Protection, Support, and Movement

Integumentary Function A. outer covering of body B. protects against injury, dehydration, UV radiation and some pathogens C. helps regulate body temperature D. excretes certain wastes E. receives external stimuli F. Produces vitamin D

Evolutionary trends in integument with move to land A. keratinization of outer layer for protection -keritinocytes –produce water resistant protein keratin -melanocytes – produce pigment, melanin, as a barrier to UV radiation B. recession of glands with ducts to surface

Human Skin i. largest organ of your body ii. see figure 37.3, p646 iii. stretches, conserves water, fixes small cuts and bruises, helps regulate body temp and protects against pathogens

Vertebrate Skin Two layers –Upper epidermis –Lower dermis Lies atop a layer of hypodermis Figure 37.3 Page 646

Layers A. epidermis – stratified epithelial cells with an abundance of cell junctions with no extracellular matrix -continual mitosis pushes cells from deep layer to surface -outer layers are dead flattened cell that continuously flake away B. dermis – dense connective tissue -stretch resistant elastin fibers -supportive collagen fibers -blood and lymph vessels, and sensory receptors thread throughout it C. hypodermis – below the skin -anchors the skin -loose connective tissue and adipose tissue to insulate and cushion the skin

Skin coloration – combination of several pigments i. melanocytes – brownish black ii. hemoglobin – pink, found in red blood cells (sometimes shows through the skin) iii. carotene – yellow orange

Exocrine Glands – their ducts extend through the skin i. types a. mammary glands – produce milk b. sweat glands -sweat = 99% water with dissolved salts, ammonia and vitamin C -controlled by sympathetic nerves -located on palms, soles, forehead and armpits -decrease body temperature c. oil glands -not on palms or soles -called sebaceous glands -lubricates and softens hair and skin -secretions kill many surface bacteria -clogged and infected = acne

Hair A. flexible, mostly keratinized (made of keratin - protein) cells B. cells divide near root, push upwards, flatten and die C. influenced by genes, nutrition and hormones (growth and density) D. root embedded in skin, shaft above its surface Nails, Claws, Scales, Horns, Hooves and Beaks A. made of keratin -a fibrous protein

Langerhans Cells White blood cells that arise in bone marrow, migrate to epidermis Engulf pathogens and alert immune system UV radiation can damage these cells and weaken body’s first line of defense

Granstein Cells Also occur in epidermis Interact with cells that carry out immune response Issue suppressor signals that keep immune response under control Less vulnerable to UV damage than Langerhans cells

Skeletal System Function – human bone function table on page 652 A. Protects and supports the body and organs B. interacts with skeletal muscles for movement C. Produces red blood cells, white blood cells, and platelets D. provides muscle attachment sites E. stores minerals (calcium and phosphorus)

muscles require the presence of some structural element to cause movement 3 types of animal skeletons i. hydrostatic – muscles work against internal body fluid and redistribute it: soft-bodied invert’s such as annelids and sea anemones ii. exoskeleton – rigid, external, receives the applied muscle contraction: arthropods iii. endoskeleton – internal, receives the applied muscle contraction: vertebrates

Human Skeleton SKULL cranial bones facial bones sternum RIB CAGE ribs VERTEBRAL COLUMN vertebrae intervertebral disks PECTORAL GIRDLES AND UPPER EXTREMITIES clavicle scapula humerus radius ulna carpals metacarpals phalanges pelvic girdle femur patella tibia fibula tarsals metatarsals phalanges PELVIC GIRDLE AND LOWER EXTREMITIES

organs consisting of connective tissue and epithelia i. bone tissue consists of mature bone cells (osteocytes) and collagen fibers in a calcium hardened substance Long bone structure i. compact bone – resists mechanical shock ii. Haversian system – within compact bone, thin cylindrical dense layers around canals for blood vessels and nerves iii. spongy bone – imparts strength but doesn’t weigh much iv. red marrow –blood cell formation, in some bones v. yellow marrow – fatty region, converts to red marrow in times of severe blood loss

Long Bone Structure Compact bone Spongy bone Central cavity contains yellow marrow compact bone tissue spongy bone tissue nutrient canal contains yellow marrow Fig (1) Page 652

Compact Bone Structure Mature compact bone consists of many cylindrical Haversian systems spongy bone tissue compact bone tissue outer layer of dense connective tissue blood vessel Haversian system Fig (2) Page 652

