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Human Physio


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-99% of all neurons -lie w/in CNS
Afferent neuron
-have sensory receptors -axon terminal in CNS -SENDS info from body to CNS
Efferent neurons
-RECIEVES info from CNS to body (effector organs) -cell body in CNS -axon terminal at effector organs
-critical connection link b/w brain and spinal cord -reception and integration of spinal cord input; activates and arosal of cerebral cortex -digestive, respiratory and cardiovascular control -Sleep/wake cycle -regulation of muscle reflexes: posture and equilibrium
-Maintenance of balance -enhances muscle tone -coordination of voluntary muscle activity
-part of forebrain -Homeostasis & associated behaviors: ~Thirst & urine output ~food intake ~body temp ~uterine contraction and milk production (oxyctocin) -Link b/w nervous system and endocrine system ~smooth & cardiac muscle control ~exocrine gland control -Emotions & basic behavioral patterns
-part of forebrain -Relay station and filter for all input to cerebral cortex -crude awareness of sensation -some degree of consciousness -role in motor control
Basal nuclei & cerebral cortex
Basal nuclei
-Inhibition of muscle tone -coordination of slow sustained movement -supression of useless movement patterns
Cerebral cortex
-Sensory perception -voluntary control of movement -lagnuage -personality -consciousness & sophisticated mental events (thinking, memory, etc)
Limbic system
-EMOTIONS -Not a separate structure -interconnects: ~cerebral cortex ~basal nuclei ~thalamus ~hypothalamus
Neural Basis of some human behaviors
1. Language and Speech 2. Emotions 3. Memory
Language & Speech
-Cerebral cortex
-Limbic system -"attaches feeling to basic survival-related programs" of brainstem (feeding, aggression and sexuality) -birth: bond to caretaker, recognize and interact -Responses can be Autonomic, motor, hormonal -triggered by sensory input or memories -some emotions seem to associate w/ certain parts of brain
1. Short term -relies on rapid changes in strength of existing nerve connections -frontal lobe 2. Long term -req's new connections among neurons -limbic system
Normal capillary
pores in walls for easy passage of materials
Brain capillaries
has tight junctions which block passageway from materials
Glial Cells
-90% of cell in CNS -50% of brain vol. -do NOT initiate or conduct nerve impulses -SUPPORT CNS neurons physically, metabolically & homeostatically
Spinal Cord
-31 pairs of nerves -carries and supports neurons b/w body to the brain
The Blood Brain barrier: Hypothalamus
Part is not subject to B-B barrier -able to monitor blood for hormones, etc.
Blood Brain barrier: what does it do?
It shields the brain from harmful blood changes
Blood brain barrier: What can pass thru (diffuse thru) the Capillary membrane?
small lipid soluble substances (CO2, alcohol, O2, steroid hormone)
The brain can only make ATP from what?
-from glucose -in presence of oxygen -can use ketones for part of energy
The brain is dependent on what?
-glucose and oxygen -4-5 min w/o Oxygen or 10-15 w/o glucose = brain damage/death
Cross sections of the spinal cord include:
Gray matter and white matter
Gray Matter
-Interneurons -Cell bodies of efferent neurons -axon terminals of afferent neurons *think ~ CNS classes
White matter
-myelinated axons organized into tracts (bundles of axons) b/w brain and spinal cord. -packaged phone lines -some ascend (to brain) and descend (from brain)
The Reflex Arc: Reflexes include:
-Spinal or Cranial -Somatic or Autonomic -Innate or Conditioned -Monosynaptic or Polysnaptic *see table 9.3 (pg 236)
Withdrawal Reflex
-complex -reflexes can be modified or overridden by CNS
The reflex arc (steps 1-5)
Stimulus --> 1. Sensory receptor --> 2. Afferent neuron --> 3. Integrating System (CNS) --> 4. Efferent neuron --> 5. Effector organs (muscle glands) --> response
Parkinson's Disease
-Destroys dopamine secreting cells in the brainstem -axon terminals from these cell arein basal nuclei -lack of dopamine = neurons in basical nuclei not getting messeages they need --> non-functional -Tremors -Rigidity -Difficulty moving -impairment of memory and thinking -1% over age 60 -cause: unknown
What is the critical connecting link between the brain and the spinal cord?
brain stem
The part of the brain most involved in regulating homeostasis is
The hypothalamus
What controls the cardiovascular, respiratory and digestive systems?
brain stem
What supports the CNS physically and metabolically?
Glial Cells
What depends on tight junctions in brain capillaries?
Blood-brain barrier
What is made of 90% of the cells in the CNS?
glial cells
What shields the brain from changes in blood composition?
Blood Brain Barrier
The Reflex arc can be defined as:
neural pathways for reflexes.
-A neurotransmitter w/ multiple functions in CNS -Basal nuclei: fine motor control -Frontal lobe: memory and learning -Reward seeking, pleasure, motivation -Addictions (drugs, gambling)

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