Interactions Between the Skeletal System and Other Organ Systems

Skeletal System Protects Organs

Indicates ways in which this system affects other systems indicates ways in which other systems affect this one Bones lying close to body surfaces shape the skin Initiates synthesis of vitamin D needed for bone deposition Bones provide leverage and sites of attachment for muscles provide calcium needed for muscle contraction Muscles move bones stress produced by muscles affects patterns of ossification and remodeling, as well as shape of mature bones Cranium and vertebral column protect brain...

Interactions Between the Integumentary System and Other Organ Systems

Indicates ways in which this system affects other systems indicates ways in which other systems affect this one The integumentary system serves all other systems by providing a physical barrier to environmental hazards Role of skin in vitamin D synthesis promotes calcium absorption needed for bone growth and maintenance Supports skin at scalp and other places where bone lies close to surface Vitamin D synthesis promotes absorption of calcium needed for muscle contraction skin dissipates heat...

Neuronal Pools and Circuits

Parallel After Discharge Circuits

So far, we have dealt with interactions involving only two or three neurons at a time. Actually, neurons function in larger ensembles called neuronal pools, each of which consists of thousands to millions of interneurons concerned with a particular body function one to control the rhythm of your breathing, one to move your limbs rhythmically as you walk, one to regulate your sense of hunger, and another to interpret smells, for example. At this point, we explore a few ways in which neuronal...

Bony Joints Synostoses

Cartilaginous Joints

A bony joint, or synostosis8 SIN-oss-TOE-sis , is a joint in which two bones, once separate, have become fused by osseous tissue and in most cases are then regarded as a single bone. Some fibrous and cartilaginous joints ossify with age that is, the gap between adjacent bones becomes filled with osseous tissue until the two bones appear as one. In the skull, for example, both the frontal bone and mandible are represented at birth by separate right and left bones in early childhood, these bones...

Positive Feedback and Rapid Change

Positive Feedback Fever

Positive feedback is a self-amplifying cycle in which a physiological change leads to even greater change in the same direction, rather than producing the corrective effects of negative feedback. Positive feedback is often a normal way of producing rapid change. When a woman is giving birth, for example, the head of the baby pushes against her cervix the neck of the uterus and stimulates its nerve endings fig. 1.13 . Nerve signals travel to the brain, which, in turn, stimulates the pituitary...

Regeneration of Nerve Fibers

Nerve Fibers Regeneration

Nerve fibers of the PNS are vulnerable to cuts, crushing injuries, and other trauma. A damaged peripheral nerve fiber can regenerate, however, if its soma is intact and at least some neurilemma remains. Within the first few weeks after injury, the severed distal end of an axon and its myelin sheath degenerate and macrophages remove the debris fig. 12.8 . A regeneration tube, formed by the neurilemma and endoneurium, is necessary for regeneration. The axon stump puts out several sprouts until...

Poliomyelitis and Amyotrophic Lateral Sclerosis

Stephen Hawking Before Als

Poliomyelitis17 and amyotrophic lateral sclerosis18 ALS are two diseases that involve destruction of motor neurons. In both diseases, the skeletal muscles atrophy from lack of innervation. Poliomyelitis is caused by the poliovirus, which destroys motor neurons in the brainstem and ventral horn of the spinal cord. Signs of polio include muscle pain, weakness, and loss of some reflexes, followed by paralysis, muscular atrophy, and sometimes respiratory arrest. The virus spreads by fecal...

Regional Characteristics of Vertebrae

Regional Characteristics Vertebrae

We are now prepared to consider how vertebrae differ from one region of the vertebral column to another and from the generalized anatomy just described. Knowing these variations will enable you to identify the region of the spine from which an isolated vertebra was taken. More importantly, these modifications in form reflect functional differences among the vertebrae. The cervical vertebrae C1-C7 are the smallest and lightest ones other than the coccygeals. The first two C1 and C2 have unique...

Diseases of the Myelin Sheath

Multiple sclerosis and Tay-Sachs disease are degenerative disorders of the myelin sheath. In multiple sclerosis MS , the oligodendrocytes and myelin sheaths of the CNS deteriorate and are replaced by hardened scar tissue, especially between the ages of 20 and 40. Nerve conduction is disrupted with effects that depend on what part of the CNS is involved double vision, blindness, speech defects, neurosis, tremors, and numbness. Patients experience variable cycles of milder and worse symptoms...

Visual Survey of the Body

Cadaver Gallbladder

Figures A.12 through A.16 provide an overview of the anatomy of the trunk and internal organs of the thoracic and abdominopelvic cavities. Figures A.17 through A.22 are photographs of the cadaver showing the major organs of the dorsal and ventral body cavities. Figure A.10 Serous Membranes of the Abdominal Cavity. Sagittal section, left lateral view. Is the urinary bladder in the peritoneal cavity Saladin Anatomy amp I Atlas A General I Text I The McGraw-Hill Physiology The Unity of Orientation...

The Importance of External Anatomy

Lateral Aspect Hand

In the study of human anatomy, it is easy to become so preoccupied with internal structure that we forget the importance of what we can see and feel externally. Yet external anatomy and appearance are major concerns in giving a physical examination and in many aspects of patient care. A knowledge of the body's surface landmarks is essential to one's competence in physical therapy, cardiopul-monary resuscitation, surgery, making X rays and electrocardiograms, giving injections, drawing blood,...

Testing Your Comprehension

What aspect of William Harvey's view of blood circulation could be considered a scientific hypothesis What would you predict from that hypothesis What observation could you carry out today to test this hypothesis 2. Which of the characteristics of living things are possessed by an automobile What bearing does this have on our definition of life 3. About 1 out of every 120 live-born infants has a structural defect in the heart such as a hole between two heart chambers. Such infants often...

Online Learning Center

The Anatomy & Physiology Online Learning Center (OLC) at www.mhhe.com saladin3 offers access to a vast array of premium online content to fortify the learning and teaching experience. Essential Study Partner A collection of interactive study modules that contains hundreds of animations, learning activities, and quizzes designed to help students grasp complex concepts. Live News Feeds The OLC offers course specific real-time news articles to help you stay current with the latest topics in...

Muscles Acting on the Foot

Anterior And Medial Aspect The Thigh

The fleshy mass of the leg proper below the knee is formed by a group of crural muscles, which act on the foot fig. 10.35 table 10.19 . These muscles are tightly bound together by deep fasciae, which compress them and aid in the return of blood from the legs. The fasciae separate the crural muscles into anterior, lateral, and posterior compartments, each with its own nerve and blood supply. Muscles of the anterior compartment dorsiflex the ankle and prevent the toes from scuffing the ground...

Muscles Acting on the Wrist and Hand

Supination Forearm

The hand is acted upon by extrinsic muscles in the forearm and intrinsic muscles in the hand itself table 10.14 . The bellies of the extrinsic muscles form the fleshy roundness of the proximal forearm their tendons extend into the wrist and hand. Their actions are mainly flexion and extension, but the wrist and fingers can be abducted and adducted, and the thumb and fingers can be opposed. Brachioradialis Flexor carpi radialis Pronator teres Saladin Anatomy amp I 10. The Muscular System I Text...