Bones, Muscles and Skin

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Bones, Muscles and Skin. Chapter 32 pages 920 - 945. Axial skeleton – skull, vertebrae and rib cage. Appendicular skeleton – arms, legs, shoulder, pelvis. Skeletal system functions. Support and shape Protection Movement Mineral Storage ( Ca ) Hematopoeisis – production of blood cells. - PowerPoint PPT Presentation

Transcript of Bones, Muscles and Skin


Bones, Muscles and SkinChapter 32 pages 920 - 945Axial skeleton skull, vertebrae and rib cage.Appendicular skeleton arms, legs, shoulder, pelvis

Skeletal system functionsSupport and shape ProtectionMovementMineral Storage (Ca)Hematopoeisis production of blood cells

Bone StructureBones are a network of living cells embedded in a protein mesh that is covered with Calcium phosphate crystals.

Osteonic canal is the same as the Haversian canalOsteon is a group of concentric rings (Lamellae)Lacuna are the little caves where the bone cells, the Osteocytes, live.Canaliculus are the small passageways that link the osteocytes together.5

Spongy bone is located inside of compact bone, often near the ends of bone. There is a trabecular network of bone that provides strength, but light weight. Within this space is where the red bone marrow can be found. Yellow bone marrow will be farther down in the middle of the bone. Red bone marrow produces blood cells, and yellow bone marrow primarily is fat.6

Endochondral bone formation ossification, osteoblasts mature into osteocytes.7Osteoclast resorbs bone putting Ca+2 in the blood stream

An osteoclast (from the Greek words for "bone" () and "broken" ()) is a type of bone cell that resorbs bone tissue. This function is critical in the maintenance and repair of compact bones in the mammalian skeleton. These bones are stronger than aluminum on a weight basis by being a composite material of approximately equal amounts of hydrated protein and mineral.[1] The osteoclast disassembles this very strong composite at a molecular level by secreting acid and a collagenase. This process is known as bone resorption. Osteoclasts and osteoblasts are instrumental in controlling the amount of bone tissue: osteoblasts form bone, osteoclasts re-absorb bone.8osteoporosis where bones meet.Three kinds:Immovable joints; skull, teeth, sacroiliacSlightly movable joints; vertebrae, lower leg, wristMovable joints; permit movement in more than one direction.

A joint or articulation (or articulate surface) is the location at which bones connect.[1][2] They are constructed to allow movement (except for skull bones) and provide mechanical support, and are classified structurally and functionall10Freely movable jointsSynovial joints are freely movable. Hard, shiny, smooth hyaline cartilage covers the ends of the bone. Softer cushioning cartilage is placed between the bones. The joint is encased in a sac (bursa) that has a fluid (synovial) circulating within. The bones are tied together with tough, collagenous ligaments.

Synovial joints are freely movable. Hard, shiny, smooth hyaline cartilage covers the ends of the bone. Softer cushioning cartilage is placed between the bones. The joint is encased in a sac (bursa) that has a fluid (synovial) circulating within. The bones are tied together with tough, collagenous ligaments.12LigamentsLigaments are composed primarily of collagen.They connect bones to bones.They are connected to bones by fibers that go deep into the bones structure.When they break they break in the middle

In anatomy, a ligament is the fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua,[1] fibrous ligament, or true ligament.Ligament can also refer to:Peritoneal ligament: a fold of peritoneum or other membranes.Fetal remnant ligament: the remnants of a fetal tubular structure.Periodontal ligament: a group of fibers that attach the cementum of teeth to the surrounding alveolar bone.The study of ligaments is known as desmology (from Greek , desmos, "bond"; and -, -logia).Ligaments are similar to tendons and fasciae as they are all made of connective tissue. The differences in them are in the connections that they make; ligaments connect one bone to another bone, tendons connect muscle to bone and fasciae connect muscles to other muscles. These are all found in the skeletal system of the human body. Ligaments cannot usually be regenerated naturally, however there are periodontal ligament stem cells located near the periodontal ligament which are involved in the adult regeneration of periodontal ligament.

