chapter 3 concepts Flashcards
what are the two major divisions of the vertebrate nervous system?
the central nervous system (CNS) and the peripheral nervous system (PNS)
explain the division of the nervous system called the central nervous system (CNS)
the central nervous system is composed of the brain and the spinal cord, and is encased in bone and covered by three meninges
explain the division of the nervous system called the peripheral nervous system (PNS)
the peripheral nervous system is located outside of the skull and the spine. its purpose is to bring information to the central nervous system, and carry signals out of the central nervous system. the peripheral nervous system can by divided into two branches. these are the somatic and autonomic divisions of the peripheral nervous system.
explain the somatic nervous system (SNS)
the somatic nervous system is the division of the nervous system that interacts with the external environment. it is composed of afferent nerves and efferent nerves
function of afferent nerves in the somatic nervous system
afferent nerves carry sensory signals from the skin, skeletal muscles, joints, eyes, ears, and so on to the central nervous system.
function of efferent nerves in the somatic nervous system
efferent nerves carry motor signals from the central nervous system to the skeletal muscles.
explain the autonomic nervous system (ANS)
the autonomic nervous system is the division of the peripheral nervous system that regulates the body’s internal environment. it is composed of afferent nerves that carry sensory signals from internal organs to the CNS, and efferent nerves that carry motor signals from the CNS to internal organs.
afferent nerves in the autonomic nervous system
carries sensory signals from internal organs to the central nervous system
efferent nerves in the autonomic nervous system
carry motor signals from the central nervous system to internal organs
parasympathetic: autonomic motor nerves projecting from the brain and sacral region of the spinal chord
sympathetic: autonomic motor nerves projecting from the central nervous system in the lumbar and thoracic regions of spinal chord
what structures protect the brain and spinal cord (CNS)?
bone and 3 protective membranes (meninges)
explain the 3 meninges
the outer layer is a tough membrane called dura mater (tough mother). inside the dura mater is the fine arachnoid membrane ( spider-web-like membrane). the innermost layer is the delicate pia matter (pious mother) which adheres to the surface of the CNS.
cerebrospinal fluid
CSF is another structure that protects the CNS. it fills, the subarachnoid space, the central canal of the spinal chord and the cerebral ventricles of the brain.
the central canal
small central channel that runs the length of the spinal chord
the cerebral ventricles
the cerebral ventricles are the four large internal chambers of the brain. the two lateral ventricles, the third ventricle and the fourth ventricle.
afferent nerves
carry sensory signals TOWARD the
CNS
efferent nerves
carry motor signals AWAY from the CNS
parasympathetic/ sympathetic
two-stage neural paths project from the CNS and only go part of the way to target organs before synapsing on other neurons that carry signals the rest of the way
cranial nerves
- 12 pairs
- nerves in the peripheral nervous system that project from the brain, NOT the spinal chord.
- purely sensory nerves (olfactory/optic nerves) but most contain both sensory and motor fibers.
what are the three important principles regarding the functions of the sympathetic and parasympathetic systems?
- sympathetic: stimulates, organizes, and mobilizes energy sources
parasympathetic: acts to conserve energy - each autonomic target organ receives opposing sympathetic/parasympathetic input
- sympathetic- “psychological arousal”
parasympathetic- “psychological relaxation”
what are the longest cranial nerves?
the longest cranial nerves are the vagus nerves which contain motor and sensory fibers traveling to and from the gut.
*12 cranial nerves
the twelve pairs of cranial nerves which project from the brain are numbered in sequence from front to back. the cranial nerves include purely sensory nerves like the olfactory nerves and the optic nerves, but most contain motor and sensory fibers traveling to and from the gut
why are cranial nerves commonly assessed by neurologists as a basis for diagnosis?
because the functions and locations of the cranial nerves are specific, disruptions of particular cranial nerve functions provide excellent clues about the location and extent of tumors and other kinds of brain pathology.
