Chapter 21: CVS Blood Vessles And Hemodynamics Flashcards
(147 cards)
1
Q
Arteries
A
Carry blood away from the heart to other organs. Do not contain values, pulse.
When damaged the smooth muscle layer contracts producing a vascular spasm
Large elastic arteries leave the heart, divide into medium muscular arteries that branch out into various regions of the body.
Have High Compliance: means walls stretch easily or expand without tearing in response to small increase in pressure.
2
Q
Arterioles
A
Medium sized arteries that divide into still smaller arteries.
Pulse in BP.
When damaged the smooth muscle layer contracts producing a vascular spasm.
Also known as resistance vessels as plays a key role in regulating blood flow into capillaries.
3
Q
Capillaries
A
Arterioles that enter tissue that branch into numerous tiny vessels. Does not pulse.
Smallest blood vessel. Diameter: 5-10 um.
Also referred as exchange vessels.
Forms the U turns that connect the arterial outflow to the venous return.
Function: is the exchange of substance between the blood and interstitial fluid.
4
Q
Venues
A
Have thin walls that do not readily maintain their shape.
Drain the capillary blood and begin the return flow of blood back towards the heart.
Groups of capillaries within a tissue that reunite to form small veins.
Serve as a large reservoir for which blood can be quickly diverted to other vessels as needed.
5
Q
Veins
A
Larger blood vessels that are formed when venues merge. Contains values.
Convey blood from the tissues back to the heart.
Eventually drain into superior and inferior vena cava and coronary sinus.
Serve as a large reservoir for which blood can be quickly diverted to other vessels as needed.
Show structural changes as they increase in size from small to medium to large.
6
Q
Tunica Interna
A
(Intima)
Garment or coat. Forms the inner lining of a blood vessel.
In direct contact with the blood as it flows through the lumen.
Has multiple layers - contributes to thickness of vessel wall.
Innermost layer: Endothelium
Second component: basement membrane
Outermost layer: internal elastic lamina
7
Q
Lumen
A
Interior opening of a vessel.
8
Q
Endothelium Of Tunica Interna
A
Innermost layer of vessel wall.
Continuous with the endocardia’s lining of the heart.
9
Q
Basement Membrane of Tunica Interna
A
Second component.
Deep to the endothelium
Provides a physical support base for the epithelial layer.
Framework of collagen fibers gives tensile strength.
Resilience for stretching and recoil.
10
Q
Internal Elastic Lamina of Tunica Interna
A
Outer most layer.
Forms boundary between the tunica Interna and tunica media.
Thin sheet of elastic fibers with window like openings (looks like Swiss cheese).
Openings facilitate diffusion of materials through tunica Interna to the thicker tunica media.
11
Q
Basic Structure of a Blood Vessel
A
Consists of 3 layers or tunica.
Inner to outermost layer:
1.Tunica Interna (intima)
2. tunica media
3. tunica externa (adventitia).
12
Q
Tunica Media
A
Middle later of blood vessel.
Thick layer of muscular, connective tissue layer comprising of smooth muscle cells and elastic fibers.
Responsible for vasoconstriction.
Displays the greatest variation amount.
Contains external elastic lamina: network of elastic fibers, separates the tunica media from the tunica externals.
13
Q
Vasoconstriction
A
Squeezing of a vessel wall and narrowing the lumen causing decrease in diameter of the lumen.
14
Q
Vasodilation
A
Smooth muscles relax causing increase in lumen diameter when sympathetic stimulation decrease, presence of chemicals (nitric oxide, H+, lactic acid) or in response to blood pressure,
15
Q
Vascular Spasm
A
Happens when a small artery or arteriole is damaged.
Spasm helps to limit loss of blood through the injured vessel.
16
Q
Tunica Externa
A
Outer most covering of a blood vessel.
Primarily consists of elastic and collagen fibers.
Contains: numerous nerves, tiny vessels that supply the tissue of the vessel wall.
Anchors the vessel to surrounding tissue.
17
Q
Vasa Vasorum
A
Small vessels that supply blood to the tissues of the vessel.
Seen on large vessel such as the aorta.
