Human Physiology Chapter 1

Physiology

The study of the normal function of living organisms

What is an example of how anatomy supports physiology?

The heart has four chambers and thick muscular walls, which allow the heart to pump blood throughout the body.

Give an example of why proper functioning of one part depends on the function of a different part(s).

Muscles cannot move without input from the nervous system.

What must happen for oxygen to be delivered to your cells?

1) Oxygen is carried in the bloodstream by red blood cells called erythrocytes.

2) RBCs are generated in the bone marrow (a tissue found in certain bones) in the skeletal system.

3) A hormone called erythropoietin is released by the kidneys, and it regulates the synthesis of RBCs (renal system)

4) The heart pumps blood and is regulated by nervous system.

5) Lungs must expand to bring in oxygen to supply RBCs (respiratory and muscular systems).

6) Nutrients are processed for energy to drive these processes (gastrointestinal system)

Four major classes of cells in the body:

1) Neurons=Nerve tissue

2) Muscle cells=Muscle tissue

3) Epithelial cells=Epithelial tissue (covers outer surfaces of the body and lines your internal parts)

4) Connective tissue cells=Connective tissue

Neurons look different but all function in communication! What do they do?

1) Neurons transmit information as electrical signals.

2) They have branches that receive signals from or transmit signals to other cells.

What is an example of neurons and how they function?

Neurons in our eyes respond to light, or neurons in the skin respond to touch. Both receive information from the outside environment and allow us to see the world through our senses.

Muscle cells

1) Made to contract, which generates force and movement.

2) Voluntary control = skeletal muscle (muscles in the arms, legs, or other body parts)

2) Involuntary = cardiac muscle

3) Involuntary = smooth muscle (blood vessels)

What are examples of muscle cells in action?

1) Flexing of an arm

2) Pumping of blood

3) Mixing of food in the stomach

Epithelial Cells

1) Lines (forms a layer/covers) external body surfaces like your skin, which is a protective layer between your body and the outside world.

2) Covers the inside walls of organs or tubes that have an open space inside. For example, your stomach has epithelial tissue, which lines the inside wall of the stomach.

3) It functions as a barrier.

How can epithelial cells function as a transport membrane?

They can transport material like organic molecules or water from one location to another. For example, cells in the lining of the stomach transport acid into the lumen of the stomach to help with digestion.

Different types of glands (organs that make and secrete something) that epithelial cells can form:

Exocrine and endocrine

Exocrine glands

Exiting into another space. For example, sweat glands and salivary glands

Endocrine glands

Secrete hormones (chemicals that communicate a message to cells of the body) into the bloodstream. Examples include the pituitary gland and adrenal glands, and they do not have ducts.

Connective tissue (most diverse!)

1) Cells include blood, bone, fat, and many other kinds of cells that don’t have much in common in terms of structure or function.

2) Anchors and links the structures of the body.

3) Consists of scattered cells in a mass of noncellular material called the extracellular matrix. In this are elastin and collagen (ability to resist stretching).

Examples of connective tissue

1) Tendons anchor muscles to bones.

2) Ligaments connect bones.

3) Bones provide support for the body’s structures.

4) Blood and fat

Tissue

A collection of cells performing similar functions

Organs

Composed of at least two tissue types performing specific functions

Organ System

Collection of organs performing a particular task. For example, the cardiovascular system includes heart, blood vessels, and blood which deliver blood to all the body’s tissues.

External-Internal Exchange

1) External, plasma, tissue fluid, cell.

2) In: Nutrients and Oxygen

Out: Wastes and unneeded material

Body Fluid Compartments

1) The body is divided into compartments, and compartments contain fluids.

2) Compartments are separated by epithelial cells and cell membranes. Membranes are semipermeable (allowing certain molecules to come through)

3) Transport happens between compartments.

Total Body Water (TBW)

1) Volume of water contained in all the body’s compartments.

2) Consists of water (intracellular fluid and extracellular fluid) and dissolved materials.

What are the different kinds of body fluid compartments?

1) TBW

2) ICF=fluid inside cells (cytoplasm)

3) ECF=Fluid ouside of cells but within the body. Is the “internal environment.” Plasma= 3 L. Contains plasma; surrounds blood cells and interstitial fluid (ISF) = surrounds all other cells.

What is the difference between absorption and reabsorption?

Absorption=substances move into the body/blood.

Reabsorption=substances that were already in the body and are taken back into the blood after being filtered or moved somewhere else. Example, kidneys filter blood then reabsorb water and useful substances back into the bloodstream.

Why is extracellular fluid referred to as the body’s internal environment?

It’s inside your body but outside your cells.

Distribution of water in the body:

1) ICF=2/3 of the body’s water

2) ECF=1/3 of the body’s water