Blood Vessels and Circulation

veins walls characteristics

- tend to have a flattened, collapsed, or irregularly shaped lumen with relatively thin walls. - the tunica interna of ________ is often smooth and the internal elastic membrane is absent. - have a thin tunica media composed of smooth muscle and collagen fibers. - lack an external elastic membrane. - The tunica externa of _______ possesses collagen and smooth muscle and the nervi vasorum and vasa vasorum are present in the tunica externa and the tunica media.

Simplest pathway for blood

1 capillary bed heart-arteries-arterioles-capillaries-venules-veins

What are the major vessels,in pulmonary circulation. What color are they & why

1) Arteries are blues because of lacking O2. 2) Veins are red because of having lots of O2

What are 2 opposing forces in capillary exchange?

1) capillary hydrostatic pressure(CHP) 2) blood colloid osmotic pressure (BCOP)

Filtration and reabsorption are determined by the interplay of two important pressures:

1. Capillary Hydrostatic Pressure 2. Blood Colloid Osmotic Pressure

companion vessels

Arteries that supply the same body region and tend to lie next to one another are called __________________________________.

Blood volume

As __________ increases (as with pregnancy) blood pressure increases. As __________ decreases (as with hemorrhaging) blood pressure decreases. Hypervolemia Hypovolemia

Cardiac output

As cardiac output increases (as during exercise) blood pressure increases. As cardiac output decreases (as with rest) blood pressure decreases.

Skeletal Muscle Pump

As skeletal muscles contract, they force blood toward the heart. Blood also flows through veins as result of normal movement such as swinging a limb.

Local control

Autoregulation

What are the 3 ways to regulate BP & blood flow

Autoregulation Neural control Endocrine control

Why do conducting arteries expand during systole

Expansion takes pressure of smaller downstream vessels

Comparison/ structure of artery

Lumen: Regular shaped Thickness of Wall: Has thick walls Internal Elastic Membrane: Is visible Thickest Coat (layer): Tunic media Valves: Has no valves. Has lots of smooth muscles in coats The diameter is smaller than veins. Dilates easier at higher pressure

Sinusoid capillary

Is an IRREGULARLY shaped capillary, with an INCOMPLETE BASEMENT membrane, that can be found in the MYELOID tissue (bone marrow) and LIVER . This capillary houses the MACROPHAGE bacteria

Hypertension

Is an abnormality of BP when the artery is constricted & can cause aneurysm & CVA(stroke) Resting Heart rate>than 140/90

Autoregulation of BP & blood flow

Is an immediate, localized chemical response. Changes usually are histamine, low o2 & high o2.

Umbilical vein

Is highly oxgenated(red in color) vein that will supply blood from the mother to the child. After birth it will become the ligamentum; TERES HEPATIS aka round ligament of liver)

Vasoconstriction

Is increase BP

Neural control regulation BP & blood flow

Is the Vasomotor center of medulla oblongata, integrates baroreceptor reflexes & chemoreceptor reflexes

capacitance of a vessel

Is the relationship between blood vessel expansion, volume of blood it contains, & blood pressure

Resistant/Resistance artery

Is the smallest artery that controls blood flow to various organs. Because of its small size it makes blood flow slow down. Can have all Tunics but generally no adventita(external)

Turbulence of blood flow/pressure

Is upset of smooth blood flow usually caused by zagging motion of formed elements. It increases resistance(friction) of formed elements & slows blood flow.

