Animal anatomy exam 1

types of cell signaling (2)

direct, indirect

direct cell signaling

signaling cell and target cell connected by gap junctions, signal passed directly

indirect cell signaling

chemical messenger carried in extracellular fluid binds to receptor on target cell and activates a signal transduction pathway causing a response, some may be released into environment

short distance cell signaling (2)

paracrine, autocrine

paracrine cell signaling

chemical messenger diffuses to a nearby cell

autocrine cell signaling

chemical message diffuses back to the same cell that produced it

mast cells

both autocrine and paracrine response, reseals histamines

long distance cell signaling

endocrine system, nervous system

endocrine system

chemical messenger transported by circulatory system, ex. gastrin secreted into bloodstream by stomach after a meal, this hormone then mediates activities associated with processing proteins that release protons into stomach by parietal cells and pepsinogen from chief cells

nervous system

electrical signal travels along a neuron releasing a neurotransmitter, neuron=signaling cell

Gap junctions

create an aqueous pore between adjacent cells, allows the movement of ions, changes the membrane potential, can be regulated

Anthropocene

current era 'dominated' by humans, indicators: nuclear pollution, plastic - causing a 6th extinction, period during which human activity has been the dominant influence on our environment, human overpopulation and over-consumption is main cause, some species more susceptible than others

August Krogh principle

"For every biological system there is an organism on which it can be most conveniently studied"

what 2 organizations regulate animal use?

USDA and NHS

exocrine gland

produce substances outside of the body: sweat, mammary glands, spider silk

which of the following terms describes signaling neighbor cells?

paracrine

6 classes of chemical messengers

peptides, steroids, amines, lipids, purines, gases

Hydrophilic messengers

rapid, dissolves in extracellular fluid, stored in vesicles, cannot pass membrane barrier bc it likes water

hydrophobic messengers

slow response, can cross lipid by-layer, synthesized on demand, binds to intracellular trans-membrane receptors

peptide

synthesized on the rough ER, stored in vesicles, secreted by exocitosis, hydrophilic, travel to a target cell to get dissolved, needs membrane receptor to get through lipid bi-layer

3 domains of a trans-membrane receptor (top-bottom)

ligand-binding domain, transmembrane domain, intracellular domain - changes shape not allowing another to bind

steroid hormones

derived from cholesterol, synthesized by the smooth ER or mitochondria, hydrophobic (diffuses though plasma menbrane), slow effect on target cell

3 classes of steroid hormones

mineralocorticoids (electrolyte balance), glucocorticoids (stress hormones), reproductive hormones

amine hormones

have amine group NH2, hydrophilic (exception of thyroid hormones) ,examples: seratonin, melatonin, dopamine

chemical messengers: gases

mostly paracrine, examples: nitric oxide and carbon monoxide

chemical messengers: purines

fuction as neuromodulators and paracrines

hydrophilic messengers

bind to transmembrane receptor

hydrophobic messengers

bind to intracellular receptors

ligand

chemical messenger that can bind to a specific receptor

exocrine examples (3):

slug mucus, spider silk, mammary glands

endocrine examples (3):

pituitary, thyroid, adrenal

ligand-receptor interactions

specific, only correctly shaped ligand can bind to the receptor, a ligand may bind to more than one type of receptor, a single cell may have receptors for many different ligands

2 ligand mimics

agonist (activates receptors-binds but not the same response), antagonist (blocks receptors ex. pain meds)

isoforms

respond to the same signal molecule but differs slightly, same family of receptors but with different functions

receptors can become saturated at high L - this means that response is

maximal

more receptors =

more complexes, more response

down-regulation

target cell decreases the number of receptors, example: heroin addiction (too much ligand too much response=down-regulation, they have to take more heroin to get the same response)

up-regulation

target cell increases the number of receptors, example: caffeine

Ligand-receptor complex must be to allow responses to changing conditions

inactivated (circulatory system can take away ligand)

Signal transduction pathways

convert the change in receptor shape to an intracellular response

4 components to signal transduction pathways

receiver, transducer, amplifier, responder (example:glucagon)

4 types of receptors

intracellular, ligand-gated ion channel, receptor enzyme, G-protein coupled receptor

intracellular receptors

hydrophobic, genomic response, increases or decreases production of mRNA (passes through membrane, binds to ligand, changes shape of the receptor, trans-locate the nucleus and interacts with DNA)

ligand-gated ion channels

ions move down electrochemical gradient, unbound and bound ligand-gated channels, can change membrane potential (can open and close, ligand is the key to the gate)

g-protein coupled receptors

activates, causes g-protein to dissociate into sub-units (conformational change), one walks and activates a second messenger, cAMP (can activate or inhibit pathways)

4 types of second messengers

Ca2+, cGMP, cAMP, phoshatidyl inositol (continuation of first chain reaction)

Ca2+

binds to calmodulin

cAMP

synthesized by the enzyme adenylate cylase, activates protein kinases, can open and close ion channels

