By Y. Einar. Cleveland Institute of Music.
Abnormalities in right or left heart function or in pul- monary vascular resistance can make it difficult to predict Small Changes in Systemic Venous Pressure left atrial pressure from central venous pressure discount 50 mg voveran mastercard. Can Cause Large Changes in Venous Volume Unfortunately purchase 50 mg voveran free shipping, measurements of the peripheral venous pressure safe 50mg voveran, such as the pressure in an arm or leg vein discount voveran 50 mg free shipping, are sub- Systemic veins are approximately 20 times more compliant ject to too many influences (e. If 500 mL of blood is infused into the circulation, about 80% (400 mL) locates in the systemic circulation. This in- crease in systemic blood volume raises mean circulatory Cardiac Output Is Sensitive to Changes filling pressure by a few mm Hg. This small rise in filling in Central Blood Volume pressure, distributed throughout the systemic circulation has a much larger effect on the volume of systemic veins Consider what happens if blood is steadily infused into the than systemic arteries. Because of the much higher compli- inferior vena cava of a normal individual. As this occurs, the ance of veins than arteries, 95% of the 400 mL (or 380 mL) volume of blood returning to the chest—venous return—is is found in veins, and only 5% (20 mL) is found in arteries. This difference between the input and output of atmospheric) results in little distention of arteries because blood produces an increase in central blood volume. It will of their low compliance, but results in considerable disten- occur first in the right atrium where the accompanying in- tion of veins because of their high compliance. In fact, ap- crease in pressure enhances right ventricular filling, end-di- proximately 550 mL of blood is needed to fill the stretched astolic fiber length, and stroke volume. Increased flow into veins of the legs and feet when an average person stands up. Left cardiac output will increase according but to a lesser extent, because the increase in transmural to Starling’s law, so that the output of the two ventricles ex- pressure is less. Cardiac output will increase until it equals Blood is redistributed to the legs from the central blood the sum of the previous venous return to the heart plus the volume by the following sequence of events. However, much of the blood reaching the legs remains in the veins as Central Blood Volume Is Influenced by they become passively stretched to their new size by the in- Total Blood Volume and Its Distribution. As cardiac output exceeds venous re- of the ventricles, and therefore, central blood volume is an turn for a few beats, the central blood volume falls (as does important influence on cardiac output. Central blood vol- the end-diastolic fiber length, stroke volume, and cardiac ume is altered by two events: changes in total blood volume output). Once the veins of the legs reach their new steady- and changes in the distribution of total blood volume be- state volume, the venous return again equals cardiac output. The equality between venous return and cardiac output is reestablished even though the central blood volume is re- Changes in Total Blood Volume. However, the new cardiac output and ve- blood volume can occur as a result of an infusion of fluid, nous return are decreased (relative to what they were before the retention of salt and water by the kidneys, or a shift in standing) because of the reduction in central blood volume. A decrease in Without compensation, the resulting decrease in systemic blood volume can occur as a result of hemorrhage, losses arterial pressure would cause a drop in brain blood flow and through sweat or other body fluids, or the transfer of fluid loss of consciousness. Compensatory events, including in- from plasma into the interstitial space. In the absence of creased activity of the sympathetic nervous system, to be compensatory events, changes in blood volume result in discussed in Chapter 18, are required to maintain arterial proportional changes in both central and extrathoracic pressure in the face of decreased cardiac output. For example, a moderate hemorrhage (10% When the smooth muscle of the systemic veins con- of blood volume) with no distribution shift would cause a tracts, the compliance of the systemic veins decreases. The reduced central results in a redistribution of blood volume toward the cen- blood volume would, in the absence of compensatory tral blood volume. Venoconstriction is an important com- events, lead to decreased filling of the ventricles and di- pensatory mechanism following hemorrhage. Central blood volume can be altered by a shift in blood volume to or away from the periphery. Shifts in the distribution of blood volume THE COUPLING OF VENOUS RETURN occur for two reasons: a change in transmural pressure or a AND CARDIAC OUTPUT change in venous compliance. Changes in the transmural pressure of vessels in the Because the blood moves in a closed circuit, venous re- chest or periphery enlarge or diminish their size.
