blood vessels

Question 1

Cardiac Output

Answer 1

Cardiac Output = Stroke volume x heart rate
* Any factor that causes cardiac output to increase by elevating heart rate or stroke
volume or both, will elevate blood pressure and promote blood flow (sympathetic stimulation - thyroid hormones, epinephrine, norepinephrine, increased calcium ions)
* Any factor that decreases cardiac output, by decreasing heart rate or stroke
volume or both, will decrease arterial pressure and blood flow (parasympathetic stimulation - increased or decreased potassium ion, decresed calcium, anoxia, acidosis)

Question 2

Vessel Length

Answer 2

• Directly related to its resistance - the longer the vessel the greater the resistance (the lower the flow)

Question 3

Vessel Diameter

Answer 3

• Changes throughout the body according to the type of vessel
• Any vessel’s diameter may change throughout the day in response to neural and chemical signals that trigger vasodilation or vasoconstriction

Question 4

Effect of Vessel Diameter on Resistance

Answer 4

• Increased diameter = lower resistance, increased flow
• Decreased diameter = increased resistance, decrased flow

Question 5

Blood Flow

Answer 5

• The movement of blood through a vessel, tissue or organ
• Expressed in terms of volume of blood per unit of time
• Initiated by the contraction of the ventricles of the heart
• Flow of blood from arteries: arteries > arterioles > capillaries > venules > veins
• Resistence = factors that impede/slow blood flow (ex. atherosclerosis narrows the lumen of a blood vessel)
• Viscosity = thickness of fluid that affects their ability to flow

Question 6

Hepatic Portal System Pt 1

Answer 6

• Instead of entering circulation directly, absorbed nutrients and certain wastes travel to the liver for processing via the hepatic portal system
• Initial capillaries from the stomach, SI, LI and spleen lead to the hepatic portal vein and end in specialized cappilaries within the liver (hapatic sinuoids)
• Consists of - hepatic portal vein and the veins that drain into it

Question 7

Hepatic Portal System Pt 2

Answer 7

• The liver recieves blood from the normal systemic circulation AND the hepatic portal vein
• Blood is processed through the liver from the portal system to remove certain wastes and excess nutrients, which are sorted for later use
• Processed and unprocessed blood from the hepatic artery exits the liver via the left, right or middle hepatic veins and flows into the inferior vena cava

Question 8

Systemic Veins Pt. 1

Answer 8

• Return de-oxygenenated blood to the right atrium
• Complementary Pattern = veins draining organs/regions of the body with the same name as arteries that supply these regions

Question 9

Systemic Veins Pt. 2

Answer 9

• The right atrium receives all of the systemic venous return through the superior or inferior vena cava
• Systemic venous circulation from above the diaphragm generally flows into the superior vena cava (blood from head, neck, chest, shoulders, upper limbs)
• Systemic venous circulation from below the diagphram flows into the inferior vena cava (blood from abdominal/pelvic regions and lower limbs)

Question 10

Head/Neck Veins

Answer 10

• Blood from the brain and superficial facial vein flow into each internal jugular vein
• Blood from the more superficial portions of the head, scalp and cranial regions (including temporal/maxxillary vein) flow into each external jugular vein
• Although they are seperate vessels, there are anastomoses between them close to the thoracic region
• External jugular vein drains into

Question 11

shared features of the major blood vessel types

Answer 11

Arteries and arterioles have thicker walls than veins and venules

Each type of vessel has a lumen—a hollow passageway through which blood flows.
Arteries have smaller lumens than veins, helps to maintain the pressure of blood. venules and veins walls are considerably thinner and their
lumens are correspondingly larger in diameter, allowing more blood to flow with less vessel resistance.

Both arteries and veins have the same three distinct tissue layers, called the tunica intima, the tunica media, and the tunica externa

Question 12

elastic vs muscular artery

Answer 12

Elastic artery - close to the heart with the thickest walls, containing a high percentage of elastic fibers in all three of their tunics. Elastic fibers allow them to expand, as blood pumped
from the ventricles passes through them, and then to recoil after the surge has passed. aka conducting artery, because the large diameter of the lumen enables it to accept a
large volume of blood from the heart and conduct it to smaller branches.

Muscular artery - located farther from the heart, where the surge of blood has dampened, the percentage of elastic fibers in an artery’s tunica intima decreases and the amount of
smooth muscle in its tunica media increases. Play a leading role in vasoconstriction.

Question 13

arteriole

Answer 13

An arteriole is a very small artery that leads to a capillary. Arterioles have the same three tunics as the larger vessels, but the thickness of each is greatly diminished. The critical endothelial lining of the tunica intima is intact. The tunica media is restricted to one or two smooth muscle cell layers in thickness. The
tunica externa remains but is very thin.

Arterioles are critical in slowing down—or resisting—blood flow and, thus,
causing a substantial drop in blood pressure. Because of this, you may see them referred to as resistance vessels.

Primary site of both resistance and regulation of blood pressure.

Question 14

capillary

Answer 14

A capillary is a microscopic channel that supplies blood to the tissues
themselves, a process called perfusion.

