3: Anatomy and Physiology

Anatomy and Physiology

Anatomy and physiology are subjects that focus on the organization, structure, and function of the human body. Dental hygienists use knowledge of anatomy and physiology most often during client assessment, treatment, and evaluation; during oral radiographic and pathologic examinations; and for the administration of local anesthetic agents. This knowledge also allows the dental hygienist to determine whether clients are functioning within normal limits, deviating from the normal, or presenting with structures that are ectopic. Moreover, this knowledge enables dental hygienists to link systemic and oral health and disease. This chapter covers basic concepts; definitions of terms, cell structure, and function; and body systems, including the skeletal, muscular, nervous, circulatory, lymphatic, digestive, endocrine, urinary, and reproductive systems.

Basic Concepts

Levels of Organization

See Figure 3-1.

Chemical level—organization of chemical structure separates living and nonliving material; atoms, molecules, and macromolecules result in living matter

Organelle level—organelles are structures made of molecules and organized to perform specific functions; allow the cell to perform vital functions; types include:

Cellular level—cells comprise the basic structural and functional units of an organism; the smallest living units in the human body

Tissue level—groups of cells and materials surrounding them that work together to perform a particular function

Organ level—different types of tissues joined together to form body structures

System level—related organs that have a common function (e.g., digestive system breaks down and absorbs molecules in food; organs include the mouth, salivary glands, pharynx, esophagus, stomach, liver, gallbladder, pancreas, small intestine, and large intestine)

Organism level—all the systems of the body combine to make up an organism

Anatomic Nomenclature

(See the section on “Anatomic Nomenclature” in Chapter 4.)

Anatomic position—erect body position with arms at the sides and palms upward (Figure 3-2)

Plane or section—imaginary flat surfaces that pass through the body (Figure 3-3)

Body Cavities

See Figure 3-4.

Cells

(See the section on “General Histology” in Chapter 2.)

Cellular Structure

See Figure 3-5.

Plasma or cell membrane

Cytoplasm—all cellular contents between the plasma membrane and the nucleus; includes:

Ribosomes

Endoplasmic reticulum—network of membranes that form flattened sacs called cisterns; arranged in parallel rows within the cytoplasm of a cell; contains enzymes involved in a variety of metabolic activities

Golgi complex

Lysosomes

Mitochondria

Nucleus

Movement of Substances Through Cell Membranes

See Table 3-1.

TABLE 3-1

Some Important Transport Processes

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(Art from Patton KT, Thibodeau GA: Anthony’s textbook of anatomy and physiology, ed 19, St Louis, 2010, Mosby.)

Passive transport processes—do not require energy expenditure of the cell membrane

1. Diffusion—a passive process

2. Simple diffusion—substances diffuse across a membrane in one of two ways: lipid-soluble substances diffuse through the lipid bilayer, and ions diffuse through pores

3. Osmosis

a. Diffusion of water through a selectively permeable membrane (limits diffusion of at least some solute particles); results in gain of volume on one side of the membrane and loss of volume on the other side of the membrane

b. A solution containing solute particles that cannot pass through a membrane exerts osmotic pressure on the membrane

c. Potential osmotic pressure—maximum pressure that could develop in a solution when it is separated from pure water by a selectively permeable membrane; knowledge of potential osmotic pressure allows the prediction of the direction of osmosis and resulting change of pressure

4. Facilitated diffusion (carrier-mediated passive transport)

5. Filtration

Active transport processes—require the expenditure of metabolic energy by the cell

1. Active transport

2. Endocytosis and exocytosis—allow substances to enter or leave the interior of a cell without actually moving through its plasma membrane

a. Endocytosis—process by which the plasma membrane “traps” some extracellular material and brings it into the cell in a vesicle; the two basic types are:

b. Exocytosis—process by which large molecules, notably proteins, can leave the cell, even though they are too large to move through the plasma membrane; large molecules are enclosed in membranous vesicles and then pulled to the plasma membrane by the cytoskeleton, where the contents are released

Cell Metabolism

Metabolism—chemical reactions in a cell

Role of enzymes

1. Enzymes—chemical catalysts, reducing activation energy needed for a reaction

2. Regulate cell metabolism

3. Chemical structure of enzymes

4. Enzyme nomenclature

5. Functions of enzymes

Catabolism

1. Cellular respiration—pathway in which glucose is broken down to yield its stored energy; an important example of cell catabolism; has three chemically linked pathways:

a. Glycolysis

b. Citric acid cycle (Krebs cycle)

c. The electron transport system (ETS)

Anabolism

1. Protein synthesis is a central anabolic pathway in cells

2. DNA (see the section on “Genetics” in Chapter 7)

3. Transcription

4. Translation

5. Processing—enzymes in the ER and Golgi apparatus link polypeptides into whole protein molecules or process them in other ways

Cell Growth and Reproduction

Cell growth and reproduction of cells are the most fundamental of all functions in a living being; together they constitute the life cycle of the cell

Cell growth

Cell reproduction

Regulating the cell’s life cycle

Tissues

(See the sections on “Concepts Relating to Dental Tissues,” “Basic Tissues,” “Epithelial Tissue,” “Connective Tissue,” “Blood and Lymph,” “Nerve Tissue,” and “Muscle Tissue” in Chapter 2.)

Body Membranes

Thin tissue layers that cover surfaces, line cavities, and divide spaces or organs

Epithelial membranes are the most common

Connective tissue membranes

Systems of the Body and Their Components

The Integumentary System

Functions—regulation of body temperature, protection, sensation, excretion, immunity, synthesis of vitamin D

Parts

Skin color—from melanin, carotene, and hemoglobin pigments

Accessory structures—hair, skin glands, and nails

The Skeletal System

(See Figure 3-6 and the section on “Connective Tissue” in Chapter 2.)

Functions

Types of bones

Parts of a long bone

Bone tissue

1. Most distinctive form of connective tissue

2. Extracellular components are hard and calcified

3. Rigidity allows its supportive and protective functions

4. Tensile strength nearly equal to cast iron at less than one third the weight

5. Bone matrix composition

Jan 1, 2015 | Posted by in Dental Hygiene | Comments Off on 3: Anatomy and Physiology
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