Download Nervous System - wlhs.wlwv.k12.or.us

NOTES: CH 49 NERVOUS SYSTEM
ORGANIZATION; THE
HUMAN BRAIN
Recall…the nervous system is
divided into 2 divisions:
● CENTRAL NERVOUS SYSTEM (CNS):
information processing; integration
● PERIPHERAL NERVOUS SYSTEM
(PNS): transmits info. to/from the CNS;
plays a large role in regulating an
animal’s movement & internal
environment
Organization of the
CENTRAL NERVOUS SYSTEM:
● consists of the BRAIN & SPINAL
CORD
● BRAIN: integration; complex behavior
● SPINAL CORD: conveys info. to / from
the brain; generates basic patterns of
locomotion
SPINAL CORD:
● can also act independently of the brain
as part of simple nerve circuits:
REFLEXES!
● a reflex protects the body by triggering
a rapid, involuntary response to a
particular stimulus
● EXAMPLE: knee-jerk reflex
Organization of the
CENTRAL NERVOUS SYSTEM:
● CEREBROSPINAL FLUID:
-formed in the brain by filtration of blood
-circulates through brain, providing
nutrients & hormones; carries away
wastes
-cushions the brain & spinal cord
GRAY & WHITE MATTER:
● GRAY MATTER:
-consists mainly of neuron cell bodies,
dendrites, unmyelinated axons, & glia
(support cells)
● WHITE MATTER:
-consists of bundled axons w/myelin
sheaths (gives the white appearance)
Organization of the
PERIPHERAL NERVOUS SYSTEM:
● consists of NERVES that branch out
from the CNS and connect it to other
parts of the body.
● includes:
SPINAL NERVES and CRANIAL
NERVES
CRANIAL NERVES
● mammals have 12 pairs of cranial nerves
● originate from the cerebrum & brain stem
● innervate parts of the head, neck and trunk
CRANIAL NERVES
SPINAL NERVES
● mammals have 31 pairs of
spinal nerves
● originate from the spinal cord
● innervate the upper & lower
limbs, neck, and trunk
SPINAL NERVES
PERIPHERAL NERVOUS
SYSTEM (PNS):
● can be subdivided into the:
1) Motor system: oversees conscious
(voluntary) activities (i.e. skeletal
muscles);
2) Autonomic nervous system: controls
unconscious (involuntary) activities (i.e.
heart, stomach, intestines, glands)
AUTONOMIC NERVOUS
SYSTEM
● branch of the PNS that is involuntary;
● includes 2 subdivisions:
1) SYMPATHETIC DIVISION;
2) PARASYMPATHETIC DIVISION.
● Sympathetic and parasympathetic
divisions may act antagonistically
(in opposition), alternately
activating or inhibiting the actions
of some organs, glands, etc.
SYMPATHETIC DIVISION:
● prepares the body for energyexpending, stressful, or emergency
situations
EXAMPLE: during an emergency, the
sympathetic division will increase the
heart rate and breathing rate, etc.
PARASYMPATHETIC DIVISION:
● is most active under ordinary, restful
conditions;
● counterbalances the effects of the
sympathetic division
EXAMPLE: after an emergency, the
parasympathetic division decreases the
heart rate, breathing rate, etc.
Parts of the Brain:
● During embryonic development,
3 brain regions become evident:
1) FOREBRAIN
2) MIDBRAIN
3) HINDBRAIN
Brain Regions:
● Forebrain includes: cerebrum,
thalamus, hypothalamus
● Midbrain
● Hindbrain includes: pons,
medulla oblongata, cerebellum
**the midbrain, along with the pons
and medulla oblongata form the
BRAINSTEM
BRAINSTEM:
● anterior end of
spinal cord;
● 3 parts that
function in:
-homeostasis
-movement coordination
-conduction of info. to higher
brain centers:
BRAINSTEM:
3 parts of the brainstem:
1) Medulla oblongata
2) Pons
3) Midbrain
1) Medulla oblongata: controls breathing,
heart and blood vessel activity / dilation (and
therefore blood pressure), respiratory
center, swallowing, vomiting, digestion
2) Pons: regulates
breathing centers in
the medulla; relays
impulses between the
cerebrum and the
medulla, and the
cerebrum and
cerebellum.
3) Midbrain:
● receives and sends sensory information;
● coordinates visual reflexes (eye
movements with other movements)
● coordinates auditory reflexes (move the
head to hear a sound more distinctly)
CEREBELLUM:
● coordination of movement;
● balance;
● hand-eye coordination
THALAMUS:
● relay center that sorts out & transmits
sensory information to and from cerebrum;
● incoming information from all the senses is
sorted here and sent on to the appropriate
higher brain center;
● involved in regulating emotion
& arousal (wakefulness)
HYPOTHALAMUS:
 important regulator of HOMEOSTASIS
 contains body’s thermostat
 includes centers for regulating hunger &
thirst
 plays role in sexual response and
mating behavior
HYPOTHALAMUS:
 fight-or-flight response, pleasure, daily
biorhythms (“biological clock”)
 source of posterior pituitary hormones &
releasing hormones for anterior pituitary
hormones
CEREBRUM:
 divided into hemispheres (R and L)
 each hemisphere divided into lobes
(frontal, parietal, temporal, occipital)
 each hemisphere has an outer covering
of gray matter = CEREBRAL CORTEX
 hemispheres are connected by white
matter called CORPUS CALLOSUM
CEREBRUM – functions!
 where memories are stored
 interprets sensory impulses arriving
from sense organs
 centers for motor coordination; send motor
impulses to muscles
 where conscious decisions are made
 intelligence and personality stem from
cerebral activity
 language, cognition / thought / problem
solving
There are 2 functional cortical areas:
1) Primary Motor Cortex: sends commands
to skeletal muscles, signaling appropriate
responses to sensory stimuli
2) Primary Somatosensory Cortex:
 receives and integrates signals from
touch, pain, pressure, and temperature
receptors;
 divided into specific areas so that we
can associate specific stimuli with
specific parts of the body.
Nervous System Disorders:
● Schizophrenia
● Depression
● Bipolar disorder (manic-depressive)
● Drug addiction
● Alzheimer’s Disease
● Parkinson’s Disease
Schizophrenia:
Drug
Addiction: