Medic 14 A&P Chapter 13 notes

pressure; baroreceptors

hair-like;capillary

device of measuring pressure; sphygmomanometer

gate; portal vein

lung;pulmonary

stroke;pulse

prominent;saphenous vein

hard;arteriosclerosis

pulse; sphygomanometer

vessel; vasoconstriction

pulmonary trunk and aorta

the major arteries

arterioles

cappillaries

barely the diameter of a single red blood cell

Chemical and gaseous exchange between the blood and interstitial fluid

the venules, the smallest vessels of the venous system

veins

• venae cavae
• pulmonary veins

• tunica interna
• tunica media
• tunica externa

• tunica intima
• innermost layer
• enodthelial lining of the vessel and underlying layer of connective tissue dominated by elastic fibers

• middle layer
• contains smooth muscle tissue in a framework of collagen and elsatic fibers
• when contracted diameter decreases
• relaxed increases

• tunica adventitia
• forms a sheath of connective  tissue around the vessel.
• collegen fibers may intertwine with those of adjacent tissues, stabilizing and anchoring the blood vessel

side by side in a narrow band of connective tissue

arteries

sympathetic division of the ANS

Vasoconstriction

vasodilation

• Elastic Artery
• Muscular Artery
• Arteriole

• large, Extremely resilient vessels
• Examples are pulmonary trunk and aorta and major branches
• Tunica media dominated by elastic fibers rather then smooth muscle cells
• allows absorbtion of pressure changes during cardiac cycle

• During ventricle systole, elastic arteries stretch and diameter increases 
• During diastole, arterial blood pressure declines and elastic fibers recoil to original dimensions

• Medium sized arteries or disribution arteries 
• distribute to skeletal muscles and internal organs
• thick tunica media contains more smooth muscle and twer elastic fibers contrasted to elastic artery

• much smaller then muscular arteries 
• tunica media contains one to two layers of smooth muscle cells these layers allow change of diameter of the lumen
• altering BP or and rate of flow through dependent tissues, characteristic found in muscular arteries as well

• Only blood vessel whose walls permit exchange between blood nad surround intersitial fluid 
• Small diameter of capillaries allow sufficient time for diffusion or active transport of materials across the capillary walls

endothelial cells inside a basement membrane. Neither tunica externa or tunica media is present

capillary bed

several venules

precapillary sphincter, a band of smooth muscle

• Contratcion narrows reducing blood flow
• relaxation dilates and allowing blood to enter cappilary more rapid

blood flow within a any one capillary is intermittent rather then a steady and consistant stream due to precapillary sphincters alternatle contracting and relaxing around a dozen times a minute

• smooth muscle fibers respond to local changes in concentraions of chemicals and dissolved gasses in the interstital fluid
• for example then dissolved oxygen levels decline in a tissue, cappillary sphincters relax and blood flows increases to the area.

joining of two tubes

blood bypasses capillary beds

a vessel that connects an arteriole to a venule

a single capillary bed is supplued by this , more then one artery fuses before giving rise to arterioles

Collect blood from all tissues and organs and return it to the heart.

• Venules 
• Medium sized
• Large size

• resemble expanded capillaries 
• they lack a tunica media

• comparable to muscular arteries 
• tunica media contains several smooth muscle layers and relatively thick tunica externa has longitudial bundles or elastic and collagen fibers

include the venae cava and their tibutaries in the abdonminopelvic and thoracic cavities. thin tunica media is sourrounded yb a think thinica externa composed if elastic and collagenous fibers

valves which are folds of endothelium that function like the valves in the heart and prevent backflow of blood

• Cardiac Output
• pressure 
• resistance

when pressure increases, flow increases.

when resistance increases, flow decreses

the resistance to blood flow in the pulmonary and systemic circuits

• hydrostatic pressue that is conducted in all directions
• if pressure difference exists a liquid will flow from an area of higher pressure to an area of lower pressure

the faster the flow

• in the systemic circuit between the base of the aorta and the entrance of the right atrium
• This pressure difference is called the circulatory pressure, averages about 100 mmHg
• This is the force needed to force blood through the arterioles and capillaries