The stapedius and tensor tympani muscles third bone discount voveran 50 mg with visa, the stapes (stirrup) buy cheap voveran 50mg online. This last bone generic voveran 50mg visa, through its modify the lever function of the ossicular chain buy voveran 50mg amex. CHAPTER 4 Sensory Physiology 79 Sound transmission through the middle ear is also af- The process of sound transmission can bypass the ossic- fected by the action of two small muscles that attach to the ular chain entirely. If a vibrating object, such as a tuning ossicular chain and help hold the bones in position and fork, is placed against a bone of the skull (typically the mas- modify their function (see Fig. The tensor tympani toid), the vibrations are transmitted mechanically to the muscle inserts on the malleus (near the center of the fluid of the inner ear, where the normal processes act to eardrum), passes diagonally through the middle ear cavity, complete the hearing process. Bone conduction is used as a and enters the tensor canal, in which it is anchored. Con- means of diagnosing hearing disorders that may arise be- traction of this muscle limits the vibration amplitude of the cause of lesions in the ossicular chain. The actual process of sound transduction contraction changes the axis of oscillation of the ossicular takes place in the inner ear, where the sensory receptors chain and causes dissipation of excess movement before it and their neural connections are located. These muscles are activated by a between its structure and function is a close and complex reflex (simultaneously in both ears) in response to moder- one. The following discussion includes the most significant ate and loud sounds; they act to reduce the transmission of aspects of this relationship. The auditory structures are located msec to operate (depending on the loudness of the stimu- in the cochlea (Fig. Left: Lower right: An enlargement of a cross section of the organ of An overview of the membranous labyrinth of Corti, showing the relationships among the hair cells and the the cochlea. Hearing: Physiological Acoustics, Neural Coding, and Psy- structures involved in the final processes of auditory sensation. The hair cells of the inner and the outer with the vestibule it contains a total fluid volume of 0. Both sets are supported and It is partitioned longitudinally into three divisions (canals) anchored to the basilar membrane by Deiters’ cells and ex- called the scala vestibuli (into which the oval window tend upward into the scala media toward the tectorial mem- opens), the scala tympani (sealed off from the middle ear brane. Extensions of the outer hair cells actually touch the by the round window), and the scala media (in which the tectorial membrane, while those of the inner hair cells ap- sensory cells are located). The hair cells make of the spiral (the modiolus) is a winding shelf called the os- synaptic contact with afferent neurons that run through seous spiral lamina; opposite it on the outer wall of the spi- channels between Deiters’ cells. A chemical transmitter of ral is the spiral ligament, and connecting these two struc- unknown identity is contained in synaptic vesicles near the tures is a highly flexible connective tissue sheet, the basilar base of the hair cells; as in other synaptic systems, the en- membrane, that runs for almost the entire length of the try of calcium ions (associated with cell membrane depo- cochlea. The basilar membrane separates the scala tympani larization) is necessary for the migration and fusion of the (below) from the scala media (above). The hair cells, which synaptic vesicles with the cell membrane prior to transmit- are the actual sensory receptors, are located on the upper ter release. They are called hair cells At the apical end of each inner hair cell is a projecting because each has a bundle of hair-like cilia at the end that bundle of about 50 stereocilia, rod-like structures packed in projects away from the basilar membrane. Minute strands link the Reissner’s membrane, a delicate sheet only two cell lay- free ends of the stereocilia together, so the bundle tends to ers thick, divides the scala media (below) from the scala move as a unit. The height of the individual stereocilia in- vestibuli (above) (see Fig. The scala vestibuli com- creases toward the outer edge of the cell (toward the stria municates with the scala tympani at the apical (distal) end vascularis), giving a sloping appearance to the bundle. The scala size, while the stereocilia increase in height from about 4 vestibuli and scala tympani are filled with perilymph, a fluid m at the basal end to 7 m at the apical end. The scala media con- cells are more elongated than the inner cells, and their size tains endolymph, a fluid high in potassium and low in increases along the cochlea from base to apex. The endolymph is secreted by the stria vascularis, ocilia (about 100 per hair cell) are also arranged in three a layer of fibrous vascular tissue along the outer wall of the rows that form an exaggerated W figure. Because the cochlea is filled with incompress- stereocilia also increases along the length of the cochlea, ible fluid and is encased in hard bone, pressure changes and they are embedded in the tectorial membrane. The caused by the in-and-out motion at the oval window stereocilia of both types of hair cells extend from the cutic- (driven by the stapes) are relieved by an out-and-in motion ular plate at the apex of the cell. Each stereocilium structures located on the upper surface of the basilar mem- contains cross-linked and closely packed actin filaments, brane and runs the length of the scala media (see Fig. It contains one row of some 3,000 inner hair cells; the arch Mechanical transduction in hair cells is shown in Figure of Corti and other specialized supporting cells separate the 4.
