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94 Cards in this Set

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  • Back
2 Types of Functions of connective tissues:
-Structural
-Metabolic
3 Components of Connective Tissue:
-Fixed cells
-Free cells
-Extracellular matrix
What are fixed cells in general?
Stable populations of long-lived cells
What do fixed cells develop from?
Mesenchyme
2 types of fixed cells:
-Fibroblasts
-Adipocytes
What do fixed fibroblasts form?
Extracellular matrix
What do adipocytes do?
Store lipids
What does the fact that fixed cells regenerate indicate?
That a population of stem cells persists.
What is the function of wandering cells? What are these?
Defense - they are white blood cells.
How do the wandering/free WBCs get to connective tissue?
Via blood vessels
What cells are included in this population of wandering cells?
-All WBCs
-Plasma cells
-Mast cells
-Macrophages
What is the DOMINANT component of connective tissue?
The extracellular matrix
How does ECM affect connective tissue?
It determines the physical properties of each type.
Where is embryonic connective tissue found?
Only in embryos as they are developing.
2 types of Embryonic Connective Tissue, and where is each found?
-Mesenchymal - in loose CT
-Mucous - in umbilical CT
2 broad categories of connective tissue (nonembryonic):
-General
-Specialized
4 types of General CT:
-Loose
-Dense
-Reticular
-Adipose
3 Types of Specialized CT:
-Cartilage
-Bone
-Blood
Loose CT is also called:
Areolar
Where is loose CT found?
Distributed in and between tissue layers in most organs
Dense CT is in:
-Tendons
-Ligaments
What is Reticular CT for?
Suppor of parenchyma in Lymphoid organs
Functions of Adipose tissue:
Synthesis, Storage and Release of Fat
5 Normal Functions of CT:
-Mechanical support
-Metabolite exchange
-Energy storage
-Protection against infection
-Repair
What are the most abundant and widely distributed cells in CT?
Fibroblasts
What is the function of fibroblasts?
Synthesis of almost all the ECM of connective tissue.
How are fibroblasts oriented in relation to collagen fibrils in connective tissue?
Parallel to the long axis
So what does the shape and orientation of fibroblasts tell us?
What direction the surrounding environment's tension and shape are.
What happens to fibroblasts during wound healing?
-Nucleoli become prominent
-Golgi apparatus is prominent
Indicates secretion of collagens and ground substance
What is ground substance again?
-Proteoglycans
-GAGs
do fibroblasts have a basal lamina?
No
What are myofibroblasts?
Fibroblasts that demonstrate features of both fibroblasts and smooth muscle cells.
What do myofibroblasts develop from?
Transdifferentiation of fibroblasts and smooth musle cells.
Do myofibroblasts have a basal lamina?
No.
What is unique about myofibroblasts?
They have actin filaments and dense bodies like smooth muscle,that link them into a synctium.
What is the function of myofibroblasts being linked?
They contract and shrink scar tissue.
What is a specific physiological function of myofibroblasts?
Assistance in tooth eruption in the periodontal ligament.
What is Dupuytren's fibromatosis?
A non-neoplastic disease characterized by hypercontraction and thickening of the palmar fascia.
Main cell type in adipose tissue:
Adipocytes
What form of lipids is stored in adipocytes?
Triglyceride droplets
3 sources of lipids for storage in adipocytes:
1. Dietary fat (chylomicrons)
2. Triglycerides from liver
3. Triglycerides made in adipocytes themselves
What is the highest calorie per volume storage of energy?
Lipid
4 receptors on Adipocytes that modulate uptake/release of fat:
1. Insulin receptor
2. Glucocorticoid receptor
3. Growth hormone receptor
4. Noradrenaline (NE) receptor
What do adipocytes secrete? What does it do?
Leptin - regulates appetite
Insulin's effect on adipocytes:
Increases conversion of glucose to triglycerides
Effect of NE on adipocytes:
Stimulates lipase to break down fats into FFA and glycerol for release into blood
What stimulates NE to act on adipocytes?
