A&P 19: The Cardiovascular System - Blood Vessels Flashcards
Blood vessels
closed delivery system that begins and ends at the heart
Arteries
vessels that carry blood away from the heart
Veins
vessels that carry blood toward the heart
Lumen
innermost tunic of blood vessel walls
Tunica intima
innermost tunic of blood vessels
Endothelium
simple squamous epithelium that lines the lumen of all vessels; continuous with the endocardial lining of the heart; provides a flat, slick surface that minimizes friction as blood moves through the lumen
Tunica media
middle tunic; mostly circularly arranged smooth muscle cells and sheets of elastin
Vasoconstriction
lumen diameter decreases as the smooth muscle contracts
Vasodilation
lumen diameter increases as the smooth muscle relaxes
Tunica externa
outermost layer of a blood vessel wall; AKA tunica adventicia; composed largely of loosely woven collagen fibers that protect and reinforce the vessel, and anchor it to surrounding structures
Vasa vasorum
system of tiny blood vessels that nourish the more external tissues of the blood vessel wall
Elastic arteries
thick-walled arteries near the heart (aorta and its major branches); AKA conducting arteries
Muscular arteries
arteries that deliver blood to specific body organs; AKA distributing arteries; have the thickest tunica media of all vessels; have an elastic membrane on each face of the tunica media
Arterioles
smallest of the arteries
Capillaries
microscopic; smallest blood vessels; exceedingly thin walls consist of just a thin tunica intima
Pericytes
spider-shaped; smooth muscle-like cells that stabilize the capillary wall and help control capillary permeability
Continuous capillaries
most common capillaries; abundant in the skin and muscles; endothelial cells are joined by tight junctions
Intercellular clefts
gaps of unjoined membrane in tight junctions, just large enough to allow limited passage of fluids and small solutes
Fenestrated capillaries
endothelial cells in these capillaries are riddled with oval pores; found wherever active capillary absorption or filtrate formation occurs
Sinusoid capillaries (sinusoids)
highly modified, leaky capillaries found only in the liver, bone marrow, spleen, and adrenal medulla; have large, irregularly shaped lumens, usually fenestrated
Stellate macrophages
hepatic macrophages which remove and destroy bacteria in the endothelium of the sinusoid lining in the liver
Capillary beds
interweaving networks of capillaries
Microcirculation
flow of blood from an arteriole to a venule
Terminal arteriole
artery feeding the capillary beds
Metarteriole
vessel structurally intermediate between an arteriole and a capillary
Thoroughfare channel
continuous with a metarteriole; intermediate between a capillary and a venule
Postcapillary venule
the thoroughfare channel joins this vein that drains the capillary bed
True capillaries
10-100 per capillary bed, depending on the organ or tissue served
Precapillary sphincter
cuff of smooth muscle fibers; surrounds the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillary
Venules
capillaries unite to form these vessels, which range from 8 to 100 micrometers in diameter
Capitance vessels/blood reservoirs
veins are called these because they can hold up to 65% of the body’s blood supply at any time
Venous valves
formed from folds of the tunica intima, resemble the SL ___ of the heart in structure and function; prevents blood from flowing backwards
Varicose veins
veins that are tortuous and dilated because of incompetent (leaky) valves; more than 15% of adults suffer from these, usually in the lower limbs
Venous sinuses
highly specialized, flattened veins with extremely thin walls composed only of endothelium; supported by the tissues that surround them, rather than by any additional tunics
Vascular anastomoses
blood vessels form these special interconnections
Arterial anastomoses
arteries supplying the same territory often merge, forming these
Collateral channels
anastomoses provide these alternate pathways for blood to reach a given body region
Arteriovenous anastomoses
metarteriole-thoroughfare channel shunts of capillary beds that connect arterioles and venules are examples of the interconnection
Venous anastomoses
veins interconnect into these more frequently than arteries form their interconnections
Arteriosclerosis
the walls of arteries become thicker and stiffen
Atheroscerosis
most common form of arteriosclerosis; small patchy thickenings (atheromas) form that can intrude into the vessel lumen, making it easy for arterial spasms or a roaming blood clot to close the vessel completely
Fatty streak
