chapter 12, nervous tissue Flashcards
What does the Central Nervous System (CNS) consist of?
The brain and spinal cord.
What does the Peripheral Nervous System (PNS) consist of?
Nerves and ganglia outside the CNS.
What is the role of the Sensory (Afferent) Division?
Carries sensory signals from receptors to the CNS.
What is the function of the Motor (Efferent) Division?
Carries motor signals from the CNS to muscles and glands.
What does the Somatic Nervous System (SNS) control?
Voluntary movement and skeletal muscles.
What functions does the Autonomic Nervous System (ANS) control?
Involuntary functions, such as heart rate and digestion.
What is the role of the Sympathetic Division?
Prepares the body for ‘fight or flight’ responses.
What does the Parasympathetic Division support?
‘Rest and digest’ functions.
What is a Neuron?
The functional unit of the nervous system.
Define Excitability in the context of neurons.
Ability of neurons to respond to stimuli.
What is Conductivity in neurons?
Ability of neurons to transmit electrical signals.
What is Secretion in neurons?
Release of neurotransmitters to communicate with other cells.
What is the Soma (Cell Body) of a neuron?
The control center of the neuron.
What are Dendrites?
Short, branched extensions of a neuron that receive signals.
What is the Axon?
The long projection that carries nerve impulses away from the soma.
What is the Axon Hillock?
The region where the axon begins; important for action potential initiation.
Define Synapse.
The junction between two neurons where communication occurs.
What is the Myelin Sheath?
Fatty covering around axons that speeds up nerve impulses.
What are Nodes of Ranvier?
Gaps in the myelin sheath that allow saltatory conduction.
What do Sensory (Afferent) Neurons do?
Carry signals from sensory receptors to the CNS.
What are Interneurons (Association Neurons)?
Process information within the CNS.
What do Motor (Efferent) Neurons do?
Carry signals from the CNS to effectors (muscles/glands).
What are Astrocytes?
Star-shaped cells that provide structural support and help maintain the blood-brain barrier.
What is the role of Oligodendrocytes?
Form myelin sheaths in the CNS.
What do Microglia do?
Small, phagocytic cells that remove debris and pathogens in the CNS.
What are Ependymal Cells responsible for?
Line the ventricles of the brain and help produce cerebrospinal fluid (CSF).
What is the function of Schwann Cells?
Form myelin sheaths around axons in the PNS.
What do Satellite Cells do?
Support and regulate the environment around neurons in the PNS.
What is Resting Membrane Potential (RMP)?
The baseline electrical charge of a neuron at rest (-70mV).
Define Depolarization.
When the inside of a neuron becomes more positive due to sodium (Na⁺) entering.
What is Repolarization?
When the neuron returns to a negative charge due to potassium (K⁺) exiting.
What is Hyperpolarization?
When the inside of the neuron becomes too negative before returning to RMP.
What is the Threshold in neuronal activity?
The minimum voltage needed to trigger an action potential (-55mV).
What is an Action Potential?
A rapid electrical signal that travels along the axon.
What does the All-or-None Principle state?
If a neuron reaches the threshold, it will fire an action potential completely.
Define Saltatory Conduction.
The jumping of action potentials between the Nodes of Ranvier in myelinated neurons, increasing speed.
What is a Presynaptic Neuron?
The neuron that sends the signal.
What is a Postsynaptic Neuron?
The neuron that receives the signal.
What is a Neurotransmitter?
A chemical that transmits signals across a synapse.
What are Excitatory Neurotransmitters?
Increase the likelihood of an action potential (e.g., glutamate, acetylcholine).
What are Inhibitory Neurotransmitters?
Decrease the likelihood of an action potential (e.g., GABA, glycine).
What are Synaptic Vesicles?
Small sacs that store neurotransmitters.
What are Receptor Proteins?
Proteins on the postsynaptic neuron that bind neurotransmitters.
What is Reuptake?
The process of neurotransmitters being absorbed back into the presynaptic neuron.
What is Enzymatic Degradation?
Breakdown of neurotransmitters (e.g., acetylcholinesterase breaking down acetylcholine).
What is a Diverging Circuit?
One neuron triggers multiple neurons, spreading the signal.
What is a Converging Circuit?
Multiple neurons send signals to a single neuron.
Define Reverberating Circuit.
Neurons loop back to previous neurons for prolonged signals.
What is a Parallel After-Discharge Circuit?
A single neuron activates multiple pathways that converge on a common output.
What is Multiple Sclerosis (MS)?
An autoimmune disease that damages myelin in the CNS, slowing nerve conduction.
What is Guillain-Barré Syndrome?
A disorder where the immune system attacks the PNS myelin.
What is Amyotrophic Lateral Sclerosis (ALS)?
A degenerative disease that affects motor neurons, leading to muscle weakness.
What is Parkinson’s Disease?
A neurodegenerative disorder caused by dopamine deficiency.
What is Epilepsy?
A condition characterized by recurring seizures due to excessive electrical activity in the brain.
What is Alzheimer’s Disease?
A progressive neurodegenerative disease causing memory loss and cognitive decline.
