Blood Vessels (Lecture)

Lecture

What are the 3 layers of blood vessels?

Tunica Externa, Tunica Media, and Tunica Intima.

What type of tissue does Tunica Intima have?

Simple squamous epithelium

What type of tissue does Tunica Media have?

Smooth muscle cells and elastic connective tissue

What type of tissue does Tunica Externa have?

Adventitia and mostly collagen fibers

What does “Vaso Vasourm” literally mean?

Vessels of the vessels

What does Vaso Vasorum do?

a small network of blood vessels that supply oxygen to arteries and veins

What are arteries?

Muscular vessels that get the blood to the capillary beds

What are elastic (conducting) arteries?

Aorta and its major branches made up primarily of elastin and collagen that allows for expansion under pressure

What are muscular (distributing) arteries?

Most named arteries that have thickest tunica media which are very active in vasoconstriction/dilation

What are Aterioles?

Smallest arteries which give way to capillary beds. The largest arterioles have all three tunics, smallest lose tunica externa and smallest arterioles can leak fluids and exchange gases

What are capillaries?

The smallest vessels that have extensive beds found in most tissues. They do exchange of gases, waste, nutrients, hormones, and etc.

What is an example of capillaries?

When you scratch something and it bleeds this is because of the capillary beds

What are continuous capillaries (caps)?

the most common that are in skin, muscles, lungs, CNS with intercellular clefts

What are fenestrated capillaries (caps)?

In urinary, digestive, and endocrine and have holes (fenestrate) that allow diffusion

What are Sinusoid capillaries?

Seen in liver, marrow, spleen, and adrenal medulla. They have BIG holes (fenestrate) and clefts which allow cells and molecules to pass through. However, this becomes macrophages hunting ground

How many capillaries can the terminal arteriole branch into?

10-20+

What can arterioles do to effect the capillary beds?

They can either constrict to dilate to allow less or more blood to go into the capillary beds.

What is the Digestive (Mesenteric) Capillary bed?

The dense network of tiny blood vessels inside the mesentery and intestinal walls that absorbs digested nutrients and delivers oxygen-rich blood to the digestive tract

What is a Metarteriole Channel?

A short micro vessel that links arterioles directly to venules. Acting as a vascular shunt that allows blood to bypass a capillary beds.

What is used to close or open vascular shunts in the capillary beds?

Precapillary Sphincters

What are some examples of the capillaries dilating or constricting?

All of the above are correct

Why would you want the capillary beds to be able to constrict or dilate blood transportation?

Because it takes the blood to places that actually need it/ uses it and vice versa

What are veins?

Thinner-walled, larger lumen vessels that return blood to heart

What are Venules?

the small vein that pick up blood from the capillaries bed

The smaller venules are porous, what could this be helpful for?

To allow movement in and out of them

What are some ways the body helps with vein flow?

Muscular pump, respiratory pump, and Sympathetic venous vasoconstriction

What are anastomoses?

Provide alternate paths of blood flow to and from tissues

What does Arterial Anastomoses do?

provide alternate routes to critical areas

What is blood flow? (BF, F)

Volume flowing through vessel, organ, system in ml/min

What is blood pressure? (BP or P)

Force/unit area exerted on a vessel wall in mm Hg; Generally refers to hydrostatic pressure in large arteries near heart

What is Resistance? (R)

resistance due to friction

What is Viscosity?

Fluid resistance of molecules moving by each other. Maple syrup is more viscous than air (Blood viscosity fairly constant)

What is Total Vessel Length?

Longer: more resistance, shorter: less resistance

What is vessel diameter?

Smaller: more resistance, Longer: less resistance

What is R=1/r^4 showing?

showing how resistance to blood flow is inversely proportional to the radius of the vessels radius

What happens when r as Radius gets larger? (In R=1/r^4)

1/r^4 gets smaller

What is Pulse Pressure?

Systolic-diastolic, so 120 – 80 = 40 mm Hg (in aorta) It also decreases as blood moves through system

What is Pulse?

palpable difference between systolic and diastolic pressures

What is Mean Arterial Pressure? (MAP)

Weighted average of systolic and diastolic. (MAP = diastolic + PP/3) → MAP = 80 + 40/3 = 93 mm Hg (in aorta)

What happens to MAP as it goes down to capillaries?

It goes down to about 35mmHg when entering caps

What does MAP go down to in Capillary Pressure?

35mmHg to 15mmHg

What does it go down to in venous pressure?

from 15mmHg to 0

What is blood pressure regulation?

BP varies directly with CO, R, and blood volume. If any of these three factors increase, BP also increases