accumulating foam cells form this first visible sign of an atheroma
Fibrous/atherosclerotic plaques
fibrous lesions with a core of dead and dying foam cells
Complicated plaque
cells at its center die, calcium is deposited, and collage fiber production by smooth muscle cells decline; now unstable and prone to rupture
Blood flow
volume of blood flowing through a vessel, an organ, or the entire circulation in a given period (mL/min); = to cardiac output
Blood pressure (BP)
force per unit area exerted on a vessel wall by the contained blood (mm Hg)
Resistance
opposition to flow; measure of the amount of friction blood encounters as it passes through the vessels
Peripheral resistance
most friction is encountered in the systemic circulation (well away from the heart)
Systolic pressure
pressure peak generated by ventricular contraction; averages 120mmHg in healthy adults
Diastolic pressure
when aortic pressure is at its lowest level (70-80mmHg in healthy adults)
Pulse pressure
difference between the systolic and diastolic pressures; felt as a throbbing pulsation in an artery during systole
Mean arterial pressure (MAP)
pressure that propels the blood to the tissues; diastolic + (pulse pressure/3)
Muscular pump
consists of skeletal muscle activity
Respiratory pump
moves blood up toward the heart as pressure changes in the ventral body cavity during breathing
Cardiovascular center
Cardioacceleratory/cardioinhibitory centers and the vasomotor center
Vasomotor center
controls the diameter of blood vessels
Vasomotor fibers
the vasomotor center transmits impulses at a fairly steady rate along these sympathetic efferents
Vasomotor tone
arterioles are almost always in this state of moderate constriction
Baroreceptors
stretch receptors that are activated when arterial blood pressure rises
Carotid sinus reflex
baroreceptors taking part in this reflex protect the blood supply to your brain
Aortic reflex
baroreceptors taking part in this reflex help maintain adequate blood pressure in the systemic circuit as a whole
Chemoreceptors
when CO2 levels rise, or pH falls, or oxygen content of the blood drops sharply, these receptors in the aortic arch and large arteries of the neck transmit impulses to the cardioacceleratory center, which then increases cardiac output, and to the vasomotor center, which causes reflex vasoconstriction
Epinephrine & norepinephrine
hormones that enhance the sympathetic response by increasing cardiac output and promoting generalized vasoconstriction
Angiotensin II
renin, acting as an enzyme, generates this, which stimulates intense vasoconstriction, promoting a rapid rise in systemic blood pressure
Atrial natriuretic peptide (ANP)
the atria of the heart produces this hormone, which leads to a reduction in blood volume and blood pressure
Antidiuretic hormone (ADH/vasopressin)
produced by the hypothalamus, stimulates the kidneys to conserve water; not important in short-term BP regulation; when BP falls to dangerously low levels, much more of this is released and helps restore arterial pressure by causing intense vasoconstriction
Renin-angiotensin-aldosterone mechanism
the kidneys can regulate blood pressure indirectly by this mechanism
Renin
when arterial blood pressure declines, certain cells in the kidneys release this enzyme into the blood
Angiotensinogen
renin enzympatically cleaves this plasma protein made by the liver, converting it to angiotensin I
Angiotensin converting enzyme (ACE)
converts angiotensin I to angiotensin II
Aldosterone
angiotensin II stimulates the adrenal cortex to secrete this hormone that enhances renal absorption of sodium (water follows)
Vital signs
pulse, blood pressure, respiratory rate, body temperature are collectively called this
Pulse
the alternating expansion and recoil of arteries during each cardiac cycle allow us to feel this pressure wave that is transmitted through the arterial tree
Pressure points
clinically important arterial pulse points; compressed to stop blood flow into distal tissues during hemorrhage
Auscultatory method
most often, systemic arterial blood pressure is measured indirectly in the brachial artery of the arm
Hypertension
chronically elevated blood pressure; characterized by a sustained increase in either systolic (above 140) or diastolic (above 90)
Primary (essential) hypertension
about 90% of hypertensive people have this type, for which no underlying cause has been identified
Secondary hypertension
accounts for 10% of hypertension cases; due to identifiable conditions (ex. obstructed renal arteries, kidney disease, endocrine disorders ~ hyperthyroidism, Cushing’s)
Hypotension
low blood pressure (below 90/60); reflects individual variations and is no cause for concern
