Module 4 Unit 2-4 Flashcards
What percentage of adipose makes up normal body weight?
15-20%
What does adipocytes store? Where do they originate from? What hormone do they produce?
Stores neutral fats
Originate from the embryonic mesenchyme as lipoblasts
Produces leptin hormone that regulates appetite
What does adipocytes in the body regulate?
Body’s metabolism
What parts of the body does the adipocytes act as cushion?
Palms, heels, toes, etc.
What are the general characteristics of adipose? Name 6 of the 11 characteristics
- A type of CT
- Made of adipocytes
- Originates from embryonic mesenchyme
- Poor conductor of heat
- Found in connective tissue proper as individual cells or small cell groups
- Highly vascularized and innervated
- Store fat (triglycerides)
- Produce hormones: Leptin hormone
- Thermal insulation of the body
- Acts as a filler tissue - keeps organs in place
- Found more on surfaces that experience more abrasion for cushion
What form is the energy molecules in the adipose called?
Form of triglycerides droplets
Where is the adipose tissue used as cushion in the vital organs?
Retroperitoneal space (around kidney), Visceral pericardium, around the eye-ball
What does the hormone Leptin do?
Leptin regulator of energy (homeostasis); inhibits food intake, loss of body weight, and stimulates metabolic rates
How many lipids droplets in the the cytoplasm in white adipose tissue?
1 large droplet of lipid
How many lipids droplets in the the cytoplasm in brown adipose tissue?
Numerous small lipid droplets
Why is the nucleus in the cytoplasm on the periphery of the cell in the white adipose tissue?
The lipid droplet is so large.
Where is the white adipose tissue found? What is the significance of this location?
Under the skin in the hypodermis
Specific as a thermal insulator - belly, buttocks, etc. as a cushion
Where is the brown adipose tissue found?
Present around blood vessels
Where is the nucleus in brown adipose tissue? What other organelle does it also have?
Central nucleus
High number of mitochondria
Who has more brown adipose tissue babies or adults? Why?
Babies because they cannot voluntarily cause their skeletal muscle cells to contract to make heat. Brown adipose tissue helps them maintain body heat.
Where is brown adipose tissue located in adults? (Hint: there are 6 places)
- Region around the kidneys
- Adrenal glands
- Around large vessels (eg. aorta)
- Regions of neck, back (interscapular) - mostly in males (near C1, C2)
- Mediastinum
- Near esophagus and trachea
What are the different functions of unilocular fat and multilocular fat?
Unilocular fats (white adipose) - hormone production, insulation, and cushion
Multilocular fats (brown adipose) - production of heat
Where is elastic cartilage found?
External ear
Epiglottis
Auditory canal
Where is the fibrocartilage located?
Intervertebral discs
Meniscus
Symphyses
Where is the hyaline cartilage located?
Articular cartilage
Costal cartilage
Nose
Larynx
Epiphyseal plates
Temporary: template of long and irregular bones
Since cartilage is avascular, how does it get its nutrients?
Diffuse through the matrix via the highly sulfated ground substance
sulfation means increased binding to water
What is a lacuna?
Space left outside a cell within the matrix after the cells stop secreting the matrix anymore and undergo atrophy (cell shrinking)
Where are the chondrocytes found in the cartilage? How active are they?
Found deeper in the cartilage tissue
less active cells, but is still alive
Where are the chondroblasts found in the cell? How active are they?
Found in the periphery of the cartilage tissue
Is very active
What happens to mature cells as they become less active? Why does this happen?
They shrink… Because the matrix of both cartilage (and bone) is more or less rigid, it does not “shrink” with the cells, so a small space remains around the cells called a lacuna.
What surrounds almost all cartilage except joint cartilage?
Perichondrium
How is the perichondrium sustained?
By the diffusion from capillaries that are found in the surrounding dense connective tissue
How is the joint cartilage sustained?
