Physiology

study of structure & function of a living organism & its component parts

Homeostasis

the maintenance of a relatively stable internal environment

Acclimatization

an environmentally induced change in physiological function with NO genetic change (does not affect offspring)

Local Control

homeostatic control where the effects are exerted on neighbouring cells

Negative Feedback

 homeostatic control which results in a change that opposes or removes the singnal thus returning the variable to its original value

Feedforward Regulation

(anticipatory control) predicts that change is about to happen, starts the response loop and prevents change

Gap Junctions

known as direct cell-to-cell communication; occurs via protein channels between adjacent cells. Are capable of opening and closing

Anchoring Junctions

 attach cells to each other or to the extracellular matrix

Connective Tissue

 provide structural support and barriers; has an extensive extracellular matrix

Neural

carry information from one part of the body to another; little ECM 

Autocrines

chemicals that act on the cell that produces them

Specificity

the  ability of an enzyme or receptor to bind to a particular molecule or a group of closely related molecules

Up - Regulation

 increase in protein number or binding affinity that increases the response of the target cell

Organ Systems

10 major systems in human body; this course focuses on 5: nervous, musculoskeletal, circulatory, respiratory and immune

Set Point

(operating point) - optimum value

Circardian Rhythm

daily biological rhythms (ex. sleep wake cycles, hormonal cycles)

Reflex Control

the reaction in one or more organs controlled from elsewhere in the body

Postitive Feedback

homeostatic control which results in a change that increases the signal thus bringing the variabel further from its original value

Cell Membrane

serves as both a gateway and a barrier for substances moving into and out of the cell

Tight Junctions

cell-to-cell junction in epithelia that does not allow much movement of material between the cells

Epithelia

protects the internal environment of the individual

Muscle

cells that have the ability to contract to produce force and movement

Paracrine

chemicals secreted by cells that act on neighbouring cells

Affinity

the degree to which a protein is attracted to its ligand

Down - Regulation

decrease in protein number or binding affinity that lessens response

CNS (central nervous system)

composed of the brain and spinal cord

PNS (peripheral nervous system) 

everything else in the nervous system

Neuron

a nerve cell, capable of generating and transmitting electrical signals

Glial Cells

associated with neurons (outnumber them 10-50:1) ; contribute to the function of neurons by aiding in nerve impulse conduction and maintaining the microenvironment around the neurons

Neurotransmitter

a chemical signal released by a neuron that influences the neuron's target cell

Cell Body (soma)

contains the nucleus; the center of the chemical processes, keeps the cell functioning and alive

Dendrite

slender processes that receive information; transmit electrical signals towards soma

Axon

cytoplasmic extension that send out information; transmit electrical signals away from soma

Axon Terminal

end of the axon; conncetion between neuron and other cells (presynaptic part of synapses)

Initial Segment (trigger zone)

the region of the axon where graded potentials are integrated and an action potential begins is the signal is above threshold

Myelin

layers of membrane that insulate an axon (electrical insulator)

Schwaan Cells

special glial cells that are wrapped around axons (to form myelin); found only in PNS 

Nodes of Ranvier

the gaps between one Schwaan cell and the next; the electrical impulse "jumps" over these gaps

Afferent Neuron

receive information from the receptor cells and transmit sensory information TO CNS

Efferent Neuron

receive information from the interneurons; cell bodies are located within the CNS

Receptor

specialized cells; convert stimuli into electrical signals and transmit information to the afferent neurons

Synapse

information is communicated from one neuron to the next via these 

Presynaptic Neuron

axon terminal of first neuron

Postsynaptic Neuron

dendrites/membrane of second neuron

Astroglia

a type of CNS glial cell; small star shaped cells that make contact with blood vessels and neurons. May also transfer nutrients

Microglia

a type of CNS glial cell; very small cells which are specialized immune cells. They remove damage cells and foreign invaders

Oligodendria

the CNS version of a Schwaan cell; wrap around axons to form myelin and insulate cells

Depolarization

a decrease in the membrane potential difference; cell becomes LESS negative

Hyperpolarization

an increase in the membrane potential difference; cell becomes MORE negative

Repolarization

hyperpolarization of the membrane after an action potential has been fired

Graded Potentials

could be depolarization OR hyperpolarization; triggered by the opening or closing of ion channels; amplitude of the potential is proportional to the strength of the triggering event

Action Potential

all identical, no "volume control", they are "on" or "off" only; unlike graded potential they do not diminish in strength as they travel long distances through the neuron

Threshold Potential

the minimum depolarization necessary to trigger an action potential (-55mV)

All - or - None

action potentials either occur as a maximal depolarization or do not occur at all

Absolute Refractory Period

lasts approx. 1 msec; NO action action potentials can be triggered at all during this time no matter how large the stimulus

Relative Refractory Potential

a really large (suprathreshold) stimulus is required to bring forth an action potential during this time

Saltatory Conduction

when action pootentials jump from one node of Ranvier to the next

IPSP - inhibitory post synaptic potentials

hyperpolarizing graded potentials that take the membrane potential father away from the threshold potential

EPSP - excitatory post synaptic potentials

depolarizing graded potentials that bring the membrane potential closer to the threshold potential

Synaptic Vessel

small secretory vesicles that release neurotransmitters into the synapse

Temporal Summation

graded potentials can sum over time

Spatial Summation

graded potentials can sum over space                                                

Acetylcholine

one of the major types of neurotransmitters; neurons that secrete or have receptors for this are called choliergic

Norepinephrine

a neurotransmitter of the autonomic system;released by most post-ganglionic sympathetic cells (onto adrenergic receptors)

Nicotinic

cholinergic receptors that are stimulated by ACh and nicotine; on both sympathetic and parasympathetic ganglia. ALWAYS excitatory

Muscarinic

cholinergic receptors that are stimlated by ACh and muscarine; receptor target tissues of the parasympathetic system. Can be excitatory OR inhibitory

Receptor Types

critical for the regulation of body systems. Two types: adrenergic and cholinergic