Tissue perfusion
blood flow through body tissues
Autoregulation
automatic adjustment of blood flow to each tissue in proportion to the tissue’s requirements at any instant
Nitric oxide (NO)
powerful vasodilator which acts via a cyclic GMP second-messenger system
Endothelins
the endothelium releases potent vasoconstrictors, including this family of peptides, which are among the most potent vasoconstrictors known
Myogenic responses
fluctuations in systemic blood pressure would cause problems for individual organs were it not for these responses of vascular smooth muscle
Reactive hypermia
dramatically increased blood flow into a tissue that occurs after the blood supply to the area has been temporarily blocked
Active (exercise) hyperemia
the phenomenon that occurs when muscles become active & blood flow increases in direct proportion to their greater metabolic activity
Vasomotion
on/off opening and closing of precapillary sphincters in response to local autoregulatory controls
Diffusion
net movement occurring along a concentration gradient (from higher to lower)
Hydrostatic pressure (HP)
force exerted by the fluid pressing against a wall
Capillary hydrostatic pressure (HPc)
pressure exerted by blood on capillary walls
Interstitial fluid hydrostatic pressure (HPif)
blood pressure acting outside the capillaries and pushing fluid in
Colloid osmotic pressure (OP)
the force opposing hydrostatic pressure; created by large nondiffusible molecules, such as plasma proteins, that are unable to cross the capillary wall; pulling/sucking pressure
Capillary colloid osmotic pressure (OPc)
oncotic pressure; ~26 mmHg; the abundant plasma proteins in capillary blood (primarily albumin)
Interstitial Fluid colloid osmotic pressure (OPif)
0.1 - 5 mm Hg; substantially lower because interstitial fluid contains few proteins
Net filtration pressure (NFP)
considers all forces acting at the capillary bed
Circulatory shock
any condition in which blood vessels are inadequately filled and blood cannot circulate normally, so blood flow is inadequate to meet tissue needs
Hypovolemic shock
the most common form of circulatory shock, which results from large-scale blood or fluid loss, as might follow acute hemorrhage, severe vomiting/diarrhea, or extensive burns
Vascular shock
blood volume is normal, but circulation is poor as a result of extreme vasodilation
Cardiogenic shock
pump failure; occurs when the heart is so inefficient that it cannot sustain adequate circulation; usual cause is myocardial damage, as might follow numerous MI’s
Vascular system
body’s complex network of blood vessels
Pulmonary trunk
oxygen-poor, dark red blood enters the pulmonary circulation as it is pumped from the right ventricle into this vessel, which runs diagonally upward for about 8 cm then divides abruptly to form the R/L pulmonary arteries
Lobar arteries
in the lungs, the pulmonary arteries subdivide into these arteries (3 in the R lung, 2 in the L lung)
Pulmonary capillaries
dense network; surround and cling to the delicate air sacs
Pulmonary veins
the pulmonary capillary beds drain into venules, which join to form these 2 vessels, exiting from each lung
Aorta
largest artery in the body
Ascending aorta
1st portion of the aorta; runs posteriorly to the right of the pulmonary trunk
Right/Left Coronary Arteries
only branches of the ascending aorta; supply the myocardium
Aortic arch
deep to the sternum; begins and ends at the sternal angle (T4 level); 3 major branches
Brachiocephalic trunk
passes superiorly under the right sternoclavicular joint and branches into the right common carotid artery and the right subclavian artery, the left common carotid artery and the left subclavian artery
Descending aorta
part of the aorta that runs along the anterior spine
Thoracic aorta
part of the aorta that runs from T5 to T12
Abdominal aorta
part of the aorta inferior to the diaphragm
R/L Common Iliac arteries
supply the pelvis and lower limbs
Carotid sinus
contains baroreceptors that assist in reflex blood pressure control
Carotid bodies
chemoreceptors involved in controlling respiratory rate
External carotid arteries
supply most tissues of the head except for the brain and orbit
Superior thyroid artery
artery supplying thyroid and larynx
Lingual artery
artery supplying the tongue
Facial artery
artery supplying the skin and muscles of the anterior face
Occiptal artery
artery supply the posterior scalp
Superficial temporal artery
each external carotid artery terminates by splitting into this, which supplies the parotid salivary gland and most of the scalp, and a maxillary artery
Maxillary artery
