Introduction to Physiology

Study Notes

Physiology is the study of how living organisms function.
It encompasses a broad range of topics, from the function of individual cells to the workings of entire organ systems.
Physiological processes are complex and integrated, enabling organisms to maintain internal stability (homeostasis).
It relies heavily on the principles of physics and chemistry to understand biological phenomena.
Physiology often overlaps with other disciplines such as anatomy and biochemistry.

Cells are the fundamental units of life.
Cellular physiology focuses on the chemical and physical processes within cells.
Key processes include:
- Membrane transport: Movement of substances across cell membranes.
- Metabolism: Chemical reactions providing energy and constructing macromolecules.
- Cellular signaling: Communication between cells.
- Cellular reproduction: Cell division processes (mitosis, meiosis).
Understanding cellular mechanisms is fundamental to comprehending the function of tissues, organs, and systems within an organism.

Organ systems work together to perform specific functions essential for life.
Key organ systems include:
- Cardiovascular system: Transports blood, oxygen, and nutrients.
- Respiratory system: Facilitates gas exchange.
- Digestive system: Breaks down food and absorbs nutrients.
- Nervous system: Controls bodily functions and responses.
- Endocrine system: Regulates bodily functions through hormones.
- Urinary system: Removes waste products.
- Musculoskeletal system: Provides support and movement.
- Immune system: Protects against pathogens.
Organ system function stems from the coordinated activity of the cells and tissues within.

Homeostasis is the ability of an organism to maintain a stable internal environment.
This involves intricate regulatory mechanisms.
Examples of regulated variables are temperature, blood glucose, and pH.
Feedback loops are crucial for homeostasis:
- Negative feedback loops: The system responds in the opposite direction to counter the initial change.
- Positive feedback loops: The response amplifies the initial change.
Maintaining homeostasis is essential for overall health and survival.

Muscles contract to generate force and movement.
Different types of muscles (skeletal, smooth, cardiac) exhibit unique properties and functions.
Muscle contraction is a complex process involving interactions between proteins, such as actin and myosin within myofibrils.
Neural stimulation initiates the process of muscle contraction.

The nervous system transmits information throughout the body.
It consists of neurons that convey signals through electrochemical impulses.
Neurons communicate at synapses, where neurotransmitters facilitate signal transmission between neurons.
The nervous system controls many functions in the body, including movement, sensation, thoughts, memories, and emotions.