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Female: ovaries, uterine tubes, uterus, vagina, clitoris, vulva

Produce and maintain egg cells, receive sperm cells, support development of an embryo and function in birth process

person ages are considered in certain chapters, beginning here.

O Name the major organ systems and list the organs of each system.

Describe the general functions of each organ system.

Life-Span Changes

Aging is a part of life. According to the dictionary, aging is the process of becoming mature or old. It is, in essence, the passage of time and the accompanying bodily changes. Because the passage of time is inevitable, so, too, is aging, claims for the anti-aging properties of various diets, cosmetics, pills and skin care products to the contrary.

Aging occurs from the whole-body level to the microscopic level. Although programmed cell death begins in the fetus, we are usually not very aware of aging until the third decade of life, when a few gray hairs, faint lines etched into facial skin, and minor joint stiffness in the morning remind us that time marches on. A woman over the age of 35 attempting to conceive a child might be shocked to learn that she is of "advanced maternal age," because the chances of conceiving an offspring with an abnormal chromosome number increase with the age of the egg. In both sexes, by the fourth or fifth decade, as hair color fades and skin etches become wrinkles, the first signs of adult-onset disorders may appear, such as increased blood pressure that one day may be considered hypertension, and slightly elevated blood glucose that could become diabetes mellitus. A person with a strong family history of heart disease, coupled with unhealthy diet and exercise habits, may be advised to change his or her lifestyle, and perhaps even begin taking a drug to lower serum cholesterol levels. The sixth decade sees grayer or whiter hair, more and deeper skin wrinkles, and a waning immunity that makes vaccinations against influenza and other infectious diseases important. Yet many if not most people in their sixties and older have sharp minds and are capable of all sorts of physical activities.

Changes at the tissue, cell and molecular levels explain the familiar signs of aging. Decreased production of the connective tissue proteins collagen and elastin account for the stiffening of skin, and diminished levels of

Skin Tissue Cholesterol Photos

Figure 1.17

The organ systems in humans interact to maintain homeostasis.

Cardiovascular system

Figure 1.17

The organ systems in humans interact to maintain homeostasis.

subcutaneous fat are responsible for wrinkling. Proportions of fat to water in the tissues change, with the percentage of fats increasing steadily in women, and increasing until about age 60 in men. These alterations explain why the elderly metabolize certain drugs at different rates than do younger people. As a person ages, tissues atrophy, and as a result, organs shrink.

Cells mark time too, many approaching the end of a limited number of predetermined cell divisions as their chromosome tips whittle down. Such cells reaching the end of their division days may enlarge, or die. Some cells may be unable to build the spindle apparatus that pulls apart replicated chromosomes in a cell on the verge of division. Impaired cell division translates into impaired wound healing, yet at the same time, the inappropriate cell division that underlies cancer becomes more likely. Certain subcellular functions lose efficiency, including the DNA repair that would otherwise patch up mutations, and the transport of substances across cell membranes. Aging cells also have fewer mitochondria, the structures that house the reactions that extract energy from nutrients, and also have fewer lysosomes, the disposal units that break down aged or damaged cell parts.

Just as changes at the tissue level cause organ-level signs of aging, certain biochemical changes fuel cellular aging. Lipofuscin and ceroid pigments accumulate as the cell can no longer prevent formation of damaging oxygen free radicals. A protein called beta amyloid may build up in the brain and blood vessels, contributing, in some individuals, to the development of Alzheimer disease. A generalized metabolic slowdown results from a dampening of thyroid gland function, impairing glucose utilization, the rate of protein synthesis, and production of digestive enzymes. At the whole body level, we notice slowed metabolism as diminished tolerance to cold, weight gain, and fatigue.

A clearer understanding of the precise steps of the aging process will emerge as researchers identify the roles of each of our genes. For example, many of the molecular and cellular changes of aging may be controlled by the action of one gene, called p21. Its protein product turns on and off about 90 other genes, whose specific actions promote the signs of older age. The p21 gene intervenes when cells are damaged by radiation or toxins, promoting their death, which prevents them from causing disease. It also stimulates production of proteins that are associated with particular disorders seen in aging, including atherosclerosis, Alzheimer disease, and arthritis.

