Cells Flashcards
Nerve cells
- Neurons
- many different varieties based on size, shape, chemistry
Support cells
- Glia
- come in different varieties
Basic structure
Large cell body = Soma
- Large Central Nucleus
- Cytoplasm: is rich in Mitochondria, Rough ER, and Golgi Apparatus (high NRG needs)
- Processes extending from the Soma
- Axons: carry impulses AWAY from the cell body
- Dendrites (carry impulses TOWARDS the cell body)
- terminals synaptic transmission
Axon and axon terminals
end of the axon terminal is a small swelling called the synaptic knob, or axon terminal=terminal bouton
- Axon Hillock and initial segment generate action potentials **
- axon conducts action potential
Dendrites
Dendrites and cell body receive and integrate inputs
Four Functions of Neurons
- Receive and integrate inputs: dendrites, soma
- Generate a nerve impulse (action potential))
- Conduct the action potential dendrites, soma, axon, hillock axon nerve
- Transmit information to target cell (neuron, muscle, gland) terminals
Classification of Neurons
based on
- Function
a. sensory neurons
b. motoneurons
c. interneurons- reflexes - Structure
a. unipolar: Only one extension which branches into a “T”.
b. bipolar: Consist of one Dendrite and one Axon.
Sensory, In eyes, nose, and ears
c. multipolar: Many ended, Motor, Efferent, Have a long axon. Several dendrites, 1 axon Sensory, Afferent. Most in the Brain and spinal are Multipolar - Shape
Ex: pyramidal, stellate, basket, granule, etc - Effect
a. Excitatory neurons: increase activity
b. inhibitory neurons: decrease activity - Axon length
a. projection/relay neurons (Golgi Type I)
b. local neurons (Golgi Type II) - Neurochemical identity
Ex: cholinergic, dopaminergic, GABAergic, etc
Types of CNS glial cells
- Astrocytes
- Microglia
- Oligodendroglia
- Ependymal cell
Astrocytes
a. mechanical support
b. metabolic support transport nutrients and wastes
c. encapsulate synapses
d. regulate chemical and ionic environment
e. form scar tissue( usually through infection to brain)
f. act as phagocytes
- Support blood-brain barrier
- maintain ion balance in extracellular space
- regulates blood flow
Microglia
Phagocytosis (major role)
- ”Security guard” of the CNS (protein build ups so we don’t develop plagues)
- Sensitive and act quick
Oligodendroglia
Myelinate (make go fast) axons of central nervous system
- Support and insulation of neuronal axons of the CNS only
- Creates a myelin sheath around axons which helps to prevent ion leakage and increase AP conduction down the axon
- Implicated in disease processes such as MS, cerebral palsy
- sensitive to drug use
Ependymal cell
Involved in the production of CSF (cerebral spinal fluid)
- Involvement in neuro-regeneration
- Cells contain cilia and microvilli on the surface – Why? Needs increase surface area for increase in absorption, cilia helps to move CSF around ventricles (holes in brain).
Types of PNS glial cells
Schwann cells, and Satellite Cells
Schwann cells
wrap themselves around the axons of neurons in the PNS
Satellite Cells
Provide nutrients and protection to neurons
in the PNS
what are presynaptic or preganglionic doing
(neuron) carry impulses to Synapse
(ganglion) carry impulses to ganglion
what are postsynaptic or postganglionic doing
(neuron) carry impulses away from Synapse
(ganglion) carry impulses away from ganglion
synapses
The functional junction between neurons or between neurons and an effector.
*neuron to muscle cell is called neuromuscular junction
Electrical synapse
“gap junctions” or bridge between 2 neurons, allowing electrical signals to quickly pass
-important in cardiac muscle cells
Chemical Synapse
The message is carried from one neuron to the next cell via neurotransmitters.
Neurotransmitters diffuse into the synaptic cleft and bind to specific receptors of the next neuron
Nuclei
collection of cell bodies of neurons in CNS
-usually have similar function
Ganglion
collection of cell bodies of neurons in PNS
- Ganglia often appear as small lumps or knots of tissue
- also usually functionally related
Reflex arc
a conduction route to and from CNS
- simplest arc only 2 neurons called monosynaptic reflex. EX: knee jerk reflex
- usually includes receptor-> sensory neuron -> interneuron -> motor neuron and effector
Nodes of Ranvier
Short lengths of spaces between schwanns cells
