Skeletal Structure and Function Flashcards
No flashcards for 13/14 - V
A 5 year old boy is rushed into the ER because he jumped off the roof of his house. He wanted to know how his bones would respond if he did that, but it turns out he broke it instead. What functions of the bone can you tell this poor boy?
Bones are meant for (1) protection of the body and give (2) support. It allows you to move (3). The bones can only bend so much from so much force but it will break
What other metabolic and homeostatic processes can skeletal bones commit to?
Bone metabolism of Ca and PO4 and Hematopoiesis - production of cellular components of the blood, RBC, WBC, and platelets
During a car pile up on the freeway, you see a motorcyclist land on his back. You suspect he may have broken some bones in that landing. What classification of bones do these fall in?
Axial - skull, ribcage, and vertebral column
This forms the axis of our body, right in the center
Appendages in literal terms, means to hang from something else. Use this definition to describe what appendicular bones are.
These bones “hang” from the axial/center bones. These include the limbs, pectoral and pelvic girdle
Contrast the different types of bone marrows found in the body
Red marrows, typically found in flat bones and epiphysis of long bones, are sites of Hematopoiesis (both RBC and WBC).
Yellow bone marrows are sites of adipose tissues. These are usually found in diaphysis of long bones
A frantic mother emails you at 12 in the morning about her 7 year old son. She’s always felt a bone on her son’s pelvis however that morning, as she is dressing him, there is not more distinction. What is your advice to this mother? How does the skeletal system change from birth?
At birth, neonates have 270 bones. As Humans grow and develop, the bones decrease to 206. Her son’s pubic bones: ischium and pubis, which unite anteriorly to form the ischiopubic ramus perhaps occurred as it tends to occur around ages between 4 and 8 years of age (no need to know this portion for MCAT)
The skeletal system is important in supporting and protecting the body from compressive forces and resisting tensile forces. What allows these properties to be possible?
ECM of the bone - made of organic matter and inorganic matter
Organic matter - collagen (gives bone the ability to resist tensile forces)
Inorganic matter - gives the bones the ability for it to resist compressive forces. Made of crystals called hydroxyapatite - these consist of Ca, PO4 and OH ions
The elements stored by bones are A. Ca2+ and I- B. I- and PO42- C. PO42- and Ca2+ D. Ca2+ and K+
C. PO42- and Ca2+ - these are the basic molecules in Hydroxyapatite - chemical formula: Ca10(PO4)6(OH)2 the inorganic matter of ECM found in bone. These are the minerals are deposited into the ECM by osteoblasts. These minerals give the bones its rigid strength and density
Mnemonic - ligaments and tendons
Ligaments for Like to Like - bone to bone
Tendons for Two Types - muscle to bone
What is the haversian system?
The basic unit of structure of compact bone, comprising a haversian/central canal. It is encompassed with concentrically, each of these layers are called a lamellae.
This basic unit is also called an osteon as well
The trabecular bone A. Osteoblast cells B. Lacunae C. Osteoclast Cells D. Cancellous Bone
D. Cancellous Bone AKA Spongy Bone AKA Trabecular Bone. These are the most inner portion of bones and these bones tend to include flat bones and irregular bones. These appear spongy due to the trabeculae (cavities) the surface area of inner bones are 10x more than compact bone
The skull is a bone composed of fused flat bones. Flat bones are composed of both spongy and compact bones. What is the significance of the spongy bone in structure?
Spongy bone allows the structure, the skull to be lighter - advantageous as the skull is supported by small vertebrates in the neck only!
Does Cancellous bones contain osteons?
No, osteons/haversian systems make up compact bones. The spongy appearance are cavities in this bone type. Instead, they contain trabeculae, which are lamellae that are arranged as rods or plates (lumenlearning)
Observing a humerus of a deceased chimpanzee, you note that the outer bone layer of the diaphysis of the long bone is porous. What creates this? What is the purpose of these?
The outer bone layer of the diaphysis is made of compact bone - this is superficial to the medullary/marrow cavity (which is the deepest layer in long bones) These holes are presumably the haversian canal (the basic unit of compact bones) and these are important for blood, lymph, and nerve vessels to travel
True or False - osteocytes and osteoblasts are housed in empty spaces in the spongy bone.
False. Though they are housed in empty spaces, it is not in the spongy bone, but in the compact bone. The empty spaces in the compact bones are called lacunas
How do osteocytes communicate to other osteocytes/osteoblasts?
Osteocytes have long cellular processes that are able to branch through the canaliculi from the lacuna to interact with other osteocytes via gap junctions
Through this communication, exchange of nutrients, etc can occur
Note: canaliculi are spaces that branch out from the central haversian canal. These are not the same as volkmann canals
Contrast Volman canals from canaliculi
Both are channels in the compact bone. However they differ in that:
Volkmann canals - canals that run perpendicular to the haversian canals. These connect osteons to one another and they have their own blood vessels as well.
What is the periosteum? What is the significance of this structure?
This is the outermost layer of the bone and therefore it is visible to the eye. In long bones, it sits just superior to the compact bone. This is the site of muscle attachments usually
Contrast Osteoblasts from osteoclasts.
Mnemonic:
OsteoBlasts - Build bones. Therefore they are are responsible for building the bone, especially building and secreting both organic (collagen) and inorganic matter into the ECM
OsteoClasts - Chew bones. Therefore they do the opposite of osteoblasts
What is the most common type of cell in the bone? What is the main function of this cell?
Osteocytes are the most common cell type in the bone. Responsible to provide the bone nutrients needed by the bone and dumping waste into the BV
They are connected to the blood vessels and therefore act as a barrier/basement membrane
Describe the origination of osteocytes.
growth factors. These Osteoblasts then differentiate into osteocytes when they have enclosed self with secreted matter around them (both organic and inorganic)
Other organic proteins secreted by osteoblasts into the ECM besides collagen, A. Osteopontin and osteocalcin B. Osteopontin and osteothyroid C. Osteocalcitonin and osteocalcin D. Osteocalcitonin and osteocaltrin
A. Osteoblasts - responsible for synthesizing collagen and protein, specifically osteocalcin and osteopontin. Together all 3 proteins make up the osteoid - the organic portion of the ECM of bone
How does the inorganic matter in the extracellular matrix of bones form?
Osteoblasts transcribe a protein called alkaline phosphatase. This enzyme produces the Ca10(PO4)6(OH)2 and then the osteoblast secrete this matter into the ECM
Mnemonic to remember Lacunae
Lacunae - “little lacs (lakes)” under the microscope. These little lakes hold starfishes (osteocytes - which are starlike shaped)
The origin of osteoclast derivation is from A. Osteoprogenitors B. Osteoblasts C. Monocytes D. Fibroblasts
C. Osteoclasts - derived from cell line, monocytes. They come from the bone marrow and are related to white blood cells. They are formed from two or more cells that fuse together, so the osteoclasts usually have more than one nucleus
