Cardiovascular System pt 3 Flashcards
Describe the anatomy of a capillary
Single endothelial layer with basement membrane, intracellular clefts, vesicular channels, and plasmalemmal vesicles
What are the 3 types of capillaries??
Continuous, fenestrated, and sinusoidal
Where are continuous capillaries found?
Adipose tissue
All three muscle type
CNS
Lungs
Where are fenestrated capillaries found?
Endocrine and Exocrine glands Gall bladder Synovial membrane Choroid plexus Renal medulla
Where are sinusoidal capillaries found?
Liver
Spleen
Bone marrow
What is the pressure entering capillaries?
25-35mmHg
What is the pressure leaving the capillaries?
10-20mmHg
Flow in the capillaries is determined by what?
Pressure gradient
The pressure gradient in capillaries is dependent on what?
Pre and post capillary resistance
How do you increase flow in capillaries?
Increase pressure on the arterial side
How do you decrease the flow in capillaries?
Increase pressure on the venous side
What are the three mechanisms for capillary exchange?
- Diffusion
- Bulk flow and Starling forces
- Pinocytosis
What is diffusion dependent on?
- Concentration gradient
- Surface area for exchange
- Diffusion coefficient
- Diffusion distance
What is convective O2 transport?
This is dependent on Q through the capillary beds and the delivery of RBC
What is diffusive O2 transport?
This is dependent on Fick’s law of diffusion and mitochondrial found in tissue
What is the old theory of capillary recruitment?
Muscle fibers are surrounded by 4 capillaries but only one has continuous flow. When you exercise the remaining ones are recruited. This increases convective and diffusive O2 transport
What is the new theory of capillary recruitment?
75-85% of capillaries have continuous flow. During exercise you increase the number of RBC running through the capillaries in order to increase conductive O2 and increase surface area
Longitudinal capillary recruitment is produced by what?
- Increase capillary flux
- increase capillary hematocrit
- increase RBC wall interface
- increase diffusive transport and exchange
What is bulk flow and the Starling forces?
This is the movement of solutes through capillary pores and is dependent on hydrostatic and osmotic pressure
What is pinocytosis?
Endothelial cells ingest substance and form vesicle. It is then transported to the interstitial space and released
What is the function of the lymphatic system?
Prevent the accumulation of excessive interstitial fluid
How does the lymphatic system prevent accumulation of fluid?
Removes fluid and plasma proteins and returns it to systemic circulation
What are the 4 factors in the formation of edema?
- Increase capillary pressure
- increase capillary permeability
- decrease concentration of plasma protein
- Obstruction of capillaries