18
Q
Elastic Arteries
A
Largest arteries in the body but thin vessel walls
Function as pressure reservoirs
When blood is ejected from the heart into these arteries, the walls stretch to accommodate the surge of blood to help propel blood onward while the ventricles are relaxing.
They recoil and convert stored potential energy in the vessel into kinetic blood which propels blood onward why the ventricle relax.
Also known as conducting arteries as they conduct blood from the heart to medium sized, more muscular arteries.
Ranges from:
1. garden hose sized aorta and pulmonary trunk
2. Finger sized branches of the aorta.
19
Q
Elastic Lamellae of Elastic Ateries
A
Characterized by :
-Well defined internal and external Lamellae
-Thick tunica media that is dominated by elastic fibers.
Includes: 2 major trunks that exit the heart.
20
Q
Muscular Arteries
A
Medium sized arteries.
Also known as distributing arteries as continues to branch and distribute blood to the various organs.
Due to the tunica media containing more smooth muscle and fewer elastic fibers than elastic arteries.
Smooth muscle (3/4 of total mass) make the walls thick.
These arteries vascoconstric and vascodilates the artery to control blood flow.
21
Q
Vascular Tone
A
The ability of the muscle to contract and maintain a state of partial contraction.
22
Q
Anastomosis
A
The union of the branches of 2 or more arteries supplying the same body region.
Knowns as collateral circulation between arteries, provides alternate routes for blood to reach a tissue or organ.
Can occur between: veins and between arterioles and venues.
23
Q
Collateral Circulation
A
The alternate route of blood flow to a body part through an anastomosis.
24
Q
End Arteries
A
Arteries that do not anastomose.
Obstruction of an end artery interrupts the blood supply to a whole segment of an organ causing necrosis of that segment.
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Metarteriole
The terminal end of the arteriole.
Tapers towards the capillary junction.
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Precapillary Sphincter
Monitors blood flow into and through the capillary.
Formed by the distal most muscle cell at the metarteriole capillaries junction.
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Resistance
The opposition to blood flow due to friction between blood and the walls of blood vessels.
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Postcapillary Venule
Venue that receives blood from a capillary.
Smallest venules, 10-50 um.
Have loosely organized intercellular junctions so are very porous.
Function: significant sites of exchange of nutrients, waste and WBC emigration.
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Micro Circulation
The flow of blood from a metareriole through capillaries and into postcapillary venue.
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Capillary Bed
Function of capillaries throughout the body.
A network of 10-100 capillaries that arises from a single metarteriole.
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Vasomotion
Intermittent contraction and relaxation of blood flow
may occur 5-10 times per minute where blood flow intermittently through capillaries due to alternating contraction and relaxation of smooth muscle of metarteriole and precapillary sphincters.
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Thoroughfare Channel
Resembles a capillary but the distal end of the vessel has no smooth muscle.
This channel provides a direct route for blood from an arteriole to a venule thus bypassing capillaries.
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3 Types of Capillaries found in the Body
1. Continuous capillaries
2. Fenestrated capillaries
3. Sinusoids
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Continuous Capillaries
Form a continuous tube that is interrupted only by intercellular clefts in plasma membranes of endothelial cells
Found in: CNS, lungs, muscle tissue (skeletal, smooth) and skin.
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Fenestrated Capillaries
Capillaries have many small pores (fenestration) in the plasma membrane of the endothelia cells.
Range from 70-100nm in diameter.
Found in: kidneys, villi of small intestine, choroid plexuses, ciliary process of eyes and most endocrine glands.
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Sinusoids
Wider and more winding than other capillaries.
Have unusually large fenestrations (pores) in the endothelial cells
Contains incomplete or absent basement membrane.
Large intercellular clefts that allow proteins and blood cells to pass from a tissue into bloodstream.
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Blood Movement Sequence
Passes from heart through arteries, arterioles, capillaries, venues and veins and then back to the heart.
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Portal System
Circulation of blood where blood passes from one capillary network into another through a vein known as portal vein.
Name gives location of capillary. (Ie) hepatic portal circulation or hypophyseal portal system.
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Muscular Venules
When postcapillary venules move away from capillaries and acquire 1 or 2 layers of circularly arranged smooth muscle.
