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Topic 6: Central Nervous System


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Central Nervous System intergrates and issues info from which 2 places in the body?
Brain spinal cord
Which 2 division are a part of the peripheral Nervous system and what do they do?
Afferent Division - sends info from body to CNS. Efferent Division - recieves info from CNS and sends to body
What are the 2 nervous system in the efferent division?
Somatic nervous system autonomic system.
What are the two nervous systems in the autonomic nervous system?
sympathetic nervous system and parasympathetic system
What are the 3 classes of neurons?
Afferent Neurons Efferent Neurons Interneurons
Describe Afferent neurons.
They have sensory receptors Axon terminals in CNS sends info to CNS from the body.
Describe Efferent Neurons.
Cell body is in CNS. Axon terminals in effector organ. Sends info from CNS to body.
Describe interneurons.
Lie withint CNS. Some connect afferent and efferent neurons (intergrates peripheral responses and peripheral info). Some connect other interneurons (responsible for activity of "mind" ie: thoughts, emotions, motivation, etc.). 99% of all neurons are interneurons.
What is the Brain Stem responsible for?
Critical connecting link between entire brain and spinal cord. Cardiovascular, respiratory, digestive control. regulation of muscle reflexes, equilibrium and posture. reception and integration of spinal cord input; arousal and activation of cerebal cortex. Sleep/wake cycle control.
What is the cerebellum responsible for?
Maintenance of balance. Enhancement of muscle tone. Coordination of voluntary muscle activity.
What are 3 things the Hypothalamus is involved in?
Regulation of many homeostatic functions and associated behaviors. Link between nervous and endocrine systems. Involved in emotion and basic behavior patterns.
Give examples of the hypothalamus regulating homeostatic functions and associated behaviors.
Body temperature. Thirst and urine output. Food intake. Uterine contraction and milk production.
What is the role of the hypothalamus in the link between nervous and endocrine systems?
Smooth and cardiac muscle control and exocrine gland control.
What is the role of the thalamus?
Relay station and filter for all input to the cerebral cortex. Crude awareness of sensation. Some degree of consciousness. Role in motor control.
What are the two parts within the Cerebrum?
Basal Nuclei and Cerebral Cortex.
What does the Basal Nuclei do?
Inhibition of muscle tone. Coordination of slow sustained movement. Suppression of useless movement patterns.
What does the Cerebral Cortex do?
Sensory perception. Voluntary control of movement. Language. Personality. Consciousness and sophisticated mental events (thinking, memory, etc).
Describe the Limbic system (3).
1.Not a seperate structure. 2. Includes interconnected portions of: cerebral cortex -basal nuclei -thalamus -hypothlamus 3. Involved in generating emotions.
What are the neural basis of some human behaviors and where are they generated? *Language and Speech *Emotion *Memory
1.Language and Speech: in multiple areas of the cerebral cortex. 2.Emotions: in limbic system. 3.Memory: -Short term - frontal lobes of cortex, relies on rapid changes in the strength of existing nerve connectsions. -Long term - limbic system and requres new connections among neurons, this is accomplished by practice and consolidation.
What do the glial cells do?
90% in CNS Occupies 50% of brain Do not initiate or conduct nerve impulses. Support CNS neurons physically, metabolically and homeostatically.
Why is the brain shielded from the blood?
To protect brain from harmful changes in blood ions and molecules.
What does a normal brain capillary have?
pores in its walls for easy passage of materials. Tight junctions that prevent passage of materials. Only small lipid soluble substances (O2, CO2, alcohol, steroid hormones) can diffuse through capillary membrane. All other molecules must be transported into brain by carrier proteins.
What portion of the brain is not subjected to the blood brain barrier?
Hypothalamus because it monitors the blood directly for levels of hormones etc.
The brain can only make ATP with what?
From glucose in the presence of O2.
How long can the brain go without O2 and glucose?
4-5 minutes without O2 10-15 minutes without glucose
What is the structure of the spinal cord?
1.Whole cord - 31 pairs of nerves. 2.Cross section - a. gray matter: cell bodies, dendrites, short interneurons, glial cells. b. White matter: mylenated axons organized into tracts (bundles of axons) 3.Some are ascending (to brain) and some are descending (from brain). packaged phone lines.
What are the functions of the spinal cord?
Carries and supports neurons (both afferent and efferent) btwn brain and body. Simple spinal reflex

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