What does blood do to the tunics in an aneurysm

It seperates them, usually because of degeneration of the tunica media

Large Veins & Medium-Sized Veins

Larger than venules Small and medium-sized veins paired with muscular arteries Large veins paired with elastic arteries Blood pressure in veins is too low to overcome the forces of gravity and possess valves Valves are formed from the tunica intima and prevent blood from pooling in the limbs

Elastic Arteries

Largest of the arteries Mostly near the heart Aorta Pulmonary Brachiocephalic Common carotids Subclavians Fibers present in all three tunics allows arteries to stretch under increased pressure generated by bloodflow from the heart Branch into muscular arteries

Tunica Interna

Lines the blood vessel and is exposed to the blood

Metarterioles

Link arterioles to capillaries. Muscle cells form a precapillary sphincter around entrance to capillary

Blood Brain Barrier

Low permeability Complete tight junctions so no intercellular clefts Continuous - not fenestrated No caveolae Transport of selected molecules only thru complex mechanisms

Diffusion

Oxygen, hormones, nutrients=from relatively high blood concentration to interstitial fluid then to area of low blood concentration(tissues) Carbon and waste diffuse from higher concentration in tissue to lower concentration in interstitial fluid then blood

Veins

This vessel's diameter is larger than arteries. Their walls are THIN; the blood pressure LOW within this vessel; has VALVES that aid skeletal muscles for UPWARD blood flow; This vessel expands easier at low pressure(capacitance vessel)

intercellular clefts

Tight junctions secure endothelial cells to one another; however, they do not form a complete "seal". The gaps between the endothelial cells are called _____________________________________. Materials can move into or out of the blood either through endothelial cells by cellular transport processes (e.g., diffusion, pinocytosis), or between endothelial cells through _____________________________- by diffusion and bulk flow.

What is the importance of blood flow

To delivery Co2, O2, & remove waste from the metabolism/ digestive system

True/ False: arteries become progressively smaller as they divide and get further from the hear

True

True/False: Veins become progressively larger as they get closer to the heart

True

True/False: vein walls are relatively thin and vein lumen is larger

True

What are the three wall vessels in veins & arteries

Tunica adventitia (tunic external) Tunica intima Tunica media

What is the outermost layer of the tunics in the blood vessel?

Tunica externa/ tunica adventitia

What tunica is the middle layer?

Tunica media

Arterial anastomosis

Two arteries merge Provides collateral (alternative) routes of blood supply to a tissue. Cornoary circulation and common around joints

skeletal muscle pump and respiratory pump

Two mechanisms support the venous return

Why does velocity increase from capillaries to vena cava

Veins are larger, create less resistance than capillaries Large amount of blood forced into smaller channels

thicker

Veins have a _________________ tunica externa, a larger lumen, and a less elastic and collagen fibers than a companion artery. The wall of a vein is typically collapsed if no blood is in it.

factors affecting resistance and hence blood pressure:

Vessel length Vessel diameter

tunics

Vessel walls are composed of layers called ______________. They surround the lumen, or inside space of the vessel, through which blood flows. The three _________________ are the tunica intima, tunica media, and tunica externa.

Thoracic (respiratory) pumps blood flow faster

When inhaling and is part of the venus return mechanism

What is the skeletal muscle pump?

When veins are squeezed to help pump blood back into the heart

Where is blood pressure measured

brachial artery close approximation of pressure at exit of left ventricle

Distributing (muscular/medium) arteries are found

brachial, femoral, renal and splenic arteries

Result from congenital weakness of ___. Most common cause is ____.

blood vessels, trauma or bacterial infections; atheroscletosis and hypertension

Variables that hinge resistance

blood viscosity, vessel length and vessel radius

What major branches join the aorta in the systemic circulation

brachiocephalic a. left common carotid a., left subclavian a.,

superficial temporal artery maxillary artery posterior auricular artery occipital artery facial artery lingual artery ascending pharyngeal artery superior thyroid artery

branches of external carotid artery

atherosclerosis

build up of lipid deposits that become plaques

Bulk Flow filtration

bulk flow out of the blood through openings in capillaries fluids and small dissolved solutes flow easily occurs in arterial end of capillary bed

autoregulation changes local perfusion

by negaative feedback

Atrial natriuretic peptide

increases urinary sodium excretion Reduces blood volume and promotes vasodilation Lowers blood pressure

Trace the blood flow of the pulmonary circulation

inferior & superior vena cava right atrium tricuspid valve right ventricle pulmonary semilunar valve pulmonary trunk right or left pulmonary artery lobar artery pulmonary capillary beds in lungs air sacs (alveoli) of lungs

