bms 300 exam 3

nervous system

the system that includes organs: brain, spinal cord, receptors for sense organs(eyes, ears, etc), nervous tissue and nerves that connect to other systems

nervous tissue

tissue of the nervous system that contains two kinds of cells: neurons and neuroglia(glial cells)

Neurons

nervous tissue cells for intercellular communication. They are the basic functional unit of the nervous system, they send and receive signals, and function in communication, information processing and control

Neuroglia

Also called glial cells, nervous tissue cells that are essential to survival and function of neurons and preserve structure of nervous tissue

bipolar neurons

sensory Neurons with two processes seperated by the cell body that aid in sight smell and hearing

Pseudounipolar neurons

the primary sensory afferent neurons that have a single elongated process with the cell body located off to the side.

multipolar neurons

motor neurons and interneurons that have more than two processes; there is a single axon and multiple dendrites

neuron input region

region of a neuron containing the cell body and dendrites

cell body

also called the soma, the part of the neuron input region containing a large nucleus, perikaryon (cytoplasm), mitochondria, Rer and ribosomes

dendrites

the part of the neuron input region that has short and highly branched processes extending from the cell body and dendritic spines

dendritic spines

the fine processes on dendrites that receive information from other neurons and make up 80-90% of neuron surface area

neuron conductile region

the axon region of the neuron

axon

the part of the neuron conductile region containing a single long cytoplasmic process and propogates electrical signals(threshos). made of axolemma, initial segment, and axon hillock

axolemma

in the neuron conductile region, the plasma membrane of the axon that covers the axoplasm

initial segment

in the neuron conductile region, the base of the axon

axon hillock

in the neuron conductile region, thick region of the axon that attaches the initial segment to the cell body

neuron output region

the part of a neuron that contains the telodendria and axon terminals

telodendria

in the neuron output region, the long highly branched processes extending from the axon

axon terminals

in the neuron output region, the button like endings of telodendria that make synaptic connections with other neurons to release neurotransmitters

nervous system model

model that consists of input, processing, and output

input

the part of the nervous system model including sensory afferents(somatic and visceral) in the peripheral nervous system

somatic sensory

a sensory input afferent that monitors the external environment

visceral sensory

the input sensory afferent that monitors internal environment

processing

the part of the nervous system model that receives sensory information, processes it, decides on response, and sends instructions to motor system

output

the part of the nervous system model containing motor efferents (somatic and visceral) in the peripheral nervous system

somatic motor

the output motor efferent that controls skeletal muscle

visceral motor

the output motor efferent that controls smooth muscle, cardiac muscle, and glands

central nervous system

the division of the nervous system that:
-contains the brain and spinal cord
-consists of nervous tissue, connective tissue, and blood vessels
- functions to process and coordinate sensory data from inside and outside the body
-motor commands control activities of peripheral organs like skeletal muscles
-higher functions of brain include intelligence memory learning and emotion

peripheral nervous system

the division of the nervous system that:
-includes all nervous tissue outside CNS
-delivers sensory information to CNS
- carries motor commands to peripheral tissues
-contains peripheral nerves

peripheral nerves

(cranial and spinal) in the PNS, the bundles of axons with connective tissues and blood vessels that carry sensory information and motor commands

cranial nerves

peripheral nerves that connect to the brain

spinal nerves

peripheral nerves that attach to the spinal cord

somatic nervous system

the efferent division of PNS that controls skeletal muscle contractions as well as voluntary/involuntary (reflexes)

autonomic nervous system

the efferent division of PNS that controls subconscious actions, contractions of smooth and cardiac muscle, and glandular secretions. sympathetic division is stimulating while parasympathetic division is relaxing

cerebrum

the largest part of the Brain that controls all conscious though and intellectual functions. it also processes somatic sensory and motor function. its gray matter is in the cerebral cortex while the white matter is deep into the cerebral cortex. the cerebral hemispheres are neurolateralized

gyri of cerebral cortex

part of the cerebrum that increases the surface area available for cortical neurons. gyri sulci are shallow depressions while gyri fissures are deep grooves

central sulcus

the structure of the cerebrum that divides the anterior frontal lobe from the parietal lobe as well as the motor and sensory areas

precentral gyrus

in the frontal lobe, forms anterior border of central sulcus

postcentral gyrus

in the parietal lobe, forms posterior border of central sulcus

primary motor cortex

the motor area of the cerebrum that makes up the surface of precentral gyrus

primary somatosensory cortex

the sensory area of the cerebrum that makes up the surface of the postcentral gyrus

association areas

the part of the cerebrum that is connected to the sensory and motor regions of the cortex and interprets incoming data or coordinates a motor response

premotor cortex

the somatic motor association area of the cerebrum that coordinates learned movements

cerebellum

the second largest part of the brain that coordinates repetitive body movements. it is split into two hemispheres and is covered by gray matter (cerebellar cortex)

diencephalon

the part of the brain containing the thalamus, hypothalamus , and pituitary gland

thlamus

the part of the diencephalon that relays and processes sensory information

hypothalamus

the part of the the diencephalon that is involved with emotions, autonomic function, and hormone production

pituitary gland

the major endocrine gland in the diencephalon that integrates nervous and endocrine systems

brainstem

the part of the brain that relays information between spinal cord cerebrum and cerebellum. it includes the midbrain pons and medulla oblongata

cerebrospinal fluid

the fluid that surrounds all exposed surfaces of CNS that functions to support brain, cushion delicate neural structures, and transport nutrients chemical messengers and wastes

blood brain barrier

ioslates CNS from general circulation. it is formed by network of tight junctions between capillary endothelial cells in the CNS. regulated by astrocytes and only lets lipid soluble compounds in

spinal cord

housed with protective membranes(meninges) and vertebral column. carries sensory and motor info between brain an most other body parts. gives rise to spinal nerves

anterior root

the ventral spinal root that contains axons of motor neurons

posterior root

the dorsal spinal root that has axons of sensory neurons

posterior root ganglia

the dorsal spinal root ganglia that contains cell bodies of sensory neurons that form the posterior root

spinal nerves

nerves formed by union of posterior and anterior roots. they are in pairs(one form each side at each vertebral level).

