chapter 3.1 Flashcards
peripheral nervous system (PNS)
division located outside the skull and spine; nerves etc.
Somatic nervous system (SNS)
part of the PNS that interacts with the external environment
afferent nerves (somatic NS)
carry sensory signals from the skin, skeletal muscles, joints, eyes, ears etc. to the CNS.
efferent nerves (somatic NS)
carry motor signals from the CNS to the skeletal muscles.
Autonomic nervous system (ANS)
part of the PNS that regulates the body’s internal environment
central nervous system (CNS)
division of the nervous system located within the skull and spine
afferent nerves (autonomic)
carry sensory signals from internal organs.
efferent nerves (autonomic)
carry motor signals to internal organs
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. Synapse on second-stage neurons a substantial distance from from their target organs.
parasympathetic nerves
autonomic motor nerves that project from the brain and sacral (lower back) region of the spinal cord. Synapse on second-stage neurons a very short distance from from their target organs
para/sympathetic nerves
Both are two stage neural paths: both project from the CNS and go only part of the way to the target organs before they synapse on other neurons that carry the signals the rest of the way
1st difference between para/sympathetic nerves
Sympathetic nerves stimulate, organize, and mobilize energy sources in threatening situations where parasympathetic nerves conserve energy
2nd difference between para/sympathetic nerves
each autonomic target organs receives opposing sympathetic and parasympathetic input, and its activity is thus controlled by relative levels of sympathetic and parasympathetic activity
3rd difference between para/sympathetic nerves
sympathetic changes are indicative of psychological arousal while parasympathetic changes are indicative of psychological relaxation.
12 pairs of cranial nerves
project from the brain and include purely sensory such as the olfactory nerves (I), optic nerves (II) but most contain motor and sensory fibers. Longest cranial nerve are the vagus nerves (X) (contain motor and sensory fibers) traveling to and from the gut
brain and spinal cord are protected by…
Three membranes aka three meninges
(1) outer menix
touch membrane called the dura mater
(2) arachnoid membrane
inside the three layers; Beneath is is a space called the subarachnoid space, which contains many large blood vessels and cerebrospinal fluid
(3) innermost menix
delicate pia mater which adheres to the surface of the CNS
Cerebrospinal fluid (CSF)
protects the CNS by filling the subarachnoid space, the central canal of the spinal cord, and the cerebral ventricles of the brain (all interconnected by a series of openings and form a single reservoir).
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
Choroid plexus
where CSF is thought to be produced; networks of capillaries that protrude into the ventricles from the pia mater. Excess is continuously absorbed from the subarachnoid space into large blood-filled spaces, or dural sinuses, which run through the dura mater and drain into the large jugular veins of the neck
hydrocephalus (water head)
Occurs If a tumor forms near one of the narrow channels (cerebral aqueduct) that link the ventricles, the buildup of fluid causes the walls of the ventricles and the entire brain to expand
blood brain barrier
in the brain, blood vessel walls are tightly packed, forming a barrier to the passage of many molecules (unlike in the rest of the body). However, some large molecules, such as glucose, can still penetrate the walls
