Chapter 8 Flashcards
What does the nervous system consist of?
Brain, Spinal cord, nerves
What are the functions of the nervous system?
- Regulates and coordinates all body activities
- Detect changes in the internal and external environment, evaluate the information, and respond to the stimuli by brining about bodily responses.
- Center of all mental activity, including thought, learning, and memory
neurology*
the study of the nervous system AND its disorders
neurologist*
the physician who specializes in treating the diseases and disorders of the nervous system
neurosurgery*
any surgery involving the brain, spinal cord, or peripheral nerves
neurosurgeon*
the physician who specializes in surgery of the brain, spinal cord, or peripheral nerves
What are the two subdivisions of the nervous system?
The central nervous system (CNS) and the peripheral nervous system* (PNS)
What does the central nervous system consist of?
What is it responsible for?
- The brain and the spinal cord
- processing and storing sensory* and motor information and for controlling consciouness
What is the peripheral nervous system* consist of?
What is it responsible for?
- 12 pairs of cranial nerves and 31 pairs of spinal nerves
- Transmits sensory and motor impulses back and forth between CNS and rest of body
True or False: Basically, the central nervous system (CNS) is the command center, and the peripheral nervous system (PNS) is the messenger.
True. The peripheral nervous system is kept quite busy carrying messages to and from the rest of the body.
What is the PNS made up of?
nerves and ganglion
What is a nerve?
cordlike bundle of nerve fibers that transmits impulses to and from the brain and spinal cord. A nerve is macroscopic-seen without a microscope
What is a ganglion*?
A knotlike mass of nerve cell bodies located outside the CNS
What two divisions does the PNS break down into?
Somatic nerve system and the autonomic nervous system
What do afferent nerves* do?
carry impulses from the body to the CNS
What do efferent nerves* do?
carry impulses from the CNS to the muscles and glands, causing the target organs to do something in response to the commands received
What does the somatic nervous system* (SNS) provide?
voluntary control over skeletal muscle contractions
What does the autonomic nervous system* (ANS) provide?
involuntary control over smooth muscle, cardiac muscle, and glandular activity and secretions in response to the commands of the CNS.
What types of nerves are found in the ANS?
sympathetic* and parasympathetic*
What do sympathetic nerves* regulate?
essential involuntary body functions such as
- increasing heart rate
- constricting blood vessels
- raising blood pressure
- responding to the “flight or fight” response
What do parasympathetic nerves* regulate?
regulates essential involuntary body functions such as
- slowing the heart rate
- increasing peristalsis of the intestines
- increasing glandular secretions
- relaxing sphincters
- therefore, serving as a complement to the SNS and returning the body to a more restful state
__________ nerves carry the impulses from the body to the CNS, while __________ nerves carry the impulses from the CNS to the body.
a. Somatic, autonomic
b. Afferent, efferent
c. Autonomic, somatic
d. Efferent, afferent
b. Afferent nerves are sensory, efferent nerves are motor.
What are the two main types of cells found int he nervous system tissue?
neurons and neuroglia*
Neuron*
What is it known as?
What are its three basic parts?
- the functional unit, the nerve cell
- a cell body, one axon, and one or more dendrites
What is within the cell body?
nucleus and cytoplasm
What is the axon*?
What does it do?
- a single slender projection that extends from the cell body
- conduct impulses away from the cell body
What are some axons covered in?
a myelin sheath*
What is the role of the myelin sheath*?
protects the axon and speeds the transmission of the impulses.
How do you tell the difference between a nerve cell with or with out the myelin sheath?
axons with a myelin sheath look white (making up the white matter of the nervous system) and without look grey (making of the grey matter within the nervous system)
Dendrites
What do they do?
branch extensively from the body (like trees)
-conduct impulses toward the cell body
What is the space between the axon of one neuron and dendrite of another neuron?
a synapse*
What is a synapse*?
the space between the two nerves over which the impulses must cross
What is released into the synapse* to activate or inhibit the transmission of nerve impulses across the synapses?
chemical substances known as neurotransmitters
How are nerves classified?
according to the direction in which they transmit impulses.
