Plendil

By A. Pavel. Wheaton College, Massachusetts.

Blood Plasma Objective 7 Describe the location of the heart in relation to other organs of the thoracic cavity and their associated Blood plasma is the fluid portion purchase plendil 5 mg without prescription, or matrix, of the blood. Blood plasma constitutes approximately 55% of a given volume of Objective 8 Describe the structure and functions of the blood. These proteins remain within the blood and interstitial fluid and assist in maintaining body homeostasis. The three types of plasma Objective 11 Describe the location of the conduction proteins are albumins, globulins, and fibrinogen. They are produced by the liver and provide the blood with carrier molecules and with the viscos- Location and General Description ity needed to maintain and regulate blood pressure. The The hollow, four-chambered, muscular heart is roughly the size three types of globulins are alpha globulins, beta globulins, and of a clenched fist. The heart contracts an estimated 42 mil- the liver and function in transporting lipids and fat-soluble vita- lion times a year, pumping 700,000 gallons of blood. Gamma globulins are produced by lymphoid tissues and are The heart is located in the thoracic cavity between the lungs antibodies of immunity. Fibrinogens are large molecules that are synthesized in the ing downward and resting on the diaphragm. The base of the heart liver and, together with platelets, play an important role in clot- is the broad superior end, where the large vessels attach. Circulatory System © The McGraw−Hill Anatomy, Sixth Edition Body Companies, 2001 546 Unit 6 Maintenance of the Body FIGURE 16. The parietal pericardium is actually The wall of the heart is composed of three distinct layers composed of an outer fibrous pericardium and an inner serous (table 16. It is the serous pericardium that produces the lu- visceral pericardium.

Because this resting force exists before contrac- it undergoes isometric relaxation at the shorter length order plendil 2,5 mg overnight delivery. In the intact heart, the Some time later, the muscle is stretched back to its original preload sets the resting fiber length according to the in- length by an external force (the returning blood), produc- tracardiac blood pressure existing prior to contraction. Be- passive tension rises steeply beyond the optimal length and cause the muscle has relaxed, only a small force is required prevents overextension of the muscle (or overfilling of the for the reextension. Note that the resting force curve is associated with by the returning blood. The heart muscle is con- completely isometric contractions (see Chapter 14), other strained by its anatomy and functional arrangements to fol- aspects of length-dependent behavior must be responsible low different pathways during contraction and relaxation. One such aspect is the rate at which isometric traction-relaxation cycle are displayed on a length-tension force develops during a twitch. Other length-depend- at a constant force (isotonic conditions) to the shortest ent aspects of contraction are encountered when we exam- length possible for that afterload. The afterload is removed ine the complete contraction cycle of cardiac muscle. With sufficient force applied tonic contraction of skeletal muscle (see Fig. Isometric contraction: the muscle force builds up to reach the afterload. Normal range of operation Total force Active force (systolic) Resting force (diastolic) Muscle length FIGURE 10. The limit to force is provided by the afterload; the limit to lated cardiac muscle.

The initial symptoms of hypothermia are When the body’s heat-producing mechanisms cannot keep numbness plendil 2,5mg amex, paleness, delirium, and uncontrolled shivering. A lengthy exposure temperature falls below 32° C (90° F), the heart loses its ability to to temperatures below 20° C (68° F) and dampness may lead to this pump blood and will go into fibrillation (erratic contractions). This is why it is so important that a hiker, for example, victim is not warmed, extreme drowsiness, coma, and death follow. Integumentary System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 114 Unit 4 Support and Movement (a) (b) FIGURE 5. During the rainy season, which may last 5 to 6 months, the children are kept indoors. Rickets develops from an improper diet and also from lack of the sunlight needed to synthesize vitamin D. Called cuta- neous receptors, these sensory nerve cells are especially abun- Because of the effective protective barriers of the integument al- dant in the skin of the face and palms, the fingers, the soles of ready described, cutaneous absorption (absorption through the the feet, and the genitalia. Some gases, such as oxygen and carbon dioxide, back and on the back of the neck and are sparse in the skin over may pass through the skin and enter the blood. Generally speaking, the thinner the UV light, necessary for synthesis of vitamin D, are absorbed read- skin, the greater the sensitivity. Of clinical consideration is the fact that certain chemicals such as lipid-soluble toxins and pesticides can easily enter the body through the skin. Communication Humans are highly social animals, and the integument plays Synthesis an important role in communication. Various emotions, such The integumentary system synthesizes melanin and keratin, which as anger or embarrassment, may be reflected in changes of remain in the skin synthesis of vitamin D, which is used elsewhere skin color. The contraction of specific facial muscles pro- in the body and begins in the skin with activation of a precursor duces facial expressions that convey an array of emotions, in- molecule by UV light.

In both of these conditions order plendil 2,5 mg free shipping, body proportions are greatly distorted (see fig. In this condition, the soft tissues rapidly proliferate and certain body features, such as the hands, feet, nose, jaw, and tongue, become greatly distorted (see fig. TSH, frequently called thyrotropin, regulates the hormonal activity of the thyroid gland. Exposure to cold, cer- tain illnesses, and emotional stress may trigger an increased output of TSH. ACTH pro- through the infundibulum, along with minute neuroglia-like cells motes normal functioning of the adrenal cortex. The The pituitary gland is the structure of the brain perhaps most release of ACTH is controlled by a corticotropin-releasing subject to neoplasms. A tumor of the pituitary is generally de- hormone (CRH) produced in the hypothalamus. As with tected easily as it begins to grow and interfere with hormonal activity. If the tumor grows superiorly, it may exert sufficient pressure on the TSH, stress further influences the release of ACTH. In females, FSH plasm of the pituitary gland (hypophysectomy) may be performed transcranially through the frontal bone or through the nasal cavity regulates the monthly development of the follicle and and sphenoidal sinus. LH works with FSH, and to- Pituitary Hormones gether they are referred to as gonadotrophins, which means The pituitary gland releases nine important hormones. The first their target cells are located within the gonads or reproduc- seven in the following list are secreted by the anterior pituitary. In females, LH works with FSH in bringing The seventh is secreted by certain cells that are remnants of the about ovulation. The last two are produced in the hypothala- pus luteum and the production of another female sex hor- mus, transported through axons in the infundibulum to the pos- mone, progesterone (see chapter 21).