Nervous Tissue and Nervous System Overview

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Questions and Answers

What shape are the cell bodies of neurons found in spinal ganglia?

Oval and elongated

Large and rounded (correct)

Small and irregularly shaped

Flat and disc-like

What type of neurons are primarily found in spinal ganglia?

Multipolar neurons

Pseudounipolar neurons (correct)

Bipolar neurons

Unipolar neurons

Which structure surrounds the cell bodies in spinal ganglia?

Oligodendrocytes

Astrocytes

Satellite cells (correct)

Ependymal cells

What is a key characteristic of the cell bodies in autonomic ganglia compared to those in spinal ganglia?

They are small and irregularly shaped. Signup and view all the answers

What role does the hypothalamus play in relation to the autonomic nervous system?

Controls the autonomic nervous system Signup and view all the answers

Which part of the autonomic nervous system is primarily responsible for preparing the body for emergencies?

Sympathetic nervous system Signup and view all the answers

In terms of blood supply, how do spinal ganglia differ from autonomic ganglia?

Spinal ganglia contain few blood capillaries. Signup and view all the answers

What action is associated with the parasympathetic nervous system?

Increasing peristalsis of the intestine Signup and view all the answers

What type of nerve fibers are primarily found in autonomic ganglia?

Scattered nerve fibers Signup and view all the answers

What system is characterized by its control of involuntary structures like the heart and glands?

Autonomic nervous system Signup and view all the answers

What is the main function of the autonomic nervous system?

Regulates activities that are involuntary Signup and view all the answers

Where are pseudounipolar neurons primarily situated?

Dorsal root ganglia of spinal nerves Signup and view all the answers

Which type of glial cell is primarily responsible for forming the myelin sheath in the peripheral nervous system?

Schwann cells Signup and view all the answers

What structure provides the supportive framework for neurons and helps create the blood-brain barrier?

Astrocytes Signup and view all the answers

Which part of a neuron carries impulses away from the cell body?

Axon Signup and view all the answers

What type of neuron serves as a connection between sensory and motor neurons within the central nervous system?

Interneurons Signup and view all the answers

What distinguishes the CNS from the PNS anatomically?

The presence of the brain and spinal cord Signup and view all the answers

Which type of connective tissue sheath surrounds each individual nerve fiber in a fascicle?

Endoneurium Signup and view all the answers

Which type of cranial nerve is responsible for the sense of smell?

Olfactory nerve Signup and view all the answers

What role do astrocytes play in the nervous system?

Supporting neurons and regulating fluid Signup and view all the answers

What is the primary shape characteristic of the cell bodies of multipolar neurons in autonomic ganglia?

Small and irregularly shaped Signup and view all the answers

Which type of connective tissue surrounds the cell bodies in autonomic ganglia?

Few flattened cells known as satellite cells Signup and view all the answers

What is a key difference in the organization of cell bodies between spinal ganglia and autonomic ganglia?

Cell bodies are grouped in spinal ganglia while scattered in autonomic ganglia Signup and view all the answers

How do the blood supply characteristics differ between spinal ganglia and autonomic ganglia?

Autonomic ganglia contain more blood capillaries Signup and view all the answers

What is the primary function of the sympathetic nervous system?

Responding to emergencies by increasing heart rate Signup and view all the answers

Which of the following best describes the nerve fibers in spinal ganglia?

They form organized bundles around the cell bodies Signup and view all the answers

What is the role of the hypothalamus in the autonomic nervous system?

It controls the autonomic nervous system Signup and view all the answers

Which of the following characteristics applies specifically to spinal ganglia?

The cell bodies are pseudounipolar and round Signup and view all the answers

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

Provide support and protection for neurons Signup and view all the answers

Which type of neuron is primarily responsible for transmitting sensory information from the PNS to the CNS?

Sensory neurons Signup and view all the answers

Which statement accurately describes the axon of a neuron?

