Nervous System Flashcards
What are afferent neurons?
Neurons that arrive with info from either internal or external stimuli
Which part of the nervous system processes the sensory information? Key word “integrative”
Central Nervous System
What are efferent neurons?
The information being sent out to the specific neurons, muscles, glands, or organs
Which part of the nervous system is the “afferent division”
Peripheral Nervous System
Which part of the nervous system is the “integrative” division?
Central Nervous System
What part of the nervous system is the efferent division?
Somatic Nervous system and Autonomic Nervous system.
The autonomic nervous system has two parts known as…..
the parasympathetic nervous system and the sympathetic nervous system
True or False:
Neurons can divide
False
What are dendrites?
The receiving end of the neuron
True or False:
The axon lacks a RER
True
What does the Axon hillock do?
Is aka the “neck” of the neuron. Connects the cell body to the axon
What is another name for axon terminals?
Telodendria
Axon collaterals are
branches of the axon
What is the purpose of the axonlemma
these are the branches of the axon
Which type of neuron has several dendrites and one axon?
multipolar neurons
Where are multipolar neurons most common?
The brain and spinal cord (CNS)
Which neuron has one dendrite, one axon, and soma in the middle?
Bipolar neurons
Where are bipolar neurons found?
Retina, inner ear, and olfactory area of the brain (special senses area)
Which type of neurons have a fused axon and dendrite?
Unipolar neurons
Where are unipolar neurons found?
These are the sensory neurons of the PNS (pain, touch, tickle)
Which neurons do not have a distinguishable axon?
Anaxonic neurons
Where are anaxonic neurons found?
The brain and sensory organs
Sensory neurons
Have exteroreceptors (touch, temp, pressure) and interoreceptors (internal organs) deliver information to CNS about environment
Motor neurons
The efferent division of the PNS (carry info OUT of the CNS)
Motor neurons are found where?
Smooth muscle, heart, and in organs
What type of neurons are motor neurons?
multipolar
Interneurons are also known as what?
Association neurons
What type of neurons are interneurons?
Multipolar
Interneurons
Small neurons serving as connectors between two other neurons. (between sensory and motor)
True or False:
Interneurons are only located within the PNS
False! Interneurons are only located within the Central Nervous System (brain and spinal cord)
True or False:
99% of all the neurons in our body are interneurons
True
What do satellite cells do for the PNS?
Adjust the environment around cell bodies. Surround the neuron cell bodies int he ganglia. Regulate CO2, O2 nutrient and neurotransmitter levels around neurons in the ganglia.
What do Schwann cells do in the PNS?
They insulate the neuron. Surround all axons in PNS. They are responsible for myelination of peripheral axons and participate in the repair process after an injury.
What do Ependymall cells do in the CNS?
Regulate the environment. Line ventricles and central canal. Assist in producing, circulating, and monitoring cerebral spinal fluid.
Which cell in the CNS is a kin to the Schwann cell in the PNS?
Oligodendrocytes
What do the Oligodendrocytes do?
Myelinate CNS axons and provide structural framework
What do Astrocytes doe in the CNS?
Maintain the blood-brain barrier, provide structural support, regulate ion, nutrients and dissolved gas. Absorb and recycle neurotransmitters. AND form scar tissue after injury
What do the microglia do in the CNS?
Remove cell debris, waste, and pathogens by phagocytosis. Also known as the garbage trucks of the CNS
Explain the process of myelin sheath formation in the Peripheral Nervous System
The schwann cell first surrounds the portion of axon within a groove of cytoplasm. Schwann cell then begins to rotate around the axon. As the schwann cell rotates, myelin is wound around the axon in multiple layers, forming a tightly packed membrane.
Which cell is the largest in CNS?
Astrocytes
What happens to the unmyelinated axons?
They are enveloped by the schwann cell, but there are no myelin sheath wraps around each neuron.
What happens during PNS axon injury/repair?
Distal to the injury site, the axon and myelin degenerate and fragment. The schwann cells do proliferate along original axon path. Macrophages remove debris. Axon grows into injury site along schwann cell path. Schwann cells wrap elongating the axon.
Oligodendrocytes
These CNS neuralgia wrap axons to insulate, leaving spaces between the wrappings. These also myelinate many axons (as opposed to Schwann cells)
Explain the role of neuroglia in neurogenative disorders
Astrocytes attempt to seal off the damaged neurological tissue by forming a scar. While the microglia clean up the site of dead or damaged tissue. This is great, because they are cleaning up the sites. However, this prevents the brain from doing any repairing
Where do synapses occur?
The terminal end of the neuron (synaptic terminal)
What are synapses?
intercellular communication between neurons.
True or False: Synapses only travel in one direction from presynaptic cell to post synaptic cell.
True
Where are neurotransmitters (chemicals) made?
Perikaryon
How do neurotransmitters travel?
Through axoplasmic transport (neurotubules)
True or False:
Neurotransmitters always travel retrograde
False. Neurotransmitters ALWAYS travel anterograde, unless the patient has RABIES virus.
What causes the difference in voltage in resting membrane potential?
Ionic composition differences inside and outside
The intracellular fluid has a high concentration of what?
K+ (Potassium)
What is also contained in the intracellular fluid?
Negatively charged proteins
What does extracellular fluid have a high concentration of?
Na+ (Sodium) and Cl- (Chloride)
How are the differences maintained in RMP?
Selectively permeable membranes of excitable cells
How does ion movement occur in RMP?
Leak channels (passive)
Active transport mechanisms
How do leak channels work?
K+ (potassium) ion channels leak to outside, draws negative toward edge of membrane, Na+ (sodium) ions leak in.
What is a voltage gated channel?
Doesn’t open or close until a particular voltage is reached.
What is a mechanically gated channel?
Pressure or deformation change of the gate will open or close this channel
What is a chemically gated channel?
Open or close based on chemicals released
What do leak channels do?
maintain RMP
What affects the flow of Na+ and K+?
Electrochemical gradients
What happens with a Na+/K+ exchange pump?
At RMP the cell removes Na+ and recaptures K+. It balances the diffusion rate exactly.
What is the electrochemical gradient for potassium?
At the normal resting potential, an electrical gradient opposes the chemical gradient for potassium ions. The net electrochemical gradient tends to force potassium ions out of the cell. If the plasma membrane were freely permeable the potassium ions, the outflow of K+ would continue until the equilibrium potential was reached.
What is the electrochemical gradient for sodium?
At the normal resting potential, chemical and electrical gradients combine to drive sodium ions into the cell. If the plasma membrane were freely permeable to sodium ions, the influx of Na+ would continue until the equilibrium potential was reached. The chemical and electrical gradients would then be equal and opposite direction, no net movement of Na+ would occur across the membrane.
What is the sodium/potassium exchange pump?
At RMP, cell removes Na+ to outside and brings K+ back inside. 3 Na+ out, 2 K+ in. This EXACTLY balances diffusion rates.
