Anatomy and Physiology Openstax Chapter 20

arteriole or resistance vessel

very small artery that leads to a capillary

arteriovenous anastomosis

short vessel connecting an arteriole directly to a venule and bypassing the capillary beds

artery

blood vessel that conducts blood away from the heart; may be a conducting or distributing vessel

capacitance

ability of a vein to distend and store blood

capillary

smallest of blood vessels where physical exchange occurs between the blood and tissue cells surrounded by interstitial fluid

capacitance vessels

veins

capillary bed

network of 10-100 capillaries connecting arterioles to venules

continuous capillary

most common type of capillary, found in virtually all tissues except epithelia and cartilage; contains very small gaps in the endothelial lining that permit exchange

elastic artery or conducting artery

artery with abundant elastic fibers located closer to the heart, which maintains the pressure gradient and conducts blood to smaller branches

external elastic membrane

membrane composed of elastic fibers that separates the tunica media from the tunica externa; seen in larger arteries

fenestrated capillary

type of capillary with pores or fenestrations in the endothelium that allow for rapid passage of certain small materials

internal elastic membrane

membrane composed of elastic fibers that separates the tunica intima from the tunica media; seen in larger arteries

lumen

interior of a tubular structure such as a blood vessel or a portion of the alimentary canal through which blood, chyme, or other substances travel

metarteriole

short vessel arising from a terminal arteriole that branches to supply a capillary bed

microcirculation

blood flow through the capillaries

muscular artery or distributing artery

artery with abundant smooth muscle in the tunica media that branches to distribute blood to the arteriole network

nervi vasorum

small nerve fibers found in arteries and veins that trigger contraction of the smooth muscle in their walls

perfusion

distribution of blood into the capillaries so the tissues can be supplied

precapillary sphincters

circular rings of smooth muscle that surround the entrance to a capillary and regulate blood flow into that capillary

sinusoid capillary

rarest type of capillary, which has extremely large intercellular gaps in the basement membrane in addition to clefts and fenestrations; found in areas such as the bone marrow and liver where passage of large molecules occurs

thoroughfare channel

continuation of the metarteriole that enables blood to bypass a capillary bed and flow directly into a venule, creating a vascular shunt

tunica externa or tunica adventitia

outermost layer or tunic of a vessel (except capillaries)

tunica intima or tunica interna

innermost lining or tunic of a vessel

tunica media

middle layer or tunic of a vessel (except capillaries)

vasa vasorum

small blood vessels located within the walls or tunics of larger vessels that supply nourishment to and remove wastes from the cells of the vessels

vascular shunt

continuation of the metarteriole and thoroughfare channel that allows blood to bypass the capillary beds to flow directly from the arterial to the venous circulation

vasoconstriction

constriction of the smooth muscle of a blood vessel, resulting in a decreased vascular diameter

vasodilation

relaxation of the smooth muscle in the wall of a blood vessel, resulting in an increased vascular diameter

vasomotion

irregular, pulsating flow of blood through capillaries and related structures

vein

blood vessel that conducts blood toward the heart

venous reserve

volume of blood contained within systemic veins in the integument, bone marrow, and liver that can be returned to the heart for circulation, if needed

venule

small vessel leading from the capillaries to veins

blood flow

movement of blood through a vessel, tissue, or organ that is usually expressed in terms of volume per unit of time

blood pressure

force exerted by the blood against the wall of a vessel or heart chamber; can be described with the more generic term hydrostatic pressure

compliance

degree to which a blood vessel can stretch as opposed to being rigid

diastolic pressure

lower number recorded when measuring arterial blood pressure; represents the minimal value corresponding to the pressure that remains during ventricular relaxation

hypervolemia

abnormally high levels of fluid and blood within the body

hypovolemia

abnormally low levels of fluid and blood within the body

hypoxia

lack of oxygen supply to the tissues

ischemia

insufficient blood flow to the tissues

Korotkoff sounds

noises created by turbulent blood flow through the vessels

mean arterial pressure (MAP)