Afferent nerves*
What are they also called?
- transmit impulses toward the brain and spinal card
- sensory nerves*
Efferent nerves*
What are they also called?
- transmit impulses away from the brain and spinal cord
- motor nerves*
What are interneurons*?
connecting neurons in the CNS that conduct impulses from afferent nerves to (or toward) motor nerves
What is neuroglia*?
a special type of connective tissue for the nervous system
What is the role of neuroglia*?
provide a support system through phagocytosis* by engulfing and digesting any unwanted substances
What are the three types of neuroglia* cells?
astrocytes, microglia, and oligodendrocytes
Astrocytes
star-shaped cells with numerous radiating processes for attachment; largest and most numerous neuroglia cell; found only in the CNS
What do astrocytes wrap around and form through this wrapping?
They wrap around the brains blood capillaries, forming a tight sheath. This sheath plus the wall of the capillary forms the blood-brain barrier*
What is the function of the blood-brain barrier*?
prevents the passage of harmful substances from the blood-stream into the brain tissue or cerebrospinal fluid*.
Microglia
- small interstitial cells that have slender branched processes stemming from their bodies
- they are phagocytic and engulf cellular debris, waste products, and pathogens within the nerve tissue
- their numbers dramatically increase when there is an injury or infection of the nerve tissue; they migrate to the injury sight
oligodendrocytes*
- found in the interstitial nervous tissue
- smaller than astrocytes and have fewer processes which fan out from the cell body and coil around the axons of many neurons to form myelin sheath*
What is the purpose of the myelin sheath*?
It acts as an electrical insulator and helps to speed the conduction of nerve impulses
What does the CNS consist of?
the brain and the spinal cord
What protects the brain and spinal column?
-brain=the cranium (skull)
-spinal cord=the vertebrae
AND connective tissue membranes—meninges* AND cerebrospinal fluid*
meninges* —What? What does it protect?
-three layers of protective membranes that surround the brain and spinal cord
What is the outermost layer of meninges*?
the dura mater*
What is dura mater*?
a tough white connective tissue
What is below the dura mater*?
the subdural space*
What is the subdural space filled with?
serous fluid
What is the space immediately outside the dura mater*? What does this space contain?
- the epidural space*
- a supporting cushion of fat and other connective tissues
What is the middle meninges layer?
the arachnoid membrane* (resembles a spider web)
What is beneath the arachnoid membrane*?
the subarachnoid space*
What is contained in the subarachnoid space*?
cerebrospinal fluid
What is the purpose of cerebrospinal fluid?
provides additional protection for the brain and spinal cord by serving as a shock absorber.
What is the innermost layer of the meninges?
the pia mater* (which is tightly bound to the surface of the brain and spinal cord
What does the cerebrospinal fluid flow in and around?
the organs of the CNS, form the blood, through the ventricles of the brain, the central canal of the spinal cord, the subarachnoid spaces around the brain and spinal cord, and back to the blood
What is the cerebrospinal made up of?
what does it provide the CNS?
How is a constant volume maintained?
- proteins, glucose, urea, salts, and some white blood cells
- some nutrients
- the fluid is absorbed as rapidly as it is formed
What is the name for the accumulation of cerebrospinal fluid because it isn’t being absorbed?
hydrocephalus* (or hydrocephaly)
How much does the brain weigh?
about 3lbs.
What age does it become full size?
around 18 yrs old
What are the four major divisions of the brain?
cerebrum*
cerebellum*
diencephalon*
brain stem
Cerebrum
Where is it?
What does it control?
- it is the largest and uppermost portion of the brain
- consciousness, memory, sensations, emotions, and voluntary movements
What is the surface of the cerebrum* called?
the cerebral cortex
cortex=outer surface
What are the striking features of the cerebral cortex?
convolutions, or elevations known as gyri (singular=gyrus*)
What are gyri separated by?
grooves called sulci (singular=sulcus*)
What deep fissure divides the cerebrum into two hemispheres?
a longitudinal fissure*
what are the two hemispheres of the cerebrum?
the right cerebral hemisphere and the left cerebral hemisphere
cerebellum*
What is it attached to?
