BI 013 exam 4

Somatic sensory/afferent

Conscious information from skin and muscles

Visceral sensory/afferent

Subconscious information from body organs

Somatic motor/efferent

Conscious commands (skeletal muscle)

Autonomic motor/efferent

Subconscious commands (smooth and cardiac muscle)

Nervous tissue

Poor repair, highly cellular, high metabolism (needs lots of glucose and oxygen)

Neurons

Also called nerve cells or neurocytes, functional unit of the nervous system, long and thin, human body contains 10^12 neurons

Central nervous system

Brain and spinal cord, integrates and controls

Peripheral nervous system

Cranial nerves and spinal nerves, communication lines between the CNS and the rest of the body

Sensory/afferent division

Conducts impulses drom receptors to the CNS

Motor/efferent division

Conducts impulses from the CNS to muscle and glands

Somatic nervous system

Conducts impulses from the CNS to the skeletal muscle

Autonomic nervous system

Conducts impulses from the CNS to cardiac muscles smooth muscles and glands

Multipolar

Many processes extend from the cell body, all are dendrites except for one axon

Bipolar

Two processes extend from the cell body. One is a fused dendrite the other is an axon

Unipolar

One process extends from the cell body and forms central and peripheral processes, which togethr comprise an axon

Nucleus

A collection if neuron cell bodies in the CNS

Ganglion

A collection if neuron cell bosies in the PNS

Tract

A bundle of axons in the CNS

Nerve

A bundle of axons in the PNS

Glial cells

Cells in nervous tissue that support neurons

Resting state

All gated Na+ and K+ channels are closed

Depolarization

Na+ channels are open. Allowing Na+ to enter

Repolarization

Na+ channels are inactivating K* channels open, allowing K+ to exit

EPSP

A local DEPOLARIZATION of the postsynaptic membrane

IPSP

A hyperpolarization of the postsynaptic membrane

No summation

A slowly firing presynaptic neurom that causes EPSPs that are far apart in time

Temporal summation

A rapidly firing presynaptic neuron causes EPSPs that are close in time

Spatial summation

More than one presynaptic neuron fires at the same time, EPSPs are generated at different locations on the neuron

Cell body

Contains the nucleus and most organelles

Dendrites

Short, branches, many, close to cell body

Axon

Single long projection, arises from axon hillock

Myelin sheath

White, fatty, segmented layer on the axon

Axon terminal

Distal tip, holds and releases neurotransmitter

Cell bodies

Gray

Myelinated axon

White

Astrocytes

CNS, most abunday and versatile support cells

Microglia

CNS, protective cells that destroys foreign microorganism

Ependymal cells

CNS, lines the edges of ventricles, produces CSF

Oligodendrocytes

CNS, wraps around neurons to form myelin sheath

Satelite cells

PNS, attaches to neuron cell bodies

Schwann cells

PNS, wraps around axons to form the myelin sheath

Voltage

Measures potential energy, Volts V

Current/flow

Measures the flow of electrocal charge from 1 point to another. Amperes I

Charge

Measures total number of charged particles by a current. Coulumbs Q

Resistance

Measures how difficult things are. Ohms R

Conductance

Measures how easy things are. Siemans

Ohms law

Voltage= current x resistance. If a current forms the voltage will change

Ligand-gated channels

Channel opens when a particular chemical binds to it. Low conductance

Voltage-gated channels

Channel opens due to a change in local charge distribution (high conductance)

Mechanicaly-gated channels

Channel opens in response to a physical stimulus

Leak channel

Channel always open. Allows K+ to pass sometimes. Low conductance

Ion direction

Based on the electrochemical gradient

Relative refractory period

Most Na+ channels are still open and repolarization is occuring

Absolute refractory period

Begins with opening of the Na+ channels and ends when the Na+ channels reset

Multiple sclerosis

Demyleninating disorder, causes hardened patches in the brain and spinal cord

Saltatory conduction

Transmission of an AP along a mylinated fiber in which the AP leaps from gap to gap

Conduction velocity

100 m/s

Group A fibers

Large diameter axon, heavily myelinated, conducts at 300 MPH, somatic pathway

Group B fibers

Small diamter axon, light mylinated, cpnduct at 30 MPH, autonomic pathways

Group C fibers

Smallest diameter axon, not mylinated, conducts at 2MPH, used by autonomic

Electrical synapses

Channels that are similar to gap junction

Chemical synapses

Uses a neurotransmitter, 1 cell is always infront of eachother

Presynaptic cell

The neuron before synapses, when the axon terminal communicates and sends the signals

Postsynaptic cell

Neurons after synapse, when the dendrites connect and recieve the signal

Graded potential

Small, local changes in voltage. Uses ligand-gated channels

EPSP

A depolarizing grading potential

IPSP

A hyperpolarizing grading potential

Axodendritic synapses

Connects to postsynaptic dendrites

Axosomatic synapses

Connects to postsynaptic cell body

Axoaxonic synapses

Connects to postsynaptic axon hillock

Acetylcholine

First neurotransmitter, used in neurotransmitter junction, can alter organ function

Norepinephrine

Alters organ function, in the CNS it is a pleasure neurotransmitter

Dopamine

In the CNS it is a pleasure neurotransmitter, excessive signaling causes schizophrenia

Serotonin

Regulates mood, release is linked to eating. Ecstacy

GABA

Main inhibitory neurotransmitter, opens ligand-gated Cl- channel

Glycine

Main inhibitory neurotransmitter of the spinal cord

Glutamate

Main excitory transmitter

Endorphins

Natural inhibitors of pain, released under stressful conditions

Kinins

Transmit pain signals released from damaged dells

Cerebral cortex

Gray, Superfical later of gray matter, neuron cell bodies contain many nuclei

Cerebral white matter

White, deep layer of white matter, myelinated axons, contains many tracts

Basal nuclei

Gray, islands of gray matter within the white. Deep isolated gray matter

Ventricles

Hollow, filled eith CSF

Lateral ventricles

Largest a pair c-shaped deep to cerebral hemisphere

Third ventricle

Thin channel deep to diencephalon

Fourth ventricle

Diamond-shaped deep to brain stem

Folding

Increases more surface area meaning more neurons meaning higher intelligence

Gyrus/gyri

An elevated ridge if brain tissue

Sulcus/sulci

A shallow grooce in brain tissue

central sulcus

Seperates frontal and parietal lobes

Lateral sulcus

Outlines the top of temporal lobes

Parieto-occipito sulcus

Seperates parietal and occipital sulcus

Left brain

Math, logic, analytic and language

Right brain

Creativity, artistic, visual, nonverbal, communication

Homunculus

oversized body parts = sensitive to touch

Epilepsy

Abnormal and excessive electrical signals generated in the brain

Petit mal

Blank facial expressions, facial muscle tics

Grand mal

Body convulsions, loss of consciousness

Premotor cortex

Used for coordinated movements of several muscle groups

Frontal eye field

Voluntarily aims the eye