Chapter 8 section 1-3

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Questions and Answers

What is the primary function of saltatory propagation in neurons?

To enhance the electrical signal throughout the neuron.

To slow down the speed of nerve impulses.

To prevent depolarization of the axon membrane.

To carry nerve impulses along the axon at higher speeds. (correct)

How does saltatory propagation compare to conventional propagation in terms of speed?

It propagates signals only in small, local regions.

It can reach speeds vastly exceeding those of unmyelinated axons. (correct)

It propagates signals at slower speeds than conventional methods.

It operates at a fixed speed regardless of axon type.

What effect would a chemical that blocks voltage-gated sodium channels have on a neuron's depolarization ability?

It would improve the ability to generate action potentials.

It would prevent depolarization by blocking sodium influx. (correct)

It would have no effect on the neuron's membrane potential.

It would enhance depolarization by increasing sodium entry.

What happens to the membrane potential of a neuron if extracellular potassium concentration decreases?

The membrane potential becomes less negative and may depolarize. Signup and view all the answers

Which of the following axons is likely myelinated if one carries action potentials at 50 meters per second and the other at 1 meter per second?

The axon carrying action potentials at 50 meters per second. Signup and view all the answers

What is the main difference between the responses of the nervous system and the endocrine system?

The nervous system responds quickly but lasts briefly, while the endocrine system responds slowly but lasts longer. Signup and view all the answers

Which of the following is NOT a function of the nervous system?

Regulating hormonal balance. Signup and view all the answers

What are the two major anatomical divisions of the nervous system?

Central nervous system and peripheral nervous system. Signup and view all the answers

Which type of information does the afferent division of the PNS carry to the CNS?

Sensory information from receptors. Signup and view all the answers

What is the role of receptors in the nervous system?

They detect changes in the environment and respond to stimuli. Signup and view all the answers

Which part of the nervous system integrates and coordinates sensory data and motor commands?

Central nervous system. Signup and view all the answers

What is the main function of the efferent division of the PNS?

To transmit motor commands from the CNS to effector organs. Signup and view all the answers

Which of the following statements about the nervous system is true?

It plays a role in emotion and memory. Signup and view all the answers

What is the primary function of the somatic nervous system (SNS)?

Controlling skeletal muscle contractions Signup and view all the answers

What type of response is an involuntary muscle contraction when placing your hand on a hot stove?

Reflex response Signup and view all the answers

Which division of the nervous system is responsible for monitoring internal conditions?

Afferent division Signup and view all the answers

What is the primary role of the autonomic nervous system?

Controlling subconscious bodily functions Signup and view all the answers

Which of the following structures are classified as effectors?

Muscles and glands Signup and view all the answers

What is the function of neuroglia in the nervous system?

Supporting and protecting neurons Signup and view all the answers

What is a unique characteristic of neurons compared to neuroglia?

Neurons cannot divide and replicate Signup and view all the answers

What is the primary role of dendrites in a neuron?

Receiving incoming signals Signup and view all the answers

What happens at the axon hillock of a neuron?

Action potentials are generated Signup and view all the answers

Which division of the autonomic nervous system is known for speeding up heart rate?

Sympathetic division Signup and view all the answers

What does the term 'afferent division' refer to?

Sensory input brought to CNS Signup and view all the answers

Which of the following best describes the central nervous system?

Comprises the brain and spinal cord Signup and view all the answers

What is the result of the parasympathetic division's activity?

Relaxation and maintenance processes Signup and view all the answers

What is the primary function of astrocytes in the central nervous system (CNS)?

Create a protective blood-brain barrier Signup and view all the answers

Which type of neuron is responsible for relaying information from sensory receptors to the central nervous system?

Sensory neurons Signup and view all the answers

What distinguishes multipolar neurons from unipolar neurons?

Multipolar neurons have multiple dendrites and a single axon. Signup and view all the answers

What is the role of interneurons in the nervous system?

Connect other neurons and coordinate motor activity Signup and view all the answers

Which of the following statements about neuroglia is true?

Neuroglia make up about half of the volume of the nervous system. Signup and view all the answers

What type of sensory neurons monitor the position and movement of skeletal muscles?

Proprioceptors Signup and view all the answers

Which type of neuron is least common in the nervous system?

Bipolar neurons Signup and view all the answers

How do astrocytes support the structure of the CNS?

By providing nutrients to neurons Signup and view all the answers

Which neurons are involved in carrying instructions from the CNS to effectors like muscles and glands?

Efferent neurons Signup and view all the answers

Which of the following is NOT a function of astrocytes?

Transmitting sensory signals Signup and view all the answers

Which division of the peripheral nervous system includes motor neurons?

Efferent division Signup and view all the answers

What type of sensory receptor provides data about external environmental stimuli?

External receptors Signup and view all the answers

What characterizes unipolar neurons?

Their cell body is positioned off to one side. Signup and view all the answers

Which functional classification includes neurons that interpret and integrate sensory information?

Interneurons Signup and view all the answers

Neurons in the peripheral nervous system are classified based on their axon structure and function. Which classification includes neurons with one axon and multiple dendrites?

