Biopsychology Chapter 3 Notes
General Layout of the Nervous System
1. Central nervous system (CNS) - the division of the nervous system that is
located within the skull and spine.
2. Peripheral nervous system (PNS) - located outside the skull and spine.
The CNS is composed of two divisions: the brain and spinal cord. The brain is the
part of the CNS that is located in the skull, and the spinal cord is the part located in
Somatic Nervous System – interacts with the external environment.
- Afferent nerves (sends sensory signals from skeletal muscles to CNS)
- Efferent nerves (motor signals from CNS to skeletal muscles
Autonomic Nervous System – regulates body’s internal environment
- Afferent nerves (sensory from internal organs to CNS)
- Efferent nerves (motor signals from the CNS to internal organs)
2 kinds of efferent nerves – sympathetic and parasympathetic
Sympathetic nerves: autonomic motor nerves that project from the CNS in the
lumbar (small of the back) and thoracic (chest area) regions of the spinal cord.
Parasympathetic nerves: autonomic motor nerves that project from the brain
and sacral (lower back) region of the spinal cord.
Sympathetic nerves and Parasympathetic nerves generally have motor effects
- sympathetic nerves stimulate, organize, and mobilize energy resources in
threatening situations, whereas parasympathetic nerves act to conserve
- Sympathetic neurons that project from the CNS synapse on second-stage
neurons at a substantial distance from their target organs, whereas the
parasympathetic neurons that project from the CNS synapse near their target
organs on very short second-stage neurons. SYM: dilates, inhibits, accelerates
PARA: constricts, stimulates, slows
PROTECTING THE BRAIN
The brain and spinal cord (the CNS) are the most protected organs in the body
- They are encased in bone and covered by 3 protective membranes, called the
meninges. The outer meninx is a tough membrane called the dura mater
(tough mother). Inside the dura mater is the arachnoid membrane (spider
web-like membrane). The innermost meninx is the pia mater which is
located on the surface of the CNS.
- Subarachnoid space is beneath the arachnoid membrane and contains
many large blood vessels and CSF.
Cerebrospinal fluid: fills the subarachnoid space, the central canal, and the
cerebral ventricles of the brain.
Central canal: small central channel that runs the length of the spinal cord
Cerebral ventricles: four large internal chambers of the brain; the two lateral
ventricles, the third ventricle, and the fourth ventricle. The cerebral aquaduct