signals

Changes in membrane potential

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What is the average membrane potential for a cell

-65 mV

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What is membrane potential

Electrical potential difference = Vm = voltage = stored energy (based on charge separation at the membrane, inside relative to outside)

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What does membrane potential depend on

Total ion concentrations (each ion’s preference) and selective membrane permeability (number of leakage channels)

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What are the two forces ions are subject to

Chemical/diffusional (based on concentration), and electrical (based on ionic charge/valence versus the charge on membrane)

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What is electrochemical equilibrium

When the chemical and electrical forces are equal and opposite for an ion species

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What is equilibrium potential (Ex)

The electrical force needed to counterbalance the chemical force (What the ion wants the membrane potential to be)

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What does E(x) depend on

Concentrations of an ion species across the membrane and the ions charge or valance

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What equation can be used to calculate E(x)

Nernst equation

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What is E(K)

-90mV

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What is E(Na)

+60 mV

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What is E(Cl)

-63 mV

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What is E(Ca)

+240 mV

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What ion is the membrane most permeable to

What equation approximates Vm

Vm proportional to pK(Ek) + pNa(ENa) + pCl(ECl)

What equation can be used to calculated Vm

Goldman-Hodgkin-Katz (GHK) Equation

How are concentration gradients maintained over time

Active transporters (Na/K ATPase) --> If not working, Vm would change very slowly over time

What changes during electrical signaling

Permeability (gated channels), NOT CONCENTRATION (because bulk of ions don't affect Vm)

What are the 3 kinds of gated channels

Chemically-gated (neurotransmitter, hormone, or phosphate), mechanically-gated, or voltage-gated (because proteins making up channels have polar amino acids)

What is depolarization

Getting more positive

What is hyperpolarization

Getting more negative

What is repolarization

Returning to Vrest

What is a ligand

A chemical used for signaling purposes

What features do receptors exhibit

Specificity, competition, and saturation

What are the 3 kinds of membrane proteins that facilitate signal transduction

Receptor-channel (gated channels), GPCRs, and catalytic receptors

What are the 2 kinds of catalytic receptors

Receptor-enzyme and integrin receptors

What is the fastest membrane protein for signal transduction

Receptor-channels

What is the most common membrane protein for signal transduction

GPCRs

What is signal transduction

Moving information from one side of the membrane to another using membrane proteins (ligand doesn't cross membrane but binds to receptors)

What is a signal transduction pathway

What happens between a ligand binding to a receptor and the cellular response occuring

What is always the 1st messenger

Ligand

What converts information to another form in a signal transduction pathway

The transducer/receptor

What are examples of cellular responses

Change in Vm, exocytosis of secretory vesicles, altered enzyme activity, movement of motor proteins, and gene activity/protein synthesis

What can receptors activate

Ion channels, protein kinases, phosphatases, or amplifier enzymes

What do protein kinases do

Phosphorylate proteins

What do phosphatases do

Dephosphorylate proteins

What 3 things can 2nd messengers do

Activate gated ion channels, increase intracellular Ca, or alter enzyme activity

What determines a cell's response to a ligand

Presence/absence of that ligand's receptor and what type of internal signal pathway that cell has

What are GPCRs

G-protein coupled receptors, membrane-spanning proteins with extracellular binding site, and a cytoplasmic tail linked to a G protein (transducer molecule with three parts)

What are the two most common amplifier enzymes

Adenyl (anedylyl, adenylate) cyclase and phospholipase C

When a G protein is activated what happens

It undergoes a conformational change that makes it swap out GDP for GTP

What are the steps of the cAMP pathway

Ligand (1st messenger) binds to GPCR (transducer), activates G protein, activates adenyl cyclase (amplifier enzyme), creates cAMP (2nd messenger), activates protein kinase A (amplifier enzyme), phosphorylates proteins

What does adenyl cyclase do

Converts ATP into cAMP

What do phosphodiesterases do

Break down cAMP

What stops signal transduction

Inherent GTPase activity (shuts off G protein), phosphodiesterase, and phosphatases

What happens in the phospholipase C system

Ligand binds, g protein activated, PL-C activated, membrane bound DAG is broken into PK-C (protein kinase C) which phosphorylates proteins and IP3 (Inositol triphosphate) which binds to the ER to release stored Ca

What can adrenergic receptors bind to

Epinephrine and norepinephrine

What does catecholamines mean

Similar in structure

What is a difference between epinephrine and norepinephrine

Epinephrine is released as a hormone, while norepinephrine is released as a neurotransmitter or neuromodulator

What is another word for receptor types

Receptor isoforms

What are agonists and antagonists

Exogenous ligands that bind to a receptor to produce the same response or block the endogenous ligand from binding

What is upregulation

Increase in cell response by increasing the number of receptors (endocytosis of receptors)

What is downregulation

Decrease in cell response by decreasing the number of receptors (via exocytosis) or altering how the receptors can bind (via phosphorylation)

What is tonic control

Like a switch, relation is either up or down (increase vs decrease, more or less)

What is antagonistic control

Balance between inputs from systems (like the sympathetic and parasympathetic nervous systems)

Is tonic or antagonistic control faster

Antagonistic