Tunica interna (intima)

innermost layer made of simple squamous epithelium called the *endothelium* and a supporting basement membrane. Large arteries also possess a layer of elastic tissue called the *internal* *elastic membrane*.

tunica intima

innermost layer of a blood vessel wall, endothelium

Distributing/Muscular artery

is a Medium sized artery is the most common artery in the body which distributes blood to specific organs. e.g. CORONARY ARTERIES

Foramen Ovale

is a communicator of oxygenated blood with the right & left atrium . After birth it will become the FOSSA OVALIS

Capillary exchange

is a dynamic process that includes diffusion by filtration and reabsorption mechanisms. Recall that diffusion is the net movement of ions or molecules from an area where their concentration is higher to an area where their concentration is lower.

Hypotension

is an abnormality of BP is usually caused by blood loss, dehydration, & anemia. Resting heart rate < 90/60

Large conducting artery

is the ELASTIC artery. e.g. AORTA

Hemodynamics

is the physical principles of blood flow based on pressure & resistance.

Elastic Arteries

largest arteries near heart some smooth muscle helps with contraction(ventricular systole) and relaxation(ventricular diastole) numerous elastic fibers branch into muscular arteries

elastic arteries

largest arteries, conducting arteries, have a large proportion of elastic fibers

high carbon dioxide, low pH, and low oxygen levels

chemoreceptors measure what in blood

cardiovascular center

chemoreceptors send signals to

Angina pectoris

chest pain due to, triggered by exertion/stress. Chest discomfort due to poor blood flow through the blood vessels in the heart.

Myocardia infarction

chest pain persist even at rest (CAD), cell necrosis. A heart attack occurs when blood flow to a part of your heart is blocked for a long enough time that part of the heart muscle is damaged or dies

hypertension

chronically high BP

hypotension

chronically low BP

anterior communicating artery anterior cerebral arteries internal carotid artery posterior communicating arteries posterior cerebral arteries

circle of willis

As blood flows superiorly into the limbs the valves do what?

close

vaso vasorum

network of small arteries that supply blood to large blood vessels, found only in large blood vessels

Capillary beds

networks of 10-100 capillaries that are usually supplied by a single arteriole or metarteriole.

40 mmHg

normal range of capillary blood pressure (arterial end)

20 mmHg

normal range of capillary blood pressure (venous end)

lymphatic system

not all fluid is reabsorbed at the venous end of capillary, about 15%, is picked up by

In order to prevent blood from pooling into the limbs, most veins contain what?

numerous valves to prevent backflow

Vesicular transport

occurs when endothelial cells use pinocytosis to form fluid-filled vesicles, which are then transported to the other side of the cell and released by exocytosis can move into or out of blood (insulin)

Why are arteioles the most significant point of control over peripheral resistance and flow

on proximal side of capillary beds and best positioned to regulate flow into the capillaries Out number any other type of artery More muscular, highly capable of changing radius. Produce half of the total peripheral resistance

parasympathetic

only SA and AV nodes

Tunica externa (adventitia)

outermost layer made of connective tissue which serves to anchor, protect, and prevent over-stretching.

tunica externa

outermost layer of blood vessel wall, areolar connective tissue with elastic and collagen fibers

sympathetic division

part of the autonomic NS activated by the vasomotor center

sympathetic division

part of the autonomic NS is activated by the cardioacceleratory center

parasympathtic division

part of the autonomic NS is activated by the cardioinhibitory center

cardiovascular center in medulla oblongata

part of the brain that controls short-term adjustments to BP

Systolic pressure

peak arterial BP taken during ventricular contraction

During exercise decreased ___ in kidneys and DI

perfusion

diaphragm

phrenic arteries supply blood to

Hydrostatic Pressure

pressure exerted by a fluid on a structure

ADH

promotes water retention and raises BP (vasoconstrictor)

