Neural Control and Coordination

Definition of Neural System:**

• A complex network of specialized cells called neurons that transmit information throughout the body.

Components of Neural System:

• Central Nervous System (CNS): Comprises brain and spinal cord
• Peripheral Nervous System (PNS): Consists of nerves, ganglia, and sensory receptors present across the body.

Organization of Human Nervous System:

• Central Nervous System (CNS):

• Brain: Consisting of cerebrum, cerebellum, brainstem (midbrain, pons, medulla oblongata)

• Spinal cord: Extends from the brain, forming the main bundle of nerves along back

• Peripheral Nervous System (PNS):

  • Somatic Nervous System: Allows conscious control over body movement

• Autonomic Nervous System (ANS): Controls involuntary functions

Structural and Functional Organization of Neuron:

• Neuron: Basic unit of Nervous system
• Cell Body/Soma: Contains nucleus, organelles
• Dendrites: Receive signals from other neurons
• Axon: Sends signals to other neurons
• Axon Terminal: Branching at end of axon
• Myelin Sheath: Covers axon, enhances impulse conduction in certain neurons

Nerve Impulse Generation and Propagation:

• Resting Membrane Potential: Electrical difference across membrane; neuron at rest
• Action Potential: Electrical signal that travels along the axon
• Sodium-Potassium Pump: Maintains resting potential, involved in repolarization
• Depolarization: Rise in membrane potential, causing action potential
• Refractory Periods: Phases during/after action potential when no response is generated

Synapse and Synaptic Transmission:

• Synapse: Junction where neurons communicate
• Chemical Synapse: Neurotransmitter release from one neuron stimulates the next
• Electrical Synapse: Ions directly flow between neurons

Neurotransmitters and their Role:

• Chemical messengers that facilitate synaptic transmission
• Acetylcholine (ACh): Muscle control, memory, sensory functions
• Serotonin (5-HT): Sleep, mood regulation
• Dopamine (DA): Movement, reward, motivation
• Glutamate: Major excitatory neurotransmitter
• γ-Aminobutyric Acid (GABA): Main inhibitory neurotransmitter

Central Nervous System (CNS)

a. Functions of Different Regions of Brain:

• Cerebrum: Higher-order functions (thinking, learning, language, memory)
• Cerebellum: Coordination, balance
• Brainstem: Breathing, cardiovascular regulation, basic motor functions

b. Functions of Spinal cord:

• Transmission of signals to/from brain and peripheral nerves
• Coordination of motor reflexes

Peripheral Nervous System (PNS)

a. Somatic Nervous System:

• Voluntary control of skeletal muscle movement

b. Autonomic Nervous System (ANS):

• Controls involuntary functions (e.g., heart rate, digestion, breathing)
• Sympathetic Nervous System (SNS): “Fight or Flight” response
• Parasympathetic Nervous System (PNS): “Rest and Digest” response

Reflex Action

• Definition: Automatic and rapid involuntary responses to stimuli
• Types:
• Inborn (Simple) Reflexes: Inherited, unlearned responses
• Conditioned Reflexes: Acquired through learning, not inherited (ex. Pavlov’s dog experiments)

Reflex Arc:

• Sensory receptor receives a stimulus
• Afferent neuron sends signals to CNS (spinal cord/brain)
• CNS coordinates and transmits the response
• Efferent neuron carries the response to the effector organ (muscle or gland)

Sense Organs and their Physiology:

• Various Sense Organs: Eyes for vision, Ears for hearing, Nose for smell, Tongue for taste, Skin for touch and temperature

• Specialized receptors: Transmits sensory information to the brain

Endocrine System:

• Glands produce chemical messengers called hormones, transported through bloodstream to target organs/cells

a. Types of Hormones:

• Steroids (ex. estrogen, testosterone), Protein/Polypeptides (ex. insulin, glucagon), Amino Acid Derivatives (ex. epinephrine)

b. Mechanism of hormone action:

• Endocrine glands: Release hormones directly into the bloodstream
• Target Organs/Cells: Contain specific receptors for specific hormones
• Hormone binding triggers various intracellular responses, like gene expression or enzyme activation

Homeostasis and Thermoregulation

• Homeostasis: Maintenance of a relatively stable internal environment
  • Role of hormones: Regulate homeostasis by controlling various physiological processes(e.g., blood glucose, blood pressure)
  • Body Temperature: Controlled through the processes like sweating, shivering, and blood flow regulation.