Module 3

Question 1

what are the functions of the skeletal system

Answer 1

provides structural support for the body

protection of internal organs

mineral homeostasis - storage of calcium and phosphorus can be released when required into the blood.

assistance in movement

triglyceride storage

blood cell production

Question 2

what are the two types of skeletal systems

Answer 2

axial

appendicular

Question 3

what bones are included in the axial skeleton

Answer 3

cranial bones (frontal, parietal, temporal and occipital, maxilla, mandible).

vertebral column
thorax (sternum and ribs)
hyoid bone
auditory ossicles

Question 4

what bones are included in the appendicular system

Answer 4

upper limb and pectoral girdle

• scapula
• clavicle
• humerus
• radius
• ulna
• carpals
• metacarpals
• phalanges

pelvic girdle
- hip, pelvis, coxal bones.

lower limbs

• femur
• patella
• fibula
• tibia
• tarsals
• metatarsals
• phalanges

Question 5

function of bone markings

Answer 5

depressions and openings allow passage of blood vessels, nerves, ligaments, tendons.

processes, projections help form joints and act as attachment sites for tendons and ligaments.

Question 6

what is the importance of the combination of compact and spongy bone?

Answer 6

The combination of compact and spongy bone structure provides different forms of support, strength and protection whilst being lightweight.

Spongy bone provides ideal weight for weightbearing, resists forces applied from different angles and requires less ATP needed for movement, whilst the compact bone resists compression.

Question 7

describe the structure and function of compact and spongy bone

Answer 7

compact - contains osteons columns.
Inorganic materials give hardness, rigidity, ability to resist compression forces and support body tissues.

Minerals of calcium, ions, phosphates, carbonate.

2/3 of matrix weight

spongy - trabeculae.
Organic materials give flexibility and great tensile strength to bone.

Collagen fibres

1/3 of matrix weight.

Question 8

describe bone growth from embryo to adolescent

Answer 8

Bone growth from embryo to adolescent

Cartilage formation and ossification occurs during week 6 of embryonic ossification.

Intramembranous ossification: bones form by sheets that resemble membranes e.g. cranial bones

Endochondral ossification: form most of the bones of the body.

Bones grow by interstitial growth by addition of bone of the diaphyseal side of the epiphyseal plate.

Bones grow in width by appositional growth by cartilage on the epiphyseal side of the epiphyseal plate.

Question 9

describe bone growth in length across lifespan

Answer 9

Growth in length

Epiphyseal plate is a layer of hyaline cartilage in the metaphysis of growing bone.

Interstitial cartilage growth occurs on epiphyseal side of the plate.

Cartilage is replaced by bone on the diaphyseal side of the plate by endochondral ossification.

Epiphyseal plate stops growing around 18 years in females and 21 years in males – bony structure called the epiphyseal line – no more long bone growth.

Question 10

describe bone growth in length across lifespan

Answer 10

Growth in length

Epiphyseal plate is a layer of hyaline cartilage in the metaphysis of growing bone.

Interstitial cartilage growth occurs on epiphyseal side of the plate.

Cartilage is replaced by bone on the diaphyseal side of the plate by endochondral ossification.

Epiphyseal plate stops growing around 18 years in females and 21 years in males – bony structure called the epiphyseal line – no more long bone growth.

Question 11

what are factors affecting growth of bones

Answer 11

Factors affecting bone growth

Exercise – builds up muscle, stress on bone stimulates osteoblast activity - extra bone mass.

Minerals – minerals needed for bone formation are calcium and phosphorus.

Vitamins – A = osteoblast activity, C needed for collagen synthesis, D increases calcium absorption from GIT, K and B12 needed for bone protein synthesis.

Hormones – calcitriol increases calcium absorption across GIT, PTH increases blood calcium, calcitonin decreases blood calcium, growth hormone increases bone matrix.

Sex hormones stimulate osteoblasts

In childhood, IGF’s produced in liver cells and osteoblasts stimulate bone growth along with thyroid hormone.

Question 12

how do synovial joints structure relate to its function/

Answer 12

Synovial joints

Joint cavity/space between articulation of bones.

Held together by joint capsule and ligaments.

Synovial fluid lubricates cartilage to reduce friction and absorb shock, supplies oxygen and nutrients to chondrocytes and removes waste, and contains phagocytic cells to remove debris and microbes.

Question 13

define synarthrosis, amphiarthrosis and diarthrosis

Answer 13

Synarthrosis: an immovable joint. E.g. suture and stenosis.

Amphiarthrosis: slightly mobile. E.g. interosseous membranes, syndesmosis and symphysis.

