Year 11 Human Biology - Musculoskeletal System

What is the skeleton

The framework of the body, including bones, cartilage, dense connective tissue and joints

name the functions of the skeleton

provide framework, protection, store minerals and fats, produce blood cells and allow movement of the body

what is the axial skeleton

bones surrounding the central axis, including the cranium, mandible, facial bones, vertebral column, rib cage and sternum

what bones make up the vertebral column

7 cervical, 12 thoracic, 5 lumbar, 5 sacarl and 4 caudal

what is the appendicular skeleton

the upper limbs, shoulder girdle, lower limbs and pelvic girdle

bones include humerus, ulna, radius, carpals, matacarpals, phalanges, clavicle, scapula, ilium, ischium, pubis, femur, fibula, tibia, tarsals, metatarsals

describe the diaphysis

long cylindrical shaft in middle of bone

hollow

compact bone walls

describe the medullary cavity

the space within the diaphysis

contains yellow bone marrow in adults and red bone marrow in kids

lined with endosteum

what is the periosteum

a tough fibrous membrane covering the outside of the diaphysis and other non articulating parts of the bone

what are the epiphyses

the wide bine ends covered in hyaline (articular cartilage)

their centres are filled with spongy bone and red bone marrow

enclosed by thin compact bone

what are the names of the 2 epiphyses

distal epiphysis (furthest from body)

proximal epiphysis (nearest to body)

what tissue type are bones

connective tissue because they are composed of a large matrix and few embedded cells

what is the rigid bone matrix made of

mineral salt deposits (calcium and phosphate ions)

and collagen fibres

what makes up compact bone

osteons which are organised parallel to eachother and the long axis

describe an osteon structure

* central canal (haversion canal)
* concentric lamellae
* lacunae (depressions between lamellae)

what do lacuane contain, and describe these structures

osteocytes which are mature bones cells

they communicate and pass materials by cytoplasmic extensions through cannaliculi (tiny canals)

what do central canals contain

blood vessels which enter through foreamens and then divide so each central canal has 1 arteriole and 1 venuole

what is trabecular bone

spongy bone made of trabeculae (bony plates)

trabeculae are loosely organised, following lines of force

there is red bone marrow and blood vessels in trabecular spaces

spongy bone is porous and strong

what are the 3 bone cell types, with descriptions

osteoblasts → build bones by depositing minerals in matrix (found under periosteum)

osteocytes → mature/maintaining bone cells

osteoclasts → bone destroying cells, for growth and remodelling (found on trabeculae edges and in lacunae between lamellae)

what is cartilage

A connective tissue which provides support and flexibility

Describe cartilage composition

the matrix is made of firm and flexible chondrin (protein carbohydrate complex) and collagen fibres

The cells are called chondrocytes found in cavities in the matrix, which originate from chondroblasts

describe hyaline cartilage

glossy white/blue

Firm and strong

Fine and tightly packed collagen fibres

Chrondrocytes in 3/4 and scattered

Found on epiphyses, nose, ribs, , trachea, bronchi

describe elastic cartilage

fine semi tight collagen fibres and thick elastic fibres

Very flexible and supportive

Found in ear, epiglottis and Eustachian tubes

Describe fibrous cartilage

weight bearing and compressable

Thick parallel collagen fibres

Chondrocytes exist in rows

Found in intervertebral discs, menisci in knees, symphisis pubis

What is a fibrous joint

a joint which allows no movement between the two bones. They are held by fibrous connective tissue and are difficult to break

E.g. In skull, teeth and jaw

What is a cartilaginous joint

joints held bybcartilage, meaning they have slight movement

E.g. Pelvic junction, vertebrae

What is a synovial joint

give maximum movement to bones

There are six types of synovial joints

What is a tendon

A strong felxible tissue joining a muscle to a bone

Fibres are in a parallel arrangement

What is the synovial cavity

the space between articulating bones in a synovial joint

Filled wihr synovial fluid

what is a bursae

sacs of synovial fluid which prevent friction between bone and ligament or tendon