It is surrounded by oligodendrocytes in the CNS. Signup and view all the answers

What distinguishes the somatic nervous system from the autonomic nervous system?

It controls voluntary movements. Signup and view all the answers

Which type of glial cell is responsible for forming the myelin sheath in the central nervous system?

Oligodendrocytes Signup and view all the answers

What structure mainly composes the myelin sheath in the peripheral nervous system?

Phospholipids Signup and view all the answers

Which type of cranial nerve conveys information related to vision?

Optic nerve Signup and view all the answers

What is the primary role of the autonomic nervous system during physical activity?

Control involuntary bodily functions Signup and view all the answers

What does the term 'pseudounipolar' refer to in the classification of neurons?

A single process that divides into two branches Signup and view all the answers

Which type of cells are classified as connective tissue of the nervous system?

Neuroglia Signup and view all the answers

What is the main difference between the dorsal root and the ventral root of spinal nerves?

Ventral root carries motor fibers; dorsal root carries sensory fibers. Signup and view all the answers

Which structure serves as a protective covering for the collection of neurons in a ganglion?

Connective tissue capsule Signup and view all the answers

What cellular structure is primarily responsible for the rapid transmission of nerve impulses in myelinated neurons?

Nodes of Ranvier Signup and view all the answers

Study Notes

Nervous Tissue

Specialized to react to stimuli and conduct impulses to various organs in the body, triggering a response.
Controls and integrates the activity of different body parts.
Composed of specialized nerve cells called neurons and supporting cells called neuroglia.
Neurons efficiently transmit electrical impulses.
Nervous tissue forms the nervous system.

Nervous System

Anatomically divided into central nervous system (CNS) and peripheral nervous system (PNS).
Central Nervous System (CNS):
- Collects information from all parts of the body, processes it, and sends nerve impulses to control bodily movements.
- Includes the brain and spinal cord.
Peripheral Nervous System (PNS):
- Connects the CNS to the rest of the body.
- Includes cranial nerves, spinal nerves, and associated ganglia.

Cells of the Nervous System

Neurons:
- The structural and functional units of the nervous system.
- Transmit electrical impulses.
- Vary in size from 4-20 microns.
- Have a cell body and processes (axon and dendrite).
Neuroglia:
- Supporting cells that do not transmit electrical impulses.
- Support and protect neurons.

Classification of Neurons

Based on Morphology (shape):
- Multipolar neurons.
- Bipolar neurons.
- Pseudounipolar neurons.
Based on Function:
- Motor neurons.
- Sensory neurons.
- Interneurons.

Functional Classification of Neurons

Motor (efferent) neurons:
- Transmit motor information from the CNS to effectors (muscles/glands) in the periphery.
- All are multipolar neurons
Sensory (afferent) neurons:
- Transmit sensory information from receptors to the CNS
- Mostly pseudounipolar, few are bipolar
Interneurons:
- Transmit information between neurons within the CNS.
- Connect sensory and motor neurons.
- Communicate with each other.
- All are multipolar neurons.

Multipolar Neuron

Located in the brain, spinal cord, and sympathetic/parasympathetic ganglia.
Has a cell body (soma or perikaryon)
Star-shaped or irregularly shaped
Has a cell membrane
Contains cytoplasm
Has a nucleus
One axon and many dendrites

Neuron Structure (Detail)

Cytoplasm contains organelles like Golgi apparatus and mitochondria.
Also contains Nissl granules (rough ER) responsible for protein synthesis.
Neurofibrils are thread-like structures providing support.
Axon hillock, the part of the cell body adjacent to the axon, lacks Nissl granules.

Dendrites and Axon

Dendrites:
- Short, numerous processes.
- Branch extensively.
- Carry nerve impulses towards the cell body.
- Contain Nissl granules.
Axon:
- One long process.
- Carries nerve impulses away from the cell body.
- Contains all organelles except Nissl granules.
- Ends in telodendria (branching terminals).