Have thicker walls across.
Prevents exchanges with the interstitial fluid.
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Veins vs Arteries
Veins structural changes are not as distant as in arteries.
Veins have thin walls
Arteries have thick walls.
Veins and arteries have the same 3 layers but thickness is different.
Veins lack internal or external elastic laminae that is found in arteries.
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Valves
Found in many veins, esp in the limbs.
Thin folds of tunica Interna that form flap like cusps. Cusps project into the lumen point towards the heart.
Aid in venous return by prevent the back flow of blood.
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Vascular (venous) Sinus
Is a vein with a thin endothelial wall that has no smooth muscle to alter its diameter.
Surrounding dense CT replaces the tunica media and tunica externa in providing support.
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Anastomotic Veins
Where double sets of veins escort arteries and connect with one another via a venous channel.
The asastomotic veins from the accompany artery to form a ladder like rung between the paired veins.
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Superficial Veins
Course through the SQ layer unaccompanied by parallel arteries.
Greatest number of veins occurs in the limbs.
Form small connections with deep veins that allows for communication between the deep and superficial flow of blood.
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Deep Veins
Travel between the skeletal muscles.
Accompany arteries of the same name in limbs. Usually travel alongside arteries and bear the same name.
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Blood Volume at Rest
Largest portion of blood volume at rest : about 64 %
Is in systemic veins and venules
Systemic arteries and arterioles: 13%
Pulmonary blood vessels: 9%
Systemic capillaries: 7%
Heat: 7%
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Blood Reservoirs
Blood that is diverted quickly if the need arises
Systemic veins and venules function at blood reservoirs due to the large percentage of blood volume: 64%
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Capillary Exchange
The movement of substance between blood and interstitial fluid.
Happens by 3 basic mechanism:
1. Diffusion: most important method. O2, co2, glucose, amino acids and hormones. Diffuses down their concentration gradient .
2. Transcytosis: sunstance in blood plasma become enclosed within tiny vesicles by Endocytosis.
3. Bulk flow: large ions, molecules or particulates in a fluid move together in the same direction.
This is the entire mission of cardiovascular system: to keep blood flowing though capillaries .
49
Diffusion
Most important method of capillary exchange is simple diffusion.
Substances that move through simple diffusion: O2, CO2, glucose, amino acids and hormones.
These substance diffuse down their concentration gradients into interstitial fluid then into body cells.
CO2 and other wasters are present in high concentration in interstitial fluid so they diffuse into blood.
Important for: solute exchange
50
Diffusion by Intercellular Clefts, through Endothelial Cell or
Fenestrations.
Water soluble substances, glucose or amino acid diffuse across capillary walls through intercellular clefts or fenestrations.
Lipid Soluble substance, O2, CO2, steroid hormones
Diffuse across capillary walls directly through lipid belayer of endothelial cells in PM.
51
Transcytosis
Used by a small quantity of materials to cross capillary walls.
Substance in blood plasma becomes enclosed within tiny pinocytic vessels that first enter endothelial cells by Endocytosis then move across the cell and exit on the other side by exocytosis.
Used by: large, lipid insoluble molecules that cant cross any other way.
52
Bulk Flow
Passive process in which large numbers of ions, molecules, or particles in a fluid move together in the same direction.
Move at rates greater than diffusion.
Occurs at area of higher pressure to an area of lower pressure and continues as long as a pressure difference exists.
Important for: regulation of relative volumes of blood and interstitial fluid.
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Filtration
Pressure driven movement of fluid and solutes from blood capillaries into interstitial fluid.
Two main pressure: blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure.
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Reabsorption
Pressure driven movement from interstitial fluid into blood capillaries.
Main pressure: blood colloid osmotic pressure
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Net Filtration Pressure (NFP)
Balance of pressures: BHP, interstitial fluid osmotic pressure and blood colloid osmotic pressure.
Determines whether the volume of blood and interstitial fluid remains steady or changes.
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Starling’s Law of the Capillaries
The near equilibrium of the volume of fluid and solutes reabsorbed normally is almost as large as the volume filtered.
