Mod X - Vacular & EKG - M&M22pg476-486 - Miller 69 & 17 - A&P Cerebral Circulation: ARTERIAL AND VENOUS CIRCULATION Flashcards by Olivier Mba

_{ARTERIAL AND VENOUS CIRCULATION}

OBJECTIVES OF THIS LECTURE ARE:

Identify the functional components of the circulatory system and their roles
Identify the branches of the ascending aorta, aortic arch, descending aorta, and abdominal aorta
Identify blood supply to the head, neck, thorax, upper extremities, and lower extremities
Explain the importance of the Artery of Adamkiewicz
Outline the main vessels of cerebral circulation
Describe the Circle of Willis

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_{ARTERIAL AND VENOUS CIRCULATION}

•Physical characteristics (2 circulations)

–Systemic circulation

–Pulmonary circulation

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_{ARTERIAL AND VENOUS CIRCULATION}

Systemic circulation

Supplies all tissue except lungs

AKA greater circulation or peripheral circulation

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_{ARTERIAL AND VENOUS CIRCULATION}

Pulmonary circulation

…

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_{ARTERIAL AND VENOUS CIRCULATION}

Functional parts of circulation:

Arteries

Arterioles

Capillaries

Venules

Veins

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_{ARTERIES AND ARTERIOLES}

Arteries

Transports blood under high pressure to the tissues

This is why arteries Have strong vascular walls

Blood flows at high velocity

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_{ARTERIES AND ARTERIOLES}

Arterioles

Last small branch of arterial system

Act as a control conduit through which blood is released into the capillaries

Strong muscular walls

Can vasoconstrict or vasodilate depending on blood flow requirements of each tissue

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_{ARTERIES AND ARTERIOLES}

What’s a benefit of Arterioles having Strong muscular walls?

Can vasoconstrict or vasodilate depending on blood flow requirements of each tissue

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_{CAPILLARIES, VENULES & VEINS}

Capillaries

Have the most important function of the circulatory system

Which is diffusion of substances back and fort between blood and tissues

Exchanges fluid, nutrients, electrolytes, hormones, etc

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_{CAPILLARIES, VENULES & VEINS}

Venules

Collect blood from the capillaries and gradually grow larger into veins

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_{CAPILLARIES, VENULES & VEINS}

Veins

Conduits for transport of blood from venules back to heart

Veins are the reservoir of extra blood

(small or large amount based on the needs of the circulation)

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_{CAPILLARIES, VENULES & VEINS}

Which characteristics of veins make them reservoir of extra blood?

Thinner walls than arteries

Much more distensible than arteries

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_{ARTERIAL AND VENOUS CIRCULATION}

Graphical representation of distribution of blood volume amoung the various component of circulation

Systemic circulation: 84%

(64% of which is in the veins)

Heart and pulmonary circulation: 16%

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_{WALLS OF ARTERIES AND VEINS}

Passageway by which blood flows and is present in both arteries and veins is known as

Lumens

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_{WALLS OF ARTERIES AND VEINS}

Btw arteries and veins which has smaller lumen?

Arteries

Smaller lumens help arteries maintain higher pressures as blood moves throughout the system

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_{WALLS OF ARTERIES AND VEINS}

There three layers to each vessel knowns respectively as:

Tunica externa/adventitia

Tunica media

Tunica intima

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_{WALLS OF ARTERIES AND VEINS}

Tunica externa/adventitia

Outermost layer of a blood vessel

(reponsible for maitaining protection and prevents collapse)

Strengthens/Anchors to surrounding tissue

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_{WALLS OF ARTERIES AND VEINS}

Tunica media

Middle layer of blood vessel

Responsible for contraction and relaxation or Vasoconstriction and vasodilation

This is normally the thickest layer in arteries

Much ticker in arteries than in veins

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_{WALLS OF ARTERIES AND VEINS}

Tunica intima

Thinnest layer

Boundary between blood in the lumen and the wall of vessel

Inner layer of blood vessel

Has innermost lining made up of Endothelial cells (Endothelium)

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_{WALLS OF ARTERIES AND VEINS}

Damage to which part of the tunica intima is the reason for clot formation?

Damage to the endothelium is the reason for clot formation

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_{WALLS OF ARTERIES AND VEINS}

Why are the lumen of the arteries more rounded that the lumen of the veins?

