Introduction to Physiology

Introduction to Physiology

• Physiology is the study of how living organisms function.
• It encompasses the physical and chemical processes within an organism that maintain life.
• It examines the structure and function of cells, tissues, organs, and organ systems at levels from molecules to the whole organism.
• Physiology is closely related to anatomy, which describes the structure of the body.
• Understanding physiology helps explain how organisms respond to their environment and maintain homeostasis.

Levels of Organization in Physiology

• Chemical Level: Atoms combine to form molecules, like proteins and carbohydrates, critical for cellular processes.
• Cellular Level: Molecules assemble into cells, the basic units of life, performing specialized functions.
• Tissue Level: Similar types of cells group together to form tissues, exemplified by muscle tissue or nervous tissue.
• Organ Level: Different tissues combine to form organs, each with a specific function, like the heart or the brain.
• Organ System Level: Organs working together form organ systems, such as the respiratory system for gas exchange.
• Organism Level: All organ systems interacting within an organism.

Homeostasis

• Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes.
• This stability is essential for proper cellular function.
• Key factors maintained include temperature, blood glucose, blood pressure, and pH.
• Various mechanisms, including feedback loops, regulate these factors.

Feedback Loops

• Negative Feedback Loops: These loops counteract a change in a regulated variable, bringing the variable back to its set point.
• A typical example is temperature regulation, where a rising temperature triggers mechanisms to cool the body.
• Positive Feedback Loops: These loops amplify a change in a regulated variable, pushing the variable further from its set point.
• An example is childbirth, where contractions stimulate further contractions.

Cellular Physiology

• Cells exhibit various physiological processes.
• Diffusion: Movement of substances down a concentration gradient.
• Active Transport: Movement of substances against a concentration gradient using energy.
• Osmosis: Movement of water across a selectively permeable membrane.
• Cell Signaling: Communication between cells using chemicals and electrical signals.

Nervous System Physiology

• The nervous system facilitates rapid communication in the body.
• Neurons: Specialized cells that transmit electrical signals.
• Neurotransmitters: Chemical messengers that carry signals across synapses.
• The nervous system controls muscle contraction and sensory perception.
• Sensory input, integration, and motor output are key functions of the nervous system.

Cardiovascular Physiology

• The cardiovascular system circulates blood throughout the body.
• Heart: Pumps blood to the body.
• Blood Vessels: Carry blood and nutrients.
• Blood: Transports oxygen, nutrients, and waste products.
• Blood pressure and flow are critical factors.

Respiratory Physiology

• The respiratory system facilitates gas exchange.
• Lungs: Organs where gas exchange occurs.
• Breathing: Movement of air into and out of the lungs.
• Oxygen uptake and carbon dioxide removal are key.

Digestive Physiology

• The digestive system breaks down food for absorption.
• Mouth, Esophagus, Stomach, Intestines: Organs involved in digestion.
• Enzymes and other processes facilitate nutrient breakdown and absorption.

Renal Physiology

• The renal system filters blood and maintains electrolyte balance.
• Kidneys: Organs that filter blood and produce urine.
• Water and electrolyte homeostasis depend on kidney function.

Endocrine System Physiology

• The endocrine system uses hormones to regulate various body functions.
• Hormones: Chemical messengers that affect target cells/tissues
• Hormones regulate metabolism, growth, and reproduction.

Other Important Concepts

• Muscle Physiology: Muscle contraction and movement, using ATP.
• Immune System Physiology: Body's defense against pathogens.
• Integumentary System Physiology: Skin's role in protection, temperature regulation.