Human Physiology Review Notes

Human Anatomy and Physiology

Anatomy: The study of the external and internal structures of the body and the physical relationships between body parts. It involves careful observation of the human body.
- Anatomical information provides clues about probable functions.
Physiology: The study of the function of bodily structures.
- Physiological mechanisms are explained in terms of the underlying anatomy.
- Specific physiological functions are performed by specific anatomical structures.
- Example: Nasal cavity functions (filtering, warming, humidifying air) are related to the shape of bones causing air turbulence.

Living organisms share common characteristics despite their diversity.
These characteristics provide a framework for understanding the structure and function of organisms.

All specific functions are performed by specific structures.
The link between structure and function is always present, but not always understood.
Example: The anatomy of the heart was described in the 15th century, but its pumping action was demonstrated 200 years later.

Anatomy (from “a cutting open”): The study of internal and external structures of the body and the physical relationships among body parts.
Gross Anatomy (Macroscopic Anatomy):
- Examination of relatively large structures and features visible with the unaided eye.
- Example: Dissected heart.
Microscopic Anatomy:
- Deals with structures that cannot be seen without magnification.
- Dissecting microscope: For seeing tissue structure.
- Light microscope: For seeing basic details of a cell structure.
- Electron microscope: For seeing individual molecules (a few nanometers (nm; billionths of a meter) across).

Physiology: The study of function and how living organisms perform their vital functions.
Focuses on functional properties, such as the timing and sequence of the heartbeat, and its effects on blood pressure in major arteries.
Example: Heartbeat coordination via electrical events, detected by electrocardiogram (ECG).

Anatomical details are significant because each has an effect on function.
Physiological mechanisms can be fully understood only in terms of the underlying structural relationships.
Example: Elbow joint functions like a hinge, with functional limits imposed by its internal structure.
Chemical Level:
- Cells communicate through chemical messengers.
- Attachment of messenger to receptor depends on three-dimensional shapes.

Free-living cells are the smallest living structures with all basic characteristics of life.
Multicellular organisms consist of thousands to billions of cells working together.
There are approximately 200 different types of cells in the human body.
Cell dimensions are usually given in micrometers (\\mu m).
- One micrometer is one-millionth of a meter (1 \,\,\, \mu m = 10^{-6} m), or approximately 1/25,000th of an inch.
Skeletal muscle cells can be very large (e.g., diameter of a small dinner plate and over 300 \,\,\mu m long at 1500x magnification).
Cell Theory Principles:
- Cells are the structural building blocks of all plants and animals.
- Cells are produced by the divisions of pre-existing cells.
- Cells are the smallest structural units that perform all vital functions.

The roughly 200 different cell types combine to form tissues.
- Tissues: Collections of similar cells and cell products that perform specific functions.
Histology: The study of tissues.
Four Primary Tissue Types:
- Epithelial Tissue:
  - Forms a barrier with specific properties.
  - Covers external surfaces, lines digestive, respiratory, reproductive, and urinary tracts, surrounds internal cavities, and lines blood vessels and the heart.
- Connective Tissue:
  - Diverse in appearance.
  - Contains cells and an extracellular matrix (protein fibers and ground substance).
  - Matrix varies; in blood, it’s watery plasma; in bone, it’s a durable matrix with calcium salts.
- Muscle Tissue:
  - Unique; cells can contract forcefully.
  - Functions include skeletal movement, soft tissue support, maintenance of blood flow, movement of materials along internal passageways, and stabilization of body temperature.
  - Three different types of muscle tissue.
- Nervous Tissue:
  - Specialized to carry information.
  - Two basic cell types: neurons (transmit information via electrical impulses) and neuroglia (supporting cells).
  - Divided into the central nervous system (brain and spinal cord) and the peripheral nervous system (nerves connecting the central nervous system with other tissues and organs).

Organ: Functional unit composed of more than one tissue type.
- The combination and organization of tissues determine and limit the organ's functions.
Organ System: Consists of organs that interact to perform a specific range of functions.
Example: Heart (organ) contains cardiac muscle tissue, epithelial tissue, connective tissues, and nervous tissue.
- Cardiac muscle cells ensure coordinated contractions.
- Nervous tissue adjusts heart rate.
Cardiovascular System:
- Includes the heart, blood vessels, and circulating blood.
- Distributes oxygen, nutrients, water, and heat throughout the body.
- Transports wastes to sites where they can be excreted.

There are 11 organ systems in the human body.
The concept of separate organ systems is artificial because nothing functions in isolation.
Organs and organ systems are interdependent.
Example: Heart cannot pump blood effectively after massive blood loss, leading to damage in all cells, tissues, and organs.