• arterial pressure(blood pressure
• capillary pressure
• venous pressure

any force that opposes movement

Must be great enough to overcome the total peripherial resistance

resistance of the entire cardiovascular system

peripheral resistance

• vascular resistance
• viscosity
• turbulence

is the resistance of blood vessels  to the blood flow

friction between blood and the vessel walls

• length of the vessel and its diameter.
• Friction inceases with increasing vessel length and with decreasing vessel diameter

which are extremely muscular

the smooth muscle tissue and can adjust the diamaters of these vessels

is the resistance to the flow that results from interactions among molecules and suspend materials in a lquid

higher pressures as opposed to liquids of a low viscosity

• is a fluid regime characterized by chaotic,stochastic property changes. Includes low momentium diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time
• Flow that is not turbulent is called laminar flow

heart murmurs

Vascular resistance

normally constant

Aorta, peak around 120mmhg

Venae cavae,average about 2 mmHg

is the peak of blood pressure measured during ventriuclar systole

is miniumim blood pressure at the end of ventricular diastole

is the rthythmic pressure oscillation that accompanies each heartbeat

the differnece between the systolic and diastolic pressure

increases

the elasticity of the arteries

elastic rebound

pressure of blood within a capillary bed

• Maintaining constant communication between plasma and intersitial fluid
• speeding the distribution of hormones,nutrients, and dissolved gases throughout tissues
• assisting the movement of insoluble lipids and tissue proteins that cannot cross capillaty walls
• flusing bacterial toxins and other chemical stimuli to lymphoid tissues and organs that function in providing immunity to disease

• diffusion
• filtration
• osmosis

their individual concentration gradient

hyrdostatic pressure or osmotic pressure

Capillary hydrostatic pressure (CHP)

the arteriolar end

the venous end

A selectively permaible membrane that separates two solutions with two soulte concentrations

water moves into the soultiuon with the higher solute concentration and the force of that is referred as Osmotic pressure

water tends to move from interstital fluid into the blood

tend to reabsorb or pull water back

• 18mmHg a in the venules, 2mmHg at the venae cavae
• 16 mmHg through medium veins

gravity as it ascends within the interior vena cava

• Muscular compression
• Respiratory pump

contratcions of skeletal muscle near a vein compress it and help push blood toward the heart

• as you inhale pressure in the thoratic cavity draws air into the lungs
• that drop in pressure causes the inferior vena cavae and right atrium to expand and fill with blood, which increases venous return
• during exhaltation increased pressure compresses venae cavae pushing blood into the right atrium

Homeostatic mechanisms that regulate cardiovascular activity to ensure tissue blood flow to meet demand for oxygen and nutrients

• cardiac output
• peripherial resistance
• blood pressure

muist increase to deliver the oxygen and nutrients they need and to carry away the waste prodycts and carbon dixoide they generate

• at the appropriate time
• in the right area
• without drasically altering blood pressure and without drastically altering blood flow to vital organs

• autoregulation
• neural mechanisms 
• endocrine mechanisms

• changes in tissue cocditions act directly on precapillary sphincters to alter peripheral resistance, producing local changes in patten of blood flow within capillary beds
• such autoregulation causes immediate localized homeostatic regulations called Homeostatic adjustments

Neural and endocrine mechanisms are activated

• respond to changes in arterial pressure or blood gas levels in specific sites
• when these changes occur the ANS adjusts cardiac output and peripheral resistance to maintain adequate blood flow

Releases  hormones the enhance the short term adjusttments and direct long term changes in cardiovascular performance

adjust cardiac output and peripheral resistance to stabilize blood pressure and blood flow to tissues

involve alterations in blood volume that affect cardiac output and the transport of oxygen and carbon dioxide to and from active tissues

