Nervous System and Tissue Overview

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Questions and Answers

What is one of the primary functions of the nervous system?

To facilitate mechanical digestion

To process and transmit information (correct)

To transport oxygen throughout the body

To absorb nutrients from food

Which of the following correctly describes the relationship between neurons and neuroglia?

Neurons and neuroglia have independent functions within the nervous system

Neurons are not dependent on neuroglia for proper function

Neuroglia primarily transmit impulses like neurons

Neuroglia support and protect neurons (correct)

What distinguishes a ganglion from a nucleus in the context of the nervous system?

A ganglion is a collection of glial cells, while a nucleus is a collection of neurons

A ganglion is a group of nerve fibers, while a nucleus is a group of neuron cell bodies

A nucleus is found in the peripheral nervous system, whereas a ganglion is found in the central nervous system

Both ganglions and nuclei refer to groups of nerve cell bodies but in different locations (correct)

What is the primary function of cerebrospinal fluid?

To protect the brain and spinal cord from injury Signup and view all the answers

Which of the following best describes the blood-brain barrier?

A selective barrier that protects the brain from harmful substances Signup and view all the answers

What type of neurons are considered the most numerous in the nervous system?

Interneurons Signup and view all the answers

What distinguishes motor (efferent) neurons from sensory (afferent) neurons?

Motor neurons carry information away from the CNS. Signup and view all the answers

Which statement accurately describes the structure of interneurons?

Interneurons generally have a multipolar structure. Signup and view all the answers

What is the primary function of the nuclei in the nervous system?

To serve as clusters of neuronal cell bodies in the CNS Signup and view all the answers

Which type of matter in the nervous system consists of neurosomas, dendrites, and synapses?

Gray matter Signup and view all the answers

Which type of neuron typically has enlarged axon terminals to facilitate specific responses?

Motor neurons Signup and view all the answers

What is the term used to describe a bundle of axons in the peripheral nervous system?

Nerve Signup and view all the answers

Which type of neuron is primarily responsible for processing and integrating information within the CNS?

Interneurons Signup and view all the answers

What is the primary function of the nervous system?

Regulate homeostasis Signup and view all the answers

Which type of cell in the nervous tissue responds to stimuli and transmits electrical signals?

Neurons Signup and view all the answers

How many times more neuroglia than neurons are present in the nervous system?

Ten times Signup and view all the answers

What is the role of Oligodendrocytes in the central nervous system?

Form myelin sheath Signup and view all the answers

What main purpose do Microglia serve in the central nervous system?

Act as immune cells Signup and view all the answers

Which type of neuroglial cell is responsible for forming a blood-brain barrier?

Astrocytes Signup and view all the answers

What distinguishes the axon from the dendrites in a neuron?

Axons transmit signals away from the cell body Signup and view all the answers

Which cell type in the peripheral nervous system covers all PNS neurons and can form the myelin sheath?

Schwann cells Signup and view all the answers

What is the primary component of the myelin sheath?

Lipids Signup and view all the answers

What is a significant characteristic of neurons regarding their ability to divide?

Most lose the ability to divide Signup and view all the answers

Which of the following is NOT a function of astrocytes?

Transmit electrical signals Signup and view all the answers

The axon hillock is significant for which reason?

It is the origin point of the axon Signup and view all the answers

What type of neuron detects and transmits information about stimuli to the central nervous system?

Sensory neurons Signup and view all the answers

What is the primary function of the cranial meninges?

Protect underlying neural tissues Signup and view all the answers

Which layer of the meninges is the most superficial?

Dura mater Signup and view all the answers

Which structure is responsible for the separation of cerebral hemispheres?

Falx cerebri Signup and view all the answers

What is cerebrospinal fluid (CSF) primarily composed of?

Filtrate from blood plasma Signup and view all the answers

How does the blood-brain barrier maintain brain protection?

By being the least permeable capillaries Signup and view all the answers

Which ion is NOT typically transported across the blood-brain barrier?

Negatively charged molecules Signup and view all the answers

Which part of the meninges contains spaces for blood vessels?

Subarachnoid space Signup and view all the answers

Astrocytes play a significant role in which of the following?

Regulating the interstitial environment Signup and view all the answers

Where is cerebrospinal fluid formed in the brain?

In the lateral ventricles Signup and view all the answers

Which statement about the dura mater is true?

It forms dural sinuses for blood collection. Signup and view all the answers

What is the primary role of the subarachnoid space?

To contain cerebrospinal fluid Signup and view all the answers

Which feature of capillaries in the blood-brain barrier is crucial for its function?

Tight junctions between endothelial cells Signup and view all the answers

What is one function of cerebrospinal fluid?

Cushioning and shock absorption Signup and view all the answers

What is the process through which cerebrospinal fluid is reabsorbed back into the bloodstream?

Arachnoid villi absorption Signup and view all the answers

Which of the following statements about astrocytes is true?

