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Nervous April Sanchez Per. 5 (Brain 4 Major Regions (Lobes of Brain…
Nervous
April Sanchez
Per. 5
Brain 4 Major Region
s
2.) Diencephalon:
sits on top of the brain stem
2 Main Parts:
Thalamus:
rely sensory info., recognizes good vs. bad sensations
Hypothalamus:
controls body temperature, water, balance, metabolism & endocrine function, etc.
Part of limbic system(thrust, appetite, sex, pain & pleasure)
1.) Cerebrum(cerebral hemisphere):
superior part of brain composed of 2 hemispheres(has grey & white matter)
Cerebrum Divided into Regions:
Sulcus(sulci):
creases, shallow, groves
Fissures:
deeper grooves usually separated large parts of brain
Gyrus(gyri):
bump, elevated ridges of tissue
Longitudinal Fissure:
divides cerebrum into lest & right hemispheres( l hem. controls r side of body)
3.) Brain Stem:
Midbrain:
reflex center for vision & hearing
Pons:
relay between cerebrum & cerebellum
Medulla Oblongata:
reflex center for heart rate, B.P, breathing, vomiting & swollowing
Reticular Formation:
controls wake/ sleep cycle
4.) Cerebellum:
controls equilibrium & balance posture, coordinates muscles of body to move smoothly(voluntary movements)
Lobes of Brain
Frontal:
personality, emotion, intelligence, attention, concentration, logic, problem solving
Parietal:
size, shape, color, pain, temperature, speech
Temporal:
hearing, speech, memory, sequencing & organization
Occipital:
processes vision(vision cortex)
Meningitis(Covering of Brain & Spinal Cord)
Dura Mater(outer layer):
tough, lining the vertebral canal
Arachnoid Mater(middle layer):
between dura mater & pia mater, looks like cobweb
Pia Mater(inner layer):
gentle, covers every fold of brain, & surrounds the actual spinal cord
Meningitis:
infection in the meningitis can spread to CNS, dangerous often fatal
Fluid in the Brain & Spinal Cord
Cerebrospinal Fluid:
fills spaces(cerebral ventricles) the brain between pia mater & arachnoid in the brain
This fluid circulates down & around the cord & up around the brain
Forms from fillration of blood by the
Choroid Plexus:
network of brain capillaries
Action Potential
Nerve impulses are transmitted
1.)
Strong enough stimulation/stimulus causes Na+ gates to open, Na+ rush into cell causing depolarization
2.)
if a strong enough depolarization occurs, threshold potential is reached & impulse is sent down axon
3.)
K+ rush out of neuron after Na+ rushes in, repolarizes membrane
4.)
membrane is hyperpolarized- too many K+ leave the cell, membrane potential dips below resting potential
5.)
final step: resting potential(nerve at rest/inactive) is restored
Refactory Period:
is the time during which no stimulus can cause another action potential
Divisions of the Nervous System
2.) Peripheral Nervous System:
all nerves that extend from brain and spinal cord
Function:
spinal nerves carry impulses to and from the spinal cord, cranial nerves carry impulses to and from the cranium
Divisions of PNS
1.) Sensory(afferent) Nerves:
relay information from skin, muscles, and glands to CNS, they affected by environment or sense the environment
Inter neuron:
nerves that connect sensory nerves to motor nerves
2.) Motor(efferent) Nerves:
carry impulses from CNS to organs, muscles(they cause an effect or response)
2 Types:
Somatic Motor Neuron:
conscious voluntary control, sense & respond to external environment(EX:muscles, skin,sense organs)
Autonomic Motor Neuron:
automatic, unconscious in voluntary control respond to internal environment (EX:digestion, blood flow, smooth muscle, etc.)
Structure of a Neuron
Dendrite:
receives impulse & sends to the cell body
Cell Body:
metabolic center
Axon:
conducts signal away from the cell body
Myelin:
fatty substance that insulates signal, allows signal to be sent faster
Node(s) of Ranvier:
space between myelin/schwann cells
3 Types of Neuron Structures:
1.) Multipolar:
many dendrites, one axon
2.) Bipolar:
one dendrite, one axon(sensory)
3.) Unpolar:
fused axon & dendrite(sensory)
3 Types of Neurons:
1.) Sensory(afferent):
transmitted impulses to the spinal cord & brain from all parts of the body
2.) Motor(efferent):
transmitted impulses away from the brain & spinal cord to only 2 kinds of tissue
3.) Interneurons(central or connecting neurons):
transmitted impulses from sensory neurons to motor neurons
1.) Central Nervous System:
brain, spinal cord
Function:
receive incoming sensory information and issue instructions
Spinal Cord
Functions:
contains centers for thousands of reflex arcs
carries impulses to and from the brain
Interneuron:
transforms sensory impulses, allows for reflexes to happen
Spinal Cord Reflex
: reflex that result from conduction over arcs in the spinal cord
Spinal Cord 2 way Conduction path to Brain:
Ascending Tracts:
sends impulses up towards the brain
Descending Tracts:
sends impulses down the cord from the brain
Tracts are composed of axons that all serve the same function
Spinal Cord Structure:
Extends from occipital bone to the first lumbar vertebra
Inner portion is an H- shaped core comprised of grey matter(dendrites & cell bodies of neurons)
Outter portion id formed by columns of white matter, which is made up of
Spinal Tracts:
bundles of myelinated nerve fibers