Nervous Tissue
What are the two major types of cells found in nervous tissue?
Neurons and glial cells (neuroglia).
Neurons are responsible for communication and electrical signaling. Glial cells support and maintain neurons.
What is the approximate resting membrane potential of a typical neuron?
−70 mV.
Why:
At rest, the inside of the neuron is electrically negative relative to the outside.
What two structures make up the central nervous system?
Brain and spinal cord.
Why:
The CNS is the main processing and integration center of the nervous system.
Which type of muscle is controlled by the somatic motor system?
Skeletal muscle.
Why:
The somatic nervous system controls skeletal muscle, including voluntary movement and somatic reflexes.
What are the two major divisions of the autonomic nervous system?
Sympathetic and parasympathetic divisions.
Why:
These two divisions generally have opposing or complementary effects that help regulate internal organs.
Which part of a neuron primarily receives information from other neurons?
Dendrites.
Dendrites receive most incoming signals, while the axon carries signals away from the cell body.
During the depolarization phase of an action potential, which ion rapidly enters the neuron?
Na⁺ (sodium).
Why:
Voltage-gated sodium channels open, allowing Na⁺ to enter and making the membrane potential more positive.
Memory:
Na⁺ = IN
Which brain region is most associated with balance and coordination of movement?
Cerebellum.
Why:
The cerebellum helps coordinate skeletal muscle activity and maintain balance and posture.
What is the basic neural pathway that produces a reflex response called?
A reflex arc.
Why:
A reflex arc connects a sensory receptor to the appropriate motor response.
Which division is most associated with the body's fight-or-flight response?
Sympathetic division.
Why:
Sympathetic activity prepares the body to respond to demanding or stressful situations.
A patient has damage to the cells that produce myelin in the central nervous system. Which cells are affected?
Oligodendrocytes.
Oligodendrocytes produce myelin in the CNS. Schwann cells perform myelination in the PNS.
Exam trap: Don't confuse oligodendrocytes with Schwann cells
A neuron is at −70 mV. A stimulus causes the membrane to reach approximately −55 mV. What has happened?
The neuron has reached threshold.
Why:
Threshold is the membrane potential that must be reached to trigger an action potential.
A patient has difficulty processing visual information after a brain injury. Which cerebral lobe would you investigate first?
Occipital lobe.
Why:
The occipital lobe contains the primary visual cortex and is heavily involved in visual processing.
Put these parts of a reflex arc in the correct order:
Motor neuron
Receptor
Effector
Sensory neuron
Integration center
Receptor → sensory neuron → integration center → motor neuron → effector
Why:
The receptor detects the stimulus, sensory neurons carry the information toward the CNS, the integration center processes it, and the motor neuron carries the response to the effector.
Which division generally promotes “rest-and-digest” activities?
A. Somatic
B. Sympathetic
C. Parasympathetic
D. Sensory
C. Parasympathetic
Why:
Parasympathetic activity supports resting functions and promotes digestive activity.
Which pairing is CORRECT?
A. CNS nucleus — PNS ganglion
B. CNS ganglion — PNS nucleus
C. CNS nerve — PNS tract
D. CNS ganglion — PNS tract
A. CNS nucleus — PNS ganglion
Why:
A nucleus is a collection of neuron cell bodies in the CNS, while a ganglion is a collection in the PNS.
Put the following events in the correct order:
1. Repolarization
2. Resting membrane potential
3. Hyperpolarization
4. Threshold
5. Depolarization
2 → 4 → 5 → 1 → 3
Resting → Threshold → Depolarization → Repolarization → Hyperpolarization
Why:
The membrane starts at rest, reaches threshold, depolarizes, repolarizes, and briefly becomes more negative than resting potential.
A spinal nerve carries both sensory and motor information. Which root carries sensory information toward the spinal cord?
A. Ventral root
B. Dorsal root
C. Anterior horn
D. Ventral horn
B. Dorsal root
Why:
The dorsal root carries afferent/sensory information into the spinal cord. The ventral root carries efferent/motor information away.
Memory:
Dorsal = sensory IN
Ventral = motor OUT
You accidentally touch a hot pan and immediately pull your hand away before consciously thinking about the pain.
Why can the withdrawal occur so quickly?
The spinal cord can integrate the reflex and generate the motor response before conscious perception occurs in the brain.
Why:
A reflex does not have to wait for conscious brain processing before producing the immediate protective response.
Question:
A person finishes exercising and begins returning to a resting state. Their heart rate decreases and digestive activity resumes.
Which division is contributing to this response?
Parasympathetic division.
Why:
Parasympathetic activity helps return the body toward its resting state and supports digestion.
A patient's axons are still structurally present, but much of their myelin has been damaged. Predict the effect on neural communication.
Neural signaling will become slower or less efficient.
Why:
Myelin electrically insulates the axon and allows rapid saltatory conduction between nodes of Ranvier. Damage to myelin interferes with this rapid conduction.
Neuron A receives a weak stimulus that reaches threshold. Neuron B receives a much stronger stimulus.
Which neuron produces the larger action potential?
A. Neuron A
B. Neuron B
C. They produce action potentials of approximately the same size
D. Neither neuron produces an action potential
C. They produce action potentials of approximately the same size.
Why:
Action potentials are all-or-none. Once threshold is reached, increasing stimulus strength does not increase the size of an individual action potential. A stronger stimulus can instead increase the frequency of action potentials.
A patient has damage to the ventral root of a spinal nerve. Which problem would you expect?
A. Loss of sensory information entering the spinal cord
B. Impaired motor information leaving the spinal cord
C. Loss of visual processing
D. Impaired balance caused by cerebellar damage
B. Impaired motor information leaving the spinal cord.
Why:
The ventral root contains motor/efferent fibers. Damage interferes with signals traveling from the spinal cord toward effectors.
A doctor taps the patellar tendon below your kneecap. Your lower leg automatically kicks forward.
Which statement BEST describes this response?
A. It is an autonomic reflex involving smooth muscle.
B. It is a somatic reflex involving skeletal muscle.
C. It is a parasympathetic response.
D. It requires conscious decision-making before the muscle contracts
B. It is a somatic reflex involving skeletal muscle.
Why:
The patellar reflex is a somatic reflex because its effector is skeletal muscle. The response is involuntary and can be integrated through the spinal cord.
A student is about to give a presentation. Their heart rate increases, pupils dilate, and digestive activity decreases.
Which division is primarily responsible?
A. Somatic
B. Parasympathetic
C. Sympathetic
D. Sensory
C. Sympathetic
Why:
These responses prepare the body for increased demand: increased cardiovascular activity, increased alertness, pupil dilation, and decreased digestive activity.