Cardiovascular System (blood vessels)

Constriction of these sphincters reduces the blood flow through their respective capillaries.

During exercise the skeletal muscles receive more blood flow.

Increase resistance:

- polycythemia - dehydration - angiogenesis - long vessels

Arteries:

- pulsatile - have systolic and diastolic pressures - have pulse pressure

Foramen Ovale

Fossa ovalis

When the sphincters are open, blood will fill the capillary bed.

Most of the redirection will occur in the arterioles.

Aldosterone

- produced in the adrenal cortex - decreases urine output

Typically fluid filters out the arterial end of a capillary.

Fluid will then osmotically reenter at the venous end.

Regression:

- inactive skeletal muscle - sedentary individuals - decreased amount of adipose tissue

Increased flow at rest:

- stomach - kidneys - intestines - gonads

Umbilical Vein

Ligamentum teres

Capillaries:

- 40 to 20 mm Hg - pressure determines net filtration - sufficient to drive exchanges at tissues

Vena Cavae

- Azygos vein - Renal - Lumbar veins - Left brachiocephalic - Hepatic

Alternative pathways:

- arterial anastamoses - portal systems - venous anastomoses

Angiotensin ll

- mainly formed in the lungs - decreases urine output - vasoconstrictor - stimulates thirst center - renin - ACE

Arteries

- marked by relatively thicker walls - profuse elastic fibers in the tunica media - marked by divergence - higher wall to lumen ratio - thicker layers of smooth muscle

Local blood flow:

- ml/min - altered directly by tissue damage - dependent upon the degree of vascularization of tissue - blood delivered to capillaries of a specific tissue

Systemic circuit

- more elastic tissues in arteries - longer vessels - higher overall blood pressure

Pulmonary circuit

- wider lumen in arteries - shorter vessels - lower overall blood pressure

Mean arterial pressure:

- average measure of blood pressure forces on arteries - diastolic pressure + 1/3 pulse pressure - show how well body tissues and organs purfused

Superior vena cava

- blood from head - blood from pelvis - blood from the lower limbs

Increased vascularization:

- brain - skeletal muscle - liver - heart

Veins

- marked by convergence - marked by comparatively larger circumference - contain valves - marked by comparatively larger lumen - sites for blood donation

Reabsorption:

- movement of fluid back into the blood - occurs at the venous end of a capillary

Filtration:

- movement of fluid out of the blood - occurs at the arterial end of a capillary

Capillary beds have precapillary sphincters at the junction of capillaries and the metarteriole.

After a meal the intestines receive priority and the skeletal muscles receive very little flow.

Decrease resistance:

- Anemia - short vessels - increased vessel diameter

Ductus Arteriosus

Ligamentum arteriosum

Coronary sinus

- blood from the myocardium

decreased vascularization:

- tendons - ligaments

Veins:

20-0 mm Hg

Blood flow to an organ will increase with vasodilation.

In these circuits, exchange takes place at the capillaries. These become larger vessels known as venules, which converge into even larger vessels known as veins before they return to the heart.

Ductus Venosus

Ligamentum venosum

The diastolic blood pressure is measured when the heart is relaxing and represents the lowest pressure exerted in the walls of the arteries during the heart cycle.

Subtracting the SBP from the DBP results in pulse pressure which is directly proportional to the overall strength of one's pulse.

The larger the radius of a vessel, the less the resistance

The cardiovascular system is really two separate circuits of blood flow. The systemic circuit delivers blood to all the cells of the body.

If an individual has a systolic blood pressure of 110 mm Hg and a diastolic pressure of 70 mm Hg:Pulse pressure for this person would be calculated as: 110 mm Hg - 70 mm Hg = 40 mm HgIf another individual has a systolic blood pressure of 117 mm Hg and a diastolic pressure of 87 mm Hg:Mean arterial pressure for this person would be calculated as: 87 mm Hg + 1/3 30 mm Hg = 97 mm Hg

abdominal cavity away from decreases diaphragm increases limbs thoracic cavity toward valves A relatively small blood pressure gradient is generally insufficient to move blood through the veins under given conditions, thus venous return must be facilitated by valves within veins and two "pumps." The skeletal muscle pump assists the movement of blood primarily within the limbs. As skeletal muscles contract, veins are squeezed to help propel the blood toward the heart. The respiratory pump assists the movement of blood within the thoracic cavity. The diaphragm contracts and flattens as we inspire. Intra-abdominal pressure increases and places pressure on the vessels within the abdominal cavity. Concomitantly, thoracic cavity volume increases and intrathoracic pressure decreases. Blood is propelled from the abdominopelvic cavity into the thoracic cavity.