Because our organs and organ systems are interrelated, aging-related changes in one influence the functioning of others. Several chapters in this book conclude with a "Lifespan Changes" box that charts changes specific to particular organ systems. These changes reflect the natural breakdown of structure and function that accompanies the passage of time, as well as events that are knitted into our genes ("nature"), and symptoms or char acteristics that might arise as a consequence of lifestyle choices and circumstances ("nurture").

Anatomical Terminology

To communicate effectively with one another, investigators over the ages have developed a set of terms with precise meanings. Some of these terms concern the relative positions of body parts, others refer to imaginary planes along which cuts may be made, and still others describe body regions. When such terms are used, it is assumed that the body is in the anatomical position; that is, it is standing erect, the face is forward, and the upper limbs are at the sides, with the palms forward.

Relative Position

Terms of relative position are used to describe the location of one body part with respect to another. They include the following:

1. Superior means a part is above another part, or closer to the head. (The thoracic cavity is superior to the abdominopelvic cavity.)

2. Inferior means a part is below another part, or toward the feet. (The neck is inferior to the head.)

3. Anterior (or ventral) means toward the front. (The eyes are anterior to the brain.)

4. Posterior (or dorsal) is the opposite of anterior; it means toward the back. (The pharynx is posterior to the oral cavity.)

5. Medial relates to an imaginary midline dividing the body into equal right and left halves. A part is medial if it is closer to this line than another part. (The nose is medial to the eyes.)

6. Lateral means toward the side with respect to the imaginary midline. (The ears are lateral to the eyes.) Ipsilateral pertains to the same side (the spleen and the descending colon are ipsilateral), whereas contralateral refers to the opposite side (the spleen and the gallbladder are contralateral).

7. Proximal is used to describe a part that is closer to the trunk of the body or closer to another specified point of reference than another part. (The elbow is proximal to the wrist.)

8. Distal is the opposite of proximal. It means a particular body part is farther from the trunk or farther from another specified point of reference than another part. (The fingers are distal to the wrist.)

9. Superficial means situated near the surface. (The epidermis is the superficial layer of the skin.)

Coronal Plane

Sagittal plane (median plane)

Transverse plane (horizontal plane)

Figure 1.18

To observe internal parts, the body may be sectioned along various planes.

Coronal plane (frontal plane)

Sagittal plane (median plane)

Transverse plane (horizontal plane)

Figure 1.18

To observe internal parts, the body may be sectioned along various planes.

Coronal plane (frontal plane)

Peripheral also means outward or near the surface. It is used to describe the location of certain blood vessels and nerves. (The nerves that branch from the brain and spinal cord are peripheral nerves.)

10. Deep is used to describe parts that are more internal. (The dermis is the deep layer of the skin.)

JF Body Sections

To observe the relative locations and arrangements of internal parts, it is necessary to cut or section the body along various planes (figs. 1.18 and 1.19). The following terms are used to describe such planes and sections:

1. Sagittal refers to a lengthwise cut that divides the body into right and left portions. If a sagittal section passes along the midline and divides the body into equal parts, it is called median (midsagittal).

2. Transverse (or horizontal) refers to a cut that divides the body into superior and inferior portions.

3. Coronal (or frontal) refers to a section that divides the body into anterior and posterior portions.

Sometimes a cylindrical organ such as a blood vessel is sectioned. In this case, a cut across the structure is called a cross section, an angular cut is called an oblique section, and a lengthwise cut is called a longitudinal section (fig. 1.20).

Body Regions

A number of terms designate body regions. The abdominal area, for example, is subdivided into the following regions, as shown in figure 1.21:

1. Epigastric region The upper middle portion.

2. Left and right hypochondriac regions On each side of the epigastric region.

3. Umbilical region The central portion.

4. Left and right lumbar regions On each side of the umbilical region.

5. Hypogastric region The lower middle portion.

6. Left and right iliac (or inguinal) regions On each side of the hypogastric region.

The abdominal area also may be subdivided into the following four quadrants, as figure 1.22 illustrates:

1. Right upper quadrant (RUQ).

2. Right lower quadrant (RLQ).

3. Left upper quadrant (LUQ).

4. Left lower quadrant (LLQ).

Figure 1.19

A human brain sectioned along (a) the sagittal plane, (b) the transverse plane, and (c) the coronal plane.

Figure 1.20

Figure 1.20

Cylindrical parts may be cut in (a) cross section, (b) oblique section, or (c) longitudinal section.

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