Both fossae are adapted to work with the ulna dur- has two articular surfaces purchase voveran 50mg. Skeletal System: The © The McGraw−Hill Anatomy order voveran 50 mg, Sixth Edition Appendicular Skeleton Companies voveran 50mg discount, 2001 Chapter 7 Skeletal System: The Appendicular Skeleton 177 Olecranon Trochlear notch Radial notch of ulna Head of radius Neck of radius Coronoid process Tuberosity of ulna Tuberosity of radius Body of Body radius of ulna Interosseous borders Ulnar notch of radius Head of ulna Styloid process Styloid process of ulna of radius FIGURE 7 purchase voveran 50mg without prescription. The medical term for tennis elbow is lateral epicondylitis, which Ulna means inflammation of the tissues surrounding the lateral epi- condyle of the humerus. At least six muscles that control backward The proximal end of the ulna articulates with the humerus and (extension) movement of the wrist and finger joints originate on the radius. A distinct depression, the trochlear notch, articulates lateral epicondyle. Repeated strenuous contractions of these mus- cles, as in stroking with a tennis racket, may strain the periosteum with the trochlea of the humerus. The coronoid process forms and muscle attachments, resulting in swelling, tenderness, and pain the anterior lip of the trochlear notch, and the olecranon forms around the epicondyle. Lateral and inferior to the coronoid can eliminate the causative factor, and recovery generally follows. On the tapered distal end of the ulna is a knobbed portion, Antebrachium (Forearm) the head, and a knoblike projection, the styloid process. The The skeletal structures of the antebrachium are the ulna on the ulna articulates at both ends with the radius. The ulna is more firmly connected to the humerus than the radius, and it is longer than the radius. The radius, however, contributes more significantly to the articulation at the wrist joint than does the ulna. Skeletal System: The © The McGraw−Hill Anatomy, Sixth Edition Appendicular Skeleton Companies, 2001 178 Unit 4 Support and Movement Radius Phalanges The radius consists of a body with a small proximal end and a The 14 phalanges are the bones of the digits. The phalanges of the fingers the capitulum of the humerus and the radial notch of the ulna. The prominent tuberosity of radius (radial tuberosity), for at- The thumb, or pollex (adjective, pollicis), lacks a middle phalanx. On the distal end of the ra- thumb—the lateral side, in reference to anatomical position. Other than sprained ligaments of the fin- the ulna and radius provide lateral and medial stability for articu- gers and joint dislocations, the most common bone injury is a fracture lation at the wrist. When immobilizing the wrist joint, the wrist is positioned in When a person falls, the natural tendency is to extend the the plane of relaxed function. This reflexive movement frequently re- about to grasp an object between the thumb and index finger. Common fractures of the radius include a fracture of the head, as it is driven forcefully against the capitulum; a fracture of the neck; or a fracture of the distal end (Colles’ fracture), Knowledge Check caused by landing on an outstretched hand. Why is the pendages, bend the knees, and let the entire body hit the surface. Carpus The carpus, or wrist, contains eight carpal bones arranged in two transverse rows of four bones each. The proximal row, naming PELVIC GIRDLE from the lateral (thumb) to the medial side, consists of the AND LOWER EXTREMITY scaphoid (navicular), lunate, triquetrum (tri-kwé-trum) and pisi- The structure of the pelvic girdle and lower extremities is adaptive form. Extensive processes and surface fea- distal row, from lateral to medial, consists of the trapezium tures on certain bones of the pelvic girdle and lower extremities (greater multangular), trapezoid (lesser multangular), capitate, accommodate massive muscles used in body movement and in and hamate. Objective 3 Describe the structure of the pelvic girdle and Metacarpus list its functions. The metacarpus, or palm of the hand, contains five metacarpal Objective 4 Describe the structural differences in the male bones. Each metacarpal bone consists of a proximal base, a body, and female pelves. The heads of the metacarpal bones are Objective 5 Identify the bones of the lower extremity and distally located and form the knuckles of a clenched fist. Objective 6 Describe the structural features and functions of the arches of the foot. Skeletal System: The © The McGraw−Hill Anatomy, Sixth Edition Appendicular Skeleton Companies, 2001 Chapter 7 Skeletal System: The Appendicular Skeleton 179 III II IV Distal phalanx Middle phalanx V Proximal phalanx I Phalanges Distal phalanx Proximal phalanx Head Body Metacarpal First metacarpal bone bones Base Trapezoid Capitate Hamate Trapezium Triquetral Scaphoid Carpal Pisiform bones Lunate (a) Distal phalanx Middle phalanx Proximal phalanx Phalanges IV V Hamate III II Metacarpal I Capitate bones Trapezoid Carpal bones Trapezium Triquetral Scaphoid Lunate (b) FIGURE 7.
