BIO 209 Exam 4- Nervous Tissue

Nodes of ranvier

gaps in the myelin sheath. only place where ions can enter the axon. action potentials jump from node to node

Functions of ependymal cells

line ventricles of brain and central canal of spinal cord. monitor/produce/assist circulation of CSF

Grey matter is made of what?

neuronal cell bodies, unmyelinated axons, glial cells

What three things lead to resting potential?

separation of charges across membrane (gradients), most anions can't diffuse across membrane, sodium and potassium pumps

What is the fourth phase of an action potential?

sodium and potassium pumps restore the gradients (from +30mV to -70mV)

What are the three divisions of the PNS?

Somatic (SNS), Autonomic (ANS), Enteric (ENS)

What is the name for the electrical signal that neurons and muscles use?

action potential

Characteristics of leak channels

always open, specific or non specific ions

Anions and cations in a resting membrane potential.

anions build up negative charges in the cytoplasm, cations build up positive energy on the extracellular side of the membrane

What is the name for the plasma membrane of the axon?

axolemma

What is the name for the cytoplasm of the axon?

axoplasm

What structures are found in the CNS?

brain and spinal cord

Functions of microglia

clear cellular debris/waste. phagocytosis

What is the conduction down unmyelinated axons?

continuous

What are the two main phases of an action potential?

depolarization and repolarization

What is the second phase of an action potential?

depolarization. sodium channels open, sodium flows in and changes internal charge to positive

What is found in the PNS?

everything outside of the CNS

What are nerve signals that cause depolarization called?

excitatory postsynaptic potential (epsp)

What are two things that are required for graded and action potentials?

existence of a resting membrane potential and presence of specific ion channels.

What does the sympathetic nervous system do?

fight or flight

What is the term for when a membrane becomes more negative?

hyperpolarization (-90mV)

What is the 5th phase of an action potential?

hyperpolarization. membrane potential becomes more negative (-90mV). ensures energy only flows one direction.

What are nerve signals that cause hyperpolarization called?

inhibitory postsynaptic potential (ipsp)

What neurons communicate between afferent and efferent nuerons?

interneurons or association neurons. multipolar

What does the ENS do?

involuntary, controls muscles and functions of the GI tract

What does the ANS do?

involuntary, controls smooth and visceral muscles

Neurotransmitter

molecules that excite or inhibit an effector

What neurons bring information away from the brain?

motor (efferent) neurons. multipolar

White matter is made of what?

myelinated axons and glial cells

Functions of oligodendrocytes

myelination

Functions of schwann cells

myelination of PNS axons.

It's called a ganglia in the PNS: what is it called in the CNS?

nuclei

Characteristics of voltage channels

open/close in response to change in membrane potentials

Characteristics of ligand gated channels

open/close in response to ligand binding. specific or non specific ions

Characteristics of mechanical channels

open/close in response to mechanical stimuli. vibration/touch/hearing, etc.

Membrane potential

plasma membrane of excitable cells

Resting membrane potential (RMP)

potential energy at resting state, rests at -70mV

what to interneurons do?

process sensory info and generate a motor response

What is the 6th phase of an action potential?

refractory period. cell can't generate another action potential

What is the third phase of an action potential?

repolarization. sodium channels close, potassium channels open and potassium flows out. negative charge returns back to negative

What does the parasympathetic nervous system do?

rest and digest

What is the first phase of an action potential?

resting phase. ready to carry action potential

What is the conduction down myelinated axons?

saltatory

Relative refractory period

second action potential can be generated if second stimulus is large enough

Absolute refractory period

second action potential cannot be generated

What neurons bring information into the brain?

sensory (afferent) neurons. unipolar

What are the three functions of the nervous system?

sensory function (detects stimuli), integrative function (provides response to stimuli), motor function (effectors activated)

Functions of astrocytes

support, regulate chemical environment, creates BBB of the capillaries

Functions of satellite cells

surround neuron cell bodies in PNS. regulate exchange of materials between cell bodies and interstitial fluid.

What are the divisions of the ANS?

sympathetic and parasympathetic

Why do action potentials travel faster down myelinated axons?

they are able to jump from node to node of ranvier

What is an effector?

things that a nerve can communicate with (another nerve, muscles, or glands)

What is the term for the point that has to be reached to send an action potential?

threshold

It's called a nerve in the PNS: what is it called in the CNS?

tract

Characteristics of action potentials

travel long distances, independent of stimulus "all or nothing", always depolarization

Characteristics of graded potentials

travel short distances, strength of response depends on strength of stimulus. depolarizing and hyperpolarizing

What does the SNS do?

voluntary, receives info from sensory receptors, control of skeletal muscles

How many sodium and potassium are exchanged by the pumps?

+3 sodium ions, +2 potassium ions

What are the two divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

What percent of the brain is glial cells?

90%