Muscular skeletal system Flashcards
What are the functions of bones?
Framework for the body
Attachment for muscles and tendons
Allows for movement
Protection for major organs
Haemopoiesis – production of blood
cells in the red bone marrow
Mineral storage – calcium phosphate.
Essential for maintaining blood calcium levels
Describe the Cellular Make up of bone
Bone is connective tissue.
About ⅔ is an inorganic mixture of calcium salts, mainly calcium phosphate. This makes the bone hard.
About ⅓ is organic material – osteoid, composed mainly of collagen fibres. This makes the bone strong with slight flexibility
The remainder is bone cells: osteoblasts, osteoclasts and osteocytes
What are osteoblasts
Osteoblasts are bone-forming cells, which deposit inorganic salts and osteoid into bone tissue.
osteoblasts deposit new bone tissue around themselves, they become trapped in lacunae (pockets) and differentiate (change) into osteocytes.
What are osteoclasts
They break down bone, releasing calcium and phosphate.
Giant cells with up to 50 nuclei.
Compact Bones make up what % of bone mass
compact bones make up 80% of bone mass
Cancellous bones make up what % of bone mass and have what type of structure.
Cancellous bone make up 20% of bone mass and a honeycomb structure
Describe the structure of the long bones.
Long bones are mainly compact bones with a central medullary canal, containing yellow bone marrow. Nutrient arteries supply the diaphysis. Sensory nerves supply the diaphysis
A bone takes how long to fully develop?
all in all it takes 21 years for bones to fully develop, development of bones start in utero
Fibrous joints are…
bones joined with fibrous tissue.
No movement between the bones
Sutures between skull bones, teeth and between the tibia and fibula.
Synovial Joints are…
are joints that have a Space or capsule between bones
The bone ends are held together by a sleeve of fibrous tissue – joint capsule.
Bone ends covered with hyaline cartilage
The joint is lubricated with synovial fluid. This fluid nourishes the joint cavity
Synovial joints have many movements ,list them.
Ball and socket – shoulder and hip
Hinge – elbow, ankle, interphalangeal
Gliding – intercarpal, intertarsal, between spinous processes
Pivot – head rotates on the pivot joint between the axis and atlas.
Condyloid – joint between the condylar process of the mandible and temporal bone; joints between metacarpals/metatarsals and phalanges.
Saddle – joint between trapezium and the first metacarpal
The knee joint is named as a hinge, but the movement is greater
Myofibril are made of protein, what are the names of the two proteins that make up Myofibril
Acitin and Myosin
Neuromuscular junction are what
Muscle contraction happens in response to stimulation from a motor nerve fibre.
The nerve fibre synapses with the muscle fibre filaments.
The neurotransmitter Acetylcholine, is released. ACh stimulates muscle cell contraction.
How does the muscle contract
Release of ACh generates an action potential (Rapid sequence of changes in voltage across a cell membrane) that spreads rapidly along the muscle fibre membrane.
Calcium is released from the intracellular stores.
This triggers binding of actin and myosin, forming cross-bridges (The myosin heads grab onto the actin fibres)
ATP provides energy for actin and myosin filaments to slide over each other, pulling the Z lines closer together and shortening the sarcomere = contraction.
(Myosin filaments pull the Actin filaments closer)
How does the muscle relax
When the motor nerve stimulation stops, calcium is pumped back to the intracellular stores
This breaks the cross-bridges between actin and myosin filaments
(The Myosin lets go of the Actin)
They slide back to their resting positions
The sarcomere lengthens and returns the muscle to its original length.