Diarthrosis: freely mobile joint, have a variety of shapes and permit different types of movements. E.g. elbow and hip.

Question 14

what is the function of flat bones

Answer 14

Provides protection for major organs and large areas for muscle attachment.

Question 15

what are the types of cartilage

Answer 15

Hyaline cartilage – contains resilient gel as ground substance, most abundant cartilage in the body, found @ ends of long bones, anterior ends of ribs, nose, parts of larynx, trachea, bronchi, bronchial tubes, embryonic and foetal skeleton. It provides smooth surfaces for movements at joints, flexibility and support; weakest type of cartilage and can be fractured.

Fibrocartilage – has chondrocytes among clearly visible thick bundles of collagen fibres within ECM and lacks perichondrium. Public symphysis, intervertebral discs, menisci, portions of tendons that insert into cartilage. It supports and joins structures together. Strength and rigidity make it the strongest type of cartilage.

Elastic cartilage – elastic cartilage has chondrocytes in threadlike network of elastic fibres within extracellular matrix; perichondrium present. Is found on top of the larynx, part of external ear, auditory tubes. It provides strength and elasticity, maintains shape of certain structures.

Question 16

fibrous joints

Answer 16

Fibrous joints:

suture – no synovial cavity, bones held very tightly together by layer of dense irregular cartilage, only found in skull.

stenosis joints – complete fusion of two bones into one. E.g. frontal bones.

Syndesmosis – greater distance between articulating surfaces, usually involves a ligament. E.g. tooth in jaw socket.

Interosseous membranes – between radius and ulna, tibia and fibula.

Question 17

cartilaginous joints

Answer 17

Cartilaginous joints

No synovial cavity.

Bones connected by hyaline cartilage or fibrocartilage.

Synchondrosis: uses hyaline cartilage. E.g epiphyseal plate.

Symphysis: uses a pad of fibrocartilage between the bones. E.g. pubic symphysis.

Question 18

what are the types of movements at joints?

Answer 18

Types of movements at synovial joints

Gliding – sliding back and forth movements between nearly flat bone surfaces. E.g. carpals.

Angular movements

Rotation

Special movements – elevation, depression, protraction, retraction, inversion, eversion, dorsiflexion, plantar flexion, supination, pronation and oppoisition.

Question 19

what is the function of muscle

Answer 19

produce movement

support soft tissues and internal organs

stabilise joints to maintain body position and posture

generation of heat (shivering)

storage of nutrients (proteins)

guards body entrances and exists in digestive and urinary tracts

Question 20

properties of muscle

Answer 20

Electrical excitability: ability to respond to certain stimuli by
producing an action potential e.g. electrical signals from
pacemaker cells in the heart or release of NTs at motor
neuron axon terminals
• Contractility: ability to contract forcefully to generate
tension while pulling on attachment points
• Extensibility: ability to stretch (within limits) without
damage; CT within the muscle limits extensibility; smooth
muscle gets most stretch; cardiac muscle stretches while
filling with blood
• Elasticity: ability to return to the original length and shape
after contraction or extension

Question 21

define hypertrophy

Answer 21

increased tissue due to increased size of cells

Question 22

hyperplasia

Answer 22

increased tissue size due to increase in cell number

Question 23

atrophy

Answer 23

decrease in tissue size due to lack of size of cells.

Question 24

3 types of muscle tissue

Answer 24

smooth, cardiac, skeletal

Question 25

smooth muscle tissue

Answer 25

located in walls of hollow internal structures (blood vessels, airway to lungs, stomach, intestine, bladder, uterus)

autonomic contraction

• slow onset, resistant to fatigue
• spontaneous rhythmic cycles
• influence by hormones, stretching, ANS.

uni-nucelated
spindle shaped
non striated
can undergo mitosis for repair or to regenerate.

function - motion (constriction of blood vessels and airways, propulsion of foods through gastrointestinal tract, contraction of urinary bladder and gall bladder).

Question 26

cardiac muscle

Answer 26

found in heart
involuntary - slow onset, resistant to fatigue.
contraction influenced by ANS and hormones by changing pacemaker depolarization rate.

function - pumps blood to all parts of body.

branched, striated fibers with usually only one centrally located nucleus (occasionally two).

intercalated discs contain gap junctions for communication, allow electrical connection and movement of ions between cells.

cannot divide - instead undergoes hypertrophy to compensate for increase workload.

Question 27

skeletal muscle tissue

Answer 27

voluntary
skeletal muscle can only pull bone - need antagonistic muscles at synovial joints.

function - motion, posture, heat production and protection.

Question 28

trapezius

Answer 28

upward rotation of the scapula, stabilize scapula, help extend head.