Exchange of gases and other substances occurs in the capillaries between the blood and the surrounding cells and their tissue fluid (interstitial fluid). The diameter of a capillary lumen are often just barely wide enough for an erythrocyte
to squeeze through. Flow through capillaries is often described as
microcirculation.

For capillaries to function, their walls must be leaky, allowing substances to pass through. Three major types of capillaries, which differ according to their degree of “leakiness:” Continuous,
fenestrated, and
sinusoid capillaries

Question 15

continuous capillaries

Answer 15

Characterized by a complete
endothelial lining with tight junctions
between endothelial cells. Allow for
exchange of water and other very
small molecules between the blood
plasma and the interstitial fluid.

skin
muscles
lung
CNS

Question 16

fenestrated capillary

Answer 16

Has pores (or fenestrations) in
addition to tight junctions in the
endothelial lining. These make the
capillary permeable to larger
molecules.

exocrine glands
renal glomeruli
intestinal mucosa

Question 17

discontinuous sinusoid

Answer 17

Least common type of capillary.
flattened. Have intercellular clefts and
fenestrations. This gives them an
appearance like Swiss cheese. Very
large openings allow for passage of
largest molecules, including plasma
proteins and even cells.

LV
SP
bone marrow

Question 18

venule

Answer 18

A venule is an extremely small vein. Postcapillary venules join multiple capillaries exiting from a capillary bed. Multiple venules join to form veins.

Venules as well as capillaries are the primary sites of emigration or diapedesis, in which the white blood cells adhere to the endothelial lining of the vessels and then squeeze through adjacent cells to enter the tissue fluid.

Question 19

veins

Answer 19

A vein is a blood vessel that conducts
blood toward the heart. thin-walled vessels with large and irregular lumens. low-pressure vessels with valves

Veins may be considered blood reservoirs, since systemic veins contain approximately 64 percent of the blood volume at any given time
Their ability to hold this much blood is due to their high capacitance, that is, their capacity to distend (expand) readily to store a high volume of blood, even at a low pressure.

When blood flow needs to be redistributed to other portions of the body, venoconstriction may be likened to a “stiffening” of the vessel wall. This increases pressure on the blood within the veins, speeding its return to the heart.

Venous reserve - about 21 percent of the venous blood is located in venous networks within the
liver, bone marrow, and integument. Through venoconstriction, this “reserve” volume of blood can get back to the heart more quickly for redistribution to other parts of the circulation.

Question 20

pulmonary circulation

Answer 20

pulmonary trunk: Single vessel exiting the right ventricle

pulmonary semilunar valve: prevents backflow of blood into the right ventricle during ventricular diastole.
at the base of the pulmonary
trunk

As the pulmonary trunk reaches the superior surface of the heart, it
curves posteriorly and rapidly bifurcates (divides) into two branches, a left and a right pulmonary artery.

The pulmonary arteries in turn branch many times within the lung, forming a series of smaller arteries and arterioles that eventually lead to the pulmonary capillaries. The pulmonary capillaries surround lung structures known as alveoli that are the sites of oxygen and carbon
dioxide exchange.

Once gas exchange is completed, oxygenated blood flows from the pulmonary capillaries into a
series of pulmonary venules that eventually lead to a series of larger pulmonary veins. Four
pulmonary veins, two on the left and two on the right, return blood to the left atrium. At this
point, the pulmonary circuit is complete.

Question 21

systemic circulation - aorta

Answer 21

Ascending aorta - superior direction for 5 cm to sternal angle.

Aortic arch - reverses direction, forming arc to the left; descends toward the inferior portions of the body and ends at the level of the intervertebral disk between the fourth and fifth thoracic vertebrae.

**Descending aorta **continues close to the bodies of the vertebrae and passes through an opening in the
diaphragm known as the aortic hiatus.

Superior to the diaphragm, the aorta is called the thoracic aorta, and inferior to the diaphragm, it is
called the abdominal aorta.
The abdominal aorta terminates when it bifurcates into the two common iliac arteries at the level of the fourth lumbar vertebra.

Question 22

branches of the aortic arch

Answer 22

Three major branches

Brachiocephalic artery - is located only on the right side of the body; there is no corresponding artery on the left.

The brachiocephalic artery branches into the right subclavian artery and the right common carotid artery.

Question 23

Subclavian arteries supply blood to

arteries of upper body

Answer 23

Subclavian arteries supplies blood to the **arms, chest, shoulders, back, and central nervous system. **

It then gives rise to three major branches:
the internal thoracic artery,
the vertebral artery, and
the thyrocervical artery.

Question 24

internal thoracic artery, or mammary artery, supplies blood to

arteries of upper body

Answer 24

The internal thoracic artery, or mammary artery, supplies blood to the thymus,
the pericardium of the heart, and
the anterior chest wall.

