Biology - Nervous Coordination - Quick Guides | Biology

Preview (7 of 22 Pages)

100%

Biology - Nervous Coordination - Page 1 preview image

Loading page ...

Study GuideBiology–Nervous Coordination1. Animal Nerve CellsLiving organisms need to react quickly to what is happening around them and inside their bodies. Inanimals, this fast response is made possible bynervous coordination, which is the job of thenervous system.Nervous coordination usually begins when astimulus(such as light, sound, heat, or pain) is detectedbyreceptorsin the sense organs, often found at the body surface. The response to this stimulususually involves amuscle or a gland. To make this happen, signals travel along a pathway made ofspecial cells callednerve cells.1.1 What Are Neurons?Animal nerve cells are calledneurons. They are highly specialized cells designed to carry messagesquickly. In humans, there are about12 billion neurons, most of which are located in thebrain andspinal cord.Each neuron has three main parts:•Cell body–the main part of the cell that contains the nucleus•Dendrites–short, branched extensions that receive incoming signals•Axon–a long extension that carries signals away from the cell bodyThe axon is usually covered by a fatty layer called themyelin sheath, which helps the signal travelfaster. A group of axons bundled together forms anerve.1.2 Types of NeuronsNeurons work together in teams, and they can be grouped into three types based on their function:•Sensory neuronsThese neurons detect stimuli from the environment (such as touch, temperature, or light) andcarry signals toward the brain or spinal cord.

Biology - Nervous Coordination - Page 2 preview image

Loading page ...

Study Guide•Interneurons (association neurons)These neurons connect sensory neurons to motor neurons. They are found in the brain and spinalcord and help process and interpret information.•Motor neuronsThese neurons carry signals from the brain or spinal cord tomuscles or glands, causing aresponse.Neurons are supported and protected by special helper cells calledglial cells. Together withsurrounding tissue, these cells form theneuroglia, which nourishes and insulates neurons.1.3 The Nerve ImpulseAnerve impulseis the signal that travels along a neuron. It is anelectrochemical event, meaning itinvolves both electrical charges and chemical movement.1.3.1 Resting PotentialWhen a neuron is not sending a signal, it is in a resting state. At this time:•The inside of the neuron isnegatively chargedcompared to the outside.•This charge difference is maintained by actively pumpingsodium ions outof the cell.A neuron in this state is said to have aresting potentialand ispolarized.1.3.2 ActionPotentialA nerve impulse begins when astimulusreaches the tip of a dendrite. This causes:•The cell membrane to become more permeable to sodium ions.•Sodium ions rush into the neuron.•The difference in electrical charge disappears.This sudden change creates a nerve impulse called anaction potential, and the neuron becomesdepolarized.The sodium ions then trigger nearby areas of the membrane to do the same. In this way, awave ofdepolarizationmoves along the neuron. This wave is the nerve impulse.

Biology - Nervous Coordination - Page 3 preview image

Loading page ...

Study GuideAfter the impulse passes, the neuron restores its original charge by:•Pumpingpotassium ions out, and•Pumpingsodium ions back inThis prepares the neuron to fire again.1.4 The SynapseThe nerve impulse travels along the dendrite, through the cell body, and down the axon. However,neurons do not touch each other directly.At the end of the axon, there is a tiny fluid-filled gap called asynapse. When a synapse occursbetween a neuron and a muscle fiber, it is called aneuromuscular junction.When the impulse reaches the end of the axon:1.Chemicals calledneurotransmitters(such as acetylcholine) are released.2.These chemicals cross the synapse.3.They increase the permeability of the next cell’s membrane.4.Sodium ions enter the nextcell.5.A new nerve impulse is generated.Once the impulse has passed on, the neurotransmitters are quickly broken down to preventcontinuous stimulation.1.5 The Reflex ArcAreflex arcis the simplest and fastest type of nervous response. It allows the body to react quickly,often without conscious thought.A reflex arc works in this order:1.Astimulusis detected by sensory receptors.2.The impulse travels along asensory neuronto the spinal cord.3.The impulse passes through one or moreinterneurons.

Biology - Nervous Coordination - Page 4 preview image

Loading page ...

