What are the two major roles of connective tissue?
Fluid dynamics
Inflammatory response
What is interstitial fluid?
Fluid that exits the blood vascular system through the capillaries
What is the function of the interstitial fluid?
Delivers nutrients to cells
Carries waste material from the cells
What causes fluid to leak out of the capillaries?
Hydrostatic pressure
What substances are carried along into the interstitial space?
Small molecular weight substances
In hydrostatic pressure, what is the driving force?
Fluid
In osmotic pressure, what is the driving force?
Particles
Where is hydrostatic pressure reduced?
In the venules
Where is osmotic pressure higher, the venules or the arterioles?
Higher in venules as a result of fluid loss from the capillaries
Why doesn’t all fluid return to the blood vascular system?
Blind-end lymphatic capillaries
When does tissue fluid become lymph?
After it enters the lymphatic system
What is edema?
Excess tissue fluid present in the connective tissue spaces
Imbalance of fluid dynamics
What are the two possible etiologies for edema?
Increased formation of tissue fluid
Decreased resorption of tissue fluid
What might cause increased formation of tissue fluid?
Increased hydrostatic pressure in capillaries
Increased permeability of capillary endothelium leaking blood colloids
Ex. Venous obstruction, thrombosis, cardiac faliure
What might cause decreased resorption of tissue fluid?
Lowered blood colloids, lowering osmotic pressure
Lymphatic obstruction
Ex. Kidney disease, lymphatic obstruction, tumors
What are the two classifications of inflammation?
Acute
Chronic
How long does acute inflammation last?
3-4 days
When does chronic inflammation occur?
Following acute inflammation if the causal agent is not removed
How long does chronic inflammation last?
Months to years
What are the 3 stages of the Lewis Triple Response?
Flush
Flare
Wheal
What causes the Lewis flush?
Dilation of capillaries and venules Histamine release (mast cells)
What causes the Lewis flare?
Dilation of arterioles - due to axonal reflex, perpetuated by histamine and protaglandins
What causes the Lewis wheal?
Fluid and large molecular weight substances leaking out of the capillaries and venules
What are the 5 cardinal signs of inflammation?
Heat (calor) Redness (rubor) Pain (dolor) Swelling (tumor) Loss of function (functio laesa)
What are the 2 purposes of inflammation?
Dilute toxins
Allow leukocytes and antibodies to access extravascular spaces
What are the stages of inflammation?
- Transient vasoconstriction
- Vasodilation
- Increased permeability
- Stasis
Vasodilation as a result of inflammation starts in ___ ___ first, then moves to ___.
Capillary beds
Arterioles
What causes increased permeability in the inflammation response?
Chemical mediators
What does increased permeability cause to happen in the inflammatory response?
An outpouring of protein-rich fluid into the extravascular spaces
The increased permeability that comes with inflammation leads to what?
Increased concentration of red blood cells
What occurs in the stasis phase of inflammation?
Increased margination of WBCs, thus increased diapedesis (WBSs moving out of the blood vessels)
What are the vasoactive amines?
Histamine
Serotonin
What do vasoactive polypeptides do?
Breakdown products of proteins and tissues (kallikrein and bradykinin)
What other agents influence inflammation?
Toxins from bacteria Prostaglandins (from endothelial cells) Lysosomal enzymes (from neutrophils) Products of DNA and RNA breakdown Antigen-antibody complexes
What are the cellular evens of acute inflammation?
Emigration of neutrophils
Some emigration of monoyctes (turn into macrophages)
Phagocytosis and release of enzymes by neutrophils and macrophages
Cell death of leukocytes and bacteria
Pus formation (if pygenic bacteria are present)
Lots of eosinophils if an allergic reaction
What are the highlights of chronic inflammation?
Reductions in number of neutrophils
Appearance of lymphocytes and plasma cells