average driving force of blood to the tissues; approximated by taking diastolic pressure and adding 1/3 of pulse pressure

pulse

alternating expansion and recoil of an artery as blood moves through the vessel; an indicator of heart rate

pulse pressure

difference between the systolic and diastolic pressures

resistance

any condition or parameter that slows or counteracts the flow of blood

respiratory pump

increase in the volume of the thorax during inhalation that decreases air pressure, enabling venous blood to flow into the thoracic region, then exhalation increases pressure, moving blood into the atria

skeletal muscle pump

effect on increasing blood pressure within veins by compression of the vessel caused by the contraction of nearby skeletal muscle

sphygmomanometer

blood pressure cuff attached to a device that measures blood pressure

systolic pressure

larger number recorded when measuring arterial blood pressure; represents the maximum value following ventricular contraction

vascular tone

contractile state of smooth muscle in a blood vessel

blood colloidal osmotic pressure (BCOP)

pressure exerted by colloids suspended in blood within a vessel; a primary determinant is the presence of plasma proteins

blood hydrostatic pressure

force blood exerts against the walls of a blood vessel or heart chamber

capillary hydrostatic pressure (CHP)

force blood exerts against a capillary

filtration

in the cardiovascular system, the movement of material from a capillary into the interstitial fluid, moving from an area of higher pressure to lower pressure

interstitial fluid colloidal osmotic pressure (IFCOP)

pressure exerted by the colloids within the interstitial fluid

interstitial fluid hydrostatic pressure (IFHP)

force exerted by the fluid in the tissue spaces

net filtration pressure (NFP)

force driving fluid out of the capillary and into the tissue spaces; equal to the difference of the capillary hydrostatic pressure and the blood colloidal osmotic pressure

reabsorption

in the cardiovascular system, the movement of material from the interstitial fluid into the capillaries

anaphylactic shock

type of shock that follows a severe allergic reaction and results from massive vasodilation

aortic sinuses

small pockets in the ascending aorta near the aortic valve that are the locations of the baroreceptors (stretch receptors) and chemoreceptors that trigger a reflex that aids in the regulation of vascular homeostasis

atrial reflex

mechanism for maintaining vascular homeostasis involving atrial baroreceptors: if blood is returning to the right atrium more rapidly than it is being ejected from the left ventricle, the atrial receptors will stimulate the cardiovascular centers to increase sympathetic firing and increase cardiac output until the situation is reversed; the opposite is also true

cardiogenic shock

type of shock that results from the inability of the heart to maintain cardiac output

carotid sinuses

small pockets near the base of the internal carotid arteries that are the locations of the baroreceptors and chemoreceptors that trigger a reflex that aids in the regulation of vascular homeostasis

circulatory shock

also simply called shock; a life-threatening medical condition in which the circulatory system is unable to supply enough blood flow to provide adequate oxygen and other nutrients to the tissues to maintain cellular metabolism

hypertension

chronic and persistent blood pressure measurements of 140/90 mm Hg or above

hypovolemic shock

type of circulatory shock caused by excessive loss of blood volume due to hemorrhage or possibly dehydration

myogenic response

constriction or dilation in the walls of arterioles in response to pressures related to blood flow; reduces high blood flow or increases low blood flow to help maintain consistent flow to the capillary network

neurogenic shock

type of shock that occurs with cranial or high spinal injuries that damage the cardiovascular centers in the medulla oblongata or the nervous fibers originating from this region

obstructive shock

type of shock that occurs when a significant portion of the vascular system is blocked

sepsis or septicemia

organismal-level inflammatory response to a massive infection

septic shock or blood poisoning

type of shock that follows a massive infection resulting in organism-wide inflammation

vascular shock

type of shock that occurs when arterioles lose their normal muscular tone and dilate dramatically

abdominal aorta

portion of the aorta inferior to the aortic hiatus and superior to the common iliac arteries

adrenal artery

branch of the abdominal aorta; supplies blood to the adrenal (suprarenal) glands

adrenal vein

drains the adrenal or suprarenal glands that are immediately superior to the kidneys; the right adrenal vein enters the inferior vena cava directly and the left adrenal vein enters the left renal vein

