Arterial And Venous System + Body Fluid Compartments - Quiz 5 Flashcards
What tissues make up the wall of the artery?
Endothelium
Elastic Tissue
Smooth Muscle
Fibrous Tissue
What are the 3 tissue layers in the artery wall?
Tunica Externa (Adventitia)
Tunica Media
Tunica Intima
What are the Arteriole Wall tissues?
Endothelium & Smooth Muscle
What are the Vein wall tissues?
Endothelium
Elastic Tissue
Smooth Muscle
Fibrous Tissue
Primary function of Arterial System
Distribute blood to capillary system
What do the Arterioles do?
Regulate distribution of blood flow to various capillary beds
Where is the pressure lowest as blood goes from aorta to RA?
Vena Cava - close to zero
What is pulse pressure?
Difference b/t systolic and diastolic BP
How to Caculate MAP
MAP = [2DBP + SBP] / 3
or
MAP = [CO x SVR] + CVP
Waveform as blood moves away from heart to extremities?
- High frequency components of pulse (incisura) become damped, then disappear
- Systolic part of wave narrow and elevate
- Hump appear on diastolic part of wave
SBP in the foot vs aorta
Higher in the foot d/t gravitational pressure
How is pulsatile flow converted to continuous flow?
Hydraulic filter makes flow continuous to minimize workload of the heart
Pumping blood thru rigid vessels is ______ work for the heart
More
What factors increase pulse pressure?
- Increased Stroke Volumes
- ↑Preload, ↑Intropy, ↓HR, ↓Afterload
- Decreased Aortic Compliance
- Age, HTN, Ateriosclerosis
Why do arteries get stiffer with age?
Loss of elastic tissue
Vein Functions
Reservoir - 70% of blood volume
Pumps blood forward for venous return
What regulates CVP
Balance of heart to pump blood out the RA and RV to lungs
and
Blood flow back to RA
What factors increase CVP
- ↓Cardiac Output
- ↑TBV
- ↑Respiratory Activity
- Venous Contriction
- Arterial Dilation
- Gravity - standing to supine
- Skeletal Muscle Pump - exercise
In a standing position, where are the highest and lowest venous pressures?
Lowest: Sagittal Sinus (Head) = -10mmHg
Highest: Feet = 90mmHg
Major risk of sitting position in neurosurgery
Air Embolism?
How does Respiration effect Venous Return?
- Spontanous Breathing
- Inspiration increases venous return, vice versa
- Mechanical Breathing
- Positive Pressure –> ↑RA pressure –> ↓venous return
- Valsalva Maneuver
- ↑Thoracic Pressure –> ↓venous return
How much TBV is in Venous System?
70%
Where are major blood reservoirs?
Spleen
Liver
Large Abdominal Veins
Venous Plexus under Skin
Heart & Lungs (Not part of venous system)
What are the stopcocks of the vascular system?
Arterioles - they can constrict and dilate as needed
What things make capillaries ideal for nutrient & fluid exchange?
Single, thin endothelial layer
Large cross section/surface area
Do capillary walls have smooth muscle?
No, just endothelial tissue
Why can capillaries withstand high intravascular pressure?
Laplace’s Law
Very thin wall with very small radius can take more pressure
Why is the vascular system distensible?
- Accommodate pulsatile heart output
- Average out the pressure pulsations
- Allows smooth, continous blood flow through small vessels
What part of the vasculature is most distensible?
Veins - reservoir for 0.5 to 1 L of extra blood
How much more distensible are veins vs arteries?
8x more distensible
How do pulmonary arteries compare to systemic arteries?
Pulmonary arteries operate at 1/6 pressure and have 6x greater distensibility.
What is vessel capacitance/compliance?
Total amt. of blood that can be stored in a given portion of circulation for each mmHg pressure rise
Which type of vessel dampens pulse and distributes blood?
Aorta (25mm)
Which vessel type has the function of only distribution?
Large arteries (1-4mm)
Which vessel type is responsible for distribution & resistance?
Small Arteries (0.5-1mm)
Which vessel type is primary for exchange?
Capillaries (.006-.01mm)
Which vessel type has the functions of exchange, collection, and capacitance?
Venules (0.5-5mm)
Which vessel has a primary function of collection?
Vena Cava (35mm)
What is the Tunica Intima comprised of?
Thinnest layer
Endothelial cells
Intercellular matrix
Subendothelial connective tissue
Internal elastic lamina
What is the Tunica Media comprised of?
Elastic tissue
Connective tissue
External elastic lamina
Smooth Muscle
Thicker in Arteries than Veins and has more elastic fibers
What is the Tunica Extern (Adventitia) comprised of?
Connective Tissue
Nerves
External elastic lamina
Nutrient capillaries in larger vessels
Usually thicker in veins to prevent vessel collapse and damage
Veins and Arteries are made up from the same tissues, whats the difference?
Artery has more elastic tissue and smooth muscle
How are small arteries and arterioles innervated?
Sympathetic adrenergic nerves - respond to changes in hormones
What is transmission of the pressure pulse?
When blood first exits the aorta, the sudden ejection causes a distension that spreads further along the aorta.
Windkessel Effect
During cardiac contraction, energy moves forward to capillaries, but some energy is stored as potential energy for the next contraction.
The degree of pulse damping is _______ proportional to resistance x compliance
Directly Proportional
Compliance is change in _______ divided by change in _______
Compliance = Δvolume/Δpressure
Is CVP a good indicator of Volume Status?
No, body will try to maintain normal CVP despite abmormal volume amounts.
What are the 2 major body fluid compartments?
Intracellular: 2/3 or 40% of Total Body Weight
Extracellular: 1/3 or 20% of Total Body Weight
What % of Total Body Weight is made of water?
~60%
How would 1L of 0.9NS distribute to the different fluid compartments?
Increases ECF Only
How would 0.5% dextrose distribute to the different fluid compartments?
D5 starts as isotonic, then becomes hypotonic after body absorbs the glucose –> water will go into cell
What parts make up ECF?
Interstitial Fluid: 75%
Plasma: 24%
RBC: 1%
Isotonic
Doesnt shrink or swell cells.
Does not upset osmotic equilibrium
EX: NS, LR
Hypotonic
Lower Solutes
Water goes into Cells
↑ECF
↑↑↑ICF
EX: D5W
Hypertonic
Higher amt of Solutes
Water goes out of Cell
↑ECF
↓ICF
EX: D5 1/2NS, D5NS (dont give to infants)
Colloid
Albumin is most commonly used
Contains human plasma proteins
Expands plasma volume
