APK2100C Exam 2

Ch 6, 9, 10, & 11

what are the 3 organs of skeletal system

bones, cartilages, joints

hyaline cartilage - where is it found

ends of long bone (articular cartilage0
growth plate within bones, also inside bones
costal cartilages
respiratory structures
embryonic skeleton during fetal development

elastic cartilage — where is it found

epiglottis
outer ear

fibrocartilage - where is it found?

Public symphysis
menisci in knee joint
intervertebral disc

what is cartilage?

connective tissue, abundant in extracellular matrix (gel-like, fibers); more matrix/ground + fibers substance than cells

what is the predominant cell type of cartilage

chondrocytes

fibrocartilage has an abundance of what type of fibers

collagen fibers

elastic cartilage has an abundance of what type of fibers

elastic fibers

what is the perichondrium

dense layer of irregular CT proper that surrounds surface of most cartilages

what areas does the perichondrium not surround

where the joints are and over fibrocartilage

functions of the bones

support
protection

movement

mineral storage

hemopoiesis

energy storage

metabolism

long bone

elongated with 2 distinct ends, consider shape not size
ex. humerus and phalanges

short bone

cube-like, short, no really distinct ends
ex. talus

flat bone

its flat but can be curved too
ex. rib & scapula

irregular bone

random with bony protrusions and processes coming off
ex. vertebra

sub-classification of short bone: sesamoid bone

sesame seed-like, derived from tendon, acts to alter direction when movement happens at a certain joint - like a pulley
ex. patella & base of big toe

what are the types of bone

compact and spongy

purpose & make of articular cartilage

made up of hyaline cartilage and reduces friction as you move

spongy bone

can have red bone marrow for hematopoiesis

epiphyseal line

indication of adult bone, calcified area of bone where growth plate used to be

periosteum

membrane around the bone

endosteum

thin membrane of CT that lines the inner surfaces of bones, including marrow cavities and spongy bone spaces; both osteoblasts and osteoclasts

diaphysis

main shaft or midsection of a long bone

proximal epiphysis

rounded head of long bone located closest to the point of attachment on body

distal epiphysis

rounded head of long bone located furthest to the point of attachment on body

metaphysis

junction between the epiphysis and diaphysis of the long bone

how do the bones get nutrients

blood vessels inside the spongy bone

what is an indication that you are looking at the epiphysis of a bone

articular cartilage

medullary cavity

central hollow space inside diaphysis of long bone that stores bone marrow and helps reduce bone weight

compact bone

tissue that forms walls of medullary cavity

perforating collagen fiber bundles

attach the periosteum to the outermost surface of the bone

describe the build of the short, flat, and irregular bones + what main components make it up

the top and bottom layer are continuous with each other; spongy bone, compact bone, periosteum, endosteum

layers of the periosteum

superficial layer (dense irregular CT)

deep layer (osteogenic - both osteoblasts and osteoclasts are present)

osteoblasts

creation - baby bone cells that secrete matrix (osteoid tissue) that then hardens into bone

osteoclasts

degrading/breaking down

trabecula

“pillars” of the spongy bone; solid with no cavities or vessels inside, receive nutrients from capillaries in surrounding endosteum

where do you find the endosteum

lining the inner surfaces of bones, including the marrow cavity and spongy bone spaces

what do bone markings mean

surface of bone reflects stresses applied to specific locations

The blood vessels in compact bone run____

straight through the osteon

interstitial lamellae

gaps between the osteon

perforating (Volkmann’s

central (haversian) canal

“pillars” that run through longitudinal axis of bone

circumfrential lamellae

entire bone circumference

concentric lamellae

the tree/onion rings around centra

canaliculi

tunnels for osteocytes allowing for communications and nutrients pass thru

what is the purpose of collagen fibers running in different directions

allows it to resist twisting forces

where specifically is red bone marrow found

in the spaces of the trabeculae

ossification/osteogenesis

process by which bone forms

what situations does bone formation occur

1. formation of bone in an embryo

2. growth of bones

first type of osteogenesis - intramembranous ossification

bone forms directly within mesenchyme (loose CT) arranged in layers that resemble membranes
only really applies to majority of skull bones + clavicles (HEAD UP)

second type of osteogenesis - endochondral ossification

bone forms within hyaline cartilage, replacing it

all bones from base of skull down (except clavicles)

how do bones get longer

1. cartilage growth on the epiphysis side of the epiphyseal plate

2. replacement of cartilage by bone on the diaphysis side

how do bones get wider

1. osteoblasts in the periosteum add bone tissue to the circumferential lamellae

2. osteoclasts remove bone from the inner diaphyseal wall at about the same rate

bone resorption

taking away bone tissue

1. osteoclasts secrete HCl and lysosomal enzymes that degrade bone

2. the degraded bones release ions (Ca+2) enter interstitial fluid and then enter the blood

3. collagen fibers and dead osteocytes are phagocytosed

bone deposition

occurs when bone is injured or added demand is placed on bone

essential ions (Ca+2, phosphates) must be present for osteoblasts to lay down osteoid (bone tissue)

osteoblasts become osteocytes when they are surrounded by bone matrix they laid down
mineral salt crystals pack together in a pattern that reduces the risk of cracks in stres

what is a joint?

the location at which the rigid elements of the skeleton meet at

what are joints classified by?