13Anterior Cruciate Surgery Muscle TissueVoluntaryMultinucleated, long (up to 30 cm) fibers.Striated, can see definite stripes caused by the overlapping myosin and actin myofibrils.Red color comes from myoglobin, a pigment that stores O2.Usually attached to bones

Skeletal muscle or "voluntary muscle" or "striated muscle" is anchored by tendons (or by aponeuroses at a few places) to bone and is used to effect skeletal movement such as locomotion and in maintaining posture. Though this postural control is generally maintained as an unconscious reflex (see proprioception), the muscles responsible react to conscious control like non-postural muscles. An average adult male is made up of 42% of skeletal muscle and an average adult female is made up of 36% (as a percentage of body mass).[2] It also has striations unlike smooth muscle.15Cardiac Muscle Tissue-Found only in the Heart. Striated and branched. Joined with other muscle cell fibers via intercalated discs. One or two nuclei/cell. Are striated.

Smooth Muscle Tissue.Non-striated. Spindle shaped cells with a single nucleus. Usually involuntary. Found in the walls of arteries, intestines, the eye, alveoli. Most can function without direct stimulation from the nervous system. Connected to each other by gap junctions

Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit (unitary) and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by gap junctions to neighboring cells such that the whole bundle or sheet contracts as a syncytium (i.e., a multinucleate mass of cytoplasm that is not separated into cells). Multiunit smooth muscle tissues innervate individual cells; as such, they allow for fine control and gradual responses, much like motor unit recruitment in skeletal muscle.Smooth muscle is found within the walls of blood vessels (such smooth muscle specifically being termed vascular smooth muscle) such as in the tunica media layer of large (aorta) and small arteries, arterioles and veins. Smooth muscle is also found in lymphatic vessels, the urinary bladder, uterus (termed uterine smooth muscle), male and female reproductive tracts, gastrointestinal tract, respiratory tract, erector pili of skin, the ciliary muscle, and iris of the eye. The structure and function is basically the same in smooth muscle cells in different organs, but the inducing stimuli differ substantially, in order to perform individual effects in the body at individual times. In addition, the glomeruli of the kidneys contain smooth muscle-like cells called mesangial cells.

17Muscle Fiber Structure.Thick myosin and thin actin myofibrils. Anchored at the Z line in a functional unit called the Sarcomere.When stimulated, paddles on the myosin attached to sites on the actin and pull causing the whole sarcomere to shorten.

The Process of Muscle Cell Contraction Neuromuscular Junction is bridged by acetylcholine.

The neuromuscular junction connects the nervous system to the muscular system via synapses between efferent nerve fibers and muscle fibers, also known as muscle cells. As an action potential reaches the end of a motor neuron, voltage-dependent calcium channels open allowing calcium to enter the neuron. Calcium binds to sensor proteins (synaptobrevin) on synaptic vesicles triggering vesicle fusion with the plasma membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft. In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which diffuses through the synapse and binds nicotinic acetylcholine receptors (nAChRs) on the plasma membrane of the muscle fiber, also known as the sarcolemma. nAChRs are ionotropic, meaning they serve as ligand gated ion channels. The binding of ACh to the receptor can depolarize the muscle fiber, causing a cascade that eventually results in muscle contraction.20Muscles and MovementMuscles are attached to bones by tendons.Tendon composition is mostly collagen.Muscles do their work by contraction.Muscles grouped in opposing pairs, what one muscle does the other undoes.

Slow Twitch (Type I)The slow muscles are more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time. They fire more slowly than fast twitch fibers and can go for a long time before they fatigue. Therefore, slow twitch fibers are great at helping athletes run marathons and bicycle for hours.Fast Twitch (Type II)Because fast twitch fibers use anaerobic metabolism to create fuel, they are much better at generating short bursts of strength or speed than slow muscles. However, they fatigue more quickly. Fast twitch fibers generally produce the same amount of force per contraction as slow muscles, but they get their name because they are able to fire more rapidly. Having more fast twitch fibers can be an asset to a sprinter since she needs to quickly generate a lot of force.

22Exercise and HealthMuscles, the circulatory system, the heart and the lungs respond to regular exercise.The system becomes more efficient, with increased size and number of calories.This also strengthens bones.Astronauts must exercise to maintain their skeletal and muscular systems.

SkinSkin is the soft outer covering of vertebrates.It is the largest organ of the body with a total area of 20 ft2.It is composed of 3 layers, epi