Nervous System Functions and Signals

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the three primary functions of the nervous system?

Sensory, Motor, and Digestive

Motor, Cognitive, and Sensory

Sensory, Integrative, and Motor (correct)

Sensory, Integrative, and Homeostatic

What is the term for the electrical signal conducted by neurons?

Action potential (correct)

Neural wave

Nerve impulse

Signal potential

Which branch of the nervous system is responsible for analyzing incoming sensory information?

Voluntary

Sensory

Integrative (correct)

Motor

Which type of cell in nervous tissue is responsible for support and protection?

Neuroglia Signup and view all the answers

What does the sensory function of the nervous system primarily involve?

Detecting changes via sensory receptors Signup and view all the answers

Which of the following best describes a neuron?

Electrically excitable cellular structures Signup and view all the answers

What is the main purpose of the nervous system in maintaining health?

To maintain homeostasis Signup and view all the answers

How do effectors function in the nervous system?

They respond to stimuli. Signup and view all the answers

What is the primary function of Action Potentials in excitable cells?

To facilitate communication over short and long distances Signup and view all the answers

Which type of ion channel is most prevalent in neurons?

K+ channels Signup and view all the answers

Which type of ion channel responds to changes in membrane potential?

Voltage-gated channels Signup and view all the answers

What characterizes Graded Potentials in comparison to Action Potentials?

Graded Potentials allow communication over short distances only Signup and view all the answers

What is a characteristic function of Ligand-gated channels?

Respond to chemical stimuli Signup and view all the answers

Leak channels are characterized by which of the following?

They alternate between opening and closing Signup and view all the answers

Which of the following statements about resting membrane potential is true?

Resting membrane potential is maintained by various ion channels Signup and view all the answers

Which type of stimuli do Mechanically-gated channels react to?

Mechanical vibration or pressure Signup and view all the answers

What primarily determines the amplitude of a graded potential?

Strength of the stimulus Signup and view all the answers

What is the main characteristic of graded potentials compared to action potentials?

Graded potentials can be summed together Signup and view all the answers

Which phase of an action potential involves the membrane potential becoming more negative?

Repolarization phase Signup and view all the answers

What must occur for an action potential to be generated?

Membrane potential reaching threshold Signup and view all the answers

Which type of channels are primarily involved in the conduction of action potentials?

Voltage-gated channels for Na+ and K+ Signup and view all the answers

How do graded potentials differ in their propagation compared to action potentials?

Graded potentials are decremental Signup and view all the answers

During which phase of an action potential does the membrane potential increase rapidly?

Depolarization phase Signup and view all the answers

What is one major feature of action potentials compared to graded potentials?

Action potentials propagate along the axon Signup and view all the answers

What is necessary for repair to occur in the peripheral nervous system (PNS)?

Functional Schwann cells Signup and view all the answers

Which step is NOT involved in the repair process in the PNS?

Myelination of axons Signup and view all the answers

What is a common symptom of multiple sclerosis?

Muscle weakness Signup and view all the answers

What is a common treatment for depression?

Selective serotonin reuptake inhibitors (SSRIs) Signup and view all the answers

Which type of depression is characterized by recurring episodes of mania and depression?

Bipolar depression Signup and view all the answers

What causes excitotoxicity in the CNS?

High levels of glutamate Signup and view all the answers

What defines epilepsy?

Short, recurrent attacks of various functions Signup and view all the answers

What type of depression is persistent but less severe than major depression?

Dysthymia Signup and view all the answers

What is the typical amplitude range of action potentials?

Typically about 100 mV Signup and view all the answers

Which factors contribute to the speed of action potential propagation?

Amount of myelination and temperature Signup and view all the answers

How does the duration of graded potentials compare to that of nerve impulses?

Graded potentials are typically longer than nerve impulses Signup and view all the answers

What distinguishes action potentials from graded potentials regarding polarity?

Action potentials consist of depolarizing and repolarizing phases Signup and view all the answers

Which statement best describes refractory periods in graded potentials?

There are no refractory periods in graded potentials Signup and view all the answers

How does myelination affect action potential propagation?

Myelination increases the speed of action potential propagation Signup and view all the answers

What occurs to action potentials as they propagate along a neuron?

They maintain their strength Signup and view all the answers

Which of the following statements is true regarding the duration of nerve impulses?

Nerve impulses can range from 0.5 to 2 msec Signup and view all the answers

What triggers ligand-gated channels to open?

Binding of a ligand Signup and view all the answers

Which type of neurons primarily contains voltage-gated channels?

All types of neurons Signup and view all the answers

What is the state of the membrane potential of a non-conducting neuron?

Positive outside and negative inside Signup and view all the answers

What maintains the resting membrane potential in neurons?

N a+/K+ pumps Signup and view all the answers

Which types of stimuli can open mechanically gated channels?

Mechanical stimuli such as touch Signup and view all the answers

Which statement best describes graded potentials?

They represent small deviations in resting membrane potential. Signup and view all the answers

Which ions are primarily responsible for determining the resting membrane potential?

Sodium and Potassium Signup and view all the answers

What effect do most anions have on the intracellular environment of a neuron?

They cannot leave the cell. Signup and view all the answers

Study Notes

Nervous Tissue Overview

The nervous system maintains homeostasis by controlling conditions within healthy limits.
The nervous system has various branches and cell types.
The chapter aims to detail the structure and function of nervous tissue.