SNS
2 main types of adipose tissue:
-White
-Brown
What % of total body weight is adipose tissue in
-Males
-Females
Males = 20%
Females = 25%
Where is white fat particularly found?
In deep layers of the skin
3 functions of white fat:
-Energy storage
-Thermal insulator
-Structural support for organs
What are White fat cells like in structure?
-Single large lipid droplet
-Thin rim of cytoplasm surrounding it
What is the single large lipid droplet called?
Unilocular
What layer surrounds the thin rim of cytoplasm in each adipocyte?
Basal lamina
What is the vascular supply of white fat TISSUE like?
Heavy
What allows for the heavy vascular supply to white fat tissue?
Septations created by collagen type III that separate the fat cells into lobules.
What secretes the type III collagen?
The fat cells
What organisms have brown fat?
-Newborn mammals
-Hibernating animals
How is brown fat compared to white?
Multilocular
Why is brown fat brown?
B/c it has lots of capillaries and mitochondria.
Function of brown fat:
Non-shivering Thermogenesis
What molecule is responsible for nonshivering thermogenesis in brown fat?
UCP-1 - it uncouples the ETC in mitochondria so heat is generated instead of ATP.
2 types of obesity in adults:
How are they different?
-Hypertrophic
-Hypercellular
Hypertrophic is just accumultn and storage of fat; hypercellular is overabundance of the actual cells.
Which form of obesity is more severe?
Hypercellular
How much can adipocytes increase in size?
4X
What hormone regulates adipose mass?
Leptin
Where are leptin receptors found?
In the appetite center of the hypothalamus
What does leptin binding in the hypothalamus do?
Activates SNS to release NE, which shifts fat from adipocytes to mobilization and oxidation.
What symptoms charactize patients with deficient leptin?
-Voracious appetites
-Uncontrollable weight gain
What happens to monocytes when they exit the blood and enter CT?
They mature into free or fixed macrophages
Lifespan of macrophages:
What system are they important in?
2 months
-Function in the MPS - mononuclear phagocytic system
2 Groups of macrophages within the MPS:
-Phagocytes
-Antigen presenting cells
In what tissue are Histiocytes?
-Connective tissue
-Lymphoid organs
-Bone marrow
Where are alveolar phagocytes?
Lungs
Kupffer cells
liver
microglia
CNS
osteoclasts
bone
What receptors do macrophages have?
-Fc receptor
-Complement receptor
What is the function of Fc receptors?
Opsonization
What is opsonization?
The process where C' proteins bind immunogens, which then are bound to the Fc receptors on macrophages - enhances phagocytosis.
What type of granules are in neutrophils?
nonspecific
Are PMNs normally found in CT?
No; only in injured tissue
What attracts white cells to injury sites?
Chemotactic factors
2 Functions of eosinophils:
-Attack of parasites
-Moderation of allergic reactions
How do eosinophils moderate allergic reactions?
By phagocytosing Ag-Ab complexes and Degrading histamines
4 regions associated with allergic reactions:
-Nasal mucosa
-Lung
-Skin
-Lamina propria of gut
What are Plasma cells derived from?
B lymphs that have interacted with Antigen and secrete Ab
Mast cell functions (2):
-Mediate inflammatory reactions
-Immediate hypersensitivity reactions
6 things that Mast cell granules contain:
-Heparin
-Histamine
-Neutral proteases
-PMN/Eos chemotactic factors
-Leukotrienes
How do mast cells mediate inflammation?
-They bind IgE via Fc receptors
-IgE binds/crosslinks antigen
Result of binding IgE and crosslinking antigens:
Degranulation
What does Histamine release cause?
Vasodilation and Mucosal edema
What syndrome results from histamine effects?
Hay fever
What causes swelling in asthmatic lungs?
Leukotrienes