In the simple pathway, one major artery delivers blood to the organ or body region and then branches into smaller and smaller arteries to become arterioles. Each arteriole feeds into a single capillary bed. A(n) venule drains blood from the capillaries and merges with other venules to form one major vein that drains blood from the organ or body region. Arteries that provide only one pathway through which blood can reach an organ are referred to as end arteries.

capillaries diffusion endothelial cells exocytosis high hormones low pinocytosis sinusoids vesicular transport Within systemic capillaries, substances such as oxygen, hormones, and nutrients move by diffusion from their relatively high concentration in the blood into the interstitial fluid and then into the tissue cells, where the concentration of these materials is low. Very small solutes and fluids may pass via the endothelial cells, while larger solutes, must pass through the fenestrations in capillaries or gaps in sinusoids. Endothelial cells may use pinocytosis to fuse fluid-filled vesicles with the plasma membrane. This type of vesicular transport can move contents either from the blood to the interstitial fluid or from the interstitial fluid into the blood. Solutes such as certain hormones and fatty acids are transported across the endothelial cells by this method.

Hydrostatic pressure:

- can promote filtration from a capillary - mainly pushes material out of a capillary - physical force exerted by a fluid on a structure

Increased flow with exercise:

- coronary vessels - skeletal muscle - skin

Total blood flow:

- dependent upon the heart and blood vessels - L/min - amount of blood throughout entire vascular over time - equivalent to cardiac output

Vasoconstrictors:

- endothelins - thromboxanes - prostaglandins - thromboxanes - incrased oxygen levels - decreased carbon dioxide levels - ADH - Aldosterone - angiotensin ll - norepinephrine bound to alpha-adrenergic receptors

Aorta

- esophageal - superior mesenteric - gonadal - left common corotid - renal

Vasodilators:

- histamine - bradykinin - decreased nutrient levels - histimines - nitric oxide - increased potassium levels - decreased nutrient levels - ANP - Epinephrine bout to beta-adrenergic receptors

Indicate whether the given condition would increase or decrease blood flow with all other factors being equal. Decrease flow:

- increasing vessel length - erythropoietin hypersecretion (or injection) - increasing red blood cell count

Indicate whether the given condition would increase or decrease blood flow with all other factors being equal. Increase flow:

- increasing vessel radius - aldosterone hypersecretion

Simple pathways:

- one major artery - a signle capillary bed - one venule - end arteries

Colloid Osmotic Pressure

- pull of water back into a tissue - typically promotes reabsorption

ADH

- released from the posterior pituitary gland - decreases urine output - vasoconstrictor - stimulates thirst center - vasopressin

ANP

- secreted by the atrium - vasodilator - increases urine output - decreases blood pressure

Angiogenesis:

- seen metabolically - liver - incrased adipose tissue - tumors - blockage of coronary vessels

Pulse pressure:

- the difference between systolic and diastolic pressures - a measure of the elasticity and recoil of arteries

Match the vessel with the tissue it supplies. 1. Bronchial artery 2. Right gastric artery 3. Hepatic artery 4. Suprarenal artery 5. Renal artery 6. Median sacral artery 7. External iliac artery 8. Inferior mesenteric artery

1. Lung tissue 2. Stomach 3. Liver 4. Adrenal gland 5. Kidney 6. Inferior vertebrae 7. Lower limb 8. Descending colon and rectum

Match the vessel with the tissue it drains. 1. Superior mesenteric vein 2. Gastro-omental vein 3. Cystic vein 4. Phrenic vein 5. Internal iliac vein 6. Femoral vein 7. Digital vein

1. Small intestine and most of the colon 2. Stomach 3. Gallbladder 4. Diaphragm 5. Pelvis and its viscera 6. Thigh 7. Toes

The smaller the radius of a vessel, the greater the resistance.

A major function of the cardiovascular system is to transport fluids. To fulfill this purpose, you have the following structures: The heart, provides pressure to pump the fluids into the large and elastic aorta, which will carry the blood to the body.

Blood flow is directly related to the pressure gradient. Thus, as the blood pressure gradient increases, total blood flow increases, and as the blood pressure gradient decreases, total blood flow lessens (assuming resistance remains the same). An increase in cardiac output will increase the pressure gradient, and a decrease in cardiac output will decrease the pressure gradient.

