Chapter 9 Anatomic Descriptors and Fundamental Body Structure
Anatomy and Physiology Defined • Anatomy is the study of the physical structure of the body and its organs. • Describes the framework and physical characteristics • Physiology is the science of the function of cells, tissues, and organs of the body. • Explains how everything works together to support life
Anatomic Directional Terms • Certain directional terms are universally used in describing anatomic structures. • A body is said to be in the anatomical position when the patient is standing erect, with the arms down at the sides, and the palms of the hands facing forward.
Anatomic Directional Terms • To describe exact location when charting, the body is divided by imaginary lines. • One line divides the body into right and left.
Terms • Medial • Toward the midline • Proximal • Nearest the point of attachment • Distal • Farthest from the point of attachment • Lateral • Away from the midline
Appropriate Terminology forAnatomical Directions • Another line divides the body into upper and lower halves. • Finally, a line divides the body into front and back.
Terms • Anterior • Toward the front • Frontal • Toward the front • Ventral • Toward the front or belly side • Superior • Above the transverse plane • Cranial • Toward the head • Inferior • Below the transverse plane • Caudal • Toward the tail or feet • Posterior • Toward the back
Body Cavities and Organs • The body is divided into two main cavities: • Anterior or ventral • Posterior or dorsal • Diaphragm • A large dome-shaped muscle that separates the thoracic cavity from the abdominal cavity
Organs of the Abdomen • The abdomen contains the: • Stomach • Small intestine • Most of the large intestine • Liver • Spleen • Pancreas • Gallbladder
The Regions of the Abdomen • Because of its size, the abdomen is first divided into four areas called quadrants.
The Regions of the Abdomen • The abdomen is then divided into 9 regions for purposes of identification and reference.
The Cell • The cell is the basic building block of the human body: • Cells need nutrients and oxygen to survive. • Cells perform specific functions. • Cells produce heat and energy. • Cells can give off waste products. • Some cells can reproduce themselves.
The Cell • Composed of a fluid called cytoplasm and is surrounded by a cell membrane • Cell membrane • Separates the cell from the surrounding environment • Cytoplasm • Semisolid fluid within the membrane where chemical reactions, such as respiration, occur
The Organelles • Within the cytoplasm of the cell are many minute bodies called organelles. • Nucleus • Mitochondria • Ribosomes • Centriole • Endoplasmic reticulum • Golgi apparatus • Lysosomes
The Organelles • Some organelles physically separate the chemical reactions that are not compatible. • Organelles also control the time when reactions take place. • For example, producing or processing a molecule in one organelle and then later using the molecule in another reaction
Organelle Structure and Function • Chromosomes • Located within the nucleus, each human has 23 pairs of chromosomes that store the hereditary material passed from one generation to the next • 22 pairs are identical. • The 23rd pair are the sex chromosomes: • XY = male • XX = female
Genes • Every individual has a different DNA code. • Code is identical in all cells of the same individual • The arrangement of the base pairs of the DNA that makes for the differences. • Division of cells is known as mitosis • Controlled by the nucleus of the cell
Passing Molecules through Cell Membranes • Six processes by which materials pass through a cell membrane: • Diffusion • Osmosis • Filtration • Active transport • Phagocytosis • Pinocytosis
Passing Molecules through Cell Membranes • Diffusion • Gas, solids, or liquids are distributed evenly through a medium. • Osmosis • Diffusion of water or another solvent through a selectively permeable membrane
Passing Molecules through Cell Membranes • Filtration • Movement of solutes and water across a semipermeable membrane • Filtration occurs as a result of force such as gravity or blood pressure.
Passing Molecules through Cell Membranes • Active transport • Molecules move across a membrane from an area of low concentration to an area of high concentration. • Phagocytosis • White blood cells become phagocytes and engulf bacteria, cell fragments, or damaged cells.
Passing Molecules through Cell Membranes • Pinocytosis • Cells engulf large molecules of liquid materials; cell drinking
Cellular Division • Division of cells is known as mitosis and is controlled by the nucleus of the cell • Sex cell (gamete) is responsible for reproduction • During meiosis, the ovum from the female and the spermatozoon from the male each reduce their respective 46 chromosomes to 23, one half the normal amounts.
Cellular Division • When fertilization occurs, the two cells combine to form a single cell called a zygote. • Zygote will then have the full set of 46 chromosomes, 23 from each parent • The zygote will subsequently, by mitosis, divide again and again until the new being is fully developed.
Homeostasis • Definition: When the internal environment is functioning properly and all the organs and tissues of the body are performing their appropriate tasks • A stable condition of the internal environment • Continues until one or more of the control systems loses the ability to maintain it
Mutations and Traits • DNA that is lost, rearranged, or paired in error results in a change in the genetic code called a mutation. • Genetic mutations can be caused by internal or external factors. • A mutation is a change in a cell resulting from a chemical and/or viral change in the structure of the gene.
Mutations and Traits • Dominant gene can produce a trait without regard to the nature of its pair member • Recessive gene is one whose presence within the pair does not result in a recognizable trait unless both members of the gene pair are of a similar mutation • People who have one dominant and one recessive gene are known as carriers.