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Blood Hydrostatic Pressure (BHP)
Pumping action of the heart.
Pushed fluid out of capillaries into interstitial fluid.
Average: 35 mmHg
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Interstitial Fluid Hydrostatic Pressure (IFHP)
Opposing pressure of BHP.
Pushes fluid from interstitial spaces back into capillaries.
Average: This is close to zero: 0 mmHg
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Blood Colloid Osmotic Pressure (BCOP)
Is the largest force that causes colloidal suspension of large proteins in plasma.
A force for pulling fluid from the interstitial spaces back into capillaries
Average: 26 mmHg
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Interstitial Fluid Osmotic Pressure (IFOP)
Opposing BCOP.
Pulls fluid out of capillaries into interstitial fluid.
Average: 0.1-5 mmHg very small due to tiny amounts of proteins present in interstitial fluid.
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Net Inward Pressure
Negative value -9mmHg at the venous end of a capillary.
Represents fluid that moves into the capillary from tissues spaces (reabsorption).
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Hemodynamics
Refers to the flow involved in circulating blood throughout the body.
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Blood Flow
Is the volume of blood that flows through any tissues in a given time period (in mL/min).
Total blood flow: Cardiac output (CO), the volume of blood that circulates through systemic blood vessels each minute.
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Cardiac Output Distribution
Depends on 2 factors:
1: Stroke Volume (pressure difference): drives the blood flow through a tissue
2: Heart Rate (resistance): blood flow in specific blood vessels.
Blood flows from regions of higher pressure to regions of lower pressure; the greater the pressure difference, the greater the blood flow.
But the higher the resistance, the smaller the blood flow.
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Blood Pressure (BP)
Generated by contraction of the ventricles, the hydrostatic pressure excreted by blood on the walls of a blood vessel.
BP is highest in the aorta.
Systolic BP: highest pressure attained in arteries durning systole.
Diastolic BP: lowest arterial pressure during diastole.
Normal BP: 120/80
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Mean Arterial Pressure (MAP)
The average BP in arteries is roughly 1/3 of the way between the diastolic and systolic pressures.
Estimated as follows:
MAP= diastolic BP + 1/3 (systolic BP - diastolic BP).
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Vascular Resistance
Is the opposition to blood flow due to friction between blood and walls of blood vessels.
Depends on:
1: size of vessel lumen.
2: blood viscosity
3: total blood vessel length
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VR: Size of the Lumen
The smaller the lumen of a blood vessel, the greater the resistance to blood flow.
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Blood Viscosity (BV)
Viscosity of blood depends on the ratio of red blood cells to plasma (fluid) volume and to a smaller extent on the concentration of proteins in plasma.
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VR: Total Blood Vessel Length
Resistance to blood flow through a vessel is directly proportional to the length of the blood vessel.
The longer a vessel the greater the resistance.
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Systemic Vascular Resistance (SVR)
Also known as: total peripheral resistance (TPR)
Refers to all of the vascular resistances offered by systemic blood vessels.
Diameters of arteries and veins are large so their resistance is very small because most of the blood does not come into physical contact with the walls of the blood vessel.
Smallest : arterioles, capillaries and venules contribute to the most resistance.
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Venous Return
The volume of blood flowing back to the heart through the systemic veins occurs due to the pressure generate by contractions of the heart left ventricle.
Aided by:
1. Skeletal muscle pump
2. Respiratory pump
3. Vasoconstriction
4. Valves
Pressure difference: venules 16 mmHg to right ventricle (0 mmHg) is normally sufficient to cause venous return.
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Skeletal Muscle Pump
Mechanism other than heart that pumps blood from lower body to the heart.
1- while at rest, the proximal and distal valve in part of the leg are open and blood flows towards the heart.
2-contraction of leg muscle compresses the veins. Compression pushes blood through proximal valve called milking. At the same time, distal valve in uncompressed segment closes as blood pushes against it.
3-just after muscle relation, pressure falls in previously compressed section of vein causing proximal valve to close. Distal valve opens then vein fill with blood. Proximal valve then reopens.
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Respiratory Pump
Based on alternating compression and decompression of veins.
