B7 tissue fluid and skeletal system
- Created by: superlouasaur
- Created on: 26-04-15 15:46
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- B7-Tissue fluid and the skeletal system
- Chemical exchange
- Between cells and capillaries
- Arteries branch into capillaries
- Capillaries have permeable walls, so substances can diffuse in and out
- Networks of capillaries in tissues are called capillary beds
- As blood passes through capillary beds small molecules (eg. water, glucose+ oxygen)
- are forced out of the capillaries to form the tissue fluid, which surrounds the cells. These substances can then diffuse into the cells
- Waste chemicals (eg. carbon dioxide and urea) diffuse out into the tissue fluid then capillaries
- The tissue fluid allows cells to get the substances they need and get rid of waste without a capillary supplying every single cell
- Jobs of the skeleton
- Support
- Move
- Protect
- Joints
- Allow the bones to move
- Bones are connected at joints by ligaments
- Ligaments have a high tensile strength but are also slightly elastic- this means they help to stabilise joints but still allow movement
- The ends of bones are covered with a smooth layer of cartilage to reduce friction between the bones
- Cartilage can be slightly compressed so it acts as a shock absorber, like a cushion between bones
- Membranes at some joints release synovial fluid to lubricate the joints, allowing them to move more easily by reducing friction
- Movement
- Muscles pull on bones to move them
- Bones are attached to muscles by tendons ( which also attach muscles to other muscles)
- Muscles move bones at a joint by contracting (becomes shorter
- Tendons can't stretch much so when a muscle contracts a tendon pulls on the bone, transmitting the force from the muscle to the bone
- Muscles can only pull on bones to move a joint. This is why muscles usually come in pairs (antagonistic pairs)
- When one muscle in the pair contracts, the joint moves in one direction.
- When the other muscle contracts, it moves in the opposite direction
- Chemical exchange
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