Nervous and Endocrine Systems Flashcards
What is the difference between Nervous and Endocrine Systems?
Nervous: uses electrical and chemical impulses in nerve cells. It’s faster and has pinpoint control (transmits directly to target organ)
Endocrine: uses chemicals released into the bloodstream (hormones)
What is the general function of the nervous system?
- Sensory Input
(Sensory information is transmitted to the central nervous systems: brain & spinal cord) - Interpretation and Integration of Sensory Information
(Setting priorities on which action to take first) - Motor Output
(responses to sensory information is carried out to effectors which then carry out various actions)
What are the three basic structures that serve to function the nervous system?
- Receptors
- Neurons (Nerve cells)
- Effectors (muscles/glands)
What is the function of receptors?
pick up messages through impulses.
What is the function of neurons?
interprets info from receptors and send instructions to muscles or glands.
What is the function of effectors?
Carry out the response. Muscles contract. Glands increase/decrease secretions.
What is a stimulus?
any factor that causes a receptor to trigger an impulse (ex. light, sound…etc.)
What is a neuron?
The basic unit of structure which function sin the nervous system.
what are the three basic parts of the neuron?
- Cell Body
- Dendrites
- Axon
What is the function of the cell body?
Contains the nucleus, cytoplasm and the organelles. controls growth and metabolic activities.
What is the function of the dendrites?
Receive impulses and conduct them towards the cell body.
What is the function of the axon?
Carries impulses away from the cell body towards other neurons or effectors.
What is a synapse?
The junction on the axon which splits into two branches.
What is the order the impulse travels through in a neuron?
Dendrites—> Cell Body—> Axon
What is a Schwann Cell?
a living sheath that envelops the axon in neurons (except brain & spinal cord) which is involved in myelin production and also in the regeneration of cut axons.
What is myelin, and what does it do?
Myelin is a layer of white lipid subsance which forms around the axon. It acts as an insulator which causes myelinated neurons to conduct impulses faster than unmyelinated ones.
What is the Neurilemma Sheath?
The outer surface of the Schwann Cell.
What is the Nodes of Ranvier?
Gaps between adjacent Schwann Cells.
Where are Schwann Cells mostly found?
Peripheral Nervous System.
What is multiple sclerosis?
A disease of the white matter in the Central Nervous System. Myelin degenerates causing the disruption of electrical impulses.
What produces myelin in the central nervous system?
Oligodentrocytes
What are sensory neurons?
Neurons that carry impulses from receptors towards the bran and spinal cord.
(Carry messages about a person’s internal and external environment)
What are motor neurons?
Neurons that carry impulses from the brain and spinal cord to the effectors
(allows a person to respond to information received)
What are interneurons?
neurons inside the brain and spinal cord that connect sensory neurons to motor neurons.
Which neuron is the most abundant type of neuron?
Interneuron (CNS)
Which neurons make up the Peripheral Nervous System?
Motor and Sensory
What are the charges of the resting neuron?
Outside (net Positive)
Inside (net Negative)
What does polarized mean?
the neuron’s cell membrane has opposite charges on either side. Caused by an unequal distribution of ions.
What is the ratio of ions in the resting neuron?
Outside (3Na+)
Inside (2K+)
What is the resting neuron?
When the neuron is at rest (not conducting impulses)
What is membrane potential?
The separation of charges
How is resting potential achieved?
The sodium-potassium pump maintains equilibrium by pumping 3Na+ out, and 2K+ in.
What is depolarization?
the process when the outside becomes negative, and the inside becomes positive.
How is depolarization achieved?
When an impulse is initated, the membrane becomes permeable to sodium ions, which enter the cell rapidly, causing the inside to become net positive.
What is action potential?
The temporary reversal of the resting potential.
What is repolarization?
As the adjacent section becomes depolarizaed, the preceding section returns back to its resting state.
What is propoagation?
Self-gernation.
How does repolarization occur?
Na+ gates close, and K+ gates open.
K+ ions move out and the interior becomes negative again.
Sodium-potassium pump restores the balance of Na+ and K+ reverting it back to resting potential.
What is the stages that occurs in the neuron membrane, after a stimulus?
Resting Potential–> Depolarization —> Action Potential –> Repolarization –> Resting Potential.
What is a Threshold Level?
The level of intensity a stimulus must pass in order to generate a response.
What is an all-or-none response?
The neuron fires, or it doesn’t.
What is the refractory period?
The period of time where the neuron cannot transmit another impulse until repolarization occurs.
What factors does the rate at which the impulse travels on depend on?
- Diameter of the axon.
(larger diameter = faster conduction) - Degree of Myelination
(Myelinated axons conduct impulses faster)
What is Salatory conduction?
Occurs in myelinated neurons where the impulse “jumps” from one node of Ranvier to the next. Action potential only occurs at the nodes of ranvier.
What two ways can the strength of a stimulus be measured?
- stronger stimulus causes more frequent impulses along the neuron.
- Strong stimulus causes more neurons to be stimulated. (threshold level of many neurons is reached)
What are synaptic knobs?
Swollen tips at the branches of the Synapse.
What do the synaptic knobs contain?
Synaptic vesicles which contain neurotransmitters inside.
what is the travel path of an impulse (at the synaptic knob)?
Presynaptic Neuron —> Synaptic Cleft —> Postsynaptic Neuron.