Blood Vessels Flashcards
Layer which contains muscles and retains the shape of the blood vessels
Middle layer
What is in the medial layer of blood vessels that makes blood circulation possible?
Muscles (elastic fibers)
What keeps the arteries round?
Attachment to surrounding tissues and presence of muscles
Why is the vein collapsed? (If the volume is low. Does it need attachment to surrounding tissues?)
Which type of blood vessel has no internal elastic membrane?
Hint: Type of artery
Elastic artery
Type of artery
Makes sure that the pressure gradient at point B will become less
Can absorb the pressure sustained during the systolic phase (in the heart)
Elastic artery
T or F
During the recoil mode, the flow continues
True
Question: What is the physiology behind this?
What happens during the state of tonic contraction (tonic state)?
There is blood in the heart
Related to the question: Why in diastole, pressure is not 0?
What happens to the blood vessels?
Diameter decreases
Active input is required
vs
Diameter increases
Related to muscle relaxation
Vasoconstriction
vs
Vasodilation
Another nerve is stimulated to counterract the signals of the constrictor nerves
True or False
As collective diameter increases, pressure increases
For example, in capillaries
False
Decreases
Diameter and pressure are inversely proportional
True or False
There is constant of blood going to the brain
True
Not an excuse to be sleepy after meals
Can’t be seen
Not anatomical
But functional
Stops the flow of blood in the capillaries
Precapillary sphincter
Leads to arteriovenous shunt (blood goes to the area of lesser pressure)
Capillaries don’t close all at once
What happens to the pressure?
Arterioles to capillaries
Why?
Decreases
Collective diameter gets bigger
Dilation of arterioles (vasodilation, decrease in pressure)
RBCs fold to pass through the capillaries (8 microns vs 4-5 microns)
Example, in diabetes, RBC unable to fold
Valves of veins
Makes sure that flow goes in one direction Flow will continue to go upwards The pressure (P1) down is not enough to push blood upwards
What drives flow in the venous system?
Relaxation of heart
How many milliseconds does the heart contract?
Which is longer: relaxation or contraction phase?
1/3 of a second, so it gets 60-70 ml (SV) in 2/3 of a second. HOW? By having extra pumps to refill the blood.
Relaxation phase
When valves in the veins fail, blood goes somewhere
Varicose veins
Bakit dalawa ang puso natin?
If the heart is a pump…
1 Heart
2 Calf muscle pump! Pump in the veins (venous return) to return the blood
3 Respiratory pump: Pressure decreases in thoracic cavity; Pressure increases in abdominal cavity
Why is it that when you are tired, then you take a bath, the veins become visible?
Tired: Engorged/dilated veins
Cold: Thins epidermis/dermis
= Visible veins
Korotkoff Sounds
Blood Pressure sounds
T or F
The higher the blood volume, the lower the blood pressure
F
Higher
Vagus nerve
Relax or contract?
Relax
Body’s largest organ
One cell thick
1-2 trillion endothelial cells
Surface area of 400 sq.m. / 6 tennis courts
Vascular endothelium
Heterogenous (many different functions)
-can promote action opposite to the first function (that was stopped)
Functions of the endothelium
Barrier and transducing functions
Hemostatic functions
Control of vascular wall functions
Leukocyte / Endothelial cell adhesive functions