In compact bone tissue buy 50mg voveran otc, mature bone cells generic voveran 50mg without a prescription, called osteocytes voveran 50 mg free shipping, are arranged in concentric layers around a central FIGURE 4 purchase voveran 50 mg amex. Histology © The McGraw−Hill Anatomy, Sixth Edition of the Body Companies, 2001 98 Unit 3 Microscopic Structure of the Body (b) Lamellae Central canal (a) Osteocyte within a lacuna Canaliculi (c) FIGURE 4. An injury to a portion of the body may stimulate tissue repair Each osteocyte occupies a cavity called a lacuna. A minor scrape or cut results in platelet and plasma activity of the exposed blood and each lacuna are numerous minute canals, or canaliculi, which the formation of a scab. The epidermis of the skin regenerates be- traverse the dense matrix of the bone tissue to adjacent lacunae. A severe open wound heals through connective tis- Nutrients diffuse through the canaliculi to reach each osteocyte. In this process, collagenous fibers form from The matrix is deposited in concentric layers called lamellae. Blood (Vascular Tissue) Knowledge Check Blood, or vascular tissue, is a highly specialized fluid connective 9. List the basic types of connective tissue and describe the tissue that plays a vital role in maintaining homeostasis. Which of the previously discussed connective tissues matrix called blood plasma (fig. Which type is elements are erythrocytes (red blood cells), leukocytes (white phagocytic? Which types bind and support various struc- blood cells), and thrombocytes (platelets). What is the developmental significance of mesenchyme and haversian canal: from Clopton Havers, English anatomist, 1650–1702 how does it differ functionally from adult connective tissue? Briefly describe reticular fibers, fibroblasts, collagenous leukocyte: Gk. Histology © The McGraw−Hill Anatomy, Sixth Edition of the Body Companies, 2001 Chapter 4 Histology 99 Erythrocytes Centrifuged blood sample Leukocytes Thrombocytes (platelets) Paras FIGURE 4. These cells are usu- Muscle tissue is responsible for the movement of materials ally grouped together in flattened sheets, forming the muscular through the body, the movement of one part of the body with re- portion of a wall around a lumen. Fibers in the three kinds of muscle tissue are adapted to contract in response to stimuli. Cardiac Muscle Objective 10 Describe the structure, location, and function Cardiac muscle tissue makes up most of the wall of the heart. This tissue is characterized by bifurcating (branching) fibers, each with a single, centrally positioned nucleus, and by trans- Muscle tissue is unique in its ability to contract, and thus make versely positioned intercalated (in-ter′ka˘-la¯t-ed) discs. The muscle cells, or fibers, are elongated in lated discs help to hold adjacent cells together and transmit the the direction of contraction, and movement is accomplished force of contraction from cell to cell. Like skeletal muscle, car- through the shortening of the fibers in response to a stimulus. Cardiac muscle is further dis- muscle tissue in the body: smooth, cardiac, and skeletal muscle tis- cussed in chapter 16. Skeletal Muscle Smooth Muscle Skeletal muscle tissue attaches to the skeleton and is responsible Smooth muscle tissue is common throughout the body, occurring for voluntary body movements. For example, in the wall of the GI tract fiber has distinct transverse striations. Fibers of this muscle tissue it provides the contractile force for the peristaltic movements in- are grouped into parallel fasciculi (bundles) that can be seen volved in the mechanical digestion of food. Both cardiac and skeletal also found in the walls of arteries, the walls of respiratory pas- muscle fibers cannot replicate once tissue formation has been sages, and in the urinary and reproductive ducts. Skeletal muscle tissue is further tion of smooth muscle is under autonomic (involuntary) nervous discussed in chapter 9. The three types of muscle tissue are sum- control, and is discussed in more detail in chapter 13. Histology © The McGraw−Hill Anatomy, Sixth Edition of the Body Companies, 2001 100 Unit 3 Microscopic Structure of the Body Nucleus (a) Smooth muscle tissue Striation Nucleus Intercalated disc (b) Cardiac muscle tissue Nucleus Striation (c) Skeletal muscle tissue FIGURE 4.