Durning inhalation, diaphragm moves downward causing decreased pressure in thoracic cavity and increase pressure in abdominal cavity.
Abdominal veins are compressed, blood moves from abd veins into the decompressed thoracic veins and then into the right atrium.
When pressure reverses during exhalation, valves in the veins prevent back flow of blood from thoracic veins to the abd veins.
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Circulation Time
The time required for a drop of blood to pass from the right atrium through the pulmonary circulation back to the left atrium through the systemic circulation down to the foot and back again to the right atrium.
Circulation time: about 1 min.
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Cardiovascular Center (CV)
In the medulla Oblongata helps regulate heart rate and stroke volume.
Also control: neural, hormonal and local negative feedbacks systems that regulate blood pressure and blood flow to specific tissues.
Receives:
-input from both high brain regions and from sensory receptors
-from medulla, limic system, hypothalamus
-output from cardiovascular center flows along sympathetic and parasympathetic neurons of the ANS.
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Proprioceptors
Monitors movements of joints and muscles and provides input to the cardiovascular system center during physical activity.
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Chemoreceptors
Sensory receptors that monitor the chemical composition of blood.
Are located close to baroreceptors of the carotid sinus and arch of the aorta in small structures called carotid bodies and aortic bodies.
Detect changes in blood level of O2, CO2 and H.
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Vasomotor Nerves
Conveys impulses from cardiovascular centers to smooth muscles in blood vessels.
Are sympathetic neurons exit the spinal cord through all thoracic and the first 1 or 2 lumbar spinal nerves and then pass into the sympathetic trunk ganglia.
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Vasomotor Tone
Moderate state of tonic contraction or vasoconstriction.
Sets the resting level of systemic vascular resistance.
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Baroreceptors
Pressure sensitive sensory receptors.
Located in: aorta, internal carotid arteries and other large arteries in the neck and chest.
Send impulses to the cardiovascular center to help regulate BP.
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Baroreceptor Reflexes
Two most important types:
Carotid sinus reflex- found in wall of carotid sinus, help regulate BP in the brain
Aortic reflex-found in wall of ascending aorta, arch of aorta, regulates systemic BP.
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Vagus Nerves (X)
-Nerves impulses from aortic baroreceptors reach the cardiovascular center via sensory axons of this nerve.
-Parasympathetic stimulation is conveyed along this nerve, decreased HR.
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Acidosis
An increase in H concentration.
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Hypercapnia
Excess CO2
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Hormonal Regulation of BP
1. Renin-angiotensin-aldosterone (RAA) system
2. Epinephrine and norepinephrine
3. Antidiuretic hormone (ADH)
4. Atrial natriuretic peptide (ANP)
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Hormonal Regulation of BP:
Renin-angiotensin-aldosterone (RAA) System
When BP falls or blood flow to kidneys decrease, juxtaglomerular cell in kidneys secrete RENIN into blood stream.
RENIN and Angiotensin converting enzyme (ACE) act on their substrates to produce the active hormone Angiotensin II.
Raises BP by (1) potential vasoconstrictor (2) stimulates secretion of aldosterone to increase reabsorption of NA+ and water by kidneys.
Water reabsorption increases blood volume in turn increase BP.
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Hormonal Regulation of BP:
Epinephrine and Norepinephrine
These hormones are released from sympathetic stimulation from the adrenal medulla.
Increase CO by increasing the rate and force of heart contractions.
Cause vasoconstriction of arterioles and veins in the skin and abd organs.
Cause vasodilation of arteriole in cardiac and skeletal muscle which help increase blood flow to muscle during exercise.
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Hormonal Regulation of BP:
Antidiuretic Hormone
Also known as vasopressin
Is produced by the hypothalamus
Released from the posterior pituitary in response to dehydration or decreased blood volume.
Causes vasoconstriction which increases BP
Promotes water from the lumen of kidney tubules into the blood stream results in increased in blood volume and decrease in urine output.
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Hormonal Regulation of BP:
Atrial Natriuretic Peptide (ANP)
Released by cells in the atria of the heart.
Lowers BP by causing vasodilation
Also by promoting the loss of salt and water in urine which reduces blood volume.