Endothelial cells secrete these vasodilators

prostacyclin and nitric oxide

vasoconstrictors

prostaglandins and thromboxanes

MAP (mean arterial pressure)

provides a numerical value for now well body tissues and organs are perfused

Colloid Osmotic Pressure

pull of water into an area by osmosis due to their higher concentration of solutes(proteins)

Precapillary sphincter

ring of smooth muscle that controls blood flow into the true capillaries Relaxation-permits blood flow into true capillaries Constriction- bypasses capillaries

fenestrated capillary

same as continuous capillaries except also contain fenestrations; small intestine, ciliary process, choroid plexus, most endocrine glands, kidneys

Aldosterone

secreted by the cortex of the adrenal gland; enhances the reabsorption of sodium ions (Na+) by the kidney which in turn increases water reabsorption by the kidneys and further reduces urine output. With the increase in water in the blood, blood volume increases and blood pressure increases.

Epinephrine and norepinephrine

secreted by the medulla of the adrenal gland; increases heart rate which in turn increases cardiac output. Increases in cardiac output causes increased blood pressure.

Baroreflexes govern __ regulation of BP

short-term

ductus venosus

shunts blood away from liver and directly toward the inferior vena cava

ductus arteriosus

shunts blood from pulmonary trunk to aorta

Endothelium

simple squamous epithelium overlying basement membrane and sparse layer of loose connective tissue

Many deep veins pass between what?

skeletal muscle groups

vasomotor tone

slightly contracted state of smooth muscle in the arterioles

Vasa vasorum

small vessels that supply blood to outer part of the larger vessels They nourish at least the outer half of the wall of a larger vessel

Arterioles

smallest and most numerous arteries fewer than 6 layers of smooth muscle Vasomotor tone=always contracted regulates systemic blood pressure and blood flow controlled by vasomotor center

arterioles

smallest arteries, not named, fewer than six layers of smooth muscles in tunica media

Venule

smallest vein & has very little tunic media.

True/False: Arteries tend to form many more anastomosis than do veins

false: veins tend to form many more anastmosis than do arteries

True/false: Blood pressure is incrased by the time it reaches the veins

false; reduced by the time it reached veins

metarteriole

feds blood to capillary bed

arterial end

filtration in capillary bed

Net filtration pressure step 4:

filtration is always greater than reabsorption causing the interstitial fluid to experience a net accumulation of water and materials. This excess fluid would increase pressure in the interstitial space and decrease vascular blood pressure if not corrected. Hence, the need for our lymphatic system (next chapter).

Laminar flow

flows in layers, faster in center (this is where it experiences the least amount of friction)

fossa ovalis

foramen ovale becomes

blood pressure

force per unit area that blood exerts against the inside wall of a vessel

How is the circle of willis formed?

from posterior cerebral arteries and posterior communicating arteries, internal carotid arteries, anterior cerebral arteries, anterior communicating arteries

valves

function to prevent blood from pooling in limbs, part of tunica intima

The greater the pressure difference between two points, the ___ the flow

greater

Why does blood velocity decrease from aorta to capillaries

greater distance, more friction to reduce speed smaller radii of arterioles and capillaries offers more resistance Farther from heart, number of vessels and their total cross-sectional area become greater and greater

Capillary Bed

group of capillaries fed by metariole, drained by post capillary venule pathway: Arteriole->metareriole->thoroughfare channel->post capillary venule->venule

capillary bed

group of capillaries that function together

Angiogensis

growth of new blood vessels. Uterine lining, coronary artery obstruction, exercised muscle and malignant tumors

Blood vessels pathway

heart-> artery->capillary->veins->back to heart

In the hepatic portal system, blood exits the liver through the ______ that merge with the _______

hepatic veins; inferior vena cava

Capillaries

smallest, most abundant type of blood vessel; permits diffusion between the bloodstream and interstitial fluids in order to facilitate nutrient and waste exchange.

What is the tunica media primarily composed of?

smooth muscle cells

precapillary sphincter

smooth muscle ring controls blood flow into the true capillaries

Tunica media

smooth muscle, collagen and elastic tissue.

