Human Musculoskeletal Anatomy Flashcards
What 3 layers make up skeletal tissue?
Ectoderm, mesoderm and endoderm
What is connective tissue?
Tissue that connects and support organs and other tissues
Cartilage
- properties (4 marks)
- What is it made up of (2 marks)
- Made from chondrocytes embedded in a matrix
- No blood vessels within cartilage so nutrients and oxygen must diffuse through the matrix in the cell (therefore doesn’t heal well)
- Hard, flexible, compressible and elastic
Describe the three types of cartilage and order them from weakest to strongest
- Hyaline cartilage is located at the ends of the bones, the nose and trachea. High proportion of collagen. Weakest
- Yellow elastic cartilage. Contains yellow elastic fibres located in external year. Chondrocytes surrounded by network of elastin fibres,
- White fibrous cartilage. Strongest. Many bundles of collagen. Great tensile strength and found between vertebrae
What does the compact bone matrix consist of?
(2 marks)
- 30% organic (mainly protein collagen to resist fracture)
- 70% inorganic (mainly hydroxyapatite containing calcium and phosphate to prevent compression)
Describe Haversian systems (osteons) and how it provides a transport system in the bone
(3 marks)
- Haversian canal at the centre of the system contains an arteriole, venule, lymph vessels and nerve fibres
- Lamellae concentric rings of hydroxyapatite around the lamellae
- Lacunae containing osteoblasts and osteoclasts. Nourished by diffusion through tissue fluid. Link to other cells via canaliculi channels.
What are osteoblasts and osteoclasts?
- Osteoblasts build lamellae up by secreting/deposit hydroxyapatite /calcium salts. Bone is reformed by osteoblasts
- Osteoclasts continually breakdown/reabsorb bone compounds/lamellae for rebuilding
What is the cause, symptoms and treatment for rickets (children) / Osteomalacia (adult)
Cause
- Deficiency in vitamin D (from butter, eggs, liver and synthesised by the skin), which leads to the inability to absorb calcium from the gut leading to defective calcification of bone
Symptoms
- Bone tenderness, fractures and skeletal deformities
Treatment
- Calcium and vitamin D supplements
What is the cause, symptoms and treatment for brittle bone disease?
Cause
- Inherited caused by a mutation in the gene for collagen. Causes an imbalance between the organic and inorganic components of bone matrix
Symptoms
- Loose joints, poor muscle tons and susceptibility to fractures
Treatment
- Drugs to increase mineral density in bone, or surgery to place metal rods in long bones
What is the cause, symptoms and treatment for osteoporosis?
Cause
- Risk factors such as age, smoking, hormone imbalance following menopause, poor diet, illness or alcohol misuse
Symptoms
- Abnormally fast loss of bone density leading to fractures
Treatment
- Calcium and vitamin D supplements
Describe the ultrastructure of skeletal muscle / The level of organisation in skeletal muscle. (3 marks)
- Skeletal muscle is made up of a bundle of fibres that are multinucleated, with a striated appearance
- Bundles of fibres are made up of fibres, which are made up of many myofibrils
- Myofibrils contain actin and myosin myofilaments arranged in repeated sarcomeres
Describe the different striations/bands in sarcomeres
(5 marks)
- Z line end of sarcomere where actin filaments are joined
- I band x 2 are actin only
- A band is the whole length of the myosin filament. Overlaps in dark areas with actin
- H band is myosin only
- M line is the centre of the sarcomere where myosin molecules are attached
Describe the structure of actin
(3 marks)
- Two twisted chains of actin monomers, with myosin head binding sides
- Protein tropomyosin is wrapped around the actin fibre. Tropomyosin blocks the binding site
- Troponin found at positions along the fibre
Describe the structure in myosin
(2 marks)
- Many myosin molecules
- Two heads with ATPase activity, which project from the surface
Describe the sliding filament theory for muscle contraction
(8 marks)
- Nervous impulse causes calcium ions to be released from the sarcoplasmic reticulum
- Calcium ions bind to troponin and change the shape of the troponin molecule
- Tropomyosin moves, exposing the myosin binding site on the actin
- Myosin heads can form cross bridges to actin
- ADP and Pi attached to the head are released changing the myosin head shape as it bends, pulling the actin past myosin aka the power stroke
- Cross bridge is broken as ATP attaches to myosin head
- ATP is hydrolysed for energy for the head to bind to actin again
- Process continues until calcium ions is actively pumped back into the sarcoplasmic reticulum