This abscess is closely related to the therefore which disc is herniated: psoas major muscle and does not seem to be related to any of the surrounding organs 50 mg voveran mastercard. These abscesses generally form from hematologic spread Disc Nerve Root Numbness/Pain Motor Deficit Lost Reflex of bacteria secondary to an infection in another part of the body 50mg voveran visa. The iliopsoas test is a physical examination maneuver performed when there muscle is suspicion of an intra-abdominal inflammation buy cheap voveran 50 mg line. The patient lies on the L4–L5 L5 Superior foot Extensor hallucis None right (unaffected) side and tries to extend her left leg at the hip against the longus muscle examiner’s hand cheap voveran 50 mg visa. Abdominal pain upon extension of the left leg occurs L5–S1 S1 Lateral foot Gastrocnemius Tendo calcaneous because of the stretching of the inflammed psoas major muscle. The fibers that surround the nucleus pulposus are naturally weakest in the 3. This is done by inserting a tube into the right and left posterior aspects. This means that herniations usually bulge to abscess and allowing it to drain over several days. Antibiotics must also be the right or to the left, thereby affecting only one leg. This may cause numbness of the perineum and dysfunction of bowel or urinary bladder control. The muscles that extend the knee joint are the rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis. Although several conditions of the lung can look like this on the radiograph, tendon, which extends to the patella. Between the patella and the tibia is this man’s history favors one diagnosis. He is a lifetime smoker, he has the patellar ligament that attaches at the tibial tuberosity. This patient is developed a chronic cough, and he has been losing weight. He most unable to extend his leg at the knee because the tibial tuberosity has avulsed assuredly has lung cancer. Two major muscle groups, the quadriceps femoris and the hamstrings span has actually eroded through the pleura and is invading the plexus, causing the knee. The quadriceps group extends the knee joint, whereas the the arm symptoms. The apex of the lung is also very close to the sympathetic chain in the upper groups are in direct opposition to one another and hold the knee in a thorax and the neck. Tumor invasion in this location afflicts sympathetic neutral, or straight, position through their resting muscle tone. The result is loss of muscle tone in the eyelid, quadriceps femoris can no longer exhibit force on the tibia because of the loss of pupil dilation, and inability of the skin to sweat on that half of the face. Van De Graaff: Human Back Matter Appendix B: Answers to © The McGraw−Hill Anatomy, Sixth Edition Clinical Practicum Companies, 2001 Questions Appendix B Answers to Clinical Practicum Questions 801 Clinical Practicum 14. The patient’s recent change in facial appearance and the change to his 1. Although the patient has an underlying pulmonary infection causing some hands and feet are due to excessive growth hormone. Growth hormone is shortness of breath, the acute worsening of his symptoms is due to a tension released by the pituitary gland. The tension pneumothorax occurred secondary to a (seen on the MR image) that is secreting excess growth hormone, and which bronchopleural fistula resulting from the patient’s underlying infection. A tension pneumothorax is Excess growth hormone during childhood greatly accelerates growth, a type of pneumothorax in which gas collects in the pleural space resulting resulting in gigantism. However, if this occurs after a person has reached full in increased intrathoracic pressure which affects both cardiac and pulmonary stature (i. As the left pleural space fills with air, it shifts the mediastinum to the soft tissue growth of the hands and feet. A MRI of the head is necessary to determine the size of the pituitary tumor. The optic chiasma sits superior and just anterior to the pituitary gland.