Deep vein thrombosis

stationary clot

Blood flow in capillaries and veins are

steady

cerebral vascular accident

stroke

Some blood vessels are also named for their?

structure they supply

Angiology

study of blood vessels and the lymphatic system

vasoconstrictor

substances that cause muscle contraction

vasodilator

substances that cause smooth muscle relaxation

common hepatic artery

supplies blood to liver, gallbladder, and stomach

splenic artery

supplies blood to spleen, stomach,and pancreas

left gastric artery

supplies blood to stomach and esophagus

Bronchial arteries

supply oxygenated blood to lungs

Rerouting blood during exercies

sympathetic system reduces blood flow to kidneys and digestive tract and increases blood flow to skeletal muscles

The mean arterial pressure most influences the risk of ___

syncope, atherosclerosis, kidney failure, edema and aneurysms

What circulation carries oxygenated blood to the body tissue?

systemic

pulse pressure

systolic pressure - diastolic pressure =

increased risk of cerebral edema

high MAP increases filtration in the capillaries in the brain, and since there is no lymph vessels to reabsorb excess fluid remains in the interstitial space

hypothalamus

higher brain center that can affect BP

vasodilators

histamine, bradykinin, and nitric oxide

Vasodilation is stimulated by --

histamine, bradykinin, prostaglandin

ANP

hormone decreases BP, vasodilation, increases urine output

ADH

hormone increases BP, decrease water loss, thirst center, vasoconstriction

Aldosterone

hormone increases BP, increases water retention

Angiotensin II

hormone that increases BP, vasoconstriction, thirst center, decrease urine

BP 140/90 or above

hypertension

BP 90/60 or below

hypotension

Hemodynamics

important in delivering nutrients and oxygen, and removing of metabolic wastes

When a blood vessel dilates, a greater portion of the blood is ___ and the average flow may be quite swift

in the middle of the stream

Sensory structures

in walls of major vessels that monitor blood pressure and chemistry. Transmit information to brain stem to regulate heart rate, blood vessel diameter and respiaration

Where are capillaries absent or scarce

tendons, ligaments, epithelia, cornea and lens of the eye

pulse pressure

the additional pressure placed on the arteries from when the heart is resting (diastolic blood pressure) to when the heart is contracting (systolic blood pressure) measure of the elasticity and recoil of arteries

total cross-sectional area

the aggregate lumen diameter across the total number of a given type of vessel if they were side by side. the greater the slower the blood flow

total blood flow

the amount of blood transported throughout the entire body at a given time, equals cardiac output

resistance

the amount of friction the blood experiences as it is transported through the blood vessels

local blood flow

the blood delivered locally to the capillaries of a specific tissue

Blood vessels often share names with

the body region they transverse the bone next to them

blood pressure gradient

the change in blood pressure from one end of a blood vessel to its other end

Blood Vessels

the conducting tubes that distribute the blood; three primary types of blood vessels are in the human body. 1. Arteries 2. Capillaries 3. Veins

Cross-sectional area

the diameter of the vessels lumen

Net filtration Pressure

the difference between HPb(pushing out) and COPb(pulling in) determines the direction of bulk flow =net hydrostatic pressure-net colloid osmotic pressure if positive=filtration if negative=reabsorption

Net filtration pressure (NFP)

the difference between the forces that favor filtration versus those that oppose it (reabsorption). *NFP = CHP - BCOP*.

net filtration pressure

the difference between the net hydrostatic pressure and the net colloid osmotic pressure

Fenestrated Capillaries

the endothelial lining of these capillaries possess many pores or "*fenestrations*" and intercellular clefts. Tight junctions are less numerous. Common in areas where filtration and absorption of dissolved particles is important organ functions. Found in the digestive tract, endocrine glands, kidneys, etc.

degree of vascularization

the extent of blood vessel distribution within a tissue, determines the potential ability of blood delivery

Vessel length

the farther liquid travels through a tube, the more friction it encouncters

Perfusion

the flow per given volume per mass of tissue in a given time

blood hydrostatic pressure

the force exerted per unit area by the blood as it presses against the vessel wall

