Exam 2 A&P

homeostasis

the body’s ability to maintain a constant environment

loops

series of reactions involving molecules, cells and tissues

negative feedback loops

body senses change and reacts to negate or reverse the condition

positive feedback loops

self-amplifying cycles in which an initial change leads to a greater change

positive feedback example

blood clotting formation

negative feedback example

temperature regulation

nervous system

nervous tissue, fast, electrical currents and chemical messages (neurotransmitters)

endocrine system

glandular tissue (secretes), slow, chemical messages (hormones)

cell body/soma

contains one nucleus

dendrites

short extensions off of the cell body, receives signals from other neurons

axon

extension away from the cell body, can be myelinated

synapse

site of communication between neurons or neuron to a tissue

what neuron is this?

psudounipolar

what neuron is this?

bipolar

what neuron is this?

multipolar

sensory (Afferent neurons)

start in PNS and travel to CNS, detect stimuli, deliver info about environment or condition of body to CNS

motor (Efferent neuron)

sends signals from CNS to effectors (muscles, organs)

interneuron

in CNS, receives and integrates information

CNS

brain and spinal cord, major site of integration, cell bodies and axons

PNS

nerves travel to or from CNS, communication for sensory and outgoing motor information

endoneurium

surrounds individual neurons

perineurium

bundles neurons into fascicles

epineurium

tough outer layer

multipolar neuron

motor neurons and interneurons

bipolar neurons

special sensory neurons

pseudounipolar

sensory neurons

myelination

a fatty insulating layer of myelin wraps around axon to help with insulation, speed, and protection

oligodendrocytes

glial cell in CNS, produces and maintains myelin sheath facilitating saltatory conduction

schwann cells

glial cells that support and protect nerve cells in PNS, insulate axons with myelin sheath

cranial nerves

originate from brain, control head and neck functions

spinal nerves

emerge from spinal cord and connect to rest of body

ganglion

group of nerve cell bodies in PNS, synaptic relay station between neurons

dorsal

posterior

ventral

anterior

white matter

neuronal axons

grey matter

cell bodies

arachnoid mater

cobweby, middle membrane

subarachnoid space

between pia and arachnoid mater where CSF circulates

meninges

dura mater, arachnoid mater, pia mater

cerebrospinal fluid

watery fluid that surrounds and protects CNS

dura mater

thick outermost layer

pia mater

innermost layer

dorsal horn

part of grey matter, receives sensory information from dorsal roots

lateral horn

contains visceral motor neurons, sense signals

ventral horn

sends out motor signals, contains cell bodies

dorsal root

posterior root, afferent nerve fibers, contains dorsal root ganglion, TO spinal cord

dorsal root ganglion

contains cell bodies of sensory neurons

ventral root

anterior root, efferent nerve fiber, AWAY from spinal cord

current

flow of charged particles from one point to another

potential (voltage)

different in electrical charge between two points

charged particles (ions)

have chemical concentration gradient, uneven distribution of molecules

electrical gradients have an…

uneven distribution of charge, combination of ion permeability, pump function, and anions

electrochemical gradient

determines which way ions flow

membrane potential

charge inside cell - charge outside cell

resting membrane potential

membrane potential when neuron is at rest

what is resting membrane potential?

-70mV

Na+/K+ protein pump create __

chemical gradient of the ions

Potassium diffuses out of cell

inside of cell membrane more negative than outside

chemical gradient for chloride CI-

ECF>ICF

sodium cation concentrated ECF

extracellular fluid, outside cell

potassium cations concentrated

ICF (intracellular fluid, inside cell)

inside of cell membrane is more - than outside (electrical gradient)

K+ can diffuse easily than sodium, large anion trapped inside

RMP (difference in charge across membrane surface when neuron is at rest)

movement of ions along electrochemical gradients and pumps counteractive those movements

graded (local) potential

change of RMP created by movement of ions near stimulus

chemically gated channel

open when a specific molecule binds to the channel protein

voltage-gated channel

open when the membrane potential (voltage) changes

mechanically gated channels

open when a physical force changes the shape of the channel protein

depolarization (excitatory potential)

Na+ channels open and Na+ ions diffuse into the cell, membrane potential becomes + (closer to 0)

hyperpolarization (inhibitory potential)

CI- channels open and enters cell or K+ channels open and diffuse out of cell, membrane potential becomes more negative

afferent

graded potentials are typically excitatory, created by stimuli in environment or organs

interneurons and efferent

local potentials are excitatory OR inhibitory, created by neurotransmitters

threshold potential

minimum membrane potential that must be reached to trigger an action potential in a neuron (-55mV)

stimulus

electrical signal generated within a cell when it receives a stimulus that reaches threshold causing a rapid change in membrane potential