artery supplying the upper and lower jaws and chewing muscles, the teeth, and the nasal cavity
Internal carotid arteries
arteries supplying the orbits and more than 80% of the cerebrum
Opthalmic arteries
arteries supplying the eyes, orbits, forehead and nose
Anterior cerebral artery
each of these arteries supplies the medial surface of the frontal and parietal lobes of the cerebral hemisphere on its side and also anastomoses with its partner on the opposite side via a short arterial shunt (anterior communicating artery)
Anterior communicating artery
short arterial shunt
Middle cerebral arteries
run in the lateral sulci of their respective cerebral hemispheres and supply the lateral parts of the temporal, parietal, and frontal lobes
Basilar artery
within the cranium, the R/L vertebral arteries join to form this artery, which ascends along the anterior aspect of the brain stem, giving off branches to the cerebellum, pons, and inner ear
Posterior cerebral arteries
at the pons-midbrain border, the basilar artery divides into a pair of these arteries, which supply the occipital lobes and the inferior parts of the temporal lobes
Posterior communicating arteries
arterial shunts that connect the posterior cerebral arteries to the middle cerebral arteries anteriorly
Cerebral arterial circle
the 2 posterior and single anterior communicating arteries complete the formation of this arterial anastomosis
Subclavian arteries
the upper limbs are supplied entirely by arteries arising from these arteries, which give off branches to the neck
Thoracoacromial artery
artery supplying the deltoid muscle and pectoral region
Lateral thoracic artery
artery supplying the lateral chest wall and breast
Subscapular artery
artery supplying the scapula, dorsal thorax wall, and part of the latissimus dorsi muscle
Anterior/posterior circumflex humeral arteries
paired arteries that wrap around the humeral neck and help supply the shoulder joint and the deltoid muscle
Deep artery of the arm
major branch of the brachial artery; serves the posterior triceps brachii muscle
Common interosseous artery
the ulnar artery gives off this short branch, which runs between the radius and ulna to serve the deep flexors and extensors of the forearm
Superficial/deep palmar arches
in the palm, branches of the radial and ulnar arteries anastomose to form these arches
Metacarpal/digital arteries
arteries supplying the fingers; arise from the palmar arches
Anterior intercostal arteries
supply the intercostal spaces anteriorly
Costocervical trunk
the superior 2 pairs of posterior intercostal arteries are derived from this trunk
Common hepatic artery
artery that gives off branches to the stomach, duodenum, and pancreas
Gastroduodenal artery
where this artery branches off, the common hepatic becomes the hepatic artery proper
Hepatic artery proper
artery which splits into R/L branches that serve the liver
Splenic artery
artery passing deep to the stomach, sends branches to the pancreas and stomach and terminates in branches to the spleen
Left gastric artery
artery supplying part of the stomach and the inferior esophagus
Right and left gastroepiploic arteries
branches of the gastroduodenal and splenic arteries; serve the greater curvature of the stomach
Right gastric artery
artery supplying the stomach’s lesser curvature
Intestinal arteries
arteries serving virtually all of the small intestine and most of the large intestine
Ileocolic and right colic arteries
arteries serving the ascending colon
Middle colic artery
artery serving part of the transverse colon
Middle suprarenal arteries
arteries flanking the origin of the superior mesenteric artery as they emerge from the abdominal aorta
Ovarian arteries
paired gonadal arteries in females
Testicular arteries
paired gonadal arteries in males
Left colic, sigmoidal, and superior rectal branches
final major branch of the abdominal aorta is unpaired and serves the distal part of the large intestine via these branches
Common iliac arteries
at the level of the sacroiliac joints, these arteries divide into these 2 major branches
Superior/inferior gluteal arteries
arteries serving the gluteal muscles
Obturator artery
artery serving the adductor muscles of the medial thigh
Internal pudendal artery
artery serving external genitalia and perineum
Deep artery of the thigh
AKA deep femoral artery; main supply to the thigh muscles (hamstrings, quads, and adductors)
Lateral/medial circumflex femoral arteries
proximal branches of the deep femoral artery; encircle the neck of the femur
Dorsalis pedis artery
the anterior tibial artery becomes this artery at the ankle; supplies the ankle and dorsum of the foot; clinically important pulse point to check for blood supply to the leg