What does it do?
- the brain stem
- maintaining muscle movement and coordinating normal movement and balance
What is located between the cerebrum and midbrain?
the diencephalon*
Which structures make up the diencephalon?
the thalamus, the hypothalamus, and the pineal gland
What does the thalamus do?
receives all the sensory stimuli (except smell) and relays them tot he cerebral cortex*
what does the hypothalamus do?
responsible for activating, controlling, and intergrating the peripheral autonomic nervous system, endocrine system processes, and many sensory functions such as body temperature, sleep, and appetite
where is the pineal body* ( or pineal gland) and what does it do?
- a small cone-shaped structure that extends from the posterior portion of the diencephalon
- thought to be involved in regulating the body’s biological clock
- produces melatonin which regulates day/night cycles and the onset of puberty and the menstrual cycle
Where is the brain stem and what components make up the brain stem?
- between the diencephalon* and the spinal cord
- it consists of the midbrain* (upper part), pons (in the middle), and medulla oblongata* (lowest part of the brain stem and is continuous with the spinal cord)
What does the brain stem do?
- it serves as a pathway for conduction of impulses between the brain and spinal cord
- controls vital functions as respiration, blood pressure, and heart rate
What does the spinal cord do?
-it is the pathway for impulses traveling to and from the brain
How many pairs of spinal nerves? What do they affect?
- 31
- the limbs and lower part of the body
What protects the spinal cord?
cerebrospinal fluid, three layers of the meninges, the bony encasement of the cervical, thoracic, and lumbar vertebrae
What the cell body?
the part of the cell that contains the nucleus and the cytoplasm
What is the central nervous system?
one of the two main divisions of the nervous system, consisting of the brain and the spinal cord
deficit
any deficiency or variation of the normal, as in a weakness deficit resulting from a cerebrovascular accident (CVA)
gray matter
the part of the nervous system consisting of axons that are not covered with myelin sheath, giving it a grey appearance
hyperesthesia
excessive sensitivity to sensory stimuli, such as pain or touch
hyper=excessive -ethesia=feeling, sensation
hyperkinesis
excessive muscular movement and physical activity; hyperactivity
hyper=excessive kinesis=movement
Kernig’s sign
A diagnostic sign for meningitis marked by the person’s inability to extend the leg completely when the thigh is flexed upon the abdomen and the person is sitting or lying down
nerve
a cordlike bundle of nerve fibers that transit impulses to and from the brain and spinal cord to other parts of the body. A nerve is macroscopic (seen without microscope)
nerve block
the injection of a local anesthetic along the course of a nerve or nerves to eliminate sensation to the area supplied by the nerve (s); also called conduction anesthesia
oligodendrocyte
a type of neuroglial cell found int he interstitial tissue of the nervous system. Its dendrite* projections coil around the axons of many neurons to form the myelin sheath
olig/o=few, little, scanty dendr/o=tree, branches
cyte=cell
pineal gland
another name for pineal body
radiculotomy
the surgical resection of a spinal nerve root ( a procedure performed to relive pain); also called a rhizotomy*
radicul/o=root -tomy=process of cutting
shunt
a tube or passage the diverts or redirects body fluid from one cavity or vessel to another; may be a congenital defect or artificially constructed for the purpose of redirecting fluid, as a shunt used in hydrocephalus*
whiplash
an injury to the cervical vertebrae and their supporting structures due to a sudden back-an-forth jerking movement of the head and neck. e.g. car accident when rear-ended
white matter
the part of the nervous system consisting of axons covered with myelin sheath, giving a white appearance
Which part of the brain enables you to read this question and answer it correctly?
a. cerebrum
b. cerebellum
c. brain stem
d. meninges
a. By knowing the answer, you just became more “cerebral.”
