Lec: Blood Vessels Flashcards
Name the five classes of blood vessels.
- Arteries
- Arterioles
- Capillaries
- Venues
- Veins
What direction do arteries carry the blood?
Away from the heart
Name three anatomical artery points.
- They start as large, elastic arteries
- They divide to form muscular arteries
- Further division creates arterioles
What do arterioles end in?
Capillary beds
What direction do veins carry blood?
Away from the heart
What is a capillary?
A very small blood vessel that has thin walls to allow for gas exchange between blood and tissues
After leaving arterioles to become capillaries, what do capillaries converge into?
Venules
What do Venules merge to create?
A vein
What is a vasa vasorum?
Vessels in the walls of large blood vessels that supply them with the blood they need to work.
Name the three layers of arteries.
- Tunica Interna
- Tunica Media
- Tunica externa
What is the tunica interna?
The inner lining of the artery or endothelium, consisting of simple squamous epithelium.
They also have a basement membrane and internal elastic lamina
What is the tunica media?
Composed of circular smooth muscle and elastic fibres that allows for immense stretch under pressure.
What is the tunica externa composed of?
This layer is composed of elastic and collagen fibres
What innervates the smooth muscle of the arteries to tell them to contract?
The sympathetic nervous system
What is vasoconstriction?
Contraction of the artery, squeezing of the smooth muscle to contract the artery
What is vasodilation?
Relaxation of the smooth muscle surrounding the artery, still contracting but not applying as much pressure
What does the sympathetic nervous system control in the arteries?
- Increase in stimulation for muscle contraction. - vasoconstriction
- Decrease in stimulating in the presence of certain chemicals - vasodilation
What occurs if there is an injury to the artery?
Vasospasm occurs causing the muscle to contract to try and reduce blood loss
Arteries _________ during ventricular systole.
Stretch
Why does arterial stretching occur during ventricular systole?
- To allow for rapid ejection of blood from ventricles
- Elastic fibres store mechanical energy during systole and release it during diastole - this recoil pushes blood onward despite ventricular relaxation.
Name 7 Elastic arteries.
- Aorta
- Brachiocephalic artery
- Common carotid
- Subclavian artery
- Vertebral artery
- Pulmonary artery
- Common iliac artery
What is an elastic artery?
Also known as a “conducting artery” is an artery that carries blood on the the next artery type - the arteriole.
What is a muscular artery?
A medium sized artery with more muscle than elastic fibres in the tunica media, these arteries are capable of greater vasoconstriction and vasodilation to adjust to the rate of flow.
What is the other name for the muscular artery?
“Distributing artery” because they distribute blood to different parts of the body
What are some functions and characteristics of arterioles?
- They are nearly microscopic
- They deliver blood to the capillaries
- They have a big role in regulation of blood pressure
- They can vary in peripheral resistance through contraction and dilation.
What does it mean that arterioles can vary in peripheral resistance through contraction and dilation?
When they contract, the resistance to blood flow goes up, increasing the overall blood pressure. When they are relaxed the resistance drops and so does blood pressure
What is the role of capillaries?
These microscopic blood vessels connect arterioles and venules to form a network of vessels between the two for microcirculation. They are found in high quantities around highly active tissues like muscle, liver, kidney, and brain cells
What is the function of capillaries?
To exchange nutrients and waste products between blood and tissue fluids. They have extensive branching in order to increase surface area, speeding up exchange.
What are capillaries composed of?
Capillaries are composed of a single layer of simple squamous epithelium and basement membrane, meaning from the blood to tissues the waste and nutrients only have one cell layer to cross which is much less compared to an artery or vein.
What is the arteriole leading into a capillary bed called?
Metarteriole
What controls the entrance of blood into the capillaries?
The precapillary sphincter
What is vasomotion?
Blood flow across the capillary bed due to regular contraction/relaxation of smooth muscles of arterioles and precapillary sphincters
How much of the capillary bed is actually carrying blood at any given time?
25%
