Introduction to Physiology - Nervous System

Introduction to Physiology - Nervous System

• Physiology is the study of how living organisms and their parts function.
• It is fundamental to understanding medicine.
• Diseases can be viewed as physiology gone wrong (pathophysiology).
• Understanding physiology is vital for the study and practice of medicine.

Objectives

• Define physiology.
• Describe the levels of organization in an organism.
• Provide an overview of human physiology.
• Describe the cell as the basic unit of life.
• Outline the basic structure and function of cell organelles.
• Discuss the hierarchical levels of organization, from cells to body systems.

What is Physiology?

• Types of Physiology: Cellular and System
  • Cellular physiology focuses on cellular components that determine organ function.
  • System physiology studies the coordinated and networked processes that maintain function and adaptation.
  • Examples include respiratory and cardiovascular systems working together for homeostasis.
• Anatomy vs. Physiology
  • Anatomy describes structure.
  • Physiology describes function.

Level of Structural Organization

• Different levels of organization exist in organisms, from atoms to organ systems.
• Atoms combine to form molecules.
• Molecules form organelles.
• Organelles combine to form cells.
• Similar cells form tissues.
• Tissues form organs.
• Multiple organs form organ systems.
• Organ systems work together to maintain homeostasis.

Tissues

• Tissues are collections of specialized cells.
• Tissues work together to form organs.
• Four major tissue types:
  • Muscle
  • Nervous
  • Epithelial
  • Connective

Types of Tissues (continued)

• Muscle tissues generate mechanical force.
  • Skeletal muscles, cardiac muscles, smooth muscles
• Nervous tissues initiate, integrate, and conduct electrical signals.

Brain Structure and Chemistry - Communication

• Understanding brain structure and chemistry is related to how the nervous system communicates.
• Receptor cells in sensory systems detect energy.
• Information is transmitted via transduction and sensory/afferent neurons to the nervous system.
• Information is received, processed, and leads to perception in the brain.
• The brain sends commands via the nervous system to control responses.
• This process involves afferent and efferent neurons.
  • Afferent neurons carry signals toward the central nervous system.
  • Efferent neurons carry signals away from the central nervous system.

The Nervous System

• Two main parts: central and peripheral.
  • Central nervous system (CNS): control center (brain and spinal cord). Receives, processes, interprets, and stores sensory information.
  • Peripheral nervous system: outside the brain and spinal cord; handles CNS input and output. Divided into somatic and autonomic nervous systems.
    • Somatic nervous system: voluntary movement, skeletal muscles, and sensory information.
    • Autonomic nervous system: regulates blood vessels, glands, and internal organs (bladder, stomach, heart). Includes sympathetic and parasympathetic systems. -Sympathetic nervous system is active during stress ("fight or flight"). -Parasympathetic nervous system is active during rest.

The Neuron (Nerve Cell)

• The neuron is the fundamental unit of the nervous system.
• Has common structures: nucleus, soma (cell body), with specialized structures: axon, dendrites.
  • Axon sends signals.
  • Dendrites receive signals.
• Myelin sheath: insulating layer that speeds signal transmission.
• Axon terminals: where the electrical signal becomes a chemical message and communicates to adjacent neurons. -Glial cells support the functions of neurons acting like glue and providing nourishment, removing waste products, and protecting neurons from harm.

Neurotransmitters

• Neurotransmitters are essential for neural communication.

• Key neurotransmitters include

  • Dopamine
  • Serotonin
  • Endorphins
  • Norepinephrine
  • GABA
  • Glutamate

Brain (continued)

• Key brain structures:
  • Medulla: regulates breathing, heart rate, and blood pressure.
  • Pons: acts as a bridge between the cerebellum and medulla.
  • Reticular formation: responsible for alertness and attention.
  • Cerebellum: coordinates movement and balance, involved in learned responses.
  • Thalamus: major sensory relay center (except smell).
  • Hypothalamus: involved in survival drives, temperature regulation, and autonomic system control.
  • Amygdala: evaluates sensory information and emotional significance.
  • Hippocampus: important for forming spatial memories and new memories.