IB Sports Test: B.1.2 - B.1.3

Bone functions

Support/ structure- attachment for tendons and soft tissue

Protection

Movement: muscles pull on bones to move

Mineral homeostasis: storage and release

Blood cells: larger bones contain red marrow that make RBC’s

Fat storage: yellow marrow

Ligaments

Connective tissue that hold bones together and prevent extra movement beyond normal range

Cartilage

A network with no blood vessels or nerves to provide cushion to joints, and reduce friction

Fascia

Made up of fibers, fats and fluid that are found between and surrounding other tissues (like muscles)

Fascia is commonly found in muscle in three forms:

Covers the muscle

Covers bundles of muscle fibers called fascicles

Covers individual muscle fibers (cells)

Tendons

When the fascia continues beyond the muscle, they become tendons that connect muscle to bone

Aponeursis

Rounded or flat sheet of tendon

Fibrous joints

Connects the edges of the bones with a thin layer of fibrous tissue, no movement is allowed at these joints

Cartilaginous joints

The bones can be separated by a fibrocartilage disc, or bu a thick layer of hyaline cartilage, these is limited movement allowed

Synovial Joints

The most common joint in the body and the most important, these joints can freely move and have multiple types

Gliding joint

Lease common, found between the carpal bones in the feet and ankle

Hinge

Bend (flex) and straighten (extend) in one direction only, ex elbow

Pivot joint

One bone forms a ring in which the other bone rolls or pivots, allowing a rotation of the joints, ex neck

Condyloid joint

Formed where an oval or egg-shaped convex surface fits into a reciprocally shaped concave surface, ex surface

Saddle joint

Bone that concave over each other to resemble a saddle and these joints can move in all directions, ex thumb

Ball and socket joint

one rounded bone fits into a socket of another securing it while allowing the greatest amount of movement and can move in all directions

Skeletal muscle

Have tendons that attach to bones, they are mant to move the skeleton with voluntary control, they have a striated appearance

Cardiac (heart) muscle

Involuntary control, contractions without you having to think about it consciously, striated appearance

Smooth muscle

Lines the walls of blood vessels and hollow organs such as the stomach and intestines, involuntary, not striated

Functions of muscles

Movement- contracting of muscle to pull on bones

Move substance through the body- smooth muscle move food to all tissues of the body

Stabilize and maintain moldy postition- ex posterior neck muscles contract to keep head in an upright position

Generate body heat

Contractibility

Ability of muscle to contract and generate force when it is stimulated by a nerve, have opposites- one contracts while the other is stretched

Extensibility

Ability of muscle to be stretched beyond its normal resting length

Elasticity

Ability to return to its original resting length after the stretched is removed

Neuromuscular function

Millions of nerve fibers carrying electrical signals in the CNS

Motor neurons

Nerves that carry information from CNS to the muscles, signal muscles to contract or relax

Molecules such as ATP and PCr provide the energy necessary to fuel muscular contraction

The soma

Cell body, contained within the spinal cord or in clusters just outside it called the ganglia

Dendrites

Link the neuron to other neurons and all information to flow between different nervers

The axon

The main component of nerve signal transmission

The myelin

Old transmission of information with gaps called nodes of ranvier

Motor unit

A single motor neuron in the muscle fibers that it innervates

All or none principle

When the motor unit is innervated by the motor neuron and all of its muscle fibers contract at once

Acetylcholine

A neurotransmitter, stimulating, skeletal muscle contraction

Type I motor Unit

Consist of mainly one type (slow twitch) muscle fibers, and have slow nerve transmission speeds and small muscle forces,

can maintain contractions for a long time, fatigue resistant

Type IIa motor units

Consist of mainly type IIa (fast twitch) muscle fibers have fast neural transmission times and stronger contraction forces, fatigue resistant

Type IIx motor units

Consist of mainly type IIa (fast twitch) muscle fibers generate the fastest contraction times in largest forces

Fatigue faster, cannot maintain contraction for long

Myofibris

The contractile element of skeletal muscles, Have light and dark bands and give muscles that striated appearance

Actin

Thin filaments (two thin for every thick)

Myosin

Thick filaments

Sarcomeres

Units that filaments are arranged in

Z disc

Separate one sarcomere from the next

A band

The middle part of the sarcomere that extends the length of the thick filaments

I band

Part of a sarcomere that contains thin filaments, a z disc passes through the center of each I band

H zone

Part of a sarcomere that contains thick filaments

M line

Part of a sarcomere consisting of proteins that hold the thick filaments together at the center of the H zone

The sliding filament theory

Muscle fibers are made up of many thousands of actin and myosin molecules, and the slide of all of these make the muscle contract

The cross bridge cycle

Refers to the repeating sequence of molecular events that occur between the myosin heads (cross bridges) and the actin

The principle of orderly recruitment

Skeletal muscle contraction involves progress recruitment of type I followed by type II motor units, order- type l, type la, type llx

Hypertrophy

an increase in the size or mass of an organ or body tissue

Transient

Hypertrophy develops mainly from fluid accumulation in the muscles, comes from blood plasma, last for a short period of time

Chronic

The increase in muscle size that happens with long term resistance training

Atrophy

The loss of size or mass of body tissue and loss in muscle strength

Isometric muscle contraction

Another name for a static (without moving) muscle contraction ex arm wresting

Isotonic concentric muscle contraction

When muscles create movement by shortening its length

Isotonic

When muscle contract at a controlled speed

Isotonic eccentric muscle contraction

When the muscle is contracting but the effect of the muscle force is less than that of the resistance, ex putting down a book

Isokinetic motion

When a muscle contacts so that the body segment to which it is arch moves at a constant speed around the joint, rare in sports, useful for rehabilitation

Agonist

(Main Mover) The muscle contracts concentrically to move the bone relative to the joint

Antagonist

Contracts eccentrically, it act in the opposite direction to its usual concentric function and gets longer

Fixator

A stabilizer, a muscle whose contraction helps an agonist in a action

Synergist

Neutralizers, contract to prevent unwanted actions of the agonist or antagonist

Reciprocal inhibition

An automatic action controlled by neurons to prevent the muscle to contract strongly

Insertion

The end of the skeletal muscle that attaches to the bone being pulled

Origin

The end of the muscle attached to a fixed bone