Nervous System Overview

Neurons are electrically excitable cells.
Nervous impulses travel in specific directions.
Key neuron types include sensory, interneurons, and motor neurons.

Nervous System Organization

The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
The CNS comprises the brain and spinal cord.
The PNS includes cranial, spinal nerves, enteric plexuses, and sensory receptors.

Functions of the Nervous System

The nervous system detects changes via sensory receptors.
It analyzes sensory data, stores aspects, and directs appropriate actions.
It responds to stimuli via effectors.

Histology of Nervous Tissue

The study of nervous tissue structure.
Includes neurons and neuroglia (nerve support cells).

Neurons (Structure)

Neurons are electrically excitable cells.
Their parts include dendrites, cell body, axon, and axon terminals.
Diagrams illustrate a nerve impulse's path and neuron structure.

Neuronal Classification

Neurons are classified structurally by the number of processes emanating from their cell body (multipolar, bipolar, pseudounipolar).
Functionally, they are classified by the direction of nerve impulse propagation (sensory, motor, interneurons).

Neuroglia

Neuroglia makes up approximately half the total volume of the nervous system.
Neuroglia are non-excitable cells that support and protect neurons.
They are crucial for maintaining the chemical environment around neurons and can multiply and divide.
Several types of neuroglia exist in the central and peripheral nervous systems (4 in CNS, 2 in PNS).
Neuroglia support neurons in a variety of ways.

Myelination of Neurons

Myelin is a fatty substance that surrounds some axons.
It's produced by Schwann cells (PNS) and oligodendrocytes (CNS).
Myelin dramatically increases the speed of impulse transmission.

Gray Matter vs. White Matter

Gray matter lacks myelin and contains neuron cell bodies.
White matter is rich in myelinated axons.
These structures are prevalent within the brain and spinal cord.

Electrical Signals in Neurons

Excitable cells communicate via action potentials and graded potentials.
Action potentials facilitate over long or short distances, while graded potentials are limited to shorter distances.
These signals depend on the existence of a resting membrane potential and specific ion channels.

Resting Membrane Potential

The membrane of a non-conducting neuron has a negative charge inside and a positive charge outside.
This difference is caused by uneven ion distribution across the membrane
Selective membrane permeability factors are involved.
The Na+/K+ pump plays a critical role in maintaining this potential.

Graded Potentials

Small deviations in the resting membrane potential.
Generated by the opening of mechanically gated or ligand-gated ion channels.
Their amplitude varies with the strength of the stimulus.
Can be summed (temporal or spatial).

Action Potentials

A rapid sequence of events that reverses and eventually restores the membrane potential.
Consists of two phases: depolarization and repolarization.
The strength of a stimulus determines whether an action potential occurs.
All-or-none principle applies to action potentials. The signal strength remains unchanged as it propagates along the axon.

Propagation of Action Potentials

Action potentials travel from the trigger zone down the axon to the axon terminals.
Propagation occurs through continuous or saltatory conduction.
Factors affecting conduction speed include axon diameter, myelination, and temperature.

Signal Transmission at Synapses

A synapse is the connection between two neurons or a neuron and an effector.
Two main types of synapses exist: electrical and chemical.
Chemical synapses involve neurotransmitters for signal transmission.

Postsynaptic Potentials

Excitatory postsynaptic potentials (EPSPs) are depolarizing.
Inhibitory postsynaptic potentials (IPSPs) are hyperpolarizing.
Often, postsynaptic potentials are summed.

Neurotransmitter Receptors

Neurotransmitters (chemical messengers) at chemical synapses can trigger excitatory or inhibitory postsynaptic potentials.
Receptors are either ionotropic or metabotropic.
Ionotropic receptors directly open ion channels, whereas metabotropic receptors utilize a second messenger system.

Removal of Neurotransmitters

Neurotransmitters are cleared from the synaptic cleft to terminate signaling.
Removal methods include diffusion, enzymatic degradation, and reuptake into cells.

Summation

Summation occurs when multiple presynaptic neurons simultaneously or sequentially release neurotransmitters onto a postsynaptic neuron.

Neural Circuits

Functional groups of interconnected neurons that perform a particular task. Different types of neural circuits (e.g., simple series, diverging, converging, reverberating, parallel after-discharge).

Regeneration & Repair of Nervous Tissue

The nervous system exhibits plasticity but neurons have limited regenerative capacity.

Neurogenesis in the CNS

There is minimal repair in the central nervous system due to inhibitory neuroglia.
Factors like the absence of growth stimulants and rapid scar tissue formation hinder repair.

Damage and Repair in the PNS

Nerve repair is more likely in the peripheral nervous system than in the central nervous system, provided the cell body is intact.

Neural Disorders (Multiple Sclerosis & Depression)

Multiple sclerosis is an autoimmune disease causing myelin sheath destruction.
Depression presents as various types with common symptoms like lack of interest, sadness, helplessness and potentially suicidal thoughts.

Other Neural Disorders (Epilepsy & Excitotoxicity)

Epilepsy involves recurrent seizures.
Excitotoxicity is neuronal damage caused by prolonged stimulation from excitatory neurotransmitters.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the primary functions and mechanisms of the nervous system. This quiz covers various aspects, including electrical signals, types of cells, and ion channels involved in neural communication. It’s perfect for students studying neurobiology or related fields.