Veins and Capillaries

The three ways blood is pumped in the body

The heart, muscular arteries and skeletal muscles

Differences between veins and arteries

veins have a larger lumen and looks more collapsed, veins have thinner tunica media and adventicia, and veins have valves

True or false: veins are large and store blood

True - they are very large and store blood

Define the process of a blood clot

• We are going to have a blood vessel that breaks and things will begin to leak out 

  • Reminder: underneath the endothelium we have the subendothelium which is made of areolar CT. The fibers that make up this tissue are: collagen, elastin, and reticular fibers. 

• When platelets get introduced to collagen, they get activated. 

  • Collagen is the rough material that is going to activate the platelets. 

• The platelets get activated, they’ll interact with other kinds of hormones that will simply say are clotting factors 

• Then we will make fibrous proteins. 

• These fibers make net-like material, the reason being is because you are able to catch a bunch of red blood cells with it. 

  • They’re catching all those red blood cells because that net is not going to be enough to prevent water and small ions from passing in between them. We will be plugging up the space with erythrocytes. 

• Once that plug is set now you have a clot 

• That clot will now allow the tissue to heal 

  • Eventually the tunica adventitia, the subendothelium, as well as the endothelium, will all heal and eventually that clot needs to be broken down as well. 

• Macrophages will play a role in cleaning up the clots after we are done using it. 

This leads to a pulmonary embolism

Deep vein thrombosis

Deep vein thrombosis

Is a blood clot that occurs in the vein, resulting from blood that does not move within the vein.

Embolism

a piece of a blood clot breaking off and moving throughout the body

Pulmonary embolism

the embolist, the blood clots, found its way to go through the pulmonary arteries and gets caught in the capillary beds leading to lungs. This is often fatal.

This fiber is the rough material that activates the platelets in a blood clot

Collagen

Define structure of a capillary

these have lumen just big enough for single red blood cell to cross through it

Importance of capillaries

For nutrient, waste and gas exchange. We want to ensure the blood flow is slow in order to maintain this exchange.

List the different types of capillaries

Continuous, fenestrated, discontinuous (sinusoid)

Capillaries are made of which tissue and why?

Simple squamous epithelium because blood cells need a smooth surface to prevent damage to the blood cells and blood clots

Describe what makes up a continuous capillary

Endothelium, erythrocytes, intercellular clefts, plasma and leukocytes leaking out

Describe what makes up a fenestrated capillary

Endothelium, erythrocytes, intercellular clefts, plasma and leukocytes leaking out, fenestrations, small openings with plasma also leaking out

Which capillary does a synovial membrane use?

Fenestrated capillaries

Describe what makes a discontinuous capillary

endothelium, erythrocytes, intercellular clefts, plasma and leukocytes leaking out

Which capillary does red marrow have?

discontinuous capillary

What consists of a capillary bed?

Arteriole, capillary bed, plasma being released, venule, cells, precapillary sphincter, lymphatic capillary

Describe the function of a pre capillary sphincter

acts as valves that open and close to regulate blood flow to capillary beds

Describe a veins basic anatomy

Tunica intima, tunica media with smooth muscle being thinner, and tunica adventicia

Explain why a vein needs to have valves

Veins do not have enough pressure to promote blood flow. In order to have unidirectional blood flow valves are needed.

Describe how to draw a venule

Just an endothelium

Describe how to draw and what makes up a vein

Tunica intima

• endothelium

• Subendothelium

Tunica media

• smooth muscle being thinner

• Elastic fibers

Tunica Adventitia

Vasa Vasorum

Describe what a varicose vein is

• Apply to superficial veins, those we see through our skin NOT our deeper veins 

• Young healthy skin tend to not have varicose veins because they have much more elastic and firm skin. 

• Older → skin loses firmness and elasticity, the skin gets pushed away and the vein does not get compressed and opens up. This causes the veins to get deformed. Will not ensure a unidirectional flow. The blood pulls and gathers and causes it to be unsightly and can be painful. 

Ways to get varicose veins

• Pregnancy 

  • Increased blood volume causes vessels to enlarge, where it causes valves to deform. 

• Stretching a body part inappropriately damaging those valves 

  • Can sometimes cause damages to those veins in a certain stretch 

• Genetics can play a role

What plays a role in cleaning up a blood clot?

Macrophage

Hardening and damaging of the arteries is known as

Arteriosclerosis

List the types of arteriosclerosis

Atherosclerosis and Hypertensive arteriosclerosis

Which artery do we commonly start with for atherosclerosis

Muscular artery

This is the most type of arteriosclerosis

atherosclerosis

Explain the role of cholesterol in atherosclerosis

LDL

1. float around the arteries and if we have a lot of them, more likely to cause LDL to go into the subendothelium of the artery 

   1. That LD should not be there, so a leukocyte will come in and get rid of it = macrophage 

Explain the role of macrophages in atherosclerosis

macrophages will eat the LDL in the artery, that macrophage becomes an obese macrophage called a foam cell. The foam cell becomes a plaque within the lumen.

The name of the plaque referred to in Atherosclerosis

atherosclerotic plaque

Explain the affects of an atherosclerotic plaque

Decreased size in lumen will result in decreased blood flow. Decreased blood flow means a tissue is not getting enough oxygen, leading to ischemia. The roughened endothelium due to the plaque will cause damage and often times a blood clot. Endothelium may rupture, platelets activate and blood clot forms.

This arteriosclerosis is due to high blood pressure

Hypertensive arteriosclerosis is due to high blood pressure

Explain the affect of hypertensive arteriosclerosis to its structure

Thicker tunica adventitia, more physical strength to artery, causes increase in blood pressure, leads to an even thicker tunica adventitia.

These are types of congenital disorders

aneurysm and arteriovenous malformation (AVM)

This is a type of varicose vein in the anus

hemorrhoid

What can result in the destruction of blood vessels?

diabetic angiopathy

This is a disease of diabetes?

diabetic angiopathy

Explain the affect of high sugar levels with diabetic angiopathy

high levels of sugar levels will disrupt capillaries and overall blood vessels, leading to blood vessels and tissues dying, also known as necrosis. This can lead to amputation of that limb or loss of vision due to diabetes killing off blood vessels.

The ____ is a specialized blood flow pathway involving the liver.

hepatic portal system

How many beds does a portal system pass through?

two capillary beds before returning to the heart

In the hepatic portal system, the second capillary bed is located in which organ?

the liver

Describe the normal circulation versus a portal circulation

normal circulation involves the following:

artery —> capillary bed —> vein —> heart

portal circulation involves the following:

artery —> capillary bed #1 —> portal vein —> capillary bed #2 —> vein —> heart

Purpose of the hepatic portal system?

it allows the liver to process the blood and make sure potentially harmful substances are dealt with before the blood continues through the rest of the body

Hepatic portal blood flow pathway

digestive organ —> capillary bed #1 —> hepatic portal vein —> liver —> capillary bed #2 —> hepatic vein —> inferior vena cava —> heart

Where can you find continuous capillaries

Skin, muscle tissues, lungs, adipose tissues, connective tissue

Where can you find fenestrated capillaries

Kidneys, endocrine glands, small intestine, synovial membrane

Where can we find discontinues capillaries

Liver, spleen, red bone marrow, lymph nodes, lymphatic organs