Question 25

vertebral artery supplies blood to | arteries of upper body

Answer 25

The vertebral artery passes through the vertebral foramen in the cervical vertebrae and then through the foramen magnum into the cranial cavity to supply blood to the **brain and spinal cord.**

Question 26

thyrocervical artery supplies blood to | arteries of upper body

Answer 26

The subclavian artery also gives rise to the thyrocervical artery that provides blood to the **thyroid,** **the cervical region of the neck** **the upper back and shoulder.**

Question 27

brachial artery supplies blood to | Arteries of the Upper Limbs

Answer 27

As the subclavian artery exits the thorax into the axillary region, it is renamed the **axillary artery**. Although it does branch and supply blood to **the region near the head of the humerus (via the humeral circumflex arteries)** the majority of the vessel continues into the upper arm, or brachium, and becomes the brachial artery. The brachial artery supplies blood to much of the **brachial region** and divides at the elbow into several smaller branches, including the deep brachial arteries, which provide blood to the posterior surface of the arm, and the ulnar collateral arteries, which supply blood to the region of the elbow.

Question 28

radial and ulnar arteries | Arteries of the Upper Limbs

Answer 28

As the brachial artery approaches the coronoid fossa (near the olecranon), it bifurcates into the **radial and ulnar arteries,** which continue into the forearm, or antebrachium. The radial artery and ulnar artery supplying the radius and ulna bones.

Question 29

digital arteries | Arteries of the Upper Limbs

Answer 29

They give off smaller branches until they reach the wrist, or carpal region. At this level, they fuse to form the superficial and deep palmar arches that supply blood to the hand, as well as the **digital arteries** that supply blood to the digits.

Question 30

common carotid artery - external | Arteries of the Head

Answer 30

The common carotid artery divides into internal and external carotid arteries. The external carotid artery supplies blood to numerous structures within the face, lower jaw, neck, esophagus, and larynx. These branches include the lingual, facial, occipital, maxillary, and superficial temporal arteries.

Question 31

common carotid artery - internal | Arteries of the Head

Answer 31

The internal carotid artery initially forms an expansion known as the carotid sinus, containing the carotid baroreceptors and chemoreceptors. The internal carotid arteries along with the vertebral arteries are the two **primary suppliers of blood to the human brain.** Given the central role and vital importance of the brain to life, it is critical that blood supply to this organ remains uninterrupted.

Question 32

anterior cerebral artery | Arteries in the Brain

Answer 32

The internal carotid artery continues through the carotid canal of the temporal bone and enters the base of the brain through the carotid foramen where it gives rise to several branches One of these branches is the **anterior cerebral artery** that supplies blood to the **frontal lobe of the cerebrum.**

Question 33

middle cerebral artery | Arteries in the Brain

Answer 33

Another branch, the **middle cerebral artery**, supplies blood to the temporal and parietal lobes, which are the most common sites of CVAs.

Question 34

ophthalmic artery | Arteries in the Brain

Answer 34

The ophthalmic artery, the third major branch, provides blood to the **eyes.**

Question 35

basilar artery | Arteries in the Brain

Answer 35

The basilar artery is an anastomosis that begins at the junction of the two vertebral arteries and sends branches to the **cerebellum and brainstem.**

Question 36

Posterior cerebral artery, | Arteries in the Brain

Answer 36

Posterior cerebral artery, provides blood to the **posterior portion of the cerebrum and brainstem.**

Question 37

thoracic aorta begins at

Answer 37

The thoracic aorta begins at the level of **vertebra T5** and continues through to the diaphragm at the level of **T12**, initially traveling within the mediastinum to the left of the vertebral column. The thoracic aorta gives rise to **visceral** branches and include the **bronchial arteries, pericardial arteries, esophageal arteries, and the mediastinal arteries, **each named after the tissues it supplies. The remaining thoracic aorta branches -- parietal branches or somatic branches. include the **intercostal and superior phrenic arteries**. Each intercostal artery provides blood to the **muscles of the thoracic cavity and vertebral column**. The superior phrenic artery provides blood to the **superior surface of the diaphragm.**

Question 38

abdominal aorta & branches pt 1

Answer 38

After crossing through the diaphragm at the **aortic hiatus**, the thoracic aorta is called the abdominal aorta. Remains to the left of the vertebral column and is embedded in adipose tissue behind the peritoneal cavity. It formally ends at approximately the level of **vertebra L4**, where it bifurcates to form the common iliac arteries. Branches of the abdominal aorta: A single celiac trunk (artery) - divides into **left gastric artery** - stomach and esophagus **Splenic artery** - spleen **Common hepatic artery** - hepatic artery proper to the liver, **right gastric artery** - stomach **cystic artery** - gallbladder, and several branches, duodenum & pancreas.

Question 39

abdominal aorta & branches pt 2

Answer 39

Gonadal artery - gonads, or reproductive organs An ovarian artery supplies blood to an ovary, uterine (Fallopian) tube, and the uterus, and is located within the suspensory ligament of the uterus. uterus: forms an anastomosis with the uterine artery that supplies blood to the uterus. Both the uterine arteries and vaginal arteries, which distribute blood to the vagina, are branches of the internal iliac artery. Testicular artery: testes, forming one component of the spermatic cord. The **four paired lumbar arteries** are the counterparts of the intercostal arteries and supply blood to the **lumbar region,** **the abdominal wall, and the spinal cord**. In some instances, a fifth pair of lumbar arteries emerges from the median sacral artery.