Exam 3 Ch 11 Flashcards
Three main functions of the nervous system
sensory input, integration, and motor output
What are two principal parts of the nervous system?
CNP and PNS
How does the nervous system achieve rapid and specific communication?
through electrical and chemical signals that usually cause almost immediate responses.
Describe the sensory (afferent) and motor (efferent) divisions of the peripheral nervous system (PNS).
Sensory of PNS conveys impulses from skin, skeletal muscles, and joints, visceral organs to the CNS.
The motor of PNS comes from CNS to muscles and glands and is divided into the somatic nervous system and the smooth muscle, cardiac muscle and glands.
Name the four types of neuroglia in the CNS and the functions
Astrocytes:
Support and brace neurons.
Microglial:
Monitor neuron health
Ependymal :
Line the central cavities of the brain and spinal column
Oligodendrocytes :
Produces Myelin sheath around CNS fibers
Two types of neuroglia in the PNS and its roles
Satellite Cells: surround neuron cell bodies in the PNS and function similarly to astrocytes
Schwann cells: form myelin sheaths around peripheral nerve fibers and are vital for the regeneration of damaged peripheral nerve fibers
What is the resting membrane potential and how is it maintained
The resting membrane potential is -70mV, maintained by Na+ /K+ pump and leakage channels.
The cytoplasmic side of the membrane is negatively charged relative to the outside.
Explain the role of sodium (Na+) and potassium (K+) in generating the resting membrane potential.
Na+ is higher outside the cell and K+is higher inside. K+ leakage channels are more permeable allowing more K+ to diffuse out, which is crucial in maintaining the resting potential.
What happens to the membrane potential during depolarization and hyperpolarization?
During depolarization, the membrane potential becomes less negative
During hyperpolarization, the membrane potential becomes more negative
What are graded potentials, and how do they differ from action potentials?
Graded potentials are short lived, localized changes in membrane potential that can depolarize or hyperpolarize the membrane. They decay over distance.
Action Potential?
Long distance neural communication.
Occurs only in muscle cells and axons of neurons
violate change of ~100mV
do NOT decay over distance
involves the opening of specific voltage-gated channels.
Four main steps in generating an action potential
- Resting state: all gated Na+ and K+ channels closed
- Depolarization: Na+ channels open, Na+ rushes in , and the membrane potential becomes less negative, reaching threshold and causing an action potential spike
- Repolarization: Na+ channels inactivate, and K+ channels open, allowing K+ to exit, returning the membrane potential to resting state
- Hyperpolarization: some K+ channels remain open, causing a slight dip below the resting membrane potential before stabilizing.
How do electrical and chemical synapses differ?
Electrical: direct electrical coupling through gap junctions, allowing rapid and bidirectional communication
ex) cardiac mucle
Chemical: neurotransmitters to transmit signals across a synaptic cleft
What is synapse, and what are the different types of synapses
A synapse is a junction that mediates information transfer from one neuron to another or to an effector cell.
Types:
- Axodendritic: axon to dendrites
- Axosomatic: axon to cell body
- Axoaxonic :axon to axon.
Explain the process of information transfer across a chemical synapse.
Arrival of an action potential at the presynaptic terminal, opening of voltage-gated Ca2+ channels, the release of neurotransmitters into the synaptic cleft, and binding of neurotransmitters to receptors on the postsynaptic membrane, resulting in graded potentials.
