Unit 2.5 The Musculoskeletal System Flashcards
What is the musculoskeletal system designed to do?
The musculoskeletal system is designed to support and protect use move us around, store essential minerals and produce red blood cells
What produces the blood cells?
Blood cells are produced by the marrow located in the bones - roughy two - three million RBS are produced each second by the bone marrow to replace those worn out and destroyed by the liver.
What does the skeletal system include?
Bones, joints, cartilage and ligaments
What do joints provide?
Joints provide the body with flexibility and allow movement to occur.
What is the dominant tissue in the body?
Muscle is the dominant tissue in the body, making up about 50% of human body mass
What are the different types of muscles?
Skeletal muscle, smooth muscle and cardiac muscle each which have different functions.
How many bones does a normal human skeletal system have?
206 bones, mainly for support and protection
What does the skeleton provide?
An achor point for the muscles and a storage centre for minerals such as calcium and phosphorus and for triglycerides in yellow bone marrow. It is also the production site for red blood cells. The skeleton provides a rigid bone framework to protect vital organs and as an anchor point for the muscles.
What has the tensile strength of bone in compression similar to?
Similar to cast iron, yet it is about one quarter of the weight.
What are the breaking stresses that bone can resist?
The breaking stresses that bone can resist in compression are up to about 12.5 tonnes per square inch.
Bone is not an inert tissue - what is it made up of?
Bone is made up of an extra-cellular matriculates containing different types of cells. The matrix is made up of 25% water, 25% collagen and 50% crystallised mineral salts, especially calcium phosphate which gives the bone its hardness whilst collagen gives its strength.
What are bones constantly doing in response to stresses in the body?
Being built up or broken down.
What do organic parts like collagen fibres provide?
Flexibility and strength.
How often is the entire skeleton regenerated?
Ever 13 years on average and makes up about 18% of the body mass.
What happens if someone lacks calcium in their diet or lac the vitamin D to absorb calcium from the digestive system?
Their bones will be too soft and flexible and they will suffer from rickets.
How many types of cell are involved in the maintenance of the healthy skeleton, what are these?
4 types of cells:
Osteogenic cells, osteoblasts, osteocytes and osteoclasts.
What are osteogenic cells?
These are unspecialised stem cells and are the only bone cells to undergo cell division.
What are osteoblasts?
These are bone building cells that synthesis and secret collagen fibres and other organic components that build the extracellular matrix of bone tissue - in this way solid bone material i continuously being build up and remodelled.
What are Osteocytes?
These are mature bone cells - they are osteoblasts that have become trapped within the matrix. They are the most plentiful cells and are an important part of the structure of the bone.
What are osteoclasts?
These are large, relatively rare cells which are responsible for the removal of bone from areas where it is no longer needed. they are part of the process by which the skeleton is continually being remodelled to be as strong and effective as possible.
What are the main bones from top to bottom?
Skull, mandible (head and jaw) Clavicle (shoulder) Scapula (back shoulder) Sternum Humerus (upper arm) Rib Vertebra Ulna (smaller bottom arm) Radius (bigger bottom arm) Pelvis Carpus, metacarpal (hand) Phalanges (fingers) Femur (top leg) Patella (knee cap) Fibula (back leg bone) Tibia (front leg bone) Tarsus, Metatarsal (foot) Phalanges (toes)
Bone is a highly vascular tissue, with a rich supply of blood vessels, nerves and lymphatic vessels that all penetrate compact bone through what?
Through perforating canals.
What do the blood vessels supply the bone cells with?
The oxygen and nutrients they needs for the constant remodelling of the bone that takes place all the time.
What type of bone has few spaces and is the strongest form of bone?
Compact bone tissue
What is spongy bone composed of?
Small needle like pieces of bone and microscopic spaces that help to make bone lighter - despite the name the bone is not soft the term only describes its appearance. .
What do bones tend to be classified by?
According to their shape.
What bones are long bones?
All the bones of the limbs except the wrist and ankle are long bones, from the humerus and femur to the phalanges.
They are longer than they are wise.
What do long bones have at each end?
They have growth plates at each end down as epiphyses.
What is the structure of long bones?
They have a hard outer later of compact bone, covering inner spongy bone - the matrix of the spongy bone is filled with bone marrow and this is where many of the blood cells are made.
What are short bone? What do they provide?
Short bones are approximately as wide as they are long - examples being the bones of the wrist and ankle such as the carpals and tarsals. They provide stability with flexibility but not large scale movement.
What is the structure of short bones?
They are made up of spongy bone with a covering of compact bone and they contain a relatively large amount of bone marrow.
What are flat bones?
These bones form strong, flattened plates that are important both for protecting vital organs and for the attachment of muscles - these include the shoulder blade (scapula), the bones of the skull, ribs, the sternum and some of the pelvic bone. In adults the flat bones are where many of the blood cells are made.
What is the structure of flat bones?
They have hard, compact bone on the outside with spongy bone and red bone marrow on the inside.
