Lecture 19 - Vascular System Flashcards by Eleanor Nicklason

What is the innervation of arteries?

Vasomotor

Sympathetic innervation that controls the smooth muscle, and thus the diameter of the lumen

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What is the structure of an artery?

Intima: endothelium
Media: smooth muscle
Adventitia: fibrous material

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What is the major division of the circulatory system?

Pulmonary

Systemic

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Describe blood flow around the heart

Venous return via IVC and SVC into right atrium
Right ventricle
Pulmonary artery
Lungs
Pulmonary vein
Left atrium
Left ventricle
Aorta
Body

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What are the different types of vessels?

Arteries
Arterioles
Capillaries
Venules
Veins
Lymphatics
Lymph vessels

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Describe the flow of lymph around the body

Interstitial fluid drains into lymph capillaries
Afferent lymph vessels
Lymph node
Efferent lymph vessel
Lymph duct
Draining back into circulation

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Why is there a pressure difference in the pulmonary and systemic circulation? What is this difference?

Pulmonary: low pressure, because the blood doesn’t have to travel far

Systemic: high pressure, because the blood must travel all around the body

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Is any part of the body avascular?

Yes:
Epidermis
Articular cartilage

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How may an artery and vein be distinguished when dissecting?

Arteries always have a lumen, due to the thick smooth muscle wall

Veins collapse, and there is no visible lumen

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When does an artery normal branch?

At a joint, such as the elbow

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What are the different branches that an artery can form?

Muscular branch
Nutrient branch
Articular
Cutaneous
Arteriae nervorum
Vasa vasorum

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Where does an artery usually run?

Down the midline, in the flexor compartment

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Arteries conduct high pressure blood. What confers this function?

The elastic fibres in the artery wall allow it to expand, and then bounce back to push the blood on

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How does the body control blood flow to different regions in different conditions?

The smooth muscle in the wall confers this property

When activated, the artery restricts in areas where excess blood is not needed.

The artery dilates where more blood is needed

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What is one of the main functions of arterioles?

‘Resistance vessels’

Control the flow and pressure into the capillaries

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What is the main function of capillaries?

‘Exchange vessels’

They have a very thin wall that allow them to carry out this function

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What is an anastomosis?

This is when two arteries meet without a communicating capillary

They provide collateral circulation

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What is collateral circulation?

Alternative routes of circulation

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We’re are anastomoses usually found?

In skeletal muscle

Joints, where circulation may be impaired due to bending of joint

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What is an anatomical end artery?

Where are they usually found?

These are arteries that do not connect with another artery

They are normally found in region that hang or stick out

Finger
Toes
Brain
Heart
Appendix

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What are the two types of end arteries?

Anatomical

* Functional / potential anastamosis

Why are end arteries clinically important?

Blockage of an end artery by an embolus will cut of all blood supply to that region
Ischemia – necrosis

Describe the vasculature of the end of a growing bone

The epiphyseal plate is avascular. Thus, there are two end arteries in the bone on either side.

When growth is finished, these arteries anastomose

What is an end organ?

It is an organ whose blood supply is an end artery

What are functional end arteries?

This is when, over time, end arteries anastomose due to some sort of pathology Eg. In heart, an ongoing condition whereby the arteries are narrowed will cause anastomosis of coronary end arteries In a sudden narrowing of vessels, there isn't time for the arteries to anastomose, and tissue ischemia and necrosis will result

What is the difference between a thrombus and an embolus?

Thrombus: fibrinous clot that forms and blocks a vessel Embolus: obstruction present in circulation, may be a detached thrombus, or a gas bubble

What is the structure of veins?

Intima: endothelium Media: thin smooth muscle Adventitia: fibrous material

Why is the lumen in veins wider than in arteries?

Greater volume of blood which is at lower pressure

Describe the function of valves

Valves are flaps of tissue in veins that close to prevent the back flow of blood

What systems allow blood to be returned to the heart by the veins?

* Venous valves * Muscular pump * Thoracic pump

What defects can occur in venous valves?

Incompetent valves --> varicosed veins

What is one of the special relationships between arteries and veins?

Venae comitantes

Where are venous valves present?

In the veins of the appendages, not in the trunk Especially in superficial veins Valves in perforating veins moving through the deep fascia

What are venae comitantes?

These are veins in close contact with arteries. Function: • Heat transfer • Pulsation of arteries moves blood back to heart

Describe how the muscular pump works

When skeletal muscle in the leg contracts, the veins embedded in the muscle are affected, and the blood in them is shunted up the veins

Describe how the thoracic pump works to return blood

During inhalation, the pressure in the thoracic cavity drops slightly. The blood flows into this region of lower pressure

What does Boyle's law say? How does this apply to inhalation

When volume increases, pressure decreases When one inhales, the volume in the thoracic cavity increases and the pressure decreases slightly

What are perforating veins?

These are veins that perforate the deep fascia, and thus move blood from superficial veins into deep veins

What is the deep fascia?

This is thick connective tissue surrounding skeletal muscle

The presence of tortuous lumps in the veins indicates...

Varicosed veins

What is the most important principle of lymph flow?

Lymph must pass through AT LEAST ONE lymph node before returning to circulation

What is lymph made up of?

The tissue fluid that it drains: - plasma proteins - white blood cells

Where is lymph returned to circulation?

In the veins in the neck Right and left side Left side receives lymph from most of the body

What are the functions of lymph?

- recovering proteins from interstitial fluid | - presenting invading organisms to the adaptive immune system

What is one commonality between veins and lymph vessels?

Valves to ensure uni-directional flow

What sort of tissue is a lymph node made up of?

Lymphatic tissue

Where are lymph nodes predominantly found?

Cervical: neck Axillary: armpits Inguinal: groin

Where is lymphatic tissue found?

``` Lymph nodes Thymus Tonsils Peyer's patches: intestine Spleen ```

What causes elephantiasis?

A thread worm blocks the lymphatics. Tissue fluid in the lower limbs is not drained Oedema in the lower legs

What is lymphedema?

This is when lymph nodes are resected in a surgery (ed. mastectomy) and the tissue fluid in the lower limbs does not drain

What would a thromboembolus from the venous system potentially cause?

Pulmonary embolysm

What would a thromboembolus from the arterial system potentially cause?

Stroke (in brain)