Topic_1_Part_1_Nervous_system_-_Modular

Page 1: Introduction

• Title: FOUNDATION IN SCIENCE BIOLOGY 3

• Prepared by: CPU Biology Team

• Topic: Human Physiology II Part 1: Nervous System

• Goal: Inspire, Empower, Elevate

Page 2: Learning Outcomes

• At the end of this lesson, students should be able to:

  • Describe the components of the nervous system and its functions.

  • State the organization of the nervous system.

  • Describe the structure of a neuron.

  • Explain the generation and propagation of resting potential and action potential.

  • Explain the structure of a synapse and the mechanism involved in synaptic activity.

Page 3: Functions of the Nervous System

• Receiving Information:

  • The nervous system receives stimuli about internal and external environments.

• Responding to Information:

  • The nervous system generates responses based on received stimuli through voluntary and involuntary actions.

• Maintaining Homeostasis:

  • Plays a crucial role in physiological balance by responding to stimuli accordingly.

Page 4: Structural Classification of the Nervous System

• Nervous System Components:

  • Central Nervous System (CNS):

    • Includes the brain and spinal cord; controls body functions.

  • Peripheral Nervous System (PNS):

    • Comprises nerves outside the brain and spinal cord.

Page 5: Overview of CNS and PNS

• Central Nervous System (CNS):

  • Brain: Integrates sensory information and coordinates motor functions.

  • Spinal cord: Pathway for nerve signals to and from the brain.

• Peripheral Nervous System (PNS):

  • Connects the CNS with limbs and organs, carrying sensory and motor information.

Page 6: Organization of the Nervous System

• Nervous System Structure:

  • CNS: Brain and spinal cord.

  • PNS: Carries messages to/from CNS, includes somatic and autonomic nervous systems.

    • Somatic nervous system: Controls voluntary movements.

    • Autonomic nervous system: Controls involuntary functions.

      • Sympathetic nervous system: Arouses body for fight or flight.

      • Parasympathetic nervous system: Calms body for rest and digestion.

Page 7: Components of the Brain

• Three Main Parts of the Brain:

  • Cerebrum: Largest part, responsible for emotions, thoughts, and movements.

  • Cerebellum: Coordinates voluntary movements and balances.

  • Brain Stem: Controls automatic functions like heart rate and breathing.

Page 8: The Cerebrum

• Functionality:

  • Divided into left and right hemispheres.

  • Involved in reasoning, planning, memory, and sensory processing.

  • Responsible for all conscious thought.

Page 9: The Cerebellum

• Functionality:

  • Regulates motor movements, posture, balance, and coordination.

  • Learning motor skills.

  • Damage can lead to balance issues and tremors.

Page 10: The Brain Stem

• Functions:

  • Responsible for automatic functions: breathing, heart rate, body temperature, etc.

• Regions: Midbrain, pons, medulla oblongata.

Page 11: The Spinal Cord

• Structure:

  • Comprised of bundles of nerve fibers.

  • Runs from the brain down through the spinal column.

• Injury Impact:

  • Can cause loss of sensation or motor function.

Page 12: Peripheral Nervous System (PNS)

• Components:

  • Spinal Nerves, Cranial Nerves, Ganglia:

  • Contains both sensory neurons (to CNS) and motor neurons (from CNS).

• Types of Motor Neurons:

  • Somatic and autonomic nervous systems.

Page 13: Autonomic Nervous System

• Functions:

  • Regulates involuntary functions: breathing, heartbeat, and digestion.

  • Controlled by medulla oblongata and hypothalamus.

  • Comprises sympathetic and parasympathetic systems.

Page 14: Sympathetic Nervous System

• Functionality:

  • Activates 'fight or flight' responses in stressful situations.

  • Increases adrenaline and initiates stress responses.

  • Can negatively impact digestive and sexual functions.

Page 15: Parasympathetic Nervous System

• Functionality:

  • Maintains body functions in relaxed state: 'rest and digest.'

  • Restores homeostasis and conserves energy.

  • Important for normal bodily processes.

Page 16: PNS Function Overview

• Effects of Systems:

  • Parasympathetic: Constricts pupils, stimulates saliva, slows heart rate.

  • Sympathetic: Dilates pupils, inhibits saliva, accelerates heart, promotes adrenaline release.

Page 17: Somatic Nervous System

• Components:

  • Controls voluntary movements via skeletal muscles.

  • Involves sensory and motor neurons.