Telodendria and Axon Structure

Telodendria end by synapsing with muscle/glands or connecting to other neuron cell bodies.
The axon membrane is called the axolemma.
The axon cytoplasm is called the axoplasm.
Axons are surrounded by Schwann cells or Oligodendrocytes.
Schwann cell myelin sheath forms around the axon.

Myelinated and Unmyelinated Neurons

Myelinated neurons:
- Sheathed by a myelin sheath.
- Myelin is composed of phospholipids.
Unmyelinated neurons:
- Without a myelin sheath.

Bipolar Neuron

Located in the retina of the eyeball, spiral ganglia, and vestibular ganglia of the inner ear.
Has a cell body
One axon
One dendrite

Pseudounipolar Neuron

Located in the spinal ganglia.
Has a cell body.
One dendrite and one axon that initially unite, then separate.

Neuroglia (Glial Cells)

Connective tissue of the nervous system.
Astrocytes.
- Create supportive framework for neurons.
- Create "blood-brain barrier."
- Monitor and regulate interstitial fluid surrounding neurons..
Microglia
- Scavenger cells
- Phagocytic
Schwann cells.
- Form myelin sheath in peripheral nerves
Oligodendrocytes.
- Form myelin sheath in the CNS
- Make up 3/4 of glial cells
- Are found in white matter, and grey matter
Ependymal cells.
- Line ventricles of the brain and central canal of the spinal cord.
- Secret cerebrospinal fluid.
Satellite/Capsular cells
- Surround neurons in ganglia
- Support and protect neurons.

Nerve Trunk

Made up of nerve fibers (axons).
Surrounded by connective tissue (epineurium, perineurium, and endoneurium).
Bundles of fascicles contain nerve fibers.
Schwann cells form a sheath around each axon.

Cranial Nerves

12 pairs of nerves originate from the brain.
Supply structures in the head and neck. (except the 10th cranial nerve).
10th cranial nerve (vagus) supplies the thorax and abdomen.

Spinal Nerves

31 pairs of nerves attached to the spinal cord.
Named according to the region of the spinal cord they arise from.
- Cervical, thoracic, lumbar, sacral, and coccygeal.

Typical Spinal Nerve

Composed of dorsal and ventral roots.
Dorsal roots contain sensory fibers.
Ventral roots contain motor fibers.
The roots unite to form the nerve trunk.
Trunk divides into Rami

Dorsal and Ventral Rami

Dorsal Ramus: Smaller branch, supplies muscles and skin of the back.
Ventral Ramus: Larger branch, supplies muscles and skin of the trunk and limbs.

Spinal Nerves: Trunks, Roots and rami

Roots:
- Each spinal nerve has ventral and dorsal roots.
- Spinal nerve is connected to spinal cord via roots.

Ganglia

Collections of neuron cell bodies outside the CNS.
Sensory or autonomic in type.
Sensory Ganglia (e.g., Spinal Ganglia):
- Covered by connective tissue.
- Contain pseudounipolar neurons with cell bodies surrounded by flattened cells.
- Contain many nerve fibers.
- Have few blood capillaries
Autonomic Ganglia:
- Consist of multipolar neurons.
- Cell bodies are small and irregularly shaped.
- Cell bodies scattered with nerve fibers and numerous blood capillaries surrounding.

Autonomic Nervous System

Controls involuntary functions like heart rate, digestion, and glandular activity.
Two divisions:
- Sympathetic NS
- Parasympathetic NS

Sympathetic Nervous System

Prepares the body for emergency situations (fight-or-flight).
Increased heart rate, blood pressure, and redistribution of blood.
Inhibits digestive and other non-emergency activities.

Parasympathetic Nervous System

Responsible for conserving energy and restoring the body to a resting state.
Decreased heart rate, blood pressure.
Promotes digestion and other non-emergency functions.

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Description

Explore the structure and function of nervous tissue, including the roles of neurons and neuroglia. Understand the divisions of the nervous system, such as the central and peripheral nervous systems, and learn how they work together to control bodily functions.