A&P lecture - muscular system

muscle tissue

-one of four primary tissue types

-consists of elongated muscle cells specialized for contraction

three types of muscle tissue

skeletal, smooth, cardiac

muscular system includes over

700 muscles

5 functions of skeletal muscle

move the skeleton → pull on tendons that then move bones

maintain posture and body position

support soft tissues → abdominal walls and pelvic cavity floor composed of skeletal muscle

guards entrances and exits → encircle openings of digestive and urinary tracts

maintain body temperature → muscle contractions generate heat

skeletal muscles contain (4)

skeletal muscle tissue, blood vessels, connective tissues, nerves

hierarchy of muscles

muscle tissue → muscle fascicle → muscle fiber→ myofibrils → myofilaments → myosin and actin

each muscle fiber is (2)

multinucleate and has more mitochondria than most other cell types

have a striated appearance

advantages of being multinucleate and having more mitochondria

more formation of protein

more energy from more mitochondria

muscles fibers contain

myofibrils

myofibrils (2)

cylinder shaped structures running the length of a muscle fiber

hundreds to thousands in each fiber

myofibrils conrain repeating units of

sarcomeres, the functional unit of muscle

sarcomeres are made of

bundles if tick and thin myofilaments

actin molecules are found in

thin filaments

myosin molecules are found in

thick filaments

Sliding filament theory (2)

explanation for sarcomere contraction

thin filaments slide towers the center of the sarcomere and thick filaments dont move

explanation if sarcomere contraction (4 steps)

wishing heads of thick filaments bind to active sites on thin filaments → heads then pivot toward center sarcomee pulling thin filament in that direction → heads detach and return to original position → process repeats

sarcomere shortening produces

tension

sarcomere shortening causes

entire muscle fiber to contract

muscle fiber contraction pulled on the

collagen fibers in tendons, creating tension

tension on tendons move the

bone that the tendon is attached to

only usable energy molecule

ATP

ATP cycling

when ATP is broken down releasing a P making ADP, breaking of bond causes energy, pick up a random P and cycle continues

aerobic cellular respiration (4)

requires oxygen

occurs mostly in the mitochondria

transforms unusable chemical energy from food mlecules to usable chemical energy in ATP molecules, transfer of energy

end products are 36-38 ATP (per glucose), water, and carbon dioxide

lactic did fermentation

also converts unusable energy in food molecules into usable energy in ATP moleculesmolecules, can only use sugars as the food molecules

lactic acid fermentation occurs

in the cytoplasm

lactic acid fermentation does not

use oxygen, anaerobic

lactic acid fermentation yeilds (2)

only 2 ATP per glucose

lactic acid, potentially causing a pH problem in cells

affects of physical activity on respiratory system

breathing, faster and harder

affects of physical activity on cardiovascular system

heart rate, increases

affects of physical activity on intwgumentary system

temp regulation, sweat gland secretions, blood flow to skin

muscle cramp

sudden, painful, involvement contraction of one or more muscles that does not immediately relax

causes of muscle cramps

overuse of muscle, dehydration, muscle strain, inadequate blood supply, mineral delepletion → potassium, calcium, magnesium

why do bananas help stop muscle cramps?

contain potassium

which is involved in the nervous control of muscle contraction