Multipolar neurons Signup and view all the answers

What is the main function of myelin in the nervous system?

To enhance the speed of action potential propagation Signup and view all the answers

Which cells are primarily responsible for myelinating axons in the CNS?

Oligodendrocytes Signup and view all the answers

What term describes the small gaps between myelinated segments of an axon?

Nodes of Ranvier Signup and view all the answers

Which neuroglial cell type helps in the circulation of cerebrospinal fluid (CSF)?

Ependymal cells Signup and view all the answers

What is the composition of myelin primarily made up of?

Lipids Signup and view all the answers

How does action potential propagation differ in myelinated versus unmyelinated axons?

Myelinated axons allow action potentials to jump from node to node Signup and view all the answers

What is the primary role of microglia in the CNS?

Engulfing cellular waste and pathogens Signup and view all the answers

What distinguishes white matter from gray matter in the CNS?

Concentration of myelinated axons Signup and view all the answers

What is the main structural difference between Schwann cells and oligodendrocytes?

Schwann cells can enclose several unmyelinated axons Signup and view all the answers

What happens at the axon hillock during action potential generation?

A local current develops and action potential begins Signup and view all the answers

Which term best describes the regions of an axon covered in myelin?

Internodes Signup and view all the answers

In which part of the nervous system are oligodendrocytes primarily located?

Central nervous system Signup and view all the answers

Why are previous segments of axons unable to respond during action potential propagation?

They are in a refractory period Signup and view all the answers

How does the structure of ependymal cells contribute to their function?

Cilia aid in the circulation of CSF Signup and view all the answers

What distinguishes action potentials from graded potentials in terms of propagation?

Graded potentials do not propagate along the entire axon Signup and view all the answers

Study Notes

Nervous System Organization

Two organ systems (nervous and endocrine) maintain homeostasis by responding to environmental changes.
Nervous system responses are fast but short-lived, while endocrine system responses are slow but lasting.
Nervous system examples include body positioning and eye movement.
Endocrine system examples include adjusting energy use and growth.

Nervous System Anatomy and Function

Nervous system has three main functions: monitoring internal/external environment, integration of sensory information, and coordinating voluntary/involuntary responses.
Two major anatomical divisions: central nervous system (CNS) and peripheral nervous system (PNS).
- CNS includes the brain and spinal cord, integrating sensory input and outputting motor commands.
- PNS contains all neural tissue outside the CNS, connecting CNS to the rest of the body.
  - Afferent division brings sensory information to the CNS from receptors.
  - Efferent division carries motor commands from CNS to muscles and glands.
    - Somatic nervous system controls skeletal muscle contractions (voluntary and involuntary).
    - Autonomic nervous system (ANS) regulates smooth muscle, cardiac muscle, and glandular secretions automatically.
      - ANS has sympathetic (accelerates heart rate) and parasympathetic (slows heart rate) divisions.

Neuron Structure and Function

Nervous system consists of neurons and neuroglia.
Neurons are the functional units communicating with one another and other cells.
Neuroglia support neurons by regulating their environment, providing framework, and acting as phagocytes. Neuroglia outnumber neurons.
- Neuroglia can divide; neurons, generally, cannot.
Neuron types:
- Multipolar: multiple dendrites, one axon (most common in CNS; motor neurons controlling skeletal muscles).
- Unipolar: dendrites and axon continuous, single cell body (common in PNS; sensory neurons).
- Bipolar: one dendrite, one axon, cell body between (rare, special sense organs).
Functional neuron classifications:
- Sensory neurons (afferent): receive info from sensory receptors and relay to other neurons.
- Motor neurons (efferent): carry instructions from CNS to effectors.
  - Somatic motor neurons innervate skeletal muscles.
  - Visceral motor neurons innervate other effectors (ANS).
- Interneurons (association neurons): entirely within the brain/spinal cord, connect other neurons.

Neuroglia in the CNS

Astrocytes: largest and most numerous, maintain blood-brain barrier, create framework, repair tissue.
Oligodendrocytes: have processes forming myelin sheaths around axons.
Microglia: smallest and least numerous, phagocytic cells (engulf waste).
Ependymal cells: simple cuboidal epithelial cells lining cavities in CNS, produce/circulate cerebrospinal fluid.

Neuroglia in the PNS

Satellite cells: surround and support neuron cell bodies.
Schwann cells: ensheath axons outside CNS (with myelin).

Organization of Neurons

Neuron cell bodies and axons organized into masses/bundles (with anatomical boundaries and specific terms).

Action Potential Propagation

Action potentials affect entire membrane surface.
Continuous propagation occurs along unmyelinated axons slowly (up to about 1 m/s).
Saltatory propagation jumps between nodes of Ranvier on myelinated axons much faster (from 18 to 140 m/s).

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Description

Explore the intricate workings of the nervous system and its role in homeostasis. This quiz covers the anatomy of the nervous system, its divisions, and the functions of both the nervous and endocrine systems. Test your understanding of how these systems respond to environmental changes and coordinate bodily functions.