The Nervous system
I: Central Nervous System
a) Brain
b) Spinal Cord
II. Peripheral Nervous System
a) Somatic
(skeletal) nervous system:
Voluntary behaviors
b) Autonomic:
Self-regulation of internal
organs and glands.
1. sympathetic NS:
arousing
Pupils dilate, HR, BP,
respiration increase,
and digestive processes
slow down.
Fight or flight response.
2. parasympathetic NS:
calming-opposite
of sympathetic nervous system
response.
Three types of Neurons
1. Sensory (afferent) neurons of the
peripheral NS take incoming sensory information to the spinal cord and
brain.
2. Motor (efferent) neurons take information from the spinal cord out to
muscles and glands.
3. Interneurons are neurons in the central NS (brain & spinal cord).
They communicate with each other and connect the sensory and motor
neurons.
The Simple Reflex
A simple reflex involves afferent
(sensory) neurons carrying sensory information to the spinal cord.
Interneurons connect the afferent neurons to the efferent (motor)
neurons. A reflex does not involve the brain.
The Brain
Studying the Brain
Phineas Gage
Lesions: Destruction of brain
tissue |
Studying the Brain (cont.)
EEG (electroencephalogram): amplified recordings of brain
wave activity.
CT (computerized tomography) scan: X-ray photos of slices of the
brain. CT (or CAT) scans show structures within the brain
but not functions of the brain.
PET (positron emission tomography): visual display of brain
activity that detects where a radioactive form of glucose is being used
while the brain performs certain tasks.
MRI (magnetic resonance imaging): technique that uses magnetic
fields and radio waves to see structures within the brain.
fMRI (functional MRI): allows us to see where oxygen is being
used in the brain while various tasks are being performed.
Structure and Function of the Brain
Brainstem: Oldest area of the brain. Also called the reptilian
brain.
1. Medulla: the base of the brainstem; controls heartbeat and
breathing.
2. Reticular Formation: A neural network within the brainstem;
important in arousal including sleep.
Thalamus: Sits on top of the brainstem; received all
incoming sensory information (except smell) and sends it to the
appropriate part of the brain for further processing.
Cerebellum: The "little brain" attached to the back of the
brainstem; it helps coordinate voluntary movement and balance.
The Limbic System: A doughnut-shaped structure between the
brainstem and the cerebral hemispheres. It is considered the "seat
of emotion" and is also involved in motivated behavior like eating,
drinking, and sex.
1. Amygdala: Involved in rage and fear as well as emotional
memories.
2. Hippocampus: Involved in memory
3: Hypothalamus: Involved in eating, drinking, and sexual
behavior. It also controls the endocrine (hormonal system) via the
pituitary gland. It is sometimes referred to as "the pleasure
center" of the brain.
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