Bone Marrow Yellow marrow –Fills the cavities of adult long bones –Is largely fat Red marrow –Occurs in spongy bone of some bones –Produces blood cells

Joints Areas of contact or near contact between bones Fibrous joints –Short connecting fibers join bones –Ex. newborn skull Synovial joints –Move freely; ligaments connect bones –pivot, saddle, hinge, ball and socket –See packet Cartilaginous joints –Straps of cartilage allow slight movement –Ex. Breastbone, ribs, vertebrae

Bone formation i. bone forms around cartilage in embryos a. osteoblasts (bone forming cells) secrete organic substance that becomes mineralized forming osteocytes and the cartilage then breaks down leaving the marrow cavity ii. bone remodeling a. mineral ions and osteocytes are constantly being removed and replaced b. this adjusts bone strength and helps maintain blood levels of calcium and phosphorus c. osteoblasts deposit new bone, osteoclasts digest (chemically breakdown) bone with enzymes d. free ions can then enter the interstitial fluid and get absorbed by the bloodstream

Bone, Blood, and Calcium i. bone and teeth store all but 1% of the bodies calcium ii. negative feedback of calcitonin and PTH help regulate blood calcium levels iii. calcitonin suppresses osteoclast activity (lowers blood calcium levels) iv. PTH enhances osteoclast activity (increases blood calcium levels)

Osteoporosis is a decrease in bone density –May occur when the action of osteoclasts outpaces that of osteoblasts –May also occur as a result of inability to absorb calcium Arthritis –Inflammation of joints Common Disorders

Muscular System I. Function a. Movement i. Limbs and trunk ii. Substances through the body - blood and food b. maintains posture c. structure and support d. generates heat

I. Structure a. 3 types of muscle – see packet picture i. skeletal –we will concentrate on this type - functional partners of bone - striated (striped) - voluntary - opposing groups (antagonistic, against) or in pairs (helping) - muscle cells contract or lengthen - humans have over 600, we will learn 10 (see packet diagram) ii. Smooth – internal organs iii. Cardiac - heart

Skeletal Muscle Bundles of striped muscle cells Attaches to bone Often works in opposition biceps triceps Figure Page 654

Major Human Muscles triceps brachii pectoralis major serratus anterior external oblique rectus abdominus adductor longus sartorius quadriceps femoris tibialis anterior biceps brachii deltoid trapezius latissimus dorsi gluteus maximus biceps femoris gastrocnemius Figure Page 655

Skeletal Muscle Structure A muscle is made up of muscle cells A muscle fiber is a single muscle cell Each fiber contains many myofibrils myofibril Figure 37.19a Page 656

Muscle Structure A muscle fiber is a single, multinucleated muscle cell A muscle could be made up of hundreds or even thousands of muscle fibers –Muscle fibers make up most of a muscle but connective tissue, blood vessels, and nerves are also present –Nerves stimulate the muscle –Arteries supply oxygen and nutrients while veins carry away metabolic wastes –Connective tissue covers and supports each fiber as well as the whole muscle

Muscle Fibers Fibers consist of bundles of threadlike structures called myofibrils – made up of two protein filaments –Myosin – thick filaments –Actin – thin filaments Myosin and actin are arranged in overlapping patterns that give the appearance of light and dark bands (striations) Actin filaments are anchored at their midpoints to a structure called a Z-line The region from one z-line to another is called a sarcomere – functional unit of muscle contraction

Sarcomere Z line sarcomere A myofibril is made up of thick and thin filaments arranged in sarcomeres Figure 37.19b Page 656

Muscle Microfilaments Actin - Thin filaments Like two strands of pearls twisted together Pearls are actin Other proteins in grooves in filament Myosin -Thick filaments Composed of myosin Each myosin molecule has tail and a double head Figure 37.19c Page 656

a. each muscle cell has many myofibrils (looked striped when stained) containing Z bands and sarcomeres i. cardiac muscle also has these, that is why they are called striated muscle b. many sarcomeres contract simultaneously causing the muscle to contract and move a bone i. remember, this is the main purpose of skeletal muscle sliding filament model – see page 657 i. actin fibers are attached to the Z –bands ii. myosin fibers run parallel but between actin fibers iii. myosin heads attach to nearby actin filaments creating a cross bridge iv. myosin heads tilt toward sarcomeres center causing the actin filaments to slide with them and shorten the sarcomere myosin head releases moves back and regrips the actin filament to move again