Angiotensin II and ADH (in high doses) increase peripheral resistance and blood pressure; and angiotensin II, aldosterone, and ADH decrease urine output to help maintain blood volume and blood pressure. ANP stimulates vasodilation, which decreases peripheral resistance and increases urine output, which decreases blood volume. The net effect is a decrease in blood pressure.

This fluid delivers materials to the cells and removes its waste.

This shift in fluid balance at the arterial end is referred to as hydrostatic pressure.

Systolic pressure is the pressure at which the first Korotkoff sound is heard.

At first, the artery is closed during diastole but as cuff pressure continues to decrease, the artery partially opens.

The highest pressure exerted on the arterial walls during the heart cycle is referred to as systolic blood pressure .

When one-third of pulse pressure is added to the diastolic pressure, a good estimate of mean arterial pressure is obtained.

Local blood flow is also regulated when vasoactive chemicals are released from damaged tissue, leukocytes, and platelets in response to tissue damage or as part of the body's defense. This process is referred to as inflammation. For example, histamine and bradykinin are released in response to a trauma, allergic reaction, infection, or even exercise. These chemicals may cause vasodilation by directly stimulating arterioles or indirectly by stimulating endothelial cells of the vessel to release nitric oxide. This is a very powerful, but short-lived, vasodilator. Other vasoactive substances, such as prostaglandins and thromboxanes, can cause vasoconstriction to help prevent blood loss through the damaged vessel.

Blood delivered to the capillaries of a specific tissue is local blood flow and is measured in milliliters per minute. The specific amount of blood entering capillaries per unit time per gram of tissue is called perfusion. The ultimate goal of the cardiovascular system is adequate perfusion of all tissues. Theamount of blood transported throughout the entire vasculature in a given period of time is total blood flow and is usually expressed in liters per minute. This type of blood flow equals cardiac output. If this increases, the amount of blood available to body tissues increases.

These molecules are responsible for the colloidal osmotic pressure, which draws water into the capillaries to help return fluids at the venular end of the capillary.

Blood flow redirects according to metabolic needs.

If HPb is 35 mm Hg, HPif is 0 mm Hg, COPb is 26 mm Hg, and COPif is 5 mm Hg at the arterial end of a capillary, calculate the net filtration pressure.(35 mm Hg − 0 mm Hg) − (26 mm Hg − 5 mm Hg) = 14 mm Hg

If HPb is 16 mm Hg, COPb is 26 mm Hg, COPif is 5 mm Hg, and HPif is 0 mm Hg at the venous end of a capillary, calculate the net filtration pressure.(16 mm Hg − 0 mm Hg) − (26 mm Hg − 5 mm Hg) = −5 mm Hg

The aorta is the first vessel blood enters upon exiting the heart.

Just prior to entering capillary beds, arterioles have become extremely thin and present only a few layers of smooth muscle.

Umbilical Arteries

Medial umbilical ligaments

The physical force exerted by a fluid on a structure is hydrostatic pressure. The main pressure is the blood hydrostatic pressure, which pushes materials out of the capillary.The other main force regulating filtration and reabsorption is osmotic pressure, which refers to the "pull" of water into an area by osmosis due to the higher relative concentration of solutes.

Net filtration pressure is the difference between the net hydrostatic pressure and the net colloid osmotic pressure. The net filtration pressure may be determined by the following equation:NFP = (HPb − HPif) − (COPb − COPif)This equation is a variation of Starling's law that shows that hydrostatic and osmotic forces work against one another to drive the filtration and reabsorption of materials across a capillary membrane.

Turbulent blood flow during systole produces pulse sounds, although the pitch of the sounds changes as the artery becomes more open.

Nonturbulent flow is reestablished and no sounds are heard.

Diastolic pressure is the pressure at which the sound disappears.

Relatively small amounts of blood are within the pulmonary circulation (about 18%) and the heart (about 12%). The largest percentage of blood is within the systemic circulation (about 70%), with the greatest amount (about 55%) within the body's systemic veins. The relatively large amount of blood within these vessels allows them to function as blood reservoirs. Blood may be shifted from these reservoirs in times of increased physical exertion with vasoconstriction. When less blood is needed at rest, it will be shifted back through by vasodilation.