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Autoregulation
The ability of a tissue to automatically adjust its blood flow to match its metabolic demands.
2 types of stimuli causes autoregulatory changes in blood flow
1. Physical changes: warming promotes vasodilation, cooling causes vasoconstriction
2. Vasodilating and vasoconstricting chemical: includes WBC, plates, smooth muscles fibers, macrophages, endothelial cells release a wide variety of chemicals that alter blood vessel diameter.
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Pulse
Expansion and recoil of elastic arteries after each systole of the left ventricle creates a traveling pressure wave.
Is the strongest in the arteries closer to the heart.
Palpated at the radial artery, brachial artery, common carotid artery, popliteal artery and dorsal artery.
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Korotkoff Sounds
Various sounds that are heard while taking blood pressure.
SBP: when cuff is deflated enough to allow the artery to open, a spurt of blood passes through resulting in the first sound heard.
DBP: as the cuff is deflated further, the sound suddenly becomes too faint to hear.
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Pulse Pressure
The difference between systolic and diastolic pressure.
Normally 40 mmHg, provides information about the condition of the cardiovascular system.
Normal BP: 120/80, Pulse Pressure would be 40;93.3
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Shock
Is a failure of the cardiovascular system to deliver O2 and nutrients to meet cellular metabolic needs.
Cause is varied but all are characterized by inadequate blood flow to body tissues.
4 types of shock:
1. Hypovolemic
2. Cardiogenic
3. Vascular
4. Obstructive
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Hypovolemic Shock
Due to decreased blood volume.
Common cause: acute hemorrhage.
Other causes: loss of body fluids through excessive sweating, diarrhea or vomiting, diabetes mellitus, inadequate intake of fluids.
Treatment: replacing fluid as quickly as possible
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Cardiogenic Shock
Due to poor heart function
The heart fails to pump adequately most often because of myocardial infarction.
Other causes: poor perfusion of the heart (ischemia), heart valve problems, excessive preload or afterload, impaired Contractility of heart muscles and arrhythmias.
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Obstructive Shock
Due to obstruction of blood flow.
Occurs when blood flow through a portion of the circulation is blocked.
Most common cause: pulmonary embolism
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Homeostatic Response to Shock
Major mechanism: negative feedback systems
This returns CO and arterial blood pressure to normal.
1. Activation of the renin-angiotensin-aldosterone system
2. Secretion of antidiuretic hormone
3. Activation of the sympathetic division of the ANS
4. Release of local vasodilators
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Signs and Symptoms of Shock
-Systolic BP is lower then 90 mmHg
-rest HR is rapid due to sympathetic stimulation and increase blood levels of epi and norepinephrine.
-pulse is weak and rapid due to CO and fast HR.
-skin cool, pale and clammy due to sympathetic constriction of skin blood vessels and sweating.
-mental state is altered due to reduces O2 to brain
-urine formation is reduced due to increase levels of aldosterone and ADH.
-increase thirst due to loss of extracellular fluid
-pH of blood is low (acidosis) due to build up of lactic acid
-the person may have because because of impaired blood flow to the digestive organs from vasoconstriction.
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Circulatory Routes
System of organization of arteries, arterioles, capillaries, venules and veins to deliver blood throughout the body.
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Systemic Circulation
Includes all arteries and arterioles that carry O2 blood from the left ventricle to systemic capillaries plus veins and venules that return de02 blood to the right atrium after flowing through body organs.
All veins of this system drains into the superior vena cave, inferior vena cava or coronary sinus into the right atrium.
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Coronary Circulation
Supplies the myocardium of the heart
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Cerebral Circulation
Supplies the brain
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Hepatic Portal Circulation
Extends from the GI tract to the liver.
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Pulmonary Circulation
Where blood returns to the heart from the systemic route it is pumped out of the right ventricle to the lungs then back to the left atrium.
2 left and 2 right pulmonary veins enter the left atrium carries o2 rich blood to the heart.
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Fetal Circulation
Only exits in the fetus.
Contains special structure that allow the developing fetus to exchange material with its mother.
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Aorta
Largest artery of the body.
Diameter of 2-3 cm.