Sliding-Filament Model Myosin heads attach to actin filaments Myosin heads tilt toward sarcomere center, pulling actin with them Fig c-g Page 657

Sliding-Filament Model Sarcomere shortens because the actin filaments are pulled inward, toward the sarcomere center Fig a,b Page 657

Muscle Contraction Sliding filament theory –Myosin and Actin filaments interact to shorten the sarcomere –Knob like projections on myosin form cross-bridges with actin filaments –When the muscle is stimulated, the filaments move across each other

Contraction Cont. When the cross-bridge has moved as far as it can, it is released and the actin filament returns to its original position; the cross-bridge attaches at another point and the cycle is repeated The synchronized shortening of sarcomeres causes the entire fiber to contract and thus the muscle shortens ATP is required to attach and detach myosin heads from actin Without ATP, the filaments would not be able to contract or relax – rigor mortis

Control of Muscle Contraction Motor neurons connect to muscles at points called neuromuscular junctions 1.When an action potential reaches the axon terminal, the neurotransmitter acetylcholine diffuse across the synapse and initiate an impulse in the muscle cell 2.Impulse causes the release of calcium ions in the cell 3.Calcium ions affect proteins that regulate the interaction of Actin and Myosin filaments 4.An enzyme, acetylcholinesterase, destroys acetylcholine to stop the impulse

Nervous System Controls Contraction Signals from nervous system travel along spinal cord, down a motor neuron Endings of motor neuron synapse on a muscle cell at a neuromuscular junction

-Motor neurons stimulate or inhibit contractions with an action potential -Muscle cells have a specialized structure called the sarcoplasmic reticulum that stores and releases calcium -When an action potential reaches a muscle cell it travels down the membrane (sarcolemma) and into a T-tubule that carries the action potential inside. This triggers the release of calcium ions from the sarcoplasmic reticulum to the actin filaments

-The calcium clears the binding site for the cross bridge so sarcomere contraction can occur i. 2 proteins are involved in this action - tropomyosin, blocks the binding site - tropomyosin is bound to the troponin - troponin binds the free calcium and changes its shape, this causes the tropomyosin to move - the binding site is therefore unblocked ii. After the contraction, the calcium is transported back into the sarcoplasmic reticulum for storage

Contraction Requires Energy Muscle cells require huge amounts of ATP energy to power contraction The cells have only a very small store of ATP Three pathways supply ATP to power muscle contraction

i. Phosphorylation - quick reaction that transfers phosphate from creatine phosphate to ADP, creating ATP - this gives the cell time to perform cellular respiration (aerobic) to further supply ATP ii. Cellular respiration - aerobic - produces lots of ATP but takes time - phosphorylation gives the cell time to do this iii. Glycolysis - anaerobic respiration - may kick in if needed (when not enough oxygen for aerobic respiration) - produces less ATP, but allows processes to continue

ATP for Contraction Pathway 1 Dephosphorylation Creatine Phosphate Pathway 2 Aerobic Respiration Pathway 3 Glycolysis Alone creatine oxygen glucose from bloodstream and from glycogen break down in cells ADP + P i relaxation contraction Figure Page 659

Motor Unit One neuron and all the muscle cells that form junctions with its endings When a motor neuron is stimulated, all the muscle cells it supplies are activated to contract simultaneously Each muscle consists of many motor units

- tetanus is a sustained contraction resulting from repeated stimulation i. also the name of a disease that disrupts muscle relaxation - muscle fatigue i. decline in a muscles capacity to generate force ii. decline in tension iii. after a time of rest, fatigues muscles can contract again a. the time depends on the amount of fatigue iv. the molecular mechanism of fatigue is not known

-- cramps i. involuntary, large, often painful contractions ii. can persist for up to 15 minutes or more iii. can be caused by fatigue - muscular dystrophies i. genetic disorders where muscles progressively weaken and degenerate - muscles, exercise, and aging i. with regular use, muscle cells increase in size and metabolic activity a. become more resistant to fatigue ii. muscle tension declines in adults (after age 30 or 40) a. regular exercise may help