This is b/c of the thicker walls and smaller diameters in arteries

The thicker walls in arteries are d/t to their close proximity to the heart, and their higher pressure in relation to veins

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_{DIFFERENCE BETWEEN ARTERIES AND VEINS - Arteries}

Direction of flow - Pressure - Walls - Lumen - Valves

Direction of flow: Blood away from Heart

Pressure: Higher

Walls: Thicker: Tunica media thicker than tunica externa

Lumen: Smaller

Valves: None

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_{DIFFERENCE BETWEEN ARTERIES AND VEINS - Veins}

Direction of flow - Pressure - Walls - Lumen - Valves

Direction of flow: Blood toward heart

Pressure: Lower

Walls: Thinner: tunica externa thicker than tunica media

Lumen: Larger

Valves: Present most commonly in limbs and in veins that are inferior to heart

_{DIFFERENCE BETWEEN ARTERIES AND VEINS}

Btw arteries and veins, which has valves? Why? What the function of these valves?

Veins have valves b/c they are low pressure vessels

Valves ensure unidirectional flow toward the heart and prevent backward flow toward the capillaries

_{DIFFERENCE BETWEEN ARTERIES AND VEINS} Swollen, twisted veins that you can see just under the skin. They usually occur in the legs, but also can form in other parts of the body

**Varicose veins** In pts w/ Varicose veins, blood pools to the lower extremities d/t the pool of gravity. and the increased blood increases the pressure w/in the vein, and promotes the blood accumulation in the vein and ultimately distension, twisting and visibility to the surface of the skin

_{AORTIC SEGMENTS} The thoracic aorta is divided into three sections:

**Ascending aorta** ^{(Portion that leaves the LV)} **Transverse aorta** ^{(aka aortic arch)} **Descending aorta** ^{(Portion that descends into the thorax)}

_{AORTIC SEGMENTS} When does the Descending aorta becomes the **Abdominal aorta**?

after in penetrates the **diaphragm** This occurs around level **T12**

_{ANATOMY OF THE CEREBRAL CIRCULATION} Ascending aorta ascends from the

aortic valve

_{ANATOMY OF THE CEREBRAL CIRCULATION} Ascending aorta ascends from the aortic valve and banches off into:

**Brachiocephalic** artery Left common carotid artery (**LCA**) branches off directly off the ascending aorta **Left subclavian artery**

_{ANATOMY OF THE CEREBRAL CIRCULATION} What the other name for the Brachiocephalic artery?

**Innominate** artery

_{ANATOMY OF THE CEREBRAL CIRCULATION} What does the Brachiocephalic artery (Innominate) branches off into?

Right subclavian artery Right common carotid artery Right common carotid artery bifurcates with right subclavian Left common carotid arises from aortic arch

_{ANATOMY OF THE CEREBRAL CIRCULATION} Which carotid Artery provides Blood supply to neck, face, and base of skull?

External Carotid Artery _{(Will not be discussed for this lecture)}

_{ANATOMY OF THE CEREBRAL CIRCULATION} Internal Carotid Artery divides into which arteries?

Middle cerebral artery Anterior cerebral artery

_{ANATOMY OF THE CEREBRAL CIRCULATION} Which artery provides Arterial blood supply to the brain?

**Internal carotid artery** Provides 80% of cerebral blood flow

_{ANATOMY OF THE CEREBRAL CIRCULATION} Which artery provides Arterial blood supply to the lateral aspect of cerebrum?

Middle cerebral artery

_{ANATOMY OF THE CEREBRAL CIRCULATION} Which artery provides Arterial blood supply to the Frontal lobe and medial aspect of cerebral hemispheres?

Anterior cerebral artery

_{ANATOMY OF THE CEREBRAL CIRCULATION} The Internal Carotid Arteries provides 80% of CBF. Where does the remaining 20% comes from?

