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
Mechanistically describe how osteoclasts are able to function in bone metabolism.
They are responsible for bone resorption, therefore break bone down with enzyme called tartrate resistant acid phosphatase, which has the ability to degrade Ca10(PO4)6(OH)2 solids. The osteoclasts then dispenses these molecules into the blood vessels
Osteoclasts occupy … A. Volkmann’s canals B. Howship’s lacunae C. Lacunae D. Haversian Canal
B. Osteoclasts also occupy segments of empty spaces in the bone as well called howship’s lacunae (a particular type of lacunae within compact bones)
These types of cells synthesize both collagen and protein. In addition, they produce alkaline phosphatase. Which type of cells are these? A. Osteoprogenitors B. Osteoblasts C. Osteoclasts D. Osteocytes
B. Osteoblasts
Bone metabolism regulated by what body system?
Endocrine hormones affect and alter the ratio of osteoclast and osteoblast activity
Osteoclast > Osteoblast = increase bone breakdown to increase Ca and Pi into the BV
Osteoclast < Osteoblast = decrease bone break down and increase bone buildup to decrease Ca and Pi in the BV
Your resident hands you the lab results of Mrs. Smith and you note that there is a high amount of Pi identified in the bloodstream? What other molecule should you suspect is high and be on the lookout for? High concentrations of these two molecules can lead to what symptoms?
Because Ca regulation goes hand in hand with PO4 in bone regulation, you should keep a lookout for high concentrations of Ca. High concentrations of Ca lead to Sx: Lethargy, fatigue, memory loss
Mnemonic to remember hormones related to bone metabolism:
Minerals regulated in bone metabolism:
Phosphate CalCium
Hormones to maintain Ca homeostasis:
Parathyroid (PTH)
Calcitonin
Calcitriol - active form of Vitamin D
Mnemonic: Functions of bone metabolism hormones
Calcitonin - tones down the calcium in blood and the other hormones do the opposite
As you’re studying the results from your mother’s blood work up, you note her calcium blood concentration is high. You move on to find that her calcitriol levels are extremely high as well. What should also be happening in the kidneys?
The kidneys and GI tract respond to endocrine hormones in terms of bone metabolism. Hormones that encourage increase of calcium [ ] in the blood, causes the GI and renal system to also absorb Ca as well. This will increase the Ca [ ] in the blood as well. The opposite is also true. Therefore Calcitriol, which causes increase in Ca will increase reabsorption of Ca in kidneys and GI.
A side effect of a new pharmaceutical drug results in hypocalcemia in the body. What Sx is directly a result of this side effect?
Too little Ca in the blood - Sx: Muscle cramps and convulsion
During your microfracture in your left rib cage, you were able to successfully heal because of the continuous bone metabolism. How can an osteoblast and osteoclast on the other side of the bone move to this location to function?
Through growth signal factors, these cells are able to respond and migrate to the site. In this fashion they are able to commit to bone degradation and proper restoration
Contrast Cartilage from the Osteoid
Both are composed of collagen but each one has more ontop of this.
The Osteoid is the organic portion of the ECM of the bone. This is composed of collagen, osteocalcin and osteopontin.
Cartilage is a protein based, connective tissue made by Chondrocytes. This tissue is the ECM outside of these cells and termed chondrin. Therefore this is what contains the proteins produce from the chondrocytes. 3 components of cartilage - collagen, elastin, and proteoglycan
A bodybuilder comes into physical therapy and you note he injured his knee 12 months ago and has been resting since. However based on an US, you noticed cartilages have not properly healed. Why does physiology explain this phenomenon?
Hyaline Cartilage tends to be found at joints, where bones meet one another. Because of this these tend to be called articular cartilages. Cartilage is not innervated and are avascular, it has a hard time to heal and recover if it were damaged by overuse or infection
Which 2 cartilage types share the same function? Name examples of these 2 cartilages can be found
Fibrous cartilage and hyaline cartilages act as shock absorbers. Ex: Fibrous Cartilage - intervertebral discs and the pubic symphysis while Hyaline Cartilage - can be found in the larynx and trachea
Fibrous cartilages are rigid, meaning they don’t have the ability to move or bend. Which joints in the body would have these types of cartilages? Why?
Joints that shouldn’t have lots of rotation or motion would most likely have these. However they should have some motion possible. Just portions of the body that has these cartilages are the intervertebral discs and the pubic symphysis
The ear consists of elastic cartilage. What functions does this type of cartilage have?
The ear acts like a funnel in transporting sounds to the eardrum. In this manner it acts like a supporting structure. Therefore these types of cartilage provide shape and support
Elastic Cartilage contains which protein in higher concentration? A. Proteoglycan B. Collagen C. Elastin D. Osteocalcin
C. Elastin
What is the determining factor in producing different types of cartilages?
The [ ] difference of the 3 proteins: collagen, elastin, and proteoglycan (proteins that contain sugar components) in the ECM determines which cartilage type the tissue will be
What types of protein creates the majority of fibrocartilage?
These contains 2 types of collagen fibers, type I and II
What is the purpose of fixed joints?
Fixed joints AKA Fibrous Joint AKA immovable Joint
Connect bones and hold them very strongly and tightly. This means no motion
What kind of cartilage tends to exist in synovial joints?
Hyaline/Articular cartilage tends to exist in these kinds of joints as these tend to be found in surfaces/areas in which the bones are articulating one another
What is one important component within synovial fluid that helps solve the problem of arthritis?
This fluid contains macrophages that engulf agents that can harm the cartilage. With over use of a joint or infection of a joint, arthritis is often a concern. But with the presence of macrophages, this can temporarily relieve or solve the problem
Which cartilage tends to accompany cartilaginous joints?
These joints provide very little movement to none. Much like this joint, fibrous cartilage is not a very motion forward cartilage. This mean that fibrous cartilage tends to be found in these cartilaginous joints such as the ribcage and pubi symphysis
Arthrose meaning
an articulation between bones OR degenerative disease of a joint
Syn meaning
Together
Synarthrosis
Articulation between two bones are together, this means that the point at which 2 bones are fused together. These kinds of joints are immovable joints where 2 bones are fused together
Amphi meaning
Greek for on both sides
Example of amphiarthrose
A bone on both sides. Ex: Vertebrae protrudes on both sides of the spinal column. These types of joints are stiff but slightly moveable.
Synovial joints are AKA A. Amphiarthrose B. Diarthroses C. Synarthrosis D. Osteoarthrosis
C. Synovial AKA Diarthroses
Many different types: Ball in socket (shoulder and hips), hinge joints (elbow or knee - moves only in one plane)
Tend to have many degrees of motion based on the subtype
Lubricated by synovial fluid (which is contained in the synovial capsule) this is why the joint is named this
How can long bones be divided?
3 major division of long bones: epiphysis, metaphysis, and diaphysis
Which portion of a long bone consists of spongy bone? Which portion of a long bone consists of compact bone?
Epiphysis - bone structure made of spongy bone AKA trabecular. The structure resembles a honeycomb
The Diaphysis contains the compact bone. This layer of bone sits superior to the marrow cavity (which is also in the diaphysis)
Where is red bone marrow located? Where on large bones are these red bone marrow located?
Red bone marrow is located in the spongy bone, which is also in the epiphysis
Your peds hit a growth spurt at 13 years of age! Where in his femur is this growth occurring?
The metaphysis of long bones, like the femur, has an epiphyseal plate - a region where bone grows and elongates in length
Your 21 year old patient is concerned about his height. He is well below average male height and is concerned he might not grow anymore. When does bone growth stop?
Humans epiphyseal plate turns into a line at 25 years of age, and growth stops then. However, this does no mean that the patient will grow any more at 21, since hige height differences tend to occur in teen years, but there maybe a chance.
Contrast endosteum and periosteum of the long bone.
The endosteum is an inner covering of the marrow cavity of diaphysis while the periosteum is the outermost lining of the whole bone.
Your friend fractured his humerus during a game of ultimate frisbee. Which portion of the long bone is important in healing and bone growth
The periosteum (the attachment points of muscles on long bones) are important in bone healing and bone growth. Therefore there are cells that have the ability to differentiate into osteoblasts (bone growth and bone healing)
Where does yellow bone marrow sit in a long bone?
Yellow bone marrow sits in the compact bone portion of long bones. This means that yellow bone marrow AKA adipose tissues are located in the diaphysis of long bones.
What portion of a long bone allows the bone to have tensile and compressive strength?
The compact bone gives the bone these properties as the osteoid and hydroxyapatite are located in compact bones
Note: indv osteons are located in the compact bone
Give an example of an Exoskeleton versus an Endoskeleton.
An Exoskeleton is a skeletal structure located on the outside of the body as in a lady bug or a turtle.
An Endoskeleton is a skeletal structure located on the inside of the body as in a human and most other mammals.
Which of the following are examples of Flat Bones? Long Bones?
- Skull
- Humerus
- Ribs
- Femur
- Pelvis
- Skull - Flat
- Humerus - Long
- Ribs - Flat
- Femur - Long
- Pelvis - Flat
