Allence Bio 12

Front 1

neuromuscular junction

Back 1

A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and a muscle fibre. It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fibre, causing muscle contraction.

Front 2

elbow joint

Back 2

In primates, including humans, the elbow joint is the synovial hinge joint between the humerus in the upper arm and the radius and ulna in the forearm which allows the hand to be moved towards and away from the body.

Front 3

synovial fluid

Back 3

is a viscous, fluid found in the cavities of synovial joints. With its egg white–like consistency, the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement.

Front 4

antagonistic muscles

Back 4

Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes. An example of an antagonisic pair is the biceps and triceps; to contract - the triceps relaxes while the biceps contracts to lift the arm.

Front 5

motor unit

Back 5

A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals. Groups of motor units often work together to coordinate the contractions of a single muscle

The more motor units stimulated the greater the force of the contraction, this is the gradation of response

Front 6

involuntary muscle

Back 6

a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart) smooth muscle.

Front 7

cardiac muscle

Back 7

Forms the muscular part of the heart and there are three types

1. atrial muscle

2. ventricular muscle

3. specialised excitatory and conducting muscle fibres

Front 8

voluntary muscle

Back 8

also know as striated or skeletal muscle

found in limbs

Front 9

sarcomere

Back 9

the smallest contractile unit of the muscle

it is the span from one Z line to the next

the length of the I band and H zone are reduced during contraction and the A band does not change in length

Front 10

thin filaments

Back 10

two strands made of the protein F-actin coiled around each other, each strand is composed of G-actin subunits. Tropomyosin molecules coil about the F-actin reinforcing it. Troponin complex is attached to each tropomyosin molecule.

Each troponin consists of three polypeptides with one binding to actin, one to tropomyosin and one to Ca ions

Front 11

thick filaments

Back 11

are bundles of the protein myosin with each myosin molecule consisting of a tail and two protruding heads

Front 12

power stroke

Back 12

with the Ca elevated around the myofibrils myosin binding sites on the actin are exposed allowing interaction of the myosin cross bridge with actin. Release of the myosin cross bridge from actin requires binding of ATP. After ATP binds it is split to ADP and inorganic phosphate. The energy derived from this is used to cock the cross-bridge in preparation for the power stroke. The power stroke is initiated when the myosin cross bridge binds to actin.

Front 13

creatine phosphate

Back 13

important in short bursts of muscle use, second source of ATP, very quick way of making ATP from ATP by providing the third phosphate. Creatine phosphate shuttle is an intracellular energy shuttle moving high energy phosphate from the mitochondria to the myofibrils.

Front 14

fight or flight response

Back 14

the full range of coordinated responses of animals to situations of perceived danger.

Front 15

stressor

Back 15

a stimulus that causes the stress response

it causes wear and tear on the bodies physical or mental resources.

Front 16

physiological changes in fight or flight

Back 16

pupils dilate

heart rate and blood pressure increase

arterioles to the digestive system and skin are constricted, while those to the liver and muscles are dilated

blood glucose levels increase

metabolic rate increases

erector pili muscles in the skin contract to make hairs stand up

ventilation rate and depth increase

endorphins are released in the brain

sweat production increases

Front 17

coordination of the physiological changes

Back 17

the cerebral activates the hypothalamus which stimulates increased activity in the sympathetic nervous system and triggers the release of adrenaline from the adrenal medulla. The hypothalamus also releases corticotropin releasing factor into the pituitary gland stimulating the release of the hormone adrenocorticotropic hormone from the anterior pituitary gland. This stimulates the release of a number of hormones from the adrenal cortex and some of these help the body to resist stressors.