Blood pressure

the force that blood exerts against a vessel wall

Blood colloid osmotic pressure

the force that draws fluid back into blood due to proteins in blood(albumin)

blood colloid osmotic pressure

the force that draws fluid back into the blood due to the proteins in blood

angiogenesis

the formation of new blood vessels in tissue that require them

mean arterial pressure

the mean pressure one would obtain by taking measurements at several intervals throughout the cardiac cycle.

reabsorption

the movement of fluid by bulk flow back into the blood

filtration

the movement of fluid by bulk flow out of the blood through the openings in the capillaries

Peripheral Resistance

the opposition to flow that blood encounters in vessels away from the heart

autoregulation

the process by which a tissue itself regulates or controls its local blood flow in response to its changing needs

Excessive blood volume or low blood pressure triggers

the secretion of *Atrial natriuretic* *peptide (or ANP)* by the right atrium and *Brain natriuretic* *peptide (or BNP)* by the muscle cells of the ventricles. ANP and BNP both reduce sodium reabsorption so that the body experiences an increase in Na+ loss in urine. Water follows the Na+ so blood volume declines. ANP and BNP inhibit the release of ADH, aldosterone, epinephrine, and norepinephrine. All of these things together will lower blood pressure.

Structure and general characteristics of capillaries

the smallest of all blood vessels with diameters less than 10 micrometers; composed of a single layer of squamous epithelium and a sparse *basal lamina*. May possess *pericytes* associate with the epithelium to help stabilize the layer.

perfusion

the specific amount of blood entering capillaries per unit time per gram of tissue

Viscosity of blood

thick fluids are more sluggish than thin fluids. Liquids with low _________ (like water) flow at low pressures. Thick, syrupy fluids, such as molasses, flow under higher pressures. Whole blood has a ___________ 4 -5 times that of water due to the presence of plasma proteins and the formed elements. Increases in ______________, as when someone is significantly dehydrated, will cause an increase in blood pressure. A decrease in _________ will decrease blood pressure.

Structure and general characteristics of arteries

thick tunica media compared to tunica externa; lack valves, and may possess large amounts of elastic tissue.

Tunic Media

this vessel wall is made up of SMOOTH MUSCLES & contains the EXTERNAL ELASTIC MEMBRANE

heart, skin, and skeletal muscle

three areas in body where blood flow will increase during exercise

blood viscosity, blood vessel length, and size of lumen of blood vessel

three factors affecting the level of PR

decreased blood volume, obstructed vein, and venous pooling

three types of low venous return shock

embolus

thrombosis breaks free and travels to lungs or brain

transient ischemic attacks

tiny, tiny strokes

Arterial System

transport blood away from the heart, generally red, generally transport oxygenated blood.

Venous System

transport blood towards the heart, generally blue, and generally transport deoxygenated blood.

Epinephine and norepinephrine in cardiac muscle blood vessels

vasodilation-bind to beta-adrenergic receptors

Neural Control

vasomotor center of medulla exerts sympathetic control over blood vessels.

Secondary role

vasoreflexes

median cubital vein

vein commonly used to take blood

Venules merge to form what?

veins

Why does venous blood never regain velocity it had in large arteries

veins are further from the pumping heart veins are more compliant (stretch more) than arteries

At distal end, capillaries transition to ____

venules or drain into a throroughfare vhannel (continuation of metarteriole)

Interstitial COP

very low compared to blood COP

sympathetic

vessels, SA node, AV node, and myocardium

How do you distinguish the three capillary types?

wall permeability

Aneurysm

weak point in artery or heart wall, and forms a bulging sac that pulsates with each heartbeat and may rupture at any time.

excess cerebrospinal fluid

what drains into the dural sinuses besides the cranial venous blood

When do venules become a vein?

