Nervous System/Quiz 2 Flashcards
Central nervous system
Brain and spinal cord
Peripheral nervous system
Cranial and spinal nerves
What are the two types of nervous systems?
1) central nervous system
2) peripheral nervous system
Sympathetic nervous system
- Prepares body for heightened levels of somatic activity
- Stimulate tissue metabolism and increase alertness
- Fight or flight syndrome
- Digestion and urinary activity suspended, increase in blood flow, breathing, heart rate
Parasympathetic nervous system
- Stimulate visceral activity
- Responsible for rest and repose following eating
- Conserves energy
- Promotes sedentary activity for digestion
- Body relaxes, heart rate and blood pressure, metabolic rate decrease
- Increase in secretions from salivary and digestive glands, blood flow to digestive system and increase in urination and defecation
What are the fundamental properties of neurons?
CSE
- Conductivity
- Secretion
- Excitability
Conductivity
Transmit electrical signals
Secretion
When electrical signal reaches end of nerve fiber, a chemical neurotransmitter is secreted
Excitability *
Responds to stimuli and also incoming neurotransmitters
*Ability to get excited by the news
Astrocytes
- Compose the blood brain barrier
- Impenetrable membrane around blood cells in the brain
- Proteins can’t go from blood to brain
- Part of brain’s inherent immune system
Microglial cell
Immune cell of the CNS, Macrophage-like function
Ependymal cell
Produce cErebrospinal fluid
Oligodendrocyte
Form the myelin sheath of the neurons in CNS; they’re insulators, help to speed up conductivity
Schwann cell
Form the myelin sheath of the neurons in PNS
Glial cells
- Not neurons!
- Help hold NS together
- Support cells other than neurons
Fifth type of glial cell?
Sensory neuron with Schwann cells and satellite cells
Multipolar *
- Many processes extend from the cell body; all dendrites except for a single axon
- Most abundant in body; major neuron type in CNS
Bipolar
- Two processes extend from the cell: one is a fused dendrite, the other is an axon
- Rare; are found in some special sensory organs
Unipolar
One process extends from the cell body and forms central and peripheral processes, which together comprise the axon. Only the distal endings of the peripheral process are dendrites
Sensory (afferent) neurons
- receptors detect (SENSE) changes in body and external environment
- this information is transmitted into brain or spinal cord
Interneurons (association neurons)
- lie between sensory and motor pathways in CNS
- 90% of our neurons are interneurons
- process, store & retrieve information
Motor (efferent) neuron
- send signals out to muscles & gland cells
- organs that carry out responses called EFFECTORS
Nervous intervention
Communication between neurons and efferent cell
Neuropeptides *
Communication from nerve cell to cell
Acetylcholine
Communication of neuron to muscle
What are the 2 types of electrical signals? *
1) graded potentials
2) action potentials
Graded potentials
Serve as short-distance signals
Action potentials
Signal over long distances
What are electrical signals caused by? *
Changes in the movement of ions thru ion channels in the plasma membrane
Polarization
- Charges are separated across the plasma membrane thus has potential
- Value of membrane potential not 0 mV
Depolarization *
- Membrane is less polarized than at resting potential
- Fewer charges are separated than at resting potential
Repolarization *
The membrane returns to resting potential after having been polarized
Hyperpolarization *
The membrane is more polarized (more -) than at resting potential
Triggering event
Results in changes in ionic movement across the membrane
What are some triggering events?
- Stimulus
- Change in electrical field
- Interaction of a chemical messenger with a surface receptor
- Spontaneous change of potential
What are 2 types of ion channels?
- leak channels
- gated channels
Leak channels
Open all time gated channels
Gated channels
Opened or closed in response to specific triggering events
What are the 3 kinds of gated channels? ***
1) voltage-gated channels
2) chemical messenger-gated channel
3) mechanically gated channels
Voltage-gated channel
Open and close in response to changes in membrane potential
Chemical messenger-gated channel
Change conformation in response to the binding of a specific chemical messenger with a membrane receptor
Mechanically gated channels
Respond to stretching or other mechanical deformation
What establishes membrane potential? ***
Equilibrium potentials for each ion and relative permeabilities
What maintains the membrane potential?
Na+/K+ pumps
Neurilemma *
Outermost coating of Schwann cell
Saltatory conduction in myelinated fibers
- voltage-gated channels needed for AP’s
- fast diffusion occurs between nodes
Multiple Sclerosis
Myelin sheath of CNS deteriorate and are replaced by scar tissue
EPSP
Excitatory postsynaptic potential
- occur at excitatory synapses
- move a postsynaptic neuron towards its threshold
Temporal summation
- One or more presynaptic neurons transmit impulses in rapid-fire order and waves of NT release occur in quick succession.
- First impulse produces a slight EPSP followed by addition EPSP impulses by subsequent impulses summing to threshold
Spatial summation
Postsynaptic neuron is stimulated by a large number of terminals form the same or different neurons at the same time which sum to threshold