Study Guide4.A response signal is sent along amotor neuron.5.Amuscle or glandresponds.This rapid pathway helps protect the body from harm, such as pulling your hand away from a hotobject.Reflexes and the BrainIn some reflexes, the brain is also involved. Interneurons send signals up the spinal cord to theconscious areas of the brain, where the stimulus is interpreted. However, the response often happensbeforeyou are fully aware of it.2. Quiz Animal Nerve Cells1. QuestionWhat type of neuron is responsible for carrying stimuli in the brain and spinal cord?Answer Choices•interneurons•motor neurons•sensory neuronsCorrect AnswerinterneuronsWhy This Is CorrectInterneurons are found within thebrain and spinal cord. Their main role is to carry nerve impulsesbetween sensory neurons and motor neurons and to help process information inside the centralnervous system.For example:When you touch something hot, interneurons in the spinal cord help relay and interpret the signalbefore a response is sent to your muscles.

Biology - Nervous Coordination - Page 5 preview image

Loading page ...

Study Guide2. QuestionWhat is the first step in nerve impulse generation?Answer Choices•increased permeability of the cell membrane to sodium ions•increased permeability to calcium ions•potassium ions pumped out of the cytoplasmCorrect Answerincreased permeability of the cell membrane to sodium ionsWhy This Is CorrectA nerve impulse begins when the neuron’s cell membrane becomes more permeable to sodium ions.Sodium ions rushinto the cell, causing depolarization of the membrane. This change in electricalcharge triggers the nerve impulse to start.For example:When a stimulus reaches a neuron, sodium channels open first, allowing sodium ions to enter andinitiate the nerve signal.3. QuestionWhat type of cell protects, nourishes, and supports neurons?Answer Choices•dendrite•glial•interneuronCorrect Answerglial

Biology - Nervous Coordination - Page 6 preview image

Loading page ...

Study GuideWhy This Is CorrectGlial cells (also called neuroglia) do not transmit nerve impulses. Instead,they protect neurons,supply them with nutrients, maintain the surrounding environment, and help support and insulatenerve cells.For example:Glial cells form myelin sheaths around neurons and help keep nerve cells healthy and functioningproperly.Here is aclear, student-friendly rewriteof the chapter. The language is simpler, ideas are brokeninto short sections, and the flow is smoother—while keepingall scientific facts accurate.3. Human Central Nervous SystemThe human nervous system isusually divided into two main parts:•Central nervous system (CNS)–made up of thebrain and spinal cord•Peripheral nervous system (PNS)–made up of all thenerves that branch out from theCNSto the rest of the bodyThe central nervous system acts as the body’scontrol center. It receives information, processes it,and decides how the body should respond.3.1 The Spinal CordThespinal cordis a long, white cord of nervous tissue that runs through a protective bony tunnelformed by thevertebrae. It starts at the base of the brain and extends down to the lower end of thebackbone.3.1.1Protection and Structure•The spinal cord is protected bythree membranes called meninges.•Theouter regionof the spinal cord is made ofwhite matter.•Theinner regionis made ofgray matter.

Biology - Nervous Coordination - Page 7 preview image

Loading page ...

Study GuideThis arrangement helps nerve impulses travel efficiently.3.1.2Nerve Roots and Fluid•Thirty-one pairs of nerve rootsextend from each side of the spinal cord.•These nerve roots contain axons fromsensory neuronsandmotor neurons.•Acentral canalruns through the spinal cord and carriescerebrospinal fluid.Cerebrospinal fluid supplies nutrients and oxygen to spinal cord tissues and helps remove waste.3.1.3Functions of the Spinal CordThe spinal cord has two main roles:1.It acts as acoordinating center for reflex actions.2.It serves as acommunication linkbetween the brain and the peripheral nervous system.3.2The BrainThebrainis the main control and processing center of the central nervous system. It is responsibleforconsciousness, sensation, memory, intelligence, and decision-making.The brain:•Receives impulses from the spinal cord•Receives information from12 pairs of cranial nerves•Can alsoinitiate actions on its own, without any external stimulus3.2.1General Structure of the BrainThe brain is divided intotwo hemispheres:•Lefthemisphere•Right hemisphereTheouter layerof the brain isgray matter, while theinner layeriswhite matter.

Preview Mode

This document has 22 pages. Sign in to access the full document!

Report

Biology - Nervous Coordination

Study Now!

Document Details

Related Documents

Biology - Vascular Plants Structure and Function

Biology - The Unity and Diversity of Life

Biology - The Science of Biology

Biology - The Origin and Evolution of Life

Biology - The Chemical Basis of Life

Biology - The Biology of Cells

Biology - Support and Movement in Animals

Biology - Reproduction

Biology - Recombinant DNA and Biotechnology

Biology - Protista

Company

Explore

Study Tools