Question 29

deltoid

Answer 29

abduction of arm at shoulder, flexion and medial rotation of arm at shoulder, extension and lateral rotation of arm at shoulder.

Question 30

biceps brachii

Answer 30

flexes forearm at elbow, flexes arm at shoulder, supinated forearm at radioulnar joint.

Question 31

triceps brachii

Answer 31

extends forearm at elbow

extends arm at shoulder

Question 32

pectoralis major

Answer 32

adducts and medially rotates arm at shoulder, flexes arm, extends flexed arm to side of trunk.

Question 33

rectus abdominus

Answer 33

flexes vertebrae column, particularly lumbar region, compress abdomen, flexes pelvis on vertebral column.

Question 34

quadriceps femoris

Answer 34

extends leg at knee, flexes thigh at hip

Question 35

hamstrings

Answer 35

flex leg at knee, extend thigh at hip

Question 36

gluteus medius

Answer 36

abducts thigh at hip, medially rotates thigh

Question 37

glut max

Answer 37

extends thigh at hip, laterally rotates thigh, helps lock knee in extension, extends torso.

Question 38

gastrocnemius

Answer 38

plantar flexion of foot at ankle, flexes leg at knee.

Question 39

what are the key skeletal muscles

Answer 39

deltoid
pectoralis major
rectus abdominis 
vastus lat, med and rec fem. 
gastrocnemius 
biceps femoris
semitendinosus 
semimembranosus 
glut med and max.

Question 40

muscle tone

Answer 40

slight degree of contraction or undertone of contraction that occurs in muscles while at rest.

Question 41

neuromuscular junction

Answer 41

the synapse between a somatic motor neuron and a skeletal muscle fiber/cell

includes the axon terminals of the motor neuron synaptic cleft and motor end plate of the muscle fiber.

sarcolemma across from the axon terminals is called the motor end plate, the motor end plate is usually midway.

Question 42

motor neuron to muscle fiber action potential

Answer 42

1. release of ACh from axon terminals
   - arrival of AP at axon terminals opens voltage-gated calcium ion channels - calcium entering and causing exocytosis of NTs into synaptic cleft.

• ACh diffuses across synpases.

2. activation of ACh receptors
   - bindnig of 2ACh to a single receptor on the motor end plate opens the ion channel - NA+ diffusing inside.
3. muscle AP - diffusion of NA+ - change in membrane potential whihc triggers AP along the sarcolemma into T tubules.
4. Stopping ACh activity
   - achetylcholinesterase rapidly breaks down ACh in the synapses.
   - reuptake into motor neuron axon terminals and repackaging into vesicles.
   - also diffusion away from synapses.

Question 43

ageing effects on bones

Answer 43

bone mass/density decreases with advancing age due to decrease in muscle mass, decreasing sex hormone level allowing osteoclast-osteoblast function imbalance, and decreased collagen to mineral content - brittle bones.

females post menopause most susceptible to bone
- density loss - osteoporosis and increased risk of fractures.

• decrease in oestrogen - osteoclast function overtakes osteoblast.
• osteoporosis is more likely in females - vetebral fractures.

Question 44

ageing effects on joints

Answer 44

articular cartilage thins
most pronounced in weight bearing joints (hips and knees)
decreased production of synovial fluid.

ligaments shorten and lose some flexibility (drop in collagen).

Question 45

outcomes of ageing effects on joints

Answer 45

destruction of articular cartilage and development of bony spurs within space reduces space - pain, inflammation and restricted joint movement.

loss of collagen weakens ligaments and tendons, which along with loss of muscle mass and slower reflexes increases risk of falls and loss of balance.

narrowing of the vertebral column can occur from bony growth - compression of spinal nerves and spinal cord - pain and decreased muscle function.

Question 46

osteoarthritis

Answer 46

degenerative, age-related wear and tear disease

arises from breakdown of articular cartilage on the ends of bones in joints

bone ends rub together - friction of bone on bone - extra bone deposited - formation of bony spurs.

bony spurs limit joint movement or lock joints.

Question 47

kyphosis

Answer 47

abnormal posterior curve in thoracic vertebrae, more common in elderly.

Question 48

ageing effects on muscle

Answer 48

slow progressive muscle mass loss (atrophy) from 30+ years.

muscle replaced by fibrous CT and adipose tissue - drop in maximum muscle strength.

number of slow oxidative fibers increases - slower speed of contraction.

• due to less physical activity
• slowing of reflexes
• reduction in flexibility

blood flow to muscles decreases as cardiovascular function decreases - reduced oxygen and nutrient supply.