anterior cerebral artery

arises from the internal carotid artery; supplies the frontal lobe of the cerebrum

anterior communicating artery

anastomosis of the right and left internal carotid arteries; supplies blood to the brain

anterior tibial artery

branches from the popliteal artery; supplies blood to the anterior tibial region; becomes the dorsalis pedis artery

anterior tibial vein

forms from the dorsal venous arch; drains the area near the tibialis anterior muscle and leads to the popliteal vein

aorta

largest artery in the body, originating from the left ventricle and descending to the abdominal region where it bifurcates into the common iliac arteries at the level of the fourth lumbar vertebra; arteries originating from the aorta distribute blood to virtually all tissues of the body

aortic arch

arc that connects the ascending aorta to the descending aorta; ends at the intervertebral disk between the fourth and fifth thoracic vertebrae

aortic hiatus

opening in the diaphragm that allows passage of the thoracic aorta into the abdominal region where it becomes the abdominal aorta

arterial circle or circle of Willis

anastomosis located at the base of the brain that ensures continual blood supply; formed from branches of the internal carotid and vertebral arteries; supplies blood to the brain

ascending aorta

initial portion of the aorta, rising from the left ventricle for a distance of approximately 5 cm

axillary artery

continuation of the subclavian artery as it penetrates the body wall and enters the axillary region; supplies blood to the region near the head of the humerus (humeral circumflex arteries); the majority of the vessel continues into the brachium and becomes the brachial artery

axillary vein

major vein in the axillary region; drains the upper limb and becomes the subclavian vein

azygos vein

originates in the lumbar region and passes through the diaphragm into the thoracic cavity on the right side of the vertebral column; drains blood from the intercostal veins, esophageal veins, bronchial veins, and other veins draining the mediastinal region; leads to the superior vena cava

basilar artery

superficial vein of the arm that arises from the palmar venous arches, intersects with the median cubital vein, parallels the ulnar vein, and continues into the upper arm; along with the brachial vein, it leads to the axillary vein

basilic vein

superficial vein of the arm that arises from the palmar venous arches, intersects with the median cubital vein, parallels the ulnar vein, and continues into the upper arm; along with the brachial vein, it leads to the axillary vein

brachial artery

continuation of the axillary artery in the brachium; supplies blood to much of the brachial region; gives off several smaller branches that provide blood to the posterior surface of the arm in the region of the elbow; bifurcates into the radial and ulnar arteries at the coronoid fossa

brachial vein

deeper vein of the arm that forms from the radial and ulnar veins in the lower arm; leads to the axillary vein

brachiocephalic artery

single vessel located on the right side of the body; the first vessel branching from the aortic arch; gives rise to the right subclavian artery and the right common carotid artery; supplies blood to the head, neck, upper limb, and wall of the thoracic region

brachiocephalic vein

deeper vein of the arm that forms from the radial and ulnar veins in the lower arm; leads to the axillary vein

bronchial artery

systemic branch from the aorta that provides oxygenated blood to the lungs in addition to the pulmonary circuit

cavernous sinus

enlarged vein that receives blood from most of the other cerebral veins and the eye socket, and leads to the petrosal sinus

celiac trunk or celiac artery

major branch of the abdominal aorta; gives rise to the left gastric artery, the splenic artery, and the common hepatic artery that forms the hepatic artery to the liver, the right gastric artery to the stomach, and the cystic artery to the gall bladder

cephalic vein

superficial vessel in the upper arm; leads to the axillary vein

cerebrovascular accident (CVA)

blockage of blood flow to the brain; also called a stroke

common carotid artery

right common carotid artery arises from the brachiocephalic artery, and the left common carotid arises from the aortic arch; gives rise to the external and internal carotid arteries; supplies the respective sides of the head and neck

common hepatic artery

branch of the celiac trunk that forms the hepatic artery, the right gastric artery, and the cystic artery