Biology 30AP: Mechanisms of Body Control

Key Systems

• Nervous System: Controls the body through electrical impulses (Chapters 37 & 38)
• Endocrine System: Hormonal control (Chapter 40)

Nervous System

Main Functions

• Maintains Equilibrium/Homeostasis: Balance is the main job of the nervous system.
• Controls all body activities along with the endocrine system.

Major Components

• Brain
• Spinal Cord
• Nerves
• Senses

Processes

• Sensory Input: Monitors external and internal environments.
• Integration: Processes information and integrates it with stored data.
• Motor Output: Signals effector organs to make appropriate responses.

Organization

• Central Nervous System (CNS): Brain and spinal cord coordinate incoming and outgoing information.
• Peripheral Nervous System (PNS): Connects the CNS with organs and effectors.

Peripheral Nervous System

Divisions

• Somatic Nervous System: Controls voluntary actions like writing.
• Autonomic Nervous System: Controls involuntary functions (e.g., blood vessels, glands).
  • Sympathetic System: Prepares body for stress (fight or flight).
  • Parasympathetic System: Restores balance (rest and digest).

Cells

• Glial Cells: Support and protect neurons.
• Neurons: Transmit nerve impulses.
  • Sensory Neurons: Relay information from sensory receptors to the CNS.
  • Interneurons: Connect neurons within the CNS.
  • Motor Neurons: Carry impulses from the CNS to effectors.

Anatomy of a Neuron

• Cell Body: Functional portion, known as a ganglion outside the CNS.
• Dendrites: Receive signals.
• Axon: Transmits impulses away.
• Myelin Sheath: Insulates axons, speeding up impulse transmission.

Nerve Impulses

States

• Resting Potential: Polarized state at -70mV.
• Action Potential: Depolarized state at +40mV.

Process

1. Depolarization: Influx of Na+.
2. Repolarization: Outflow of K+.
3. Refractory Period: Recovery phase.

Synapses

• Synaptic Cleft: Gap between neurons.
• Neurotransmitters: Chemicals that transmit signals across synapses.
  • Excitatory: Trigger positive ion influx.
  • Inhibitory: Trigger hyperpolarization.

Common Neurotransmitters

• Dopamine: Pleasure and movement.
• Serotonin: Mood and temperature regulation.
• Endorphins: Natural painkillers.
• Norepinephrine: Works with epinephrine for stress response.

Central Nervous System Protection

• Skull/Vertebrae: Protects brain and spinal cord.
• Meninges: Three protective membranes.
• Cerebrospinal Fluid: Acts as a shock absorber.

Brain Regions

• Forebrain: Intellect, memory, personality.
• Midbrain: Relay center for eye and ear.
• Hindbrain: Balance and autonomic control.

Brain Functions

• Cerebrum: Largest portion; controls reasoning and personality.
• Thalamus: Sensory information relay.
• Hypothalamus & Pituitary: Connect nervous and endocrine systems.

Imaging Technologies

• PET and MRI: Used for brain mapping and understanding functions.

Peripheral Nervous System Functions

• Maintains internal homeostasis via the autonomic system.
• Responds to external stimuli through the somatic system.

Disorders

• Parkinson's Disease: Lack of dopamine.
• Alzheimer's Disease: Lack of acetylcholine.

These notes cover the essential components and functions of the nervous system as outlined in the lecture, providing a comprehensive guide to the mechanisms of body control.