Thursday, June 28, 2012

Biological Science 10 (Muscle and Skeletal Systems)

Muscle and Skeletal Systems

Day 19:

Muscle and Skeletal Systems
McGraw Hill

A. Muscle System

1. Functions
The muscle of the body is more important them just movement, also support and protection, driving blood flow, driving digestion, tramping and generating heat and also facial expressions and body language.

A. Support, Mobility
The bones are cushioned by muscle, joints are stabilized by muscle, shortening of muscle pulls bones causing mobility.

B. Peripheral Circulatory Assistance
The main way for veins to return blood to the heart is by muscles squeezing the blood vessels. So if people don't get much exercise blood flow in the limbs is poor, therefore lymph flow in the limbs is very poor and many disease arise (such as peripheral vascular disease).

C. Thermoregulation (Shivering Reflex)
The arrector pilli muscles can generate a lot of heat by contracting (known as shivering).

2. Structural Characteristics of Skeletal, Smooth, and Cardiac Muscle; Striated versus Nonstriated
Both skeletal and cardiac muscle are striated (have stripes); Smooth muscle is solid. Booth smooth muscle and cardiac muscle are involuntary and have a single nucleus; skeletal muscle is voluntary and multinucleated. Smooth muscle is "eye" shaped, cardiac muscle is branched or "Y" shaped, skeletal muscle is "l" shaped/straight. Cardiac tissue has automautaticity, it can beat on it's own apart from the body (even a small piece of heart tissue can beat on its own outside the body).

Cardiac Tissue Automautaticity (Rat Heart)

3. Nervous Control
The muscles are always controlled by nerves, even during a reflex arc (even when the brain is not signaling the muscles, the nerves still do).

A. Motor Neurons
The motor neurons cause motion or other effects. Also called efferent neurons. They are the actuators of the body. Somatic motor neurons provide conscious control of the skeletal muscles. The autonomic motor neurons provide unconscious control of both smooth and cardiac muscle.

B. Neuromuscular Junctions, Motor End Plates
The small gap between a neuron and a muscle is aptly named, the neuromuscular junction. Here the axon terminal sends neurotransmitters to the motor end plate/sarcolemma, triggering a release of calcium that causes muscle contraction.

C. Voluntary and Involuntary Muscles
The voluntary muscles are skeletal. The involuntary muscles are smooth and cardiac muscle.

D. Sympathetic and Parasympathetic Innervation
The sympathetic nervous system is in response to stress, threat or exercise (faster heart rate, pupil dilation, increased blood pressure, increased blood to muscles). The parasympathetic nervous system is in response to relaxation, digestion or sleep (slower heart rate, pupil constriction, lower blood pressure, and increased blood to digestive organs). 

B. Skeletal System

The skeleton does more then provide a frame for movement, it is a living tissue that creates blood, helps the immune system, stores calcium, fat and other minerals, protects

1.  Functions
The main functions are: support, protection, blood production and calcium storage.

A. Structural Rigidity and Support
The bones are made of a calcium salt crystal. Compact bone is very rigid allowing it to bear weight. Bone has a lattice structure that is strengthened by exercise, especially weight lifting.

B. Calcium Storage
Bones store calcium. Calcitonin puts calcium in, parathyroid takes calcium out of the bones.

C. Physical Protection
The internal organs are protected by the ribs and sternum, the brain is protected by the skull and the spinal cord is protected by the vertebrae.

2. Skeletal Structure
The adult has 206 bones. Many were fused together like the sacrum. 

The Skeleton Typogram
Aaron Kuehn

A. Specialization of Bone Types; Structures
The types of bones include: long bones (the humerus/arm and femur/leg), short bones (the carpal/wrist bones), flat bones (the cranium/skull, scapula/shoulder, costals/ribs), irregular bones (the vertebrae/spine, the pelvic bones/the hip) and seasamoid bones (within a tendon ex. patella/knee cap).

B. Joint Structures
The joints are the weak points of the body (exploited by jiu jitsu for weaker fighters to control stronger opponents), where bones connect allowing motions. All joints are slightly movable (craniosacral massage moves the skulls sutures, which actually move on their own too). Joints are called non-mobile (synarthrotic), when they move very little (usually connect bones with cartilage or fibrocartilage). Mobile joints (diarthrotic) contain synovial fluid to lubricate the bones. This fluid is kept in bursae, sacks that will burst under too much pressure trying to save the joint by giving it maximum lubrication when it is being overstretched (like during an armbar). 

  • Ball and socket joints/enarthrosis (hip and shoulder) have the most motion. 
  • Hinge joints/ginglymus (elbow and knee) only have motion across one plane.
  • Gliding joint/arthrodial joint (acromioclavicular joint, wrist joints) allow gliding/sliding.
  • Pivot joints/trochoid joint (radioulnar joints, atlanto-axial joint) allow rotation.
  • Condyloid joints/ellipsoidal joint (metacarpophalangeal joints, metatarsophalangeal joints) permit motion across two planes. 
  • Saddle joints/sellar joints (thumb and sternoclavicular joint) have motion across two planes. One side in convex the other concave.

C. Endoskeleton versus Exoskeleton
The endoskeleton (within skeleton) is what humans have. The exoskeleton (outside skeleton) is what aliens, predators, insects and lobsters have. Exoskeletons are usually chitin.

3. Cartilage (Structure, Function)
The cells are chondrocytes, the cells are scattered around a gel (matrix) that has fiber in it. It is squishy due to the matrix, flexible and tough due to the fibers (elastic and collagen). Cartilage functions in protecting bone ends from damage and supporting the vertebrata from shock. This tissue is avascular meaning no blood, it required movement to squish nutrients into its matrix and toxins out. Movement is essential for joint health.

4. Ligaments, Tendons
The ligaments (link bone to bone) and tendons (tie bone to muscle) are made of tough bands of connective tissue. Avascular are well. Tendons contain Golgi body receptors that let the body know when the tendon is being stretched. 

5. Bone Structure
There are two types of bone structure, compact (looks like tree stumps) and cancellous bone (looks like lace). The membrane of a bone is called periosteum (containing stem cells). Marrow, blood vessels and nerves run down the center of lone bones. The cells are known as osteocytes. 

A. Calcium–Protein Matrix
The martix is calcium salt, collagen fibers and a gel like ground substance.

B. Bone Growth (Osteoblasts, Osteoclasts)
Osteoblasts make bone. Osteoclasts destroy bone. Longitudinal growth is height, appositional growth is width.

No comments:

Post a Comment