1. presence or absence of synovial cavity

2. type of CT binding bones together

what are the classes of joints

fibrous joints, cartilaginous joints, synovial joints

fibrous joints

bones held together by dense collagen fibers - do not have a synovial cavity ex.suture, syndesmosis, gomphosis

cartilaginous joints

bones held together by cartilage - do not have a synovial cavity ex. synchondroses, symphyses

synovial joints

bones held together by ligaments; all synovial joints are diarthrotic - synovial cavity is present

what are the functional classifications of joints?

synarthroses, amphiarthroses, and diarthroses

synarthroses

immovable joints - no movement associated

amphiarthroses

slightly movable joints

diarthroses

freely movable joints

suture

dense + super tight joint, held together with very short, interconnecting fibers, and bone edges interlock
ex. the only place it is found in is the skull

syndesmosis

joint is held together by a ligament; fibrous tissue can vary in length but is longer than sutures ex. interoseous membrane between radius + ulna

gomphosis

peg - in - socket fibrous joint; periodontal ligament holds tooth in socket with short collagen fibers

synchondroses

bones united by hyaline cartilage ex. epiphyseal plate & joint between first rib and sternum

symphyses

bones united by fibro cartilage ex. pubic symphyses & intervertebral discs

synovial capsule

sleeve-like capsule that encloses the synovial cavity

fibrous layer

continuous with the periosteum; dense irregular CT proper; strengthens the joint

synovial membrane

covers any bony surface inside the joint capsule not covered by hyaline cartilage; loose CT proper; secretes synovial fluid

synovium (synovial fluid)

viscous fluid secreted by the inner synovial membrane
similar consistency as egg whites
it is filtrate of plasma from blood
located in the joint cavity and in articular cartilages
functions to reduce friction between bones and nourishes joint cartilages

articular disc

piece of fibrocartilage that acts as shock absorber and makes better fit between 2 bones

what are the reinforcing ligaments of synovial joints and their function

band-like ligaments that strengthen the joint - capsular, extracapsular, intracapsular

capsular ligament

thickened band in the joint capsule itself ex. glenohumeral ligaments

extracapsular ligament

outside the joint capsule ex. medial and lateral collateral ligaments

intracapsular ligament

inside the joint capsule ex. anterior and posterior cruciate ligaments (ACL, PCL)

nervous innervation of synovial joints

pain, stretch, and positional information

blood supply of synovial joints

nearby vessels send branches to ligaments and synovial membrane

function functional redundancy of nerves and vessels

overlapping supply of nerves and vessels means it wont matter what movement or position the joint is in because multiple in one area ensures that if one is cut off (say u bend ur arm) then the others are still there to keep the blood supply going

bursa

sac-like structure containing synovial fluid
reduce friction between body parts which rub against one another

ex. elbow & knee

tendon sheats

tube-like bursa that wrap around tendons in small areas or where there are a lot of structures to prevent rubbing

types of synovial joints

planar/gliding joint, hinge, pivot, condyloid, saddle, ball-and-socket

movements of synovial joint

gliding movements (sliding over e/o)

angular movements (increase or decrease in angle between 2 bones)

rotation movement

myocyte

muscle cell = muscle fiber

sacrolemma

plasma membrane of the muscle fiber

sarcoplasm

the cytoplasm of a muscle fiber

sarcoplasmic reticulum

ER of a muscle fiber, Ca+2 storage

muscle tissue types

skeletal - multinucleated cells, elongated, striated (voluntary control)

cardiac - artery walls of heart, mononucleated intercalated disks that join the cells to make sure contractions happen synchronously (involuntary control)

smooth muscle - hollow organs, pushes stuff (baby, food, pee) (involuntary control)

contractility

ability to shorten and generate force

muscles only pull on the bone or structure they’re attached to

excitability

ability to respond to stimuli by producing electrical signals

extensibility

ability to stretch without being damaged

elasticity

ability to return to its original length/shape following distension

functions of skeletal muscle

movement - attached to bones and cause movement
posture (stay upright) and joint stabilization (keep synovial joints stable)

open/close body passageways (sphincters)

thermogenesis - contractions produces heat

epimysium

CT sheet covering entire skeletal muscle

fascicle

bundle of individual muscle fibers

endomysium

between individual muscle fibers

tendon

cord-like CT structure that attaches skeletal muscle to a bone’s periosteum
continuous with all 3 CT sheaths of a muscle (epimysium, perimysium, endomysium)