Transcript The Brain - Downey Unified School District

The Brain
Ale Robles
MinJeong Cho
Joseline Dubon
Function
The brain is responsible for integrating most
sensory information and coordinating body
functions. The brain includes:
● Two cerebral hemispheres
● Diencephalon
● Brain stem
● Cerebellum
Development
Basic structure of the brain
begins as the neural tube that
gives rise to the CNS. The
Portion that becomes the brain
has three cavities:
● Forebrain (prosencephalon)
● Midbrain (mesencephalon)
● Hindbrain (rhombencephalon)
Cont...
● The forebrain divides into
the telencephalon and
diencephalon.
● The hindbrain divides into
the metencephalon and
myelencephalon.
Meninges
Three layers: Dura mater, arachnoid mater, and pia mater.
● Dura mater-outermost layer. composed of tough, white, dense connective
tissue. Contains many blood vessels and nerves.
● Arachnoid mater- thin, web like membrane that lacks blood vessels and is
located between the dura and pia matters.
● Pia mater- thin and contains many nerves, and blood vessels that nourish the
underlying cells of the brain and spinal cord.
cont...
Spinal Cord
● It is a slender column of nervous tissue
that is continuous with the brain and
extends downward through the vertebral
canal.
● Like the brain, the spinal cord is covered
by the meninges and cushioned by
cerebrospinal fluid.
Cont...
Cont...
● The spinal cord is a center for spinal
reflexes.
● Nerve impulses follow nerve pathways.
The simplest of these pathways,
constitutes a reflex arc.
Reflex Behavior
● They are automatic, subconscious
responses to stimuli within the body.
Examples: Knee-jerk reflex, Withdrawal
reflex
● They both use two neurons- a sensory
neuron communicating directly to a
motor neuron.
Knee-jerk Reflex
Withdrawal Reflex
Different sections of the brain
Cerebrum
● Develops from anterior portion of the forebrain.
● Consists of two large cerebral hemispheres, which
are mirror images.
● Lobes of the hemispheres are named after the skull
bones they underline.
Cerebral hemisphere lobes
Frontal lobe- forms anterior portion of each
cerebral hemisphere.
Parietal lobe- Posterior to the frontal lobe and
is separated from it by the central sulcus.
Temporal lobe- Lies inferior to the frontal and
parietal lobes and is separated by the lateral
sulcus.
Occipital lobe- Forms the posterior portion of
each cerebral hemisphere.
Insula- Located deep within the lateral sulcus.
It is covered by parts of the frontal, parietal,
and temporal lobes.
Cont...
Involved in several functions of the body including:
● Determining Intelligence
● Determining Personality
● Thinking
● Perceiving
● Producing and Understanding Language
● Interpretation of Sensory Impulses
● Motor Function
● Planning and Organization
● Touch Sensation
Hemisphere Dominance
● One hemisphere of the brain
is dominant for a certain
function.
● Nerve fibers enable dominant
hemisphere to control motor
cortex of the nondominant
hemisphere.
● MEMORY: located in the
temporal lobe, specifically in
the hippocampus.
- short term
- long term
Basal Nuclei
● Masses of grey matter
deep in cerebral
hemisphere.
● 3 parts:
- Caudate nucleus
- Putamen
- Globus pallidus
● Produces dopamine.
Diencephalon
● Develops from posterior
forebrain, made up of
the hypothalamus and
thalamus.
● Links the
phylogenetically older
brainstem to various
structures in the
phylogenetically newer
telencephalon.
Diencephalon cont.
● Optic tracts, optic
chiasma, infundibulum,
posterior pituitary
gland, mammillary
bodies, and pineal
gland.
Limbic System
Portions of cerebral cortex in the medial parts of the
frontal and temporal lobes that connect with deep nuclei
from the limbic system.
● Controls emotional experience and expression, by
modifying how someone acts (anger, fear, pleasure)
● Fight or Flight
● Can interpret sensory impulses
Brainstem
● Connects brain to spinal cord.
