[RAP0 21LAB] PRELIM: Lesson 4 Nerve Cell

Nerve Cell

• A ___, or neuron, is the fundamental unit of the nervous system, responsible for transmitting electrical and chemical signals throughout the body.

• Neurons are specialized to process and communicate information, playing a crucial role in everything from reflexes to complex thought processes.

Neurons

___ are specialized to process and communicate information, playing a crucial role in everything from reflexes to complex thought processes.

Sensory Neurons; Motor Neurons; Interneurons

3 Types of Neurons

Sensory Neurons

• ___ are nerve cells responsible for transmitting sensory information from the body to the central nervous system (CNS), which includes the brain and spinal cord.

• They detect stimuli from the external environment (such as touch, temperature, and sound) and internal conditions (such as pain and proprioception) and convert them into electrical signals that the brain can interpret

4 Structure of Sensory Neurons

• Dendrites

• Cell body (Soma)

• Axon

• Axon terminals

Dendrites

• Structure of Sensory Neurons

• Receive sensory input from receptors.

Cell body (Soma)

• Structure of Sensory Neurons

• Located in a dorsal root ganglion near the spinal cord.

Axon

• Structure of Sensory Neurons

• Carries the signal to the CNS

Axon terminals

• Structure of Sensory Neurons

• Connect with other neurons in the spinal cord or brain to relay signals.

5 Types of Sensory Neurons

• Mechanoreceptors

• Thermoreceptors

• Nociceptors

• Photoreceptors

• Chemoreceptors

Mechanoreceptors

• Types of Sensory Neurons

• Detect touch, pressure, and vibration (e.g., in the skin).

Thermoreceptors

• Types of Sensory Neurons

• Detect temperature changes.

Nociceptors

• Types of Sensory Neurons

• Detect pain and harmful stimuli.

Photoreceptors

• Types of Sensory Neurons

• Detect light (found in the eyes)

Chemoreceptors

• Types of Sensory Neurons

• Detect chemicals (e.g., taste and smell).

transmit; chemical

• Function of Nerve Cell

• Nerve cells, or neurons, are specialized cells in the nervous system that ___ electrical and ___ signals throughout the body.

6 Main Function of Nerve Cell

1. Signal Transmission

2. Sensory Input

3. Motor Control

4. Integration and Processing

5. Homeostasis Regulation

6. Memory and Learning

Signal Transmission

• Main Function of Nerve Cell

• Neurons send and receive electrical impulses to coordinate body functions.

Sensory Input

• Main Function of Nerve Cell

• Sensory neurons detect external and internal stimuli (e.g., pain, temperature, touch) and relay information to the brain.

Motor Control

• Main Function of Nerve Cell

• Motor neurons carry signals from the brain and spinal cord to muscles, enabling movement.

Integration and Processing

• Main Function of Nerve Cell

• Interneurons connect sensory and motor neurons, processing information and enabling complex reflexes and responses.

Homeostasis Regulation

• Main Function of Nerve Cell

• Neurons help regulate vital functions like heart rate, breathing, and digestion through autonomic signals.

Memory and Learning

• Main Function of Nerve Cell

• Neurons in the brain form networks that store and process information, allowing for learning and recall

Motor Neurons

• ___ are nerve cells that carry signals from the central nervous system (CNS) to muscles and glands, enabling movement and bodily functions.

• They play a crucial role in voluntary and involuntary muscle control.

carry signals

Motor neurons are nerve cells that ___ from the central nervous system (CNS) to muscles and glands, enabling movement and bodily functions.

Central Nervous System

CNS

Upper Motor Neurons (UMNs) and Lower Motor Neurons (LMNs)

2 Types of Motor Neurons

Upper Motor Neurons

UMNs

Upper Motor Neurons (UMNs)

• Located in the brain (cerebral cortex) and brainstem.

• Send signals down the spinal cord to lower motor neurons.

• Involved in voluntary movement and muscle coordination.

• Damage to ___ can cause conditions like spastic paralysis and hyperreflexia (overactive reflexes).

spastic paralysis and hyperreflexia

Damage to UMNs can cause conditions like ___ & ___ (overactive reflexes).

Lower Motor Neurons (LMNs)

• Located in the spinal cord and brainstem.

• Directly innervate muscles to cause contraction.

• Control both voluntary and involuntary movements.

• Damage to ___ can lead to flaccid paralysis, muscle weakness, and hyporeflexia (reduced reflexes).

flaccid paralysis, muscle weakness, and hyporeflexia

Damage to LMNs can lead to ___, ____, ____

5 Structure of Motor Neurons

• Cell Body (Soma)

• Dendrites

• Axon

• Myelin Sheath

• Axon Terminals

Cell Body (Soma)

• Structure of Motor Neurons

• Contains the nucleus and controls cell functions.

