Unit 1 chapter 1 body regulation systems Flashcards
What is homeostasis
the steady state of body functioning a state of equilibrium characterized by a dynamic interplay between the outside environment and the internal control mechanisms that oppose such changes. These changes are done around a narrow, set point inside your body
what is positive feedback
body ENHANCES original stimulus to make deviation greater
- reinforces or exaggerates deviations from normal
What is negative feedback
Body REVERESES an original stimulus to regain balance
- most common form of feedback loop
- variations from the normal that are decreases are brought back up
What are the two human systems that control homeostasis?
endoctrine system
and nervous system
what is endocrine system?
the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream
-Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.
what is the nervous system ?
the network of nerve cells and fibers that transmits nerve impulses between parts of the body.
brain, spinal cord, nerves
What is the function of glial cells?
cells in the nervous system that support, nourish, and protect neurons
- glial or neuroglia cells provide: scaffoldings for neurone for neutrons to form, make myelin sheaths and offer defence against bacteria and cellular waste.
what is the difference between glial and neurones?
Neurons are the structural and functional cells reacting to the physical and chemical changes in their environment. Neuroglia are the supporting cells necessary for nourishing and maintaining the neurons, among other functions.
what are the three different neurones?
1.motor neuron
2. Interneuron
3. sensory neuron
What is a motor neuron?
neurons that carry outgoing information from the central nervous system to the muscles and glands
- the cell body is located at the top of the neuron
- has myelin sheaths
- physically moves body into homeostasis
what is a interneuron ?
a neuron that carries nerve impulses from one neuron to another
-has no myelin sheaths and has the cell body located at the middle of the structure
- receives incoming sensory information and sends out motor information via the spinal cord to the CNS only
what are afferent neurons?
Nerve cells that carry impulses towards the central nervous system
what are efferent neurons?
Nerve cells that conduct impulses away from the central nervous system
what is a sensory neuron?
A neuron that picks up stimuli from the internal or external environment and converts each stimulus into a nerve impulse.
What is the cell body?
Largest part of a typical neuron; contains the nucleus and much of the cytoplasm
What are dendrites?
a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body
What is an axon?
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
1. speeds up the role of transmission because the impulse jumps from node to node and skips the parts covered by the myelin sheaths.
2. myelin can regenerate due to the presence of neurilemma
3. myelin protects the impulse and keeps it moving along the correct pathway.
What are axon endings or axon terminal endings?
Axon branches and forms endings that innervate muscle fibres or other neurons. to pass along information regarding a sensation or to communicate a homeostatic response.
Ends of axons that contain vesicles with NTs (neurotransmitter)
What is neurilemma ?
additional external myelin sheath that is formed by Schwann cells and found only on axons in the peripheral nervous system
What is threshold potential?
The minimum membrane potential that must be reached in order for an action potential to be generated.
What is resting potential?
the state of the neuron when not firing a neural impulse
What is depolarization?
The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.
What is action potential?
a neural impulse; a brief electrical charge that travels down an axon.
- here all the Na+ ions are inside the axon
- maximum depolarization
- causes it to spike
What is repolarization
Na+ channels close and K+ channels open will occur all along the axon.
-k+ ions rush outside the cell membrane
What is refractory period?
time taken to actively pump NA+ out of the axon and to actively pump k+ ions into the axon using an enzyme and ATP
- the cell cannot be stimulated again until refractory period is complete.
-only when ions and charge are back to their original conditions can the neuron fire a successive time.
all or none law?
principle that the action potential in a neuron does not vary in strength; the neuron either fires at full strength or it does not fire at all
What is sodium potassium pump?
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
-helps maintain the resting potential of the membrane
- and makes sure that action potential not does arise again (not being able to fire again)
What is a synapse and explain how acetylcholine is used to transmit an impulse across the synapse?
Gap between neurons
- the acetylcholine helps to send impulse across the neurons.
- the process of acetylcholine causing impulse to the muscle involves:
1. action potential arrives
2. exocytosis : calcium channels open allowing calcium ions to diffuse in. This process allows for the vesicles containing NT (neurotransmitters) such as acetylcholine to fuse with the cell membrane through exocytosis in the synapse.
3. diffusion across the synapse
3. Depolarization : ACh diffuses across the synapse and binds to a receptor on the postsynaptic membrane.
4. degradation- enzymes: Depolarization ends as acetylcholine is broken down by enzymes
5. endocytosis: the degraded molecules diffuse back across the synapse and are taken into the synaptic knob (presynaptic neuron) by the vesicles, then the cycle repeats as the ACh are resythesized back into the vesicles.