The diffusion of oxygen and nutrients from the synovial fluid
What type of collagen is perichondrium made of?
Collagen Type 1
Why is the perichondrium important?
For the growth and maintenance of cartilage
What is it called when 1 cell can give rise to a group of up to eight cells by mitosis?
Isogenous groups or nest cells
What is the darker color matrix surrounds the isogenous group of chrondrocytes called?
Territorial matrix
Does the territorial matrix have high or low proteoglycans? Does the territorial matrix have high or low collagen type 2?
High in proteoglycans and low in collagen type 2
Does the interterritorial matrix have high or low proteoglycans? Does the interterritorial matrix have high or low collagen type 2?
Low in proteoglycans and high in collagen type 2
What is the percentage of water weight is the hyaline cartilage?
75%
What is the most common cartilage type?
Hyaline Cartilage
What collagen type is found in hyaline cartilage?
Type 2 collagen
Where does hyaline cartilage receive its nutrients from?
Perichondrium or synovial fluid
What is elastic cartilage made up of?
Type 2 collagen and elastic fibers
What are the group of cells called in elastic cartilage?
Isogenic cells… NOT nest cells.
Only nest cells in hyaline cartilage
What is the strongest/ most resilient cartilage?
Fibrocartilage
Does the fibrocartilage have a perichondrium? What collagen type(s) are found here?
Lacks perichondrium
Majority type 2 collagen. Type 1 collagen is also found as supporting tissue and framework around the chondrocytes
What is the functions of cartilage? (Hint: 6 functions)
- Mechanical shock absorber
- Provide smooth-surfaced - lining surfaces of joints
- Structural support for respiratory tract and bronchial tree
- Gives shape and support to soft tissues - external ear pinna
- Provide cushioning and tensile strength
- May act as a model for bone formation
From this function list, what cartilage is mostly responsible?
1. Mechanical shock absorber
2. Provide smooth-surfaced - lining surfaces of joints
3. Structural support for respiratory tract and bronchial tree
4. Gives shape and support to soft tissues - external ear pinna
5. Provide cushioning and tensile strength
6. May act as a model for bone formation
- Hyaline, also fibrocartilage
- Hyaline
- Hyaline
- Elastic
- All type, but mostly fibro
- Hyaline
What are the bone functions?
Structural: Provide structural support to the body; attachment for muscles
Protection: Protects organs
Storage: Main depot of calcium and phosphorus
Sanctuary: Postnatal hematopoiesis (hosts the red bone marrow)
What do the living and non-living portion of bone consist of?
Living components: Osteoblasts, Osteocytes, Osteoclast
Non-living components: bone-matrix
What kind of cells are osteoblasts? Where is it found?
Mononuclear cells
Found on the surface of bone trabeculae
What does osteoblast produce? What enzyme does osteoblasts have?
Extracellular matrix (osteoid)
Alkaline phosphatase activity
What are mature version of osteoblasts?
Osteocytes
How do osteocytes communicate with each other? What do they extend through?
Filopodial processes
Canaliculi
How many osteocytes per lacuna?
1 osteocyte per 1 lacuna
What is a motile multinucleated cell in the bone?
Osteoclasts
What is the depression called when active osteoclast break down bone tissue?
Howship’s lacuna
What are the function of osteoclasts?
Maintenance, repair, and remodeling of bones
What is the bone matrix (intercellular substance) produced by?
Osteoblasts
What does the bone matrix consist of? Name the organic components and the inorganic components
Organic components:
- Type 1 collagen (90%)
- Proteoglycans
- Glycoproteins: osteonectin, osteocalcin
Inorganic components:
- Calcium hydroxyapatite: Ca10(PO4)6(OH)2
Bicarbonate, citrate, magnesium, potassium, sodium, calcium phosphate
- water
What are the 2 types of bone?
- Cancellous (spongy/trabecular) bone
- Compact bone
What is cancellous (spongy) bone made of?