What is the meniscus

in the knee it is a cartilage pad which acts as a shock absorber and divides joint

What is the cruciate ligament

in the knee its a cross shaped ligamen twhihc holds the joint together (connects the two bones)

What is the synovial membrane

membrane which secretes synovial fluid

Made of loose connective tissue and elastic fibres + some fat storing tissue

Describe a ball and socket joint

a spherical bone head fits into a cup like cavity of another bone

E.g. Femur into pelvis

Describe a hinge joint

convex bone fits into concavity of another bone

Movement on one plane only

E.g. Elbow or knee

Describe a pivot joint

a round point or conical end articulates into a ring of bone and ligament

E.g. In 1st and 2nd vertebrae

Describe a gliding joint

two bones rub against one another and provides back and forth or side to side movement

Surrounding ligaments can restrict movement

E.g. In wrist (carpals)

Describe a saddle joint

only true saddle joint is where thumb joins the hand

One bone is convex one way and other bone is convex other way

They can move side to side or back and forth

Describe and ellipsoidal joint

slightly concave bone slips into a slightly convex bone

Can move two ways e.g. Side to side and up and down

E.g. Radius and carpals or metatarsals and phalanges

What is flexion

the angle between the articulating bones descreases

Bones move closer together

together

What is extension

increase the angle between articulating bones

The bones move further apart

What is adduction

limbs move towards the midline of body

What is abduction

limbs move away from midline of body

What is rotation

the movement of a bonebaround its long axis

What is a muscle classified as and why

muscles are organs because they cknsist of two or more tissues i.e. Muscle tissue, connective tissue, tendons, blood vessels, nerves

What are the 4 features of muscle tissue with descriptions

extensibiltiy - lengthen

Contractibility - shorten

Elasticity - return to originl length

Excitability - responds to stimuli i.e. Electrical nerve impulse

what makes up a muscle fibre with descriptions

sarcolemma the plasma membrane

Sarcoplasm the cytoplasm

Sarcoplasmic reticulum the ER surrounding myofibrils

Numerous mitochondria

Many periphery nuclei

Myofibrils the rod like structures running the fibres length

What makes up a myofibril

the two protein myofilmanets myosin (thick) and actin (thin)

Describe the parts of a myofibril

A band - length of myosin (dark band)

I band - length of action only (light band)

H zone - area of myosin only

Z line - where sarcomeres meet

M line - line in middle of A band

List the structural order of a muscle

myofilament, sarcomere, myofibril, muscle fibre, muscle fibre bundle, muscle

What does the sliding filament model suggest

It explains how muscles contract by proposing that sarcomeres shorten because actin and myosin myofilaments slide past one another and overlap

What are the 3 connective tissue is a muscle

Epimysium - surrounds entire muscle allowing musclez to contract

Perimysium - sheath covering each fascicle (fibre bundle) separating them

Endomysium - separates individual muscle fibres from one another

Describe in full the sliding filament model

sarcomeres, the contractile unit of muscles, are made of thick myofilaments myosin and thin myofilaments actin

Between sarcomeres are dense areas called Z lines where actin filaments join

Upon nervous stimulation of action potential the actin and myosin slide past each other and overlap

Z lines move closer and sarcomere shortens

All sarcomeres shorten, shortening myofibril length hence shortening whole muscle

During contraction the H zone shortens, or disappears and the I band shortens but myofilament lengths stay the same

What is an antagonistic pair

a pair of muscles which work in opposites to make actions possible

What is the agonsit

The muscle which makes the desired action by contracting

Also known as the prime mover

What is the antagonist

the muscle which relaxes during movement

What are synergists

muscles which assist agonist

if agonsit crosses 2 or more joints, synergists will prevent undesired actions

What is the origin of a muscle

where it connects to the stationary bone

What is the insertion of a muscle

where it connects to the movable bone

What is the muscle belly

The section between tendons of origin and insertion

What is an extensor

a muscle which straightens a limb

what is a flexor

a muscle which bends a limb or joint