● Made up of:
- Midbrain: controls visual and
auditory systems
- Pons: contains nuclei that relay
signals from forebrain to the
cerebellum.
- Medulla Oblongata: nerve fibers
that control visceral activity pass
through.
Cerebellum
● Large mass of tissue located
inferior to the occipital lobes of
the cerebrum.
● Primarily composed of white
matter with a thin layer of gray
matter (cerebellar cortex).
● Communicates with other parts
of the CNS by means of three
pairs of nerve tracts called
cerebellar peduncles.
Cranial Nerves
● 12 pairs
● Except for first two pairs,
originated from
brainstem.
● 12 pairs are named and
numbered in Roman
Numerals (I - XII)
I - IV
1.
2.
3.
4.
Olfactory Nerves (I)
a. Sense of smell
b. Only sensory neurons
c. Located upper nasal cavity
Optic Nerves (II)
a. Vision
b. Sensory neurons
c. Lead from eyes
Oculomotor Nerves (III)
a. Part 1
i. Movement of eyes, four of six
muscles that move eyes.
ii. From mid brain, pass into orbots
of the eyes
Trochlear Nerves (IV)
a. Carry motor impulses
b. Motor neurons
c. From mid brain to a fifth pair of external
eye muscles
V - VIII
1.
2.
3.
4.
Trigeminal Nerves (V)
a. Mixed; sensory and motor neurons
b. From the pons to different parts of face
i.
Ophthalmic
ii. Maxillary
iii. Mandibular
Absucens Nerves (VI)
a. Supply motor impulses
b. Motor neurons
c. Originated from pons, enter the orbits of
eye.
Facial Nerves (VII)
a. Taste receptors on tongue and transmit
impulses to muscles of face
b. Mixed; sensory and motor neurons
c. From floor plans two side of the face
Vestibulocochlear Nerves (VIII)
a. Sensory Neurons
b. Originatedd from medulla oblongata
IX - XII
1.
2.
3.
4.
Glossopharyngeal Nerves (IX)
a. Associated with tongue and pharynx
b. Mixed; sensory and motor neurons
c. Arise from medulla oblongata
Vagus Nerves (X)
a. Carries impulses
b. Mixed neurons
c. Originated in medulla oblongata, extend
downward through neck into chest and
abdomen
Accessory Nerves (XI)
a. Carries impulses to muscles of soft
palate, pharynx and larynx
b. Motor neurons
c. From medulla oblongata and spinal cord
Hypoglossal Nerves (XII)
a. Carry impulses to muscles to move
tongue
b. Motor neurons
c. From medulla oblongata and pass into
tongue
Overview
Spinal Nerves
●
grouped by the level from which they
arise number in sequence
●
8 pairs of cervical nerves, 12 pairs of
thoracic nerves, 5 pairs of lumbar
nerves, 5 pairs of sacral nerves, 1 pair
of coccygeal nerves.
o
Each spinal nerves consist of...
o
Dorsal root
o
Ventral root
Spinal Nerves Cont.
●
Each spinal nerves has a dorsal and
ventral branches
●
o
Dorsal: turns posteriorly
o
Ventral: continues forward
The thoracic and lumbar spinal
nerves also have a the visceral
branch
o
Visceral: part of autonomic
nervous system
Spinal Nerves Cont.
1. Autonomic nervous system:
i. Preganglionic fiber
ii. Postganglionic fiber
a. Sympathetic
i. Ganglionic fibers originate from
neurons
ii. found in upper two lumbar segments
of the cord
iii. Sympathetic chain ganglia and
sympathetic trunks
b. Whute and Gray rami
i. gray rami communicantes to ALL
spinal nerves; result in autonomic
sympathetic fibers being incorporated
ii. white rami communicantes carry
presynaptic sympathetic fibers
Works Cited
http://www.healthline.com/human-body-maps/brain
http://psychology.about.com/od/biopsychology/ss/brainstructure_4.htm
http://brainmadesimple.com/pons.html