Notes

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skeletal system is made of 206 individual bones makes up 30-40% of an adult's body mass. A nonliving bone matrix and tiny bony cells(osteocytes). Roughly half of the matrix is water while the other half is collagen protein and solid crystals of calcium carbonate and calcium phosphate. Each end bone are called the epiphysis while middle bone is called diaphysis. The epiphysis and the diaphysis grow towards one another and eventually fuse to be the metaphysis. what Hyaline cartilage left is then found as articular cartilage on the ends of the bone that form joints with other bones. The outside of the bone is covered in a thin layer of dense irregular connective tissue called the periosteum. Stem cells and osteoblast cells in the perioseum are involved in the growth and repair of the outside of the bone due to stress and injury. Blood vesels present in the periosteum provide energy to the cells on the surface of the bone and penetrate into the bone itself to nourish the cells within. It also contains nervous tissue and many nerve endings to give bones its sensitivity to pain when injured. compact bone is deep into the periosteum and it is a matrix of hard salts and reinforced with tough collagen fibers. Tiny cells calls osteocytes reside in small spaces in the matrix. Deep within the compact bone is a layer of spongy bone where the bone tissues grow in columns called trabeculae with spaces for red bone marrow in between. The trabiculae grows in a specific way to resist stress with the least amount of mass possible. long bones have a spongy bone on their ends but have a hoolow medullary cavity in the middle of the diaphysis. The medullary cavity contains red bone marrow during childhood, eventually turning into yellow bone marrow after puberty. hematopoiesis is the process where bones create white blood cells. THe skeletal system's cell matrix also holds the calcium banks by storing or releasing calcium ions into the blood if needed. The bone cells also release osteocalcin, a hormone which regulates blood sugar and fat deposition. The yellow bone marrow is used to store energy in the form of lipids and red bone marrow stores some iron in the form of molecule ferritin and uses the iron to form hemoglobin in red blood cells.
two major divisions:
[Axial skeleton]- runs along the body's midline axis and consist of 80 bones

~skull - consist of 22 bones fused together except for the mandible. 21 seperate in children for brain growth but fuse as adults. Mandible the only moveable joint in skull and fused with temporal bone.

~hyoid - u shaped bone inferior or below the mandible. Only bone in body that does not form a joint. A floating bone.
F: help supports the trachea open and form a bony connection for the tongue muscles.

~auditory ossicles - consist of malleus, incus, and stapes. Are the smallest bones in the body and found in a small cavity inside the temporal bone.
F: Serve to transmit and amplify sound from the eardrum to the inner ear.

~ribs - 12 pairs of ribs along with sternum form the thoracic region. The first seven ribs are known as true ribs since they connect the thoracic vertebrae directly to sternum through its own band of costal cartilage. Ribs 8,9, and 10 connect to the sternum through cartilage that is connected to the cartilage of the seventh rib. Ribs 11 and 12 are considered false ribs and floating ribs because they do not have any cartilage attachment to the sternum at all.
~sternum - located midline of anterior side of thoracic region of the skeleton. Connects to the ribs by a thin band of cartilage called the costal cartilage.

~vertebral column - 26 vertebrae form the vertebral column and named my region:
cervical(neck) - 7 vertebrae
thoracic(chest) - 12 vertebrae
lumbar(lower back) - 5 vertebrae
sacrum - 1 vertebrae
coccyx(tailbone) - 1 vertebra
(aside from sacrum and coccyx, each vertebra is named for the first letter of its region and position along the superior-inferior axis)

[appendicular skeleton]- made up of 126 bones

~upper limbs - humerus is the bone of the upper arm. It forms the ball and socket joint of the shoulder with the scapula and forms the elbow joint with the lower arm bones. The radius and ulna are the two bones of the forearm. The ulna is on the medial side of the forearm and forms a hinge joint with the humerus at the elbow. he radius allows the forearm and hand to turn over at the wrist joint. Lower arm bones form the wrist joint with the carpals, a group of eight bones that give flexibility to the wrist.
groups are: lunate(medial side connecting ulna), scaphoid(where radius connects to), triquetrum (medial side, middle of hand), hamate(connects intersection of metacarpals for pinky and ring finger), capitate (connects intersection of metacarpal for ring and middle finger), trapezoid( connects intersection of metacarpals for middle finger and index finger), and trapezium( connects intersection of metacarpals for index and thumb)
The carpals are connected to the five metacarpals that form the bones of the hand and connect to each of the fingers. Each finger has three bones known as phalanges but the thumb has two. per hand 5 proximal phalanges at base, 4 middle phalanges, and 5 distal phalanges at tip of fingers.
~pectoral (shoulder) girdle- Connects the upper limb arm bones to the axial skeleton and consists of the left/right clavicles and left and right scapulae.

~lower limbs - Femur is the largest bone in the body and the only bone of the thigh's femoral region. The Femur forms the ball and socket hip joint with the hip bone and the knee joint with the tibia and patella. Commonly known as the kneecap, the patella is not present at birth, and forms in early childhood to support the knee for walking and crawling.
Tibia and fibula are the bones of the lower leg, the tibia is much larger than the fibula and bears almost all of the body's weight. The fibula is mainly a muscle attachment point and is used to help maintain balance. The tibia and fibula form the ankle joint with the talus, one of the seven tarsal bones in the foot. The tarsal group are seven small bones that form the posterior end of the foots and heel which then form joints with the five long metatarsals of the foot.
tarsal groups: talus (connects joint of tibia), calcaneus (connects where joint to tibula connects), navicular(medial side bone is center of tarsal groups), cuboid (connects intersection of metatarsals for pink and ring toe), lateral cuneiform (connects intersection of metatarsals for ring and middle toe), intermediate cuneiform (connects intersection of metatarsals for middle and index toe), and medial cuneiform (connects intersection of metatarsals for index and big toe)
Each of the metatarsals forms a joint with one of the set of phalanges in the toes. Each toe has three phalanges, except for the big toe with two phalanges.
5 proximal phalanges, 4 middle phalanges, and 5 distal phalanges. Same as hands.
~pelvic girdle - formed by the left and right hip bones and connects the lower limb (leg) bones to the axial skeleton.

Muscles-Muscles typically undergo aerobic respiration for low to moderate level of force which can convert glucose to 36-38 molecules of ATP, when high levels of force are needed, the muscles tend to be constricted and decrease the flow of oxygen causing the muscles to rely on anaerobic respiration, lactic fermentation, which yields 2 ATP. Works around, Myoglobin, a red pigment found in muscles contain iron and stores oxygen similar to hemoglobin in blood cells. This allows aerobic respiration to continue. Another chemical is creatine phosphate, creatine phosphate donates its phosphate group to ADP to convert it to ATP. Muscle fibers contain energy storing glycogen, a large macromolecule made up of many linked glycoses. Active muscles break glucose off of glycogen molecules to provide an internal fuel supply.

When the muscles run out of energy, itll tire out and lose the ability to contract. This condition is known as muscle fatigue. A tired muscles contains little to none oxygen, glucose or ATP, but have respiration waste such as ADP or lactic acid. Oxygen debt is when the body must take in extra oxygen to restore the muscle cells to resting state. Which is why one is out of breath when over exertion happens.