Week 10 Flashcards
(36 cards)
What are the key functions of the skeletal system?
- protects internal organs: Brian and lungs
- facilitates movement: skeletal muscle, tendon, ligament, cartilage
- supports body
- stores and releases fat: bone marrow
- stores and releases minerals: Ca2+, PO4,3-
- produces blood cells
What is the axial skeleton comprised of?
- skull
- vertebrae of spine
- thoracic cage (ribs and sternum)
what is the appendicular skeleton comprised of?
- upper and lower limbs
- pelvis
- pectoral girdle (shoulder)
What are the key components of the connective tissue?
- cells - small volume
- extracellular matrix
- fibres eg. collagen, elastin
- ground substance (gel between fibres) - organic matrix in bone
What is the ground substance comprised of?
portroglycan - fills space between fibres, provides swelling pressure
glycosaminoglycan
water and electrolytes, contributes to swelling pressure
What are the two types of connective tissue?
loose, dense (skeletal tissues are dense connective tissues)
What fires are there in connective tissue?
- collagen (29 diff types), most abundant protein in body, provides tensile strength, helical
- Elastin, allows to recoil after stretch, mesh
What is the structure of the bone?
- cortical bone (very dense): outer layer- periosteum, inner layer- endosperm
- spongy bone (less dense)
- bone marrow
What are the two types of bone marrow?
red - site of production of blood cells
yellow - fat storage site
- proportion changes w age, red decreases
Explain the different type of bone cells
outside: osteogenic cells (stem cell)
route 1: differentiate into osteoblast - line surface of bone, creates ECM, lays down minerals, surround themselves with bone besides leaving small channels
route 2: differentiate into osteocytes - sense nature of bone in terms of how they respond to leading, signal other cell types to make/ break
osteoclasts - distinct form the rest, further in
What is the origin of osteoblasts and chondrocytes?
mesenchymal stem cells
what is the origin of osteoclasts?
hematopoietic stem cells
What are the two types of bone formation?
interamembranous
endochondral
How does intra-membranous ossification work?
- directly from undifferentiated mesenchymal connective tissue
- occurs only in some bones: skull, flat bones of face, clavicle (collarbone)
How does endochondral ossification work?
- via cartilage intermediary
- occurs only in most bones (except skull, collarbones)
- growth plate
What are the zones of the growth plate?
outside to inside
- reserve zone
- proliferative zone
- hypertrophic zone (cells get larger)
- calcification (mineralised cartilage, cell death)
- ossification (mineralised cartilage remodelled to form bone)
What does the growth plate allow for?
growth of bone length
How does bone formation occur for fracture healing?
- directly building new bone onto fracture site (direct or contact healing)
- heal in a process similar to endochondral ossification - via cartilage intermediate (intermediate healing)
control of bone maintenance
bone formation (osteoblast activity - reduces blood Ca2+)
bone resorption (osteoclast activity - increased blood Ca2+)
also impacts on growth plate - bone elongation
Why is it so important to maintain blood Ca?
too little
- muscle twitching/ spasm
- numbness
- paresthesia
too much
- thirst/ frequent urination
- digestive distress
- bone pain
- muscle weakness
- fatigue
- cardiac arhythmia
- kindey stones
-> needs a higher conc inside to trigger depolarisation, if conc is too similar its harder, if conc is too steep, too easy -> spasm
What hormones are involved in control of bone maintenance?
- GH - anterior pituitary - increases length, improves density
- Thyroxine -thyroid - stimulates bone growth, promotes synthesis if bone matrix
- calcitriol (vitD) - stimulates osteoclast proliferation, resorption of bone by osteoclasts
- calcitonin - thyroid - inhibits osteoclast activity and stimulates calcium uptake by bones
What does Wolff’s law state?
form follows function
What does mechanical strain lead to?
- re-distribution of Ca2+ between the blood and bone tissue
How does mechanotransduction in the bone work?
- mesenchymal stem cells
-> osteoblasts
-> osteocytes
-> intern, primary cilium, piezo1 channel