What are irregular bones?
These bones have very non-uniform shapes - they include the vertebrae, the lower jaw and the sacrum
What are the sesamoid bones?
These are small, irregular floating bones found embedded in tendons over joints but not connected directly to the joint the best known i the patella (knee cap)
How are muscle cells unique?
They can shorten (contract)
Where are muscle cells often found? what do they do?
Muscle cells are often found in large blocks called muscles, working together to move the bones of the body.
How many type of muscles are there?
3 main types - Skeletal muscles, Smooth muscles and cardiac muscles.
What manner do skeletal muscle tissue work?
Skeletal muscle tissue works mainly in a voluntary manner - its activity cane controlled consciously by the brain and nervous system so it is sometimes known as voluntary muscle.
How does skeletal muscle look under the light microscope?
Looks striped or striated under the light microscope so can also be referred to as striated muscle.
What do normal adult skeletal cells not do?
Normal adult skeletal cells do not undergo cell division
What do the contractions of the skeletal muscle do?
The contractions of the skeletal muscle squeeze the blood through the veins towards the heart and also move the lymph through the lymphatic vessels.
What do most skeletal muscles have to be capable of?
Rapid movement.
The contraction of the skeletal muscle and the return of the muscle fibres to their relaxed state ready to contract again use a lot of what?
Energy.
What do muscle cell contain a lot of and what to the contraction of the skeletal muscles generate a lot of?
Muscle cells contain many mitochondria to supply this energy and the contraction of the skeletal muscles generates a lot of heat.
What is smooth muscle composed of?
Elongated, spindle-shaped cells.
What is smooth muscle not under control of?
Not under voluntary control.
Where is smooth muscle found?
It is found in the walls of hollow internal structure such as blood vessels and most of the visceral organs, such as the stomach, urinary bladder and respiratory passages - it is also found in the skin attached to hair follicles.
What function does smooth muscle have?
Smooth muscle propels substances through pathways in the body - for example, the movement of food through the digestive tract and the emptying of bowels and the bladder are a result of smooth muscle function.
What does the smooth muscle contraction tend to be? What does it use efficiently?
Smooth muscle contraction tends to be slow and sustained and compared with skeletal muscle, smooth muscle uses adenosine triphosphate very efficiently - it can maintain a high force of contraction with very little ATP breakdown so relatively little heat is generated by smooth muscle contraction.
What does cardiac muscle consist of?
A branching network of cells that are lined electrically and mechanically to function as a unit.
What is cardiac muscle less than compared to skeletal muscle but more resistant to?
Cardiac muscle is much less powerful than skeletal muscle but it is much more resistant to fatigue.
What is different about cardiac cells compared to skeletal cells?
Cardiac muscle cells are much shorter than those of skeletal michele.
What aren’t there many of in cardiac muscle cells?
Relatively few stem cells are found in cardiac muscle so it cannot heal itself if it is damaged.
Where does cardiac muscle extend into?
Cardiac muscle extends into the walls of the large veins where they enter the heart.
How does cardiac muscle contract?
It contracts with an intrinsic (built in) rhythm but also responds to the autonomic nervous system and to hormones, which can speed up or slow down the rate of contraction.
What are some of the main striated muscle blocks of the body (top to bottom)
Front: Deltoids (shoulders) Pectoralis Major (chest) Biceps (top arm) Anterior forearms Obliques Rectus abdominis ilopsoas (V line) Quadriceps Adductors Dorsi flextors (shin)
Back: Deltoids Trapezius (middle top back) Latissimus Dorsi (rest of back) Triceps Posterior forearms Gluteals Hamstrings Calves.
What is the whole muscle contained within? What does this do?
The whole muscle is containing within a tough outer layer called the epimysium - this stop the muscle from bulging and getting damaged when the muscle fibres contact.
What is each muscle fibre composed of?
Each muscle fibre is composed of main individual structures called myofibrils, the basic unit of the muscle cells.
What are myofibrils formed from?
2 proteins, actin and myosin.
In a muscle contraction, what slide along what?
In a muscle contraction, the actin filaments slide along the myosin filaments - it is the overlapping of these proteins in a smooth, sliding fashion that allows the muscle to shorten and contract.
What can muscle cells transfer energy from respiration into?
Muscle cells transfer energy from respiration into mechanical work as the myofibrils contraction.
Muscle tissue has 4 special properties, what are these?
- Electrical excitability - the membrane of the muscle cells conducts an action potential that initiates the flow of ions which cause the muscle to contract.
- Contractility - When a muscle contracts, it generates tension and pulls on its anchor points.
- Extensibility is the ability of muscle to stretch without being damaged, smooth muscle is most often stretched significantly for example when the stomach fills with food.
- Elasticity is the ability of muscle tissue to return to its original length and shape.
Where are muscles often found?
Muscles are often found joining 2 bones, where one bone essentially remains stationary while the other moves in some way.
What is the point called where the muscle attaches to the stationary bone?
Its point of origin.
