Anatomy and Physio. - Bones

skeletal system

composed of 206 bones that, with cartilage, tendons, and ligaments, make up the framework or skeleton of the body

fibrous membranes, hyaline

in the early stages of embryonic development, skeleton consists of \_____________ \_________________ and \_________________ cartilage

ossification

process of bone formation
this begins by the 6th or seventh week of embryonic life

osteogenesis

this process begins with progenitor cells

progenitor cells

descendants of stem cells that further differentiate to create specialized cell types
-many throughout the body
-each is only capable of differentiating into cells that belong to the same tissue or organ
-already have a target tissue or organ

stem cells vs progenitor cells

stem cells can become any cell as they do not have a job yet (they come out during afterbirth). progenitor cells have a job, but not a specialized one. For example, a progenitor cell can be a lung cell, but it does not have a specific job in the lung yet (like making up tissue, carrying oxygen, making the left side of the lung work).

framework of the skeleton

flexible and has a semi-solid matrix

matrix

a large network of proteins and other molecules that surround, support, and give structure to cells and tissues in the body
-produced by chondroblasts (immature), water, and other material
-surrounds and isolates chondrocytes (mature)

connective tissue cartilage

hyaline, elastic, fibrocartilage
avascular\----\> nutrients are brought in by diffusion through the matrix. this is why damaged cartilage doesn't repair itself as readily as most tissues do

female vs male pelvis

Female pelvis is lighter, thinner, and wider. it is tilted a bit due to the birth canal and uterus
male pelvis

hyaline cartilage, models

most bones develop using \________ \___________ structures and their \__________

2 steps before bone is formed

1. during fetal development, a framework is laid down that determines where bones will form. fetus's bones form, blood vessels form, medullary cavity form, and growth happens from the center of the bone in both directions

2. final formation- hyaline cartilage dissolves but remains at the ends of the bones and in the epiphyseal plates

bone collar

osteoblasts secrete bone matrix and results in a collar made of compact bone
-covers hyaline cartilage

functions of bones

support, protection, movement, storage, blood cell formation
-also provides a place for muscles to attach

functions of bones: support

forms the internal framework of the body and cradles internal organs

functions of bones: protection

incases internal organs and protects them, especially with the brain (skull), the spinal cord (spine), and the heart/lungs in the thoracic cavity (ribs)

functions of bones: allow movement

skeletal muscles are attached to bone by tendons and are used for movement through articulation

two places where hyaline cartilage remains after final formation of bone

1. at the ends of the bones
2. in the epiphyseal plates

epiphyseal plates

allow for growth of long bone during childhood

active, dynamic

bones are \__________ tissue and are \________ in their structure. They are constantly changing

remodeling

The process of resorption and formation of bone; the changing of the skeleton; replaces old parts with new ones

bones are remodeled continuously in response to these two factors

1. calcium levels in the blood
2. the pull of gravity and muscles on the skeleton

When blood calcium levels are low

the parathyroid glands in the throat are stimulated to release PTH to the blood. this activates osteoclasts to break down the bone matrix to release calcium into the blood

osteoclasts

Bone-destroying cells
-multinucleic cells
-have lots of mitochondria and lysosomes with digestive enzymes to break down bones to get calcium

when calcium in the blood is too high

calcium is deposited into the bone matrix

calcium

the matrix is a storage area for \____________
this mineral is needed for blood clotting, muscle contraction, and for the nervous system to transmit messages

resorption

the process that osteoclasts go through of removing or digesting old bone tissue

muscle pull, gravity, osteoclasts

the stress of \________ \_______ and \___________acting on the skeleton determines where the bone matrix is to be broken down by \__________ or formed so that the skeleton is strong

weak, fragile, estrogen, mass

older women often have \_________ and \______ bones due to the deficiency of \___________. This leads to increased bone remodeling where bone resorption out paces bone formation and decreases bone \___________

two parts of the skeleton

1. Axial
2. Appendicular

axial skeleton

The portion of the skeletal system that consists of the skull, rib cage, sternum, and vertebral column
consists of 80 bones

appendicular skeleton

bones of the shoulder, pelvis, legs, feet, arms, hands, and other upper and lower extremities
consists of 126 bones

Diagram of Axial and Appendicular

*see diagram that Mrs. Pine gave out

diagram of bone formation

bones

composed of 50% water and 50% osseous tissue

osseous tissue

bone tissue that is rigid and solidicalcified

function of bones: storage

minerals (calcium, salts, and phosphorus) and growth factors
-most common mineral that is in bone is calcium salts (which give the bone its hardness)
-collagen fibers allows flexibility

function of bones: blood cell formation

hematopoiesis occurs within the marrow cavities of bones

Hematopoiesis

the formation of blood cells that takes place in bone marrow

blood

made of plasma, white blood cells, red blood cells, platelets, and bone marrow

articulation

manner in which the parts of the body come together at joints

Four classifications of bones

long, short, flat, irregular

Long bones

longer than they are wide
-femur, tibia, fibula, humerus, radius, ulna

short bones

cube shaped
include carpals, phalanges, meta-carpals, tarsals, meta-tarsals
sesamoid bone- form within tendons

flat bones

These bones are thin, flat, and curved
-ribs, sternum, and skull, scapula

irregular bones

bones of the vertebrae, pelvic region, and face

bone structure parts

epiphysis, diaphysis, periosteum, medullary, endosteum

epiphysis

growing end of bone

diaphysis

shaft of bone

periosteum

Outside double-layered connective tissue that covers and nourishes the bone.