4 principle Divison:
1. Ascending aorta
2. Arch of aorta
3. Thoracic aorta
4. Abdominal aorta
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Ascending Aorta
Beginning of the aorta: aortic valve
Portion of the aorta that emerges from the left ventricle posterior to the pulmonary truck, ends at the level of sternal angle to form the arch of aorta.
At origin contains: 3 aortic sinuses. 2 give off to
left and right coronary arteries that supply the myocardium.
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Arch of the Aorta
Formed by the ascending aorta that arches to the left.
Emerges from pericardium posterior to sternum at level of sternal angle
Descends and ends at the level of the intervertebral disc between the 4th and 5th thoracic vertebrae, here become thoracic aorta.
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Thoracic Aorta
Arch of Aorta continuation.
Begins: level of intervertebral discs between 4th and 5th thoracic vertebrae. Lies left of vertebral column.
As it descends it moves closer to the midline and extends through an opening in the diaphragm (aortic hiatus).
Visceral branch includes: pericardial, esophageal and mediatinal arteries.
Parietal branch includes: posterior intercostal, subcoastal and superior phrenic arteries.
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Abdominal Aorta
Continuation of thoracic aorta after it passes through the aortic hiatus of the diaphragm.
Begin: aortic hiatus
Ends: about level of the 4th lumbar. Here it divers into the right and left common iliac arteries.
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Common Iliac Arteries
The abdominal aorta descends to the level of the 4th lumbar vertebra, ends by divides forming these arteries.
Divide into internal and external iliac arteries:
Carry blood to the pelvis and lower limbs.
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Arteries of the Arch or Aorta
3 major arteries branch from the superior aspect of the arch of the aorta:
1. Brachiocephalic trunk
2. Left common carotid
3. Left subclavian
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Branchiocephalic Trunk: Arch of Aorta
First branch of arch of aorta.
Extends superiorly, bends slightly to the right. Divides to form right subclavian artery and right common carotid artery.
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Left Common Carotid Artery: Arch of Aorta
Second branch of arch or aorta.
Divides into the same branches of the same names as the right common carotid artery.
Supplies both ventricles.
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Left Subclavian Artery: Arch of Aorta
Third branch of arch of aorta.
Distributes blood to the left vertebral artery and vessels of the left upper limb.
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Axillary Artery
Continuation of right subclavian artery into the axilla.
Begins: inferior border of 1st rib
Ends: as it crosses Teres major muscle
Gives rise to numerous branches in axilla
Supplies: thoracic, shoulder, scapular muscles and humerus.
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Brachial Artery
Continuation of Axillary artery into arm.
Begins: distal border of Teres major muscle
Terminates: by bifurcating into radial and ulnar arteries just distal to elbow.
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Unpaired and Paired Visceral Branches: Abdominal Aorta
Upaired - Arise from the anterior surface of the aorta
Include:
Celiac trunk arteries
Superior Mesenteric arteries
Inferior mesenteric arteries
Paired - Arise from the lateral surfaces of the aorta
Include:
Suprarenal arteries
Renal arteries
Gonadal Arteries
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External Iliac Arteries
Formed by the divided common iliac arteries
Becomes:
Femoral arteries: in the thighs
Popliteal arteries: posterior to the knee
Anterior and Posterior Tibial arteries: in the legs
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Coronary Sinus
Main vein of the heart.
Receives almost all venous blood from myocardium.
Drains to all tissue of the heart
Located: in coronary sulcus on posterior aspect of heart, opens into right articular between orifice of inferior vena cava and tricuspid valve.
Receives:
-Great cardiac vein into left end
-Middle cardiac vein
-Small cardiac vein into right end
-Anterior cardiac vein into right atrium
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Superior Vena Cava
7.5 cm Long, 2 cm diameter
Formed from the fusion of the two brachiocephalic veins.
Empires its blood into superior part of the right atrium
Begins: posterior to right 1st costal cartilage by union of right and left brachiocephalic veins
Ends: at level of right third costal cartilage where is enters right atrium
Drains to : head, neck, upper limbs and thorax.
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Inferior Vena Cava
Largest vein in the body, about 3.5 cm in diameter.