3 components of biological control system (3 steps)

sensor (detects the level of a regulated variable and sends signal to an integrating center), integrating center (evaluated input from sensor and sends signal to effector), effector (target tissue that responds to signal from integrating sensor)

set point

the value of the variable that the body is trying to maintain

positive feedback loop

output of effector amplifies variable away from the set point, example: labor (not common in physiological systems)

negative feedback loop

output of effector brings variable back to the set point

direct feedback loop

no neuron, from endocrine gland to target organ (regulation of blood glucose)

direct feedback

precisely controlled, no neurons, hormones insulin and glucagon, example: regulation of blood glucose secreted by pancreas, antagonistic pairing

pituitary gland

in the brain, secretes hormones, anterior pituitary, posterior pituitary

posterior pituitary

extension of the hypothalamus, endocrine pathway, neurons that originate in hypothalamus terminate here, example: Oxycontin - positive feedback loop during labor and breastfeeding trigger release (1st order-hypothalumus receives sensory input), ex: vasopressin (water resorption)

anterior pituitary

releases hormones coming from the hypothalamus that synthesizes and secretes neurohormones to the hypothalamic-pituitary portal system, examples: sex hormones, in insects: hormones that change it from larval forms to adult forms - trophic hormones (cause release of another hormone) 3rd order endocrine pathway

additivity

when hormones cause same response in a target cell, not the same signaling pathway

synergism

when hormones enhance affect of other hormones, response of target cell to combinations of these hormones is more than additive

sympathetic nerve activation

response to stressor: increased heart-rate, increased respiration, less insulin, add glucagon

example of hormones that have the same affect in different animals:

human growth hormone increase growth rate in fish, estrogen from pregnant mares can be used in post-menopausal woman

electrical signaling

no neurons, no synapses, mainly use Ca2+, seen in unicellular organisms and in sponges

which part of the pituitary is most often associated with 3rd order endocrine pathway?

anterior pituitary

typical motor neuron zones (4) **

signal reception (cell body, dendrites), signal integration (axon), signal conduction (schwann cells), signal transmission (synapse, axon terminal,conversion of electrical back to chemical)

inside the cell is about _ millivolts compared to the outside of the cell **

-70

True or False, ligand mimics are generally agonist

false

does insulin trigger an increase or decrease in blood glucose?

decrease

what are the integrators for the stretch receptors in your stomach? (2)

medulla and enteric nervous system

what is prolactin used for in different animals? (3)

milk in mammals, inhibits metamorphosis in insects, water regulation in fish

order of signal transduction in a neuron cell

dendrite, cell body, axon, synapse

Electrical signals in neurons **

changes in membrane potential act as electrical signals

factors contributing to membrane potential (3) **

distribution of ions across the membrane, relative permeability of the ions (Na+, K, Cl-), charges of the ions

depolarization event **

membrane potential changes such that the difference between the inside of the cell and the outside of the cell decreases, also called exitatory post synaptic potential (EPSP)

repolarization event **

returning the cell to its original membrane potential

hyperpolarizaion event **

the inside of the cell becomes more negative, the difference inside of the cell and outside of the cell increases, also called inhibitory post synaptic potential (IPSP)

gated ion channels **

open or close in response to a stimulus (neurotransmitter), channels only allow specific ions to pass through the membrane, ions move down its electrochemical gradient

Na + potential **

• 70, has huge impact on the change of membrane potential (-70),kept far from equilibrium potential

K + potential **

cell becomes hyperpolarized, not as far from membrane potential (-70), -90

Dendrites **

receive incoming signal (neurotransmitter), have membrane bound receptors that bind to neurotransmitters and cause a change in membrane potential

receptors of dendrites ____ the chemical signal to an electrical signal by changing ion permeability of membrane

transduce (signal transduction)

graded potential **

varies in number of gates that open over time (how many ions went in and out) (some ions cancel each-other out), very in magnitude depending on strength of the signal, depolarization and hyperpolarization

graded potential: depolarization **

Na+ or Ca+ channels open (rush out)

graded potentials: hyperpolarization **

K+ and Cl- channels open (rush in)

decrement of conduction/signal due to (3) **

leakage of charged ions, electrical resistance of cytoplasm, electrical properties of membrane

Electrotonic current spread **

charge spreads through the cytoplasm along inner membrane (positive=depolarization)

types of summation (axon hillock) (2) **

spatial summation and temporal summation

spatial summation **

simultaneous stimulation my SEVERAL presynaptic neurons

temporal summation **

high frequency stimulation by ONE presynaptic neuron

All inputs are _, and if threshold is reached, and action potential travels down the axon

"summed"

characteristics of action potentials (4) ***

always the same magnitude, always the same duration, can be transmitted across long distance, occur in axons

characteristics of graded potentials (4) ***

vary in magnitude, vary in duration, decay with distance, occur in dendrites and cell body

Action Potentials only occur when … ** (AP action potential)

the membrane potential reached axon hillock threshold (-50)

absolute refractory period

cell is incapable of generating new AP while experiencing an AP, prevents backward transmission and summation of action potentials

relative refractory period

more difficult to generate new AP, requires a very strong stimulus to cause another AP

why does action potential only go in one direction?

absolute refractory period

voltage gated channels

change shape due to changes in membrane potential, closed at resting potential, positive feedback, Na+ channels open first, K+ channels open more slowly (delayed opening at threshold-hyperpolarization), Na+ channels close, K+ channels close, have an activation gate and an in-activation gate

self propagating

an AP triggers the next AP in adjacent areas of membrane without degration

electronic current spread

charge spreads along membrane

Nodes of Ranvier

areas of exposed axonal membrane between schwann cells, action potentials occur at nodes of ranvier and an electronic current spreads through internodes, rapid conduction

internodes

mylinated region