Mutations and Traits • Sex- or X-linked - defective gene is carried on the X chromosome • Multifactorial - the combined influence of a number of genes and environmental factors causing a trait to be expressed. • Chromosomal abnormalities - the result of either a group of genes occurring in excess or as a deficit of genetic materials
Genetic and Congenital Disorders • Cleft lip • Structural defect present in the upper lip caused by failure of the soft or bony tissues to unite during the 8th to 12th week of gestation • Cleft palate • Structural defect present in the roof of the mouth caused by failure of the soft or bony tissues to unite during the 8th to 12th week of gestation
Genetic and Congenital Disorders • Color Vision Deficiency • Inaccurately called “colorblindness” – most people see some colors. • The most common problem is an inability to distinguish between red and green. • There is no treatment to correct the problem; people must learn to compensate.
Genetic and Congenital Disorders • Cystic Fibrosis • Affects multiple systems; a generalized dysfunction of the exocrine glands. • 30,000 people affected in the U.S.; median age of survival is 37 years. • All states require infant screening to identify cystic fibrosis before leaving the hospital. • Currently, there is no cure.
Genetic and Congenital Disorders • Down Syndrome • A genetic syndrome caused by improper cell division • Occurs in about 1 in every 1,000 births, depending on the mother’s age • The result is an extra chromosome 21.
Genetic and Congenital Disorders • Down Syndrome, continued • Several physical characteristics, e.g., slanting eyes, large tongue, pug nose, and a small head • Mental retardation occurs in all cases and there is some degree of growth restriction.
Genetic and Congenital Disorders • Dwarfism • Condition that results in an abnormally short or undersized person • About 200 conditions that result in dwarfism; achondroplastic dwarfism accounts for 70% of cases.
Genetic and Congenital Disorders • Galactosemia • Inherited metabolic disorder involving the processing of a simple sugar called galactose as is present in milk and milk products, into glucose • Infant will fail to thrive within one week of birth unless galactose and lactose are removed from the diet
Genetic and Congenital Disorders • Hemochromatosis • Genetic condition of iron overload in the body • Common genetic disorder, affecting approximately 5 out of every 1,000 people • Most prevalent in Caucasians of northern European descent
Genetic and Congenital Disorders • Hemophilia • Sex-linked inherited pattern caused by a defect in the gene located on the X chromosome that is involved in the production of blood clotting factor VIII or IX • A male with the abnormal gene on his X-chromosome will have hemophilia. • A female must have the gene on both her X chromosomes to have the disease.
Genetic and Congenital Disorders • Klinefelter’s Syndrome • Sex-linked disorder caused by one or more extra X chromosomes resulting from abnormal meiosis • Affects 1 in every 600 males • At puberty, the penis and testicles fail to mature and there is little body hair. • Breasts may enlarge and long legs with a short, obese trunk are noted.
Genetic and Congenital Disorders • Phenylketonuria • Devastating, genetic metabolic disease, requiring early intervention to prevent its development and progress • Characterized by the presence of phenylpyruvic acid in the urine due to the failure of the body to oxidize the amino acid phenylalanine
Genetic and Congenital Disorders • Spina Bifida • A structural malformation of the spine • The posterior portion of the spinal tissues fails to close during the first 3 months of pregnancy. • Malformations occur in three forms: • Spinal bifida occulta • Meningocele • Myelomeningocele
Genetic and Congenital Disorders • Talipes • A structural deformity of one or both feet • Commonly called clubfoot • There may be varying degrees of inward, outward, downward, or upward turning of one or both feet.
Genetic and Congenital Disorders • Turner’s Syndrome • Sex-linked defect that affects about 1 in every 10,000 females • Only 45 chromosomes are present because the sex cells failed to divide correctly. • Ovaries fail to develop. • Chest is wide; poor breast development and underdevelopment of the genitalia
System Interaction Associated with Disease Conditions • Because the body is so dependent on multiple systems to function, when diseases and disorders develop, often multiple systems are involved. • Table 9–3 summarizes the systems involved and the pathology that is present in two examples of genetic disease or disorder.
Age-Related Body Characteristics • Persons with genetic or congenital disorders may have age-related characteristics associated with their disorder. • Life expectancy is shortened so aging is not a significant factor. • Early diagnosis and intervention prevents the development of many of the devastating effects of the disorders. • See Table 9-3.
Discoveries in Human Genetics • The Human Genome Project identified a 3 billion letter code of human DNA, which is the chemical sequence containing the basic information for building and running a human body. • This sequence determines every human characteristic from eye color to vulnerability to disease.
New Genetic Techniques • Polymerase Chain Reaction • DNA Fingerprinting • Genetic Counseling • Gene Therapy • Genetic Engineering • Stem Cell Research
Tissues • When cells of the same type group together for a common purpose, they form a tissue. • Opposites of tissue fluid balance • Dehydration • Edema • Tissue Classifications • Epithelial, connective, nerve, and muscle
Tissues • Epithelial tissues form the body’s glands, cover the surface of the body, and line the cavities. • Connective tissue forms the supporting structure of the body, connecting other tissues together to form the organs and body parts. • Connective tissue proper; supportive connective tissue; fluid connective tissue
Nerve • Nerve tissue is found throughout the body. • It serves as the body’s communication network. • The basic structural unit of the tissue is the neuron. • Three types of neurons: sensory neuron; interneuron; connecting neuron