Arcuate artery
artery that issues the dorsal metatarsal arteries to the metatarsus of the fott
Plantar arch
the superficial dorsalis pedis ends by penetrating into the sole where it forms the medial part of this arch
Fibular (peroneal) artery
supplies the lateral fibularis muscles of the leg
Lateral/medial plantar arteries
arteries serving the plantar surface of the foot
Plantar metatarsal arteries
with the digital arteries to the toes, arteries arising from the plantar arch
R/L brachiocephalic veins
union of these veins forms the superior vena cava
Internal jugular and subclavian veins
each brachiocephalic vein is formed by the joining of these veins
Common iliac veins
paired veins joined at L5 to form the distal end of the inferior vena cava
Dural venous sinuses
most veins of the brain drain into these interconnected series of enlarged chambers located between the dura mater layers
Superior/inferior sagittal sinuses
AKA falx cerebri; dips down between the cerebral hemispheres
Straight sinus
the inferior sagittal sinus drains into this sinus posteriorly
Transverse sinuses
sinuses running in shallow grooves on the internal surface of the occipital bone
Sigmoid sinuses
S-shaped sinuses that become the internal jugular veins as they leave the skull through the jugular foramen
Cavernous sinuses
sinuses flanking the sphenoid body; receive venous blood from the ophthalmic veins
Ophthalmic veins
veins that drain the nose and upper lip area
Facial/superficial temporal veins
deep veins of the face and neck
Superior vena cava
2 brachiocephalic veins unite to form this large vein
Brachiocephalic veins
blood draining from the mammary glands and the 1st 2-3 intercostal spaces enters these veins
Azygos system
the vast majority of thoracic tissues and the thorax wall are drained by this complex network of veins; provides a collateral circulation for draining the abdominal wall and other areas served by the inferior vena cava
Deep/superficial venous palmar arches
arches of the hand
Radial/ulnar veins
veins of the forearm
Brachial vein
radial/ulnar veins unite to form this vein of the arm
Axillary vein
as the brachial vein enters the axilla, it becomes this vein
Subclavian vein
the axillary vein becomes this vein at the level of the 1st rib
Cephalic vein
vein that bends around the radius as it travels superiorly and then continues up the lateral superficial aspect of the arm to the shoulder, where it runs in the groove between the deltoid and pectoralis muscles to join the axillary vein
Basilic vein
vein that courses along the posteromedial aspect of the forearm, crosses the elbow, then joins the brachial vein in the axilla, forming the axillary vein
Median cubital vein
at the anterior aspect of the elbow, this vein connects the basilica and cephalic veins
Median antebrachial vein
vein lying between the radial and ulnar veins in the forearm and terminates at the elbow by entering either the basilica or cephalic vein
Azygos vein
vein located against the right side of the vertebral column; originates in the abdomen
Right ascending lumbar vein
vein that drains most of the R abdominal cavity wall
Right posterior intercostal veins
veins that drain the chest muscles (except the 1st)
Hemiazygos vein
vein with its origin in the left ascending lumbar vein and the lower (9th - 11th) posterior intercostal veins
Inferior vena cava
vein that returns blood from the abdominopelvic viscera and abdominal walls to the heart
Hepatic portal system
veins connecting 3 capillary beds; carries nutrient-rich blood from the digestive organs to the liver where it can be “treated” before it reaches the rest of the body
Hepatic portal vein
vein beginning at the L2 level; short
Medial/lateral plantar veins
unite to form the posterior tibial vein
Fibular (peroneal) vein
the posterior tibial vein ascends deep into the calf muscle and receives this vein
Anterior tibial vein
superior continuation of the dorsalis pedis vein of the foot
Popliteal vein
vein that crosses the back of the knee
Femoral vein
as the popliteal vein emerges from the knee, it becomes this vein, which drains the deep structures of the thigh
External iliac vein
the femoral vein becomes this vein as it enters the pelvis
Internal iliac vein
the external iliac vein unites with this vein to form the common iliac vein
Great/small saphenous veins
veins that issue from the dorsal venous arch of the foot; 1 = the longest vein in the body
Blood islands
the endothelial lining of blood vessels is formed by mesodermal cells, which collect in these little masses throughout the microscopic embryo
