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44 Cards in this Set
- Front
- Back
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What is Homeostasis?
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The body's response to maintain internal balance
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Give some examples of Homeostasis
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Glucoreceptors, pH, water(osmoreceptors), body temp(thermoreceptors).
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What is Negative Feedback?
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Body's response to negate a situation and return to homeostasis.
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Describe the following:
Monitor->Control Center->Regulator |
Monitor: detects change
Control Center: Selects adjustments Regulator: Carries out adjustments |
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Describe the sequence that generally occurs when Negative Feedback is applied to body temperature lower than 37.3C.
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Thermoreceptors in the skin carries out signals to the Hypothalamus which excites the muscles under the skin to contract and generate heat.
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What are errector pili muscles?
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Muscles under the skin that generate heat. (Goosebumps)
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Describe Stress.
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Any stimulus that activates the pituitary gland (pleasant/unpleasant)
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What is General Adaptation Syndrom?
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Non-specific response of body to stress.
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What is an Alarm Reaction?
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Adrenal gland releases epinephrine.
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What are the effects of the resistance/readjustment portion of stress?
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Continued stress releases contisol, which leads to illness (depressed immune system)
eg: ulcer... |
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What can exhaustion due to stress lead to?
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More serious illnesses
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What is positive Feedback?
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An uncommon response in the body which increases the stimulus.
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What is the autonomic nervous system and what are its main components?
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Acts as a control station which performs maintenance without conscious control or sensation. It's main components are the Parasympathetic and Sympathetic nervous systems.
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What is the somatic nervous system and what are its main components?
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The voluntary control of body movements. Its main components are to receive sensory signals through the use of Motor neurons.
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What are Neurons?
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Specialized microscopic cells located in the Nervous system.
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What are the 3 types of Neurons and what do they do?
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Sensory neurons: carry impluses to the brain and spinal cord
Interneurons: In the CNS (associate neuron) Motor Neurons: Carry impulses away from CNS |
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What are the three main structures of a Neuron and what do they do?
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Dendrites:receive impulses (receptors). Always transmits towards cell body
Cell Body: Processes impulses, contains nucleous and organelles. Axon:long tail, always transmits impulses away from cell body |
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What are glia cells?
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Glia cells are in the CNS but do not conduct impulses. (Supportive cells)
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What is the Myelin Sheath?
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All axons in the PNS and some axons in the CNS are covered with a specialized structure called the Myelin Sheath.
(in the CNS: White mater=mylenated fibers and grey matter=unmylenated fibers) |
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What is the Myelin Sheath composed of?
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Composed of specialized fatty cells called Schwann cells, these schwann cells wrap around the axon acting like insulation. The myelin sheath is not continuous.
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What are the nodes of Ranvier and what is it's functions?
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Sections of unmylinated axons that increase the speed of neural impulses. Greater regeneration (?)
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What is Multiple Sclerosis (MS)?
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The immune system destroys the myelin sheath resulting in progressive loss in muscle function.
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What is the thin membrane surrounding the myelin called? it's only in the PNS.
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Neurilemma
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What is the Nerve Impulse?
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Electrochemical process in which the membrane of the neuron has specialized protein channels (pumps) which allow certain ions in/out.
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Describe the electrochemical process of the Nerve impulse.
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At rest, the [K+] is higher inside the axon whilst outside the axon [Na+] is higher; the [Na+] on the outside is much greater than the [K+]inside. This gradient is maintained by the sodium/potassium pumps. (gates closed)
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What is a neuron at rest during a nerve impulse?
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A neuron is polarized at rest, the inside is more negative than the outside with a resting membrane potential of -70mv.
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When does the Nerve Impulse occur?
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The impulse occurs when a threshold stimulus is applied: the pump slow(stop), the gates open, Na+ floods into the neurons whilst some K+ moves out resulting in a more positive charge inside the neuron rather than outside=depolarization=impulse. (inside membrane potential=40mv)
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How does a section of the axon re polarize?
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Immediately after a section of axon has depolarized, the pumps start and quickly try to return that section of axon to its polarized state.
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How does repolarization occur?
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The pumps start and begin pumping K+ (and Na+) out of the neuron to quickly re-establish the polarized state, then K+ can move back in to return to -70mv.
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Describe the all or none function in the Nerve Impulse.
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The stimulus causes an impulse, and the impulse is conducted at max speed(all) or no depolarization(none)
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What is Absolute refractory and how does it determine the transmission speed?
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During repolarization another action potential cannot occur until polarization is restored(+/-1ms). K+ ions are pumped out to quickly establish polarity. The length of time of absolute refractory will determine transmission speed. (range 500-1000sec)
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What is Saltatorial Conduction?
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in a myelinated nerve fiber, the waves of depolarization occur only at the nodes (SA over which the wave must travel Faster!)
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What is Synapse and how does it work?
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Neurons are not attached to each other physically; there is a small space (+/-1nm) between the axon of one neuron and the dendrites of the next neuron. The transmission of impulse across this gap=synapse.
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How will the transmission of impulse cross the synapse?
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The axon reaches the end of the axon (presynaptic fiber) and the impulse will cause [CA 2+] to bind to vesicles and these vesicles fuse to the knob and release a chemical called Acetylcholine (ACH)-neurotransmitter. The ACH (or other nt) diffuse over the gap.
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How does the Neuron get rid of ACH?
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The ACH will bind to the receptor sites on the dendrites of the post synaptic neuron. The dendrites then depolarize.
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How does the Neuron keep each impulse separate?
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Immediately after the ACH is released, an enzyme (Acetyl cholinestrase) in released. This enzyme diffuses across the gap and binds to ACH and deactivates it. The enzyme and the ACH are then pumped back into the axon vesicle (reuptake)
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What are Excitatory neurotransmitters?
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Neurotransmitters that cause an action potential in the post synaptic fiber. eg:ACH, dopamine, glutamate, seratonin
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What and inhibitory neurotransmitters?
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Neurotransmitter that cause Cl- to enter neuron decreasing the negative charge resulting in a greater threshold required for depolarization, thus few impulses(these neurons are said to be hyperpolarized). eg: GABA, glycine
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What is Parkinson disease?
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Individual secretes too little dopamine, result is muscle tremors and speech problems. These areas of the brain are not stimulated enough due to the lack of dopamine.
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What is a possible treatment for Parkinson's disease?
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L-Dopa
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Describe the effects of Nerve gas (neostigmine).
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Inhibits cholinosterase, paralysis due to muscle staying contracted.
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What is the effect of selective Seratonin Reuptake Inhibitors (SSRIS)?
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Allows seratonin to remain in the gap, longer stimulating pleasure centers. eg: Prosac
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What increases the effectiveness of GABA?
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Valium
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What are Endorphines?
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"morphiac-like" effect
Inhibitory chemical reduce transmission in the "pain" centers. |