Resistance also influences total blood flow. Resistance is defined as the amount of friction the blood experiences as it travels through the blood vessels. Blood flow is always opposed by resistance. Friction is due to the contact between blood and the blood vessel wall. The term peripheral resistance is typically used when discussing the resistance of blood in the blood vessels (as opposed to the resistance of blood in the heart). Several factors affect this friction, including blood viscosity, blood vessel length, and the size of the lumen of blood vessels (as indicated by vessel radius).

The volume of blood that leaves the capillary must be close to the volume that returns.

Although net filtration occurs at the arterial end of a capillary and net reabsorption at its venous end, not all of the fluid is reabsorbed. The capillary typically reabsorbs only about 85% of the fluid that has passed into the interstitial fluid. The lymphatic system is responsible for picking up 15% of this excess fluid and returning it to the blood.

The formation of new blood vessels in tissues that require them is called angiogenesis. This process helps provide adequate perfusion through long-term anatomic changes that occur over several weeks to months. This is seen in skeletal muscle in response to aerobic training; in adipose tissue, this process occurs when an individual gains weight in the form of fat deposits. Another situation where the formation of new blood vessels occurs in response to occlusion of coronary vessels, thus providing alternative routes to deliver blood to the heart wall.

After exiting the capillary, venules contain no muscle and are the first vessel that blood enters on its way back to the heart.

The medium veins contain abundant but irregularly spaced smooth muscle with frequent valves present in the tunica interna.

Blood flow to an organ will decrease with vasoconstriction.

The other circuit will involve the same structures you named but functions to deliver oxygen-poor and carbon dioxide-rich blood to the lungs and is the pulmonary circuit.

The large (elastic) arteries expand and recoil with every heartbeat due to a histologically dominant network of elastic tissue in the tunica media.

The site of gaseous exchange, or capillaries, are characterized by extremely thin walls with only endothelium and basal lamina, which better suits diffusional requirements.

As the radius of a vessel increases, the resistance decreases.

The vessels leaving the heart will branch and become smaller in diameter, these are the arteries.

As the resistance decreases, the blood flow increases.

The vessels will continue to branch and get smaller into arterioles. Eventually, they will become the capillaries, which are the sites of gas, nutrient, and waste exchange.

Blood pressure comes from the volume of blood and the contractions of the ventricles and is known as hydrostatic pressure.

This pressure forces fluid out of the capillaries especially at the arteriolar end. In the capillaries very large molecules, which are not lipid soluble, remain. An example of these would be plasma proteins.

When the cuff pressure is high enough to keep the brachial artery closed, no blood flows through it and no sound is heard.

When cuff pressure decreases and is no longer able to keep the artery closed, blood is pushed through, producing turbulent blood flow and a sound.

Blood is transported from the veins of the digestive organs into a hepatic portal system that drains the blood into the liver before this blood drains to the inferior vena cava. The hepatic portal system is needed because the veins of the GI tract absorb digested nutrients, and these must be processed by the liver. The liver also detoxifies any harmful agents absorbed by the gastrointestinal blood vessels. The hepatic portal system also receives products of erythrocyte destruction from the spleen, so that the liver can recycle some of these components.

Within the hepatic portal system, blood from the digestive organs drains into three main venous branches:1. The splenic vein, a horizontally positioned vein2. The inferior mesenteric vein, a vertically positioned vein3. The superior mesenteric vein, another vertically positioned vein on the right side of the bodyAll three of these drain into the hepatic portal vein that connects to the liver. Blood leaves the liver through hepatic veins that merge with the inferior vena cava.

During exercise, there is an increase in total blood flow due to a faster and stronger heartbeat and because blood is removed from the "reservoirs" of the veins to the active circulation. There is also a redistribution of blood. In contrast, less total blood flow is distributed to the abdominal organs, slowing digestive processes; less is transported to the kidneys, which decreases urine output to maintain blood volume and blood pressure.

anterior intercostal inferior epigastric internal thoracic lumbar median sacral musculophrenic superior epigastric The internal thoracic artery becomes the superior epigastric artery, which carries blood to the superior abdominal wall. The inferior epigastric artery, a branch of the external iliac artery, supplies the inferior abdominal wall. This artery anastomoses extensively with the superior epigastric artery. Five pairs of lumbar arteries branch from the descending abdominal aorta to supply the posterolateral abdominal wall. In addition, a single median sacral artery arises at the bifurcation of the aorta in the pelvic region to supply the sacrum and coccyx.