Vertebral arteries (2) Arise from subclavian arteries to form basilar artery Then give rise to the Posterior cerebral artery

_{ANATOMY OF THE CEREBRAL CIRCULATION} Which vascular structure is considered Cornerstone of inflow of blood to brain

**Circle of Willis** Hexagonal ring shaped that lies in the subarachnoid space and circles the pituitary gland

_{ANATOMY OF THE CEREBRAL CIRCULATION} The Three paired arteries originate from the circle of Willis to perfuse brain are:

Anterior cerebral arteries Middle cerebral arteries Posterior cerebral arteries

_{ANATOMY OF THE CEREBRAL CIRCULATION} communicating arteries that complete the circle of Willis are known as:

Anterior and posterior _communicating arteries_, AKA **Willsians channels**

_{CIRCLE OF WILLIS} In what % of the population is the Circle of Willis Abnormal or incomplete

in majority of patients (50-80%) W/ complete occlusion of a major vessel, infarction can occur if collateral flow is not adequate _{CIRCLE OF WILLIS} _{Under normal circumstances when there is no occlusion, blood flow btw the}anterior-posterior or side-to-side or left-to-right circulations does not mix In the event of an occlusion, the Circle of Willis can act as a shunt btw either anterior-posterior, or Willisian channels, increase collateral flow in an effort to maintain pressure Collateral flow can also occur through the extrenal carotid arteries The Willisian channels become important during periods of vessel occlusion of one of the carotid arteries Collateral circulation from the Willisian channels allows cross filling of the cerebral vessels to maintain blood flow

_{THORACIC AORTA} The Thoracic aorta is also known as:

Descending aorta

_{THORACIC AORTA} What's the thoracic aorta span?

Begins at T4 and extends to T12

_{THORACIC AORTA} Where does the thoracic aorta begins in reference the the vertebral column?

begins **_left_** of the vertebral column but approaches **_midline_** as it descends into the chest

_{THORACIC AORTA} Arterial Branches of the thoracic aorta include:

Bronchial arteries Mediastinal arteries Oesophageal arteries Pericardial arteries Superior phrenic arteries Intercostal and subcostal arteries

_{ABDOMINAL AORTA} Thoracic aorta becomes abdominal aorta once it passes through

**Diaphragm** Ends above pelvis, dividing into iliac arteries

_{ABDOMINAL AORTA} Major branches of abdominal aorta include:

Inferior phrenic (T12) =\> inferior aspect of the diaphragm Celiac trunk (T12) =\> organs of upper abdomen Superior mesenteric artery (L1) =\>Jejunum, ileum and transverse colon Inferior mesenteric artery (L3) =\> transverse, descending, sigmoid colon and rectum Renal arteries (L1-2) =\> kidneys

_{ABDOMINAL AORTA} Where does the abdominal aorta terminates?

Common illiac arteries (L4) Which branches into internal and external iliacs Internal iliacs =\> pelvic structures External iliacs =\> legs

_{BLOOD SUPPLY TO SPINAL CORD} How does the Spinal cord receives its blood supply?

about 25% from two posterior arteries and about 75% from one anterior spinal artery

_{BLOOD SUPPLY TO SPINAL CORD} Thoracic portion of anterior spinal artery supplied by

2-3 anterior radicular arteries The larger radicular artery is the Artery of Adamkiewicz Artery of Adamkiewicz, also known as the Great Radicular Artery

_{BLOOD SUPPLY TO SPINAL CORD} Artery of Adamkiewicz rpovides blood supply to:

Major blood supply to lower 2/3 of spinal cord Provides major blood supply to lumbar and sacral cord

_{BLOOD SUPPLY TO SPINAL CORD} Variations on the origin of the Artery of Adamkiewicz. Where does is originate in most people?

In 75% of people, originates on the left side of the aorta between T9 and T12 vertebral segments Segmental supplier of Adamkiewicz varies, (T5-L5)

_{LOWER EXTREMITY ARTERIAL CIRCULATION} At what vertebral level does the common iliac artery divides to become the internal and external iliacs?

_{LOWER EXTREMITY ARTERIAL CIRCULATION} Internal iliac artery provides blood supply to:

**Pelvic structures** Internal iliac artery =\> anterior and posterior trunks Anterior trunk =\> obturator artery, vesical artery (men) and vaginal artery (females) Posterior trunk =\> posterior pelvic wall, gluteal region

_{LOWER EXTREMITY ARTERIAL CIRCULATION} **External iliac artery** provides blood supply to:

**Lower extremities** External iliac artery =\> femoral and deep femoral artery =\> popliteal artery --\> dorsal artery