Begins: anterior to 5th lumbar ventral by union of common iliac veins
Ascends: behind periosteum to right of midline, at opening of diaphragm at 8th vertebrae then enters inferior part of right atrium.
Drains in: abdomen, pelvic and lower limbs.
Compressed in later pregnancy by enlarged uterus, causes edema in ankles and feet and temporary varicose veins.
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Veins of the Head and Neck
Internal and external Jugular:
Most of the blood draining from the head passes into these veins
Internal jugular anastomosis with the subclavin vein to form brachiopceptalic vein that drains blood back o the heart.
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Cephalic Veins
Begin: lateral aspect of dorsal venous networks of hands
Drain to: dorsal digital veins that pass along fingers.
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Basilic Veins
Begin: medial aspect of dorsal venous networks of hands.
Ascends: along psoteriormedial surface of forearm and anteromedial surface of arm.
Connect to cephalic veins by: median cubital veins.
After receiving median cubital veins they continue to ascend until they reach middle of arm.
*median cubital veins are preferred for IV.
Drain in: integumentary and superficial muscles of medial aspect of upper limbs.
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Hepatic Portal Vein
Receives blood directly from capillaries of:
GI tract, spleen, pancreas, gallbladder.
Delivers blood to the liver.
Formed by: united superior mesenteric and splenic veins.
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Portal Vein
A vein that carries blood from one capillary network to another.
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Pulmonary Circulation
Carries deO2 blood from the right ventricle to the air sacs within the lungs and returns O2 blood from air sacs to left atrium.
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Pulmonary Trunk
Emerges from the right ventricle and passes superior, posterior and to the left.
Divides into 2 branches:
1. Right pulmonary artery: right lung
2: Left pulmonary artery: left lung
After birth these arteries are the only arteries that carry deO2 blood.
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Pulmonary Veins
Formed by the pulmonary capillary that unit to form venules then veins.
Exits the lungs and carry the O2 blood to the left atrium.
After birth the pulmonary veins are the only veins that carry O2 blood.
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Cardiac Output
The volume of blood that circulates through systemic (or pulmonary) blood vessels per min.
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Causes of an Increased Arterial BP
Increased blood volume
Increased sympathetic stimulation
Increase HR
increased stroke volume
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Causes of Increases Systemic Vascular Resistance
Decreased diameter of systemic arterioles
Increased blood viscosity
Increased vasoconstriction of systemic arterioles
Increased red blood cell count
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Contribution of Cardiovascular System to Other Body Systems
1. Blood delivers clotting factors and WBCs that aid in hemostasis when skin is damaged.
2. Blood delivers calcium and phosphate ions that are needed for building bone extracellular matrix.
3. Blood carries newly absorbed nutrients and water to the liver.
4. Blood circulates cells and chemicals that carry out immune functions.
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Cardiovascular System Response to Decreased Action Potential of Baroreceptors
When BP falls the baroreceptors are stretched less and send nerve impulses at a slower rate to the cardiovascular center causing increased systemic vascular resistance.
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Hormones that Increase BP
1. Antidiuretic hormone
2. Aldosterone
3. Angiotensin
4. Epinephrine.
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Chemoreceptors Response to Increase of CO2 in Blood
1. Increase vasoconstriction of arterioles
2. Increased BP
3. Increase sympathetic stimulation of arterioles and veins
4. Increase vasoconstriction of veins
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Myogenic (Contraction) Response of Smooth Muscle in Blood Vessels
Results in more forceful contractions when stretched.
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Atherosclerosis
Abnormal condition that causes a large increase in pulse pressure.
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Angioblasts
Forms blood vessels during the embryonic development after formed from pluripotent cells.
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Effectors that are Activated During Hypovolemic Shock
1. Adrenal cortex releases aldosterone
2. Kidney conserve salt and water
3. Heart rate increases
4. Heart Contractility increases.
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Ace Inhibtors
Block formation of angiotensin II to lower BP.
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Lactic Acid in Shock
Lactic builds up during shock which causes pH of blood to decrease.
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Vertebral Artery
Supplies blood top structures of the brain
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Carotid Sinus Baroreceptors
Impulses from the receptor travel along the Glossopharyngeal nerve.