when its diameter is greater than 100 micrometers

vasoconstriction

when smooth muscle of tunica media contracts

brachiocephalic

where blood of internal and external jugular veins moves

subclavian arteries

where the vertebral arteries originate

pituitary gland

which gland sits in the sella turica

capillaries

blood vessel with highest total cross sectional area

Factors that determine BP

cardiac output, blood volume and resistance to flow

umbilical vein

carries high-oxygenated blood from placenta

Hypotension

caused by blood loss, dehydration and anemia

regession

return to previous state in relation to angiogenesis

Where do systemic veins carry deoxygenated blood?

right atrium of the heart

Blood is pumped out of the ____ventricle into the ______trunk

right;pulmonary

Blood vessles are not?

rigid and immobile

Internal Elastic Lamina

Separates the tunica intima and tunica media

External Elastic Lamina

Separates the tunica media and the tunica externa

Structure and general characteristics of veins:

- Possesses *valves* which are formed from folds of the tunica interna function to prevent backflow of blood. If a valve fails, blood will pool abnormally in the vessel causing it to become grossly distended. If near the surface, it is visible through the skin and is called a *varicose vein*. Varicose veins of the anal canal are called *hemorrhoids*. - Serve as *blood reservoirs* (capacitance vessels) because the pressure is so low within these vessels compared to arteries or capillaries. In fact, 64% of blood total volume is in systemic veins at any given time.

Changes in blood pressure occur as blood flows through the cardiovascular system:

- The heart generates a pressure of around 100 mmHg as it pumps blood into the aorta which has a cross sectional area of roughly 4.5 cm2. - At each branching of the arterial system, the arterial pressure drops as blood is pushed into ever-increasing numbers of smaller and smaller branches. - At the start of peripheral capillaries, arterial pressure has fallen to approximately 35 mmHg, and by the time blood reaches the venules, it has fallen to approximately 18 mmHg. - By the time blood reaches the vena cavae, pressure is approximately 5 mmHg. - Because pressure is so low in veins, blood tends to pool in veins and the venous flow depends upon the *muscular pump* and *respiratory pump* to keep the blood moving toward the heart.

Arterial pressure is not constant; it rises during ventricular contraction and falls during ventricular relaxation as the elastic arterial walls stretch and recoil.

- The peak blood pressure measured during ventricular contraction is called the *systolic* *pressure*, and the minimum blood pressure at the end of the ventricular relaxation phase is called the *diastolic pressure*. In recording blood pressure, we separate systolic and diastolic pressure with a slash. Average adult blood pressure is 120/80 mmHg. - The difference between systolic and diastolic pressure is the *pulse* *pressure*. Systolic pressure - Diastolic pressure = pulse pressure. - The *mean arterial pressure* (or MAP) is calculated by adding one third of pulse pressure to the diastolic pressure. - Be sure you can identify the various *pulse points* of the body. See diagram. - In the laboratory, you will have an opportunity to measure your partner's blood pressure using a *sphygmomanometer* and *stethoscope*.

Diffusion occurs continuously across capillary walls, but different substances use different routes and mechanisms for movement into and out of the bloodstream:

- Water, ions, and small organic molecules diffuse between adjacent endothelial cells or through the pores of the fenestrated capillaries. - Some ions, including Na+, K+, Ca+, or Cl-, can diffuse across endothelial cells by pass through their plasma membrane channels. - Large water-soluble compounds are unable to enter and leave the bloodstream except at fenestrated capillaries. - Lipids and lipid-soluble materials can cross capillary walls by diffusion through the endothelial plasma membrane. - Plasma proteins are normally unable to cross the endothelial lining anywhere except in sinusoidal capillaries like those of the liver.

Capillary Beds

- are also called "microcirculation". - possess several important structures: - *True capillaries* where exchange occurs (about 10 to 100 per capillary bed). - *Precapillary sphincters* circular muscles which open and close to allow blood to flow into the true capillary vessels or to bypass them. - *Metarteriole*—thoroughfare channels (a vascular shunt) these are the vessels that allow the blood to bypass the true capillaries and be redirected to tissues that need an increased blood supply. - *Arteriovenous* anastomosis may bypass the capillary bed and lead directly to the venous system. These