• as Co2 levels rise and pH falls, these changes signal the smooth muscle cells in precapillary sphincters to relax and blood flow increases.
• release of NO by capillary cells stimulated by high shear forces along the capillary walls or presence of histamine at an injury site during inflamation triggers relaxation of precapillary sphincters

vasodilators

vasoconstrictors

the cardiac centers and vasomotor centers of the medulla oblongata

Cardiac/vasomotor centers of the medulla oblongata

• a cardioacceleeratory cemter
• cardioinhibitory center

Increases cardiac output through sympathetic innervation

reduces cardiac output through parasympathetic innervaition

• primarily control the diameters of the arterioles through sympathetic innervation
• Inhibiton of the vasomotor center leads to vasodilation

arterial blood, for BP, pH , and dissolved gas concentrations

BP

respond to changes in chemical composition

negative feedback

monitor the degree of stretch in the walls of expandable organs

• aortic sinuses (pockets in the wall of the aorta adjacent to the heart)
• Carotid sinuses(in the walls of, which are expanded chambers near the bases of the internal carotid arteries of the neck)
• In the wall of the right atrium

autonomic reflexes that adjust cardiac output and peripheral resistance to maintain normal arterial pressures

monitor  blood presure within the ascening aorta

• adjusts BP in response to changes in pressure
• maintain adequate BP and blood blow through the systemic circuit

• respond to changes in bp at the carotid sinuses
• Trigger reflexes that mainatain adequate blood flow to the brain

extremely sensitive

• Under command of the cardioinhibitory center , the vagus nerves release ACh, which reduces rate and strength of cardiac contracions,decreading cadiac output
• inhibition of the vaomotor center leads to dilation of peripheral aterioles throughout the body

• sympathetic neurons that innervate the SA node and AV node nad general myocardium
• this stimulation leads to increased heart rate and stroke volume
• immediate cardiac output increase

rapid vasoconstriction

monitor bp at the end of the systemic circuit at the venae cavae and right atrium

stretching of the wall of the right atrium

blood is arriving at the heart faster then it is being pumped out

stimulating cardioacceleratory enter, inceasing cardiac output untill the backlog of venous blood is removed, the atrial pressure retunrs ot normal

respond to changes in Co2 oxygen, and pH in  blood/CSF

• carotid bodies
• aortic bodies 
• on the medulla oblongata

• drop in pH, or in plasma O2 or by a rise in CO2
• these changes lead to stimulation of cardioacceleratoy and vasomotor centers

the respiratory centers in the medualla oblongata

this coordination of cardiovasuclar and respiratory activity is vital, due to oxygen demands and rise in respiratory rate accelerates venous return through the respiratory pump

short term and long term regulation of the cardiovascular system

N, NE from adrenal medullae stimulate cardiac output and peripheral vasoconstricion

• involves participation  of hormonessuch as
• ADH
• Angiotension II
• EPO
• ANP
• hormones help in regulation of BP and blood volume

• ADH is realeased at the posterior of the piuitary gland in response to a decrease in blood volume, increase in osotic concentraion of the plasma, or in repsonse to presence of angiotension II
• Immediate result is peripheral vasoconstriction that elevates blood pressure.
• ADH  has water conveserving effect on the kidneys, prevents a reduction in blood volume

• formed by the release of the enzyme renin by specialized kidney cells in response to a fall in blood pressure.
• renin starts chain reaciton that converts inacitve plasma protein,angiotension to hormone angiotension II.
• angiotension II stimulates cardiac output and triggers arteriole constiction, which in tirn elevates systemic blood pressure
• Stimulates release of ADH and aldosterone by the adrenal cortex

stimulates the reabsorption of sodium ions and water from urine

• is released by the kidneys when blood pressure falls or the oxygen content of the blood becomes abnormally low
• EPO stimulates RBC production

• ANP release is stimulated by increased blood pressure 
• ANP is produced by specialized cardiac muscle cells in the arial walls when they are streched by excessive venous return.

• increasing the loss of sodium ions at the kidneys
• promoting water losses by increasing the volume of urine produced
• reducing thirst
• blocking the relase of ADH,aldosetrone, E,NE, stimulating peripheral vasodiaton
• as blood volume and blood pressure decline , tension on the atrial wealls is removed and ANP production ceases

• Extensive vasodilation
• venous return increases 
• cardiac output rises