Dendrites

• Structure of Motor Neurons

• Receive input from other neurons.

Axon

• Structure of Motor Neurons

• A long fiber that transmits impulses to muscles.

Myelin Sheath

• Structure of Motor Neurons

• A protective covering that speeds up signal transmission.

Axon Terminals

• Structure of Motor Neurons

• Release neurotransmitters (e.g., acetylcholine) to stimulate muscle contraction.

4 Function of Motor Neurons

• Receiving signals from the brain and spinal cord.

• Transmitting electrical impulses along their axons.

• Releasing neurotransmitters at neuromuscular junctions.

• Activating muscle contraction or gland secretion.

3 Motor Neuron Diseases (MNDs)

• Amyotrophic Lateral Sclerosis (ALS)

• Spinal Muscular Atrophy (SMA)

• Multiple Sclerosis (MS)

Motor Neuron Diseases

MNDs

Amyotrophic Lateral Sclerosis

ALS

Amyotrophic Lateral Sclerosis (ALS)

• Motor Neuron Diseases (MNDs)

• A progressive disease that affects both upper and lower motor neurons, leading to muscle weakness and paralysis.

Spinal Muscular Atrophy

SMA

Spinal Muscular Atrophy (SMA)

• Motor Neuron Diseases (MNDs)

• A genetic condition that primarily affects lower motor neurons, causing muscle wasting.

Multiple Sclerosis

MS

Multiple Sclerosis (MS)

• Motor Neuron Diseases (MNDs)

• A condition where the immune system damages myelin, disrupting motor neuron function.

Interneurons

___, also known as association neurons, are nerve cells that connect sensory and motor neurons within the central nervous system (CNS).

association neurons

Interneurons, also known as ___, are nerve cells that connect sensory and motor neurons within the central nervous system (CNS).

4 Structures of Interneurons

• Cell Body (Soma)

• Dendrites

• Axon

• Axon Terminals

Cell Body (Soma)

• Structures of Interneurons

• Contains the nucleus and organelles.

Dendrites

• Structures of Interneurons

• Receive signals from other neurons.

Axon

• Structures of Interneurons

• Can be short or long, depending on the function.

Axon Terminals

• Structures of Interneurons

• Transmit signals to motor neurons or other interneurons.

4 Types of Interneurons

• Excitatory Interneurons

• Inhibitory Interneurons

• Relay Interneurons

• Local Interneurons

Excitatory Interneurons

• Types of Interneurons

• Increase the activity of other neurons by releasing excitatory neurotransmitters (e.g., glutamate).

Inhibitory Interneurons

• Types of Interneurons

• Decrease neuronal activity by releasing inhibitory neurotransmitters (e.g., GABA, glycine).

Relay Interneurons

• Types of Interneurons

• Transmit signals over long distances within the CNS (e.g., from the spinal cord to the brain).

Local Interneurons

• Types of Interneurons

• Connect nearby neurons for rapid processing (e.g., in the brain’s cortex).

4 Function of Interneurons

• Processing sensory input

• Coordinating motor output

• Reflex actions

• Higher cognitive functions

Processing sensory input

• Function of Interneurons

• They receive signals from sensory neurons and help interpret the information.

Coordinating motor output

• Function of Interneurons

• They relay signals to motor neurons for appropriate responses.

Reflex actions

• Function of Interneurons

• In spinal reflexes (like the knee-jerk reflex), interneurons quickly transmit signals without involving the brain.

Higher cognitive functions

• Function of Interneurons

• They are involved in complex processes like thinking, learning, memory, and emotions.

3 Interneurons Activity

• Reflex Arc

• Brain Function

• Inhibitory Control

Reflex Arc

• Interneurons Activity

• When you touch something hot, sensory neurons send signals to interneurons in the spinal cord, which then quickly relay the signal to motor neurons to pull your hand away.

Brain Function

• Interneurons Activity

• Interneurons in the cerebral cortex help process thoughts, memory, and decision-making.

Inhibitory Control

• Interneurons Activity

• Some interneurons suppress unwanted movements, preventing muscle spasms or tremors.

Epilepsy; Parkinson’s Disease; Schizophrenia

• 3 Interneurons Disorders

• Dysfunction of interneurons is linked to various neurological disorders.

Epilepsy

• Interneurons Disorders

• Due to an imbalance between excitatory and inhibitory interneurons.

Parkinson’s Disease

• Interneurons Disorders

• A loss of certain interneurons disrupts motor control.

Schizophrenia

• Interneurons Disorders

• Altered interneuron function affects cognitive processing.