Animal and Human Neural Systems

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Questions and Answers

What is the primary role of axons in neurons?

Transmit nerve impulses towards the cell body

Store neurotransmitters

Transmit nerve impulses away from the cell body (correct)

Form myelin sheaths

Which type of neuron is characterized by having one axon and one dendrite?

Tripolar neuron

Unipolar neuron

Multipolar neuron

Bipolar neuron (correct)

What is the function of the nodes of Ranvier?

Store ions for future nerve impulses

Increase the thickness of the myelin sheath

Conduct electrical impulses slower

Allow for saltatory conduction of nerve impulses (correct)

When a neuron is at rest, which ion is the axonal membrane more permeable to?

Potassium ions (K+) Signup and view all the answers

What maintains the ionic gradients across the resting membrane of a neuron?

Sodium-potassium pump Signup and view all the answers

Which of the following statements correctly describes myelinated nerve fibers?

They are enveloped by Schwann cells forming a myelin sheath. Signup and view all the answers

Why is the inner surface of the axonal membrane negatively charged at rest?

High concentration of negatively charged proteins Signup and view all the answers

In which stage is a unipolar neuron primarily found?

Embryonic stage Signup and view all the answers

What are the two main parts of the human neural system?

Central neural system and peripheral neural system Signup and view all the answers

Which type of nerve fibres transmit regulatory impulses from the CNS to peripheral tissues?

Efferent fibres Signup and view all the answers

Which division of the peripheral neural system is responsible for relaying impulses to skeletal muscles?

Somatic neural system Signup and view all the answers

What are the three major parts of a neuron?

Cell body, dendrites, and axon Signup and view all the answers

What role do dendrites play in a neuron?

Receive impulses towards the cell body Signup and view all the answers

Which component of the peripheral nervous system sends impulses to involuntary organs?

Visceral nervous system Signup and view all the answers

What are Nissl's granules primarily associated with in a neuron?

Cytoplasmic organization within the cell body Signup and view all the answers

Which structure at the end of the axon contains synaptic vesicles?

Axon terminal Signup and view all the answers

Study Notes

Animal Neural Systems

Animal nervous systems are composed of specialized cells called neurons that detect, receive, and transmit stimuli.
Lower invertebrates have simple neural networks (e.g., Hydra).
Insects have a more organized system with a brain, ganglia, and neural tissues.
Vertebrates possess the most developed neural systems.

Human Neural System

Divided into central nervous system (CNS) and peripheral nervous system (PNS).
CNS: brain and spinal cord; responsible for information processing and control.
PNS: all nerves connected to the CNS; contains afferent and efferent fibers.
- Afferent fibers: transmit impulses from tissues/organs to the CNS.
- Efferent fibers: transmit impulses from the CNS to peripheral tissues/organs.
PNS also includes:
- Somatic neural system: relays impulses to skeletal muscles.
- Autonomic neural system: regulates involuntary organs/smooth muscles.
  - Sympathetic and parasympathetic systems: further subdivisions of the autonomic system.
- Visceral nervous system: complex network involving nerves, fibers, ganglia, and plexuses for visceral impulse transmission.

Neuron Structure and Function

Neurons are microscopic, structural and functional units of the nervous system.
- Three main parts: cell body, dendrites, and axon.
- Cell body: contains cytoplasm and Nissl's granules.
- Dendrites: short, branching fibers extending from the cell body; receive impulses. Have Nissl's granules.
- Axon: long fiber that transmits impulses away from the cell body; also has branches ending in synaptic knobs. Synaptic knobs contain synaptic vesicles with neurotransmitters.
Neuron types based on axon and dendrite configuration:
- Multipolar: one axon, multiple dendrites (e.g., cerebral cortex)
- Bipolar: one axon, one dendrite (e.g., retina)
- Unipolar: one axon, single projection that branches into separate afferent and efferent fibers.
Axon types:
- Myelinated: insulated by Schwann cells forming a myelin sheath; have gaps (nodes of Ranvier) between myelin segments.
  - Found in cranial and spinal nerves.
- Unmyelinated: Schwann cell surrounds axon but doesn't create a myelin sheath.
  - Common in autonomic and somatic neural systems.

Nerve Impulse Generation and Conduction

Neuron membranes are polarized.
Ion channels allow selective ion permeability.
At rest, axonal membranes are more permeable to potassium ions (K+) and less permeable to sodium ions (Na+). Inner membrane has high K+, negatively charged proteins, and low Na+, outer membrane is more positive.
Ionic gradients maintained by active transport (sodium-potassium pump): 3 Na+ pumped out, 2 K+ pumped in.

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Description

Explore the complexities of neural systems in both animals and humans. This quiz covers the structure and functions of the nervous systems, including examples from invertebrates to vertebrates, as well as the central and peripheral nervous systems in humans. Test your knowledge on how these systems control and coordinate bodily functions.