mixed nerves

spinal nerves that contain both afferent(sensory) and efferent(motor) fibers

dermatome

a specific bilateral region of skin supplied by a single pair of spinal nerves

peripheral neuropathy

regional losses of neural function that affects dermatomes. often from nerve traumas, compression, or various illnesses

shingles

rash/symptoms that occur along dermatomes

axonal transport

movement of materials along neurotubules within axons between cell body and axon terminals

neurotubules

similar to microtubules, made of tubulin, have plus and minus ends, and use kinesin (+) and dynein(-) as motor proteins

fast axonal transport

anterograde transport by vesicles(transmembrane, secreted, lysosomal proteins synthesized on membrane bound ribosomes)

slow axonal transport

anterograde transport by non vesicle transport(cytoplasmic proteins synthesized on free ribosomes)

neuroglia

support and protect neurons, make up half the volume of the nervous system

astrocytes

neuroglia that have large cell bodies that function in maintaining blood brain barrier, creating 3d framework for cns, repair damaged nervous tissue, guide neuron development, and control interstitial environments

ependymal cells

neuroglia that form epithelium that lines central canal of spinal cord and ventricles of brain. they produce cerebrospinal fluid and use cilia to aid in its circulation.

oligodendrocytes

neuroglia that have small cell bodies with multiple processes. each process can form a myelin wrap. can myelinated multiple portions of axons

myelination

insulates axons, increases action potential speed, increases resistance, decreases capacitance, makes nerves appear white

internodes

myelinated segments of axons with no channels

nodes of ranvier

lie in between internodes. where axons may branch and where channels are located

multiple sclerosis

when non glial immune cells get past the blood brain barrier and destroy myelin. this forms scar tissue which leads to difficulty myelinating and loss of neurons(weakness, numbness, blindess)

microglia

smallest and least numerous neuroglia that have many fine branched processes. they migrate through nervous tissue and clean up cellular debris, waste, and pathogens

neuroglia of the PNS

(satellite and schwann cells)neuroglia that insulate neuronal cell bodies and axons.

satellite cells

neuroglia of the PNS that surround ganglia to regulate interstitial fluid around neurons(similar to astrocytes)

schwann cells

form myelin sheath. one can sheath only one axon

wallerian degeneration

when an axon distal to injury degenerates. nerves can regenerate but it is difficult due to astrocytes

membrane potential

the difference in charge across the membrane in neurons.

ohm's law

Voltage= current*resistance

resting membrane potential

membrane potential of a resting cell

graded potential

temporary, localized change in resting potential caused by stimulus. in the input region

action potential

electrical impulse produced by graded potential that propagates along surface of axon synapse. in the conductile region

chemical gradients

concentration of gradients of ions (Na+ and K+) along the cell membrane

electrical gradients

charges are separated by cell membrane. cytosol is negative relative to extracellular fluid

electrochemical gradient

sum of chemical and electrical forces acting on an ion across the membrane. this is a form of potential energy

equilibrium potential

membrane potential at which there is no net movement of a particular ion across cell membrane. the membrane potential seeks the equilibrium potential of the ion with dominate permeabilty

passive ion channels

permeability changes with conditions, but always move down their electrochemical gradients. leak channels are always open while gated channels open and close in response to stimuli

active ion channels

use energy to move ions against gradient

ligand gated ion channels

gated channel that opens once it binds to to specific chemicals such as hormones or neurotransmitters. allows ion movement

voltage gated ion channels

gated ion channel that responds to changes in membrane potential. the inactivation gate is a ball and chain system. part of conductile and output regions. can be closed open, or inactivated(cannot reopen until membrane is hyperpolarized)

mechanically gated ion channels

gated ion channel that responds to membrane distortion. found in sensory receptors

generator potentials

the graded potential that is mechanically gated on input regions of primary sensory afferent

post synaptic potentials

graded potentials that are ligand gated on all other input regions

graded potentials

the changes in membrane potential of the input region that are produced by specific stimuli. they cannot spread far from the site of stimulation and their change is proportional to stimulus

depolarization

the rise in membrane potential

repolarization

when stimulus is removed and the membrane potential returns to rest

hyperpolarization

when membrane potential becomes more negative than resting membrane potential

threshold

the tipping point where na influx equals K+ efflux. if na increases and has dominant permeability, it will pull membrane closer to na equilibrium and action potential. if na decreases and k has dominant permeability it will pull towards k eq potential and membrane will return to rest

all or none principle

any stimulus that changes the membrane potential to threshold will cause an action potential. all action potentials are the same no matter how large the stimulus. an action potential is either triggered or not

frequency coding

because action potentials are invariable, use frequency to code for strength of stimulus. the frequency is the number of action potentials in a time frame. more graded potential= higher frequency