Download Nervous System Nervous System

Nervous System
Biology Content Standards
4. Anatomy and Physiology
Broad Concept: There is a relationship between the
organization of cells into tissues, and tissues into organs. The
structure and function of organs determine their
relationships within body systems of an organism.
Homeostasis allows the body to perform its normal functions.
4.4
By:
Mrs. Bailey
Explain how the nervous system (brain, spinal cord, sensory
neurons, motor neurons) mediates communication between
different parts of the body and the body’
’s interactions with the
environment. Identify the basic unit of the nervous system, the
neuron, and explain generally how it works.
Nervous System
Central Nervous System (CNS)
Components:
• Brain
Brain, spinal cord, nerves, sensory receptors
Responsible for:
Sensory perceptions, mental activities, stimulating
muscle movements, secretions of many glands
Classical Subdivisions:
• Central nervous system (C(S)
• Peripheral nervous system (P(S)
• Spinal cord
• Integration and
command center
1
Peripheral Nervous System (PNS)
•
Cranial nerves
•
Spinal nerves
•
Carries messages to
and from the spinal
cord and brain
Cells of the Nervous System
It’
It’s all about the Impulse …
NEURON
The two major cell types are:
– (eurons – excitable cells that transmit
electrical signals or IMPULSES.
AXO(
HILLOCK
DE(DRITE
AXO(
(UCLEUS
– Glia – cells that surround and support
neurons.
CELL BODY
GLIA
2
NEURON
_______________
______________
A nerve impulse follows
the all-or-none principle!
_____________
_________
_________
_________
Once threshold is reached,
a neuron fires!
__________
__________
________
________
_____________
__________
__________
Synaptic
knobs
The impulse is an
electrochemical
message !
(a+ gates open and
Na+ floods the cell.
The inside is now
positive!
(a+ / K+
pump at work!
The cell membrane allows more K+ ions to leak out. That is
why, at rest, the inside of the cell membrane is negative.
3
SYNAPSE
SYNAPSE
1.
2.
3.
(eurons talk to
each other by
way of a special
chemical called a
neurotransmitter.
How cool
A neuron
may receive
input from
hundreds of
other neurons
via thousands
of synaptic
knobs
4.
5.
6.
7.
Neuron Classification
Functional:
– Sensory (Afferent) neurons
transmit impulses toward the C(S
– Interneurons (Association neurons)
shuttle signals through C(S pathways.
Found entirely within the C(S.
– Motor (Efferent) neurons
carry impulses away from the C(S
4
Mouth
is
dry Sensory Neurons
I’
’m
Thirsty!
Interneurons
I am going to
pick up the
glass of water
Pick up
glass
and
drink.
Motor Neurons
CNS and Protection
The Meninges
• Cranium & Vertebrae
• Meninges
• Cerebrospinal fluid
5
Cerebrospinal Fluid
The Brain
1. CEREBRUM – Largest!
Three functions:
•
Cushions C(S
•
Supports the brain. The brain actually floats
in the cranial cavity!
• Responsible for all the voluntary activities of the body.
• Site of intelligence, learning, and judgment.
2. CEREBELLUM
• 2nd largest part found at the back of the skull.
•
Transport of nutrients, chemical messages
(Ex: CO2 and pH levels) and waste products
• Coordinates and balances the actions of the muscles
3. BRAI(STEM
• Connects brain to spinal cord
• 3 parts: Medulla oblongata, Pons, Midbrain
4. DIE(CEPHALO(
• Thalamus, Hypothalamus, Optic chiasma, Pineal body
Cerebrum
Surface forms a series of
elevated ridges called
gyri and shallow
depressions called sulci.
The outermost layer
of the cerebrum is called
the cerebral
cortex.
6
Occipital Lobe
Frontal Lobe
Parietal Lobe
Primary motor cortex
Primary sensory cortex
Controls voluntary skeletal
muscle
• Touch
Brocca’s speech area
Involved in speech
Prefrontal area
Intellectual functions –
predicting consequences
of possible actions
• Pain
• Temperature
• Taste
7
Temporal Lobe
Occipital Lobe
Auditory cortex
Visual cortex
Cerebellum
• 2nd largest part found at
the back of the skull.
• Functions at the
subconscious level to:
- Coordinate and balance
the actions of the muscles.
- Control posture.
Fill in the blanks:
The cerebellum compares the motor
commands of the _________ to the information coming
from the receptors in the _______ .
Brainstem
Medulla oblongata
Most primitive part of the brain; lowest part of the brainstem
which controls involuntary functions that include breathing,
blood pressure, heart rate, swallowing, coughing, and vomiting.
Pons
Just above medulla oblongata ; link
between the cerebral cortex and the
cerebellum.
Midbrain
Smallest part; hearing and vision.
Diencephalon: Thalamus
1. Conscious recognition of pain, temperature, and touch.
2. Relays all kinds of
sensory impulses
to the cerebrum
(except smell).
3. Associates sensory
impulses with
feelings
of pleasantness &
unpleasantness.
8
Diencephalon: Hypothalamus
Hypothalamus
Regulator & coordinator of autonomic activities!
1. Body temperature
Just below
the thalamus
2. Water balance
3. Hunger & thirst
4. Fatigue
Diencephalon: Optic Chiasma
Region where
right and left
optic nerves
enter the
brain
5. Anger
Diencephalon: Pineal Body
1.
2.
Body’
’s
biological
clock.
Produces
hormone
melatonin.
3.
4.
5.
6.
9
8.
7.
Spinal Cord
8.
9.
10.
Spinal (erve
11.
12.
13.
14.
Vertebra
15.
15.
Functions of Spinal Cord
Ascending Tracts
Descending Tracts
1. Provides conduction routes to and
from the brain via tracts.
2. Serves as the integrator,
or reflex center, for
all spinal reflexes.
10
Reflex arc
Interneuron
• Reflex = rapid
motor response
to a stimulus.
Sensory neuron
• Involuntary
• Can involve all
muscle types
and/or glands
• O brain
involvement!
Motor neuron
11