They have essential regulatory and structural roles. Signup and view all the answers

Study Notes

Nervous System Organization

The nervous system's main function is to coordinate activities to maintain homeostasis.
The central nervous system (CNS) includes the brain and spinal cord.
The peripheral nervous system (PNS) includes nerves and ganglia.
The nervous system consists of sensory and motor components.
The nervous system has different divisions that cooperate with each other.
Sensory components collect information from receptors and relay to CNS.
Motor components transfer information from CNS to target organs (like muscles or glands).

Nervous Tissue

Nervous tissue is made up of neurons and neuroglia.
Neurons respond to stimuli and transmit electrical signals.
Neuroglia includes cells that support neurons, like oligodendrocytes, ependymal cells, microglia, and astrocytes.

Neuroglia (Support Cells of the Nervous System)

Neuroglia are the support staff of the nervous system.
There are typically ten times more neuroglia than neurons.
Neuroglia provide neurons with physical and regulatory support and communicate with them on how to carry out their functions.
Oligodendrocytes create the myelin sheath, that surrounds axons in the CNS.
Ependymal cells line cavities of CNS and produce cerebrospinal fluid.
Microglia are the immune cells that act like macrophages to remove debris, etc.
Astrocytes regulate the environment around neurons by maintaining the blood-brain barrier and help repair damaged tissue.

PNS Neuroglia

Satellite cells surround neuron cell bodies in the ganglia and provide support.
Schwann cells surround axons and produce myelin sheath in the PNS.

Myelin

Myelin is a protective covering around axons that increases electrical signal transmission speed.
Myelin is created by Oligodendrocytes in the CNS and Schwann cells in the PNS.
It increases the speed of signals.
Myelin minimizes ion leakage.
Myelin thickness can be hundreds of times thicker than the cell membrane.

Neurons

Neurons are the functional units of the nervous system.
Neurons have unique characteristics including excitability (respond to stimuli).
Neurons conduct (transmit) electrical signals.
Neurons secrete signaling molecules.
They have an extreme longevity.
Neurons cannot divide.
They have a high metabolic rate, and their function depends on glucose and oxygen.

Generic Neuron Structure

Dendrites are thin, branched extensions radiating outward from the cell body.
The neurosoma (cell body) contains the nucleus and organelles.
The axon is a long extension that transmits signals from the cell body to ending branches.
The axon hillock is the origin point of the axon.
Axons vary in length from micrometers to meters.
Extensive cytoskeleton extends into both the axon and dendrites.
Terminal arborization are multiple branches at the end of an axon.
These branches form synapses with the target cells, using synaptic vesicles to release signaling molecules.
Some neurons do not have extensive axons, but they use varicosities instead.
Neurons have an actual size that corresponds to certain proportions, for example, axons around a meter in length, dendrites that spread out in the classroom, or neurosoma the size of a tennis ball.

Neuron Classification

Sensory (afferent) neurons detect and transmit information from sensory receptors to the CNS about stimuli. (e.g. temp, light, smell, body position).
Interneurons completely reside within the CNS, to integrate and connect sensory and motor pathways.
Motor (efferent) neurons carry information away from the CNS to the effector (such as muscle and glands)

Neuron Structure Variations

Neurons vary in structure based on function and location in the body.

The Central Nervous System

The brain is 1350 ccs and 3 lbs of processing power and contains 20 billion neurons.
Its key functions are for complex responses and utilization of 100% of its processing power.
Different parts of the brain (like the frontal or temporal lobe) have various functions.

Cranial Meninges

Cranial meninges are connective tissue coverings that protect and anchor the brain in the cranial cavity.
Layers include dura mater, arachnoid mater, and pia mater.
Spaces between the layers contain cerebrospinal fluid (CSF).

Cerebrospinal Fluid (CSF)

CSF is a clear, colorless fluid in the CNS's ventricles and canals.
It's a filtrate from plasma/blood, with glucose, oxygen, ions, and other substances.
CSF functions include cushioning/shock absorption, chemical protection, and exchange of nutrients/wastes.

Ventricles of the Brain

Ventricles are fluid-filled chambers within the brain.
They're numbered and create flow pathways for CSF.
CSF flows from ventricles to spinal cord then into the subarachnoid space.

CSF Formation & Pathways of Flow

CSF is created in the lateral ventricles by the choroid plexus.
Ependymal cells produce CSF. Flow through different ventricles and into subarachnoid space
CSF is absorbed into the venous sinuses.

Blood-Brain Barrier (BBB)

The BBB is the least permeable capillaries in the body.
It maintains a stable environment for the brain.
It shields the brain from foreign substances, hormones, and other neurotransmitters in the bloodstream moving through the body.
Lipid soluble molecules pass through.

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Description

Explore the organization of the nervous system, including the central and peripheral nervous systems, and the crucial role of nervous tissue. Understand the components of neurons and neuroglia, as well as how they interact to maintain homeostasis and transmit signals throughout the body.