Page 18: Reflexes

• Definition:

  • Automatic responses without conscious thought.

• Components of Reflex Arc:

  • Sensory neuron, interneuron, and effector.

Page 19: Types of Sensory Receptors

• Illustrative diagram outlining the pathway of a reflex action including sensory neurons and effectors (like muscles).

Page 20: Neuron Structure

• Definition:

  • Functional unit of the nervous system specialized for impulse transmission.

Page 21: Neuron Components

• Cell Body: Contains the nucleus and organelles.

• Dendrites: Extensions for carrying impulses towards the cell body.

Page 22: Axons in Neurons

• Functionality:

  • Long fiber transmitting impulses away from the cell body.

  • Surrounded by Schwann cells for protection and insulation.

Page 23: Myelin Sheath

• Function:

  • Multi-layered membrane around axons, enhancing impulse speed.

  • Not all axons have myelin sheaths (invertebrates lack them).

  • Axons with myelin transmit impulses faster.

Page 24: Classes of Neurons

• Types:

  • Sensory Neurons: Relay information from the environment to the CNS.

  • Interneurons: Integrate sensory input and motor output.

  • Motor Neurons: Convey impulses from the CNS to effectors (muscles or glands).

Page 25: Nerve Impulses

• Description:

  • Electrical impulses travel along neurons during communication.

  • Involve resting potential and action potential transitions.

Page 26: Resting Potential

• Definition:

  • In resting state, axon inside is negative and outside positive (approx. -70mV).

• Mechanism:

  • Maintained by sodium-potassium pumps, ensuring Na+ and K+ gradient.

Page 27: Resting Potential Maintenance

• Sodium-Potassium Pump:

  • Moves Na+ out and K+ in actively.

  • More K+ inside and less Na+ to maintain the resting potential.

Page 28: Action Potential Overview

• Mechanism of Action Potential:

  • Results from stimulus-induced membrane potential changes, involving Na+ and K+ channels.

Page 29: Action Potential Initiation

• Process:

  • When a sufficient stimulus is received, Na+ channels open, initiating depolarization, leading to action potential generation.

Page 30: Action Potential: Depolarization

• Detail:

  • Na+ influx occurs when threshold is met, triggering further openings of Na+ channels, resulting in a rapid rise in membrane potential.

Page 31: Action Potential: Repolarization

• Process:

  • As Na+ channels close, K+ channels open causing K+ to exit, restoring the resting membrane potential.

Page 32: Hyperpolarization and Return to Rest

• Detail:

  • Temporary overshoot makes the inside of the neuron more negative (hyperpolarization) before returning to resting potential.

Page 33: Action Potential Graph

• Depiction:

  • A visual representation of membrane potential changes through resting, depolarization, repolarization, and hyperpolarization phases.

Page 34: Membrane Potential Graph

• Description:

  • Graph illustrating changes in membrane potential over time during an action potential cycle.

Page 35: Refractory Period

• Definition:

  • A brief period post-action potential when a neuron is unresponsive to new stimuli.

• Types:

  • Absolute refractory period: No action potential possible.

  • Relative refractory period: Action potential possible with strong stimulus.

Page 36: Propagation of Action Potential

• Process:

  • Action potential moves in one direction along the axon; depolarization of one segment leads to depolarization downstream.

Page 37: Speed of Conduction

• Factors Influencing Speed:

  • Axon Diameter: Larger diameters lead to faster conduction.

  • Myelination: Myelinated axons transmit impulses more rapidly via saltatory conduction across nodes of Ranvier.

Page 38: Structure of a Synapse

• Components:

  • Presynaptic Neuron: Terminal axon end of the transmitting neuron.

  • Postsynaptic Neuron: Begins at the synapse.

  • Synaptic Cleft: Gap between neurons.

Page 39: Visualization of a Synapse

• Diagram indicating presynaptic and postsynaptic neurons and synaptic structures.

Page 40: Mechanism of Synaptic Transmission

• Process:

  • Arrival of action potential at axon terminal opens voltage-gated Ca2+ channels, triggering synaptic vesicle fusion and neurotransmitter release into the synaptic cleft.

Page 41: Acetylcholine Action

• Mechanism:

  • Synthesized from choline and acetyl CoA, quickly broken down by acetylcholinesterase; choline is recycled for further use.

Page 42: Conclusion

• Closing Notes:

  • A brief mention of the educational institution and gratitude.