Trabecula and spicules
What is compact bone made of?
Osteon/ Haversian systems
What is the periosteum?
An outer layer of collagen fibers and bibroblasts
Where is the endosperm found?
Found lining the marrow cavity
What enzyme is related to bone mineralization?
High alkaline phosphatase activity
Due to what two components are bones able to undergo calcification?
Osteoblasts secrete a ton of alkaline phosphatase which works in conjunction with another glycoprotein called OSTEOCALCIN
What is trabecula? What does it form?
Trabecula is that stellate, branched structure found in the spongy bone. Numerous trabeculae come together to make a branched network of trabeculae and has a gaps inbetween. This is typical of spongy bone.
What type of collagen does bone have?
Type 1 collagen
What are the cells in the gaps between the bone trabeculae called?
Hematopoitic stem cells
In the cytoplasm of osteoclasts, what are the vesicles called? What enzymes are the vesicles filled with?
Lysosomes
Acid phosphatase and Cathepsin K
What is an osteocytes life-span?
25 years
What is an osteoclast life-span?
7 weeks
Where is compact bone found?
Diaphyses
Where is cancellous (spongy) bone?
Epiphysis of bones and marrow cavities
Where are the neurovascular bundles?
Which areas are lined by endosteum in compact bone? What is endosteum?
What does the Volkmann’s canal transverse?
Transverse blood vessels and nerves
What is the arrangement of concentric lamellae of bone?
Arrangement of the matrix like a tree-ring-Lamellae is just another term for ‘Layer’
How are the canaliculi formed? What purpose do they serve?
Formed by the shrunken cells that formed tube like gaps
Purpose is to help transport nutrients to the osteocytes from the blood vessels
How does the osteon tissue grow?
Numerous layers of cells come together
When the cells are done secreting the matrix? What is the space that they leave called?
They shrink
Lacuna
What type of bone takes longer to remodel? Compact or spongy?
Spongy bone = long
Compact = short time period
What is the interstitial lamella?
Remnants of old osteons
Why does bone remodeling happen?
Remodeling is primarily in response to the new blood vessels that have invaded the area as you got bigger, stronger and did new physical activities
What are the inner and outer layers of circumferential lamella?
Inner adjacent to the endosteum and outer adjacent to periosteum
What is periosteum?
dense irregular CT like the perichondrium
What is endosteum?
consists of pleuripotent squamous like cells that can differentiate into several kinds of cells- like osteoblasts/ blood cells/ chondroblasts and others as well….
a reservoir of stem cells- when you break a bone- this will supply new cells like the osteoblasts to help remake the bone.
What do Sharpey’s fibers act like?
Acts like a compression bandage over the bone
Name the tissues making up the periosteum and endosteum. What are the functions of each?
Periosteum - collagen fibers and fibroblasts; osteoprogenitor cells
- Function: Bone covering
Endosteum - single layer of osteoprogenitor cells and connective tissue
- Function: It lines the marrow cavity as well as the big canals
How is a fractured bone repaired? (Hint: 4 Steps)
Bone repair involves the formation of a fibrocartilage initially followed by osteogenic activity of bone cells.
1. When the bone breaks, the cells around the fracture area die. Because the blood vessels are also punctured due to the break, hemorrhage occurs.
2. Dead cells and blood clot is removed by macrophages that invade this area after the fracture. The damaged matrix part of the tissue is dissolved/ reabsorbed by the osteoclasts. The osteoprogenitor cells found in the surrounding periosteum and endosteum quickly proliferate and produce new osteoblasts and a fibrocartilage like tissue called a Callus.
3. The fibrocartilaginous callus undergoes ossification and turns into a bony callus ( which looks like a spongy bone)
4. The spongy bone-like callus is gradually replaced by the compact bone by remodeling process and physical activity plays a major role in remodeling the bone callus.
Osteoblasts vs. Osteoclasts
Cancellous bone vs Compact bone