medullary

Refers to an inner region of the bone with bone marrow inside

endosteum

membranous lining of the hollow cavity of the bone

joints

a place where 2 or more bones connect
-the manner in which they connect determines the type of movement allowed

fissures

when a baby's skull is still not fully formed, it makes \________, which are marks on the skull

synathrosis

a joint that allows no movement

amphiarthrosis

a joint that allows slight movement

diarthrosis

a joint that allows free movement in a variety of directions
-includes the knee, hip, elbow, wrist, and foot

Diarthrosis- types of movement

1. abduction
2. adduction
3. flexion
4. extension
5. supination
6. pronation
7. circumduction
8. protraction
9. retraction
10. dorsiflexion
11. inversion
12. eversion
13. rotation
14. Fowler's position
15. Trendelenburg position
16. lateral recumbent

abduction

Movement away from the midline of the body

adduction

Movement toward the midline of the body

flexion

bending a joint

extension

Straightening of a joint

supination

lying on your back and facing upward (supine)
turning your palm upward

pronation

turning the palm downward
lying prone or facing downward

circumduction

moving a body part in a circular motion

protraction

moving a body part forward

retraction

moving a body part backward

dorsiflexion

bending of the foot or the toes upward

inversion

turning inward

eversion

turning outward

rotation

moving a body part around a central axis (medial- middle, lateral- away)

Fowler's position

sitting straight up or reclining slightly; legs bent or straight

Trendelenburg position

lying on back with body tilted so that the head is lower than the feet
-good for when someone feels faint so more blood will go to their head

lateral recumbent position

The patient is lying on their right or left side.
-good for when someone is throwing up so they do not choke on their vomit

vertebral column

A series of irregularly shaped bones called vertebrae that houses the spinal cord.
-a curve has more strength than a straight line so it can support the weight of the body and provide balance to walk
-4 curves

cervical curve

a secondary curve that contains 7 vertebrae

thoracic curve

primary curve with 12 vertebrae

lumbar curve

secondary curve with 5 vertebrae

sacral curve

has no vertebrae but contains the sacrum and the coccyx (tailbone)

pelvis

the lower portion of the trunk of the body
-hip bones, sacrum, and coccyx form the pelvic basin

ilium, pubis, and ischium

hip bones include...

male vs female pelvis

Male pelvis:
-Larger, heavier, more marrow
-shaped like a funnel
-stronger

Female pelvis:
-Rounder, wider pelvic opening to assist childbirth
-more moveable pubic symphysis
-More flexible coccyx

Resorption

bone is continually remodeled through this process
-bone broken down by osteoclasts and formed again by osteoblasts
-bone formation and healing slow down as you age

osteoporosis

age related loss of bone mass or density in bone matrix

two types of bone tissue

compact and spongy

compact bone

dense bone composed of osteons that make up the outer layer of flat, short irregular bones; major component of long bones
-looks smooth and homogeneous

spongy bone

internal layer of bone in flat, short, and irregular bones, and in the epiphyses of long bones.
-spiky open appearance

perforating fibers (Sharpey's fibers)

connective tissue fibers that secure the periosteum to the underlying bone

articular cartilage

hyaline cartilage that covers ends of bones in synovial joints
-needed for cushioning and lubrication between bones

red marrow

produces blood cells

yellow marrow

stores fat

bone markings

surface features of bones where muscles, tendons, and ligaments attach, and where blood vessels and nerves pass.

Explain the changes in the bone as it develops from fetus to child.

In the fetus, the hyaline cartilage is replaced by bone while the center is digested to open up the medullary cavity. By the time the baby is born, or shortly afterward, most hyaline cartilage models have transformed into the bone besides in the epiphyseal plates and the articular cartilage. New cartilage is continuously formed on the external face of the articular cartilage and on the epiphyseal plate area that is turned toward the end of the bone in order for it to grow in length. During the same time, the old cartilage on the articular surface and the medullary cavity is broken down and replaced by a bony matrix. Growing bones grow in width when osteoblasts in the periosteum add bone matrix to the outside of the diaphysis wall as osteoclasts in the endosteum destroy bone inside of the diaphysis wall, making the medullary cavity larger. This process is called appositional growth and the process of bone growth in length is controlled by growth hormones. At the end of adolescence, the epiphyseal plates have been completely transformed into bone.

PTH (parathyroid hormone)

a parathyroid hormone released by the parathyroid glands in your throat. It activates osteoclasts, which are cells that destroy bones, to break down bone matrix in order to release calcium into the blood. It controls blood calcium homeostasis and helps the body when calcium levels are too low. It determines when bones are to be broken down or to be formed

rickets

a disease that affects children where bone does not calcify and begin to soften. Their legs can become bowed due to the weigh of gravity and muscles pulling on their bones. This illness is due to the lack of calcium or vitamin D in the body, as it is needed to absorb calcium in the blood.

membranes, cartilage

bones begin as \_____________ or \____________

Herniated discs

are the soft inner gel-liked material of an intervertebral disc pushes out of the tougher outer layer of the disc. It can also be called a slipped disc. They are most common in older people due to the drying of discs and the weakening of the ligaments of the vertebral column. It can also happen when the vertebral column goes through lots of twists. If the slipped disc extends so much that it presses up against the spinal cord or spinal nerves, numbness and pain can occur.

three spine abnormalities

Scoliosis, Kyphosis, Lordosis
These can be present at birth or form due to the development of a disease, poor posture, unequal muscle pull on the spine, or injury. The treatment for these abnormalities includes braces, casts, and surgery.

scolosis

the abnormal curvature of the spine in a lateral direction. The spine looks like an "s."

kyphosis

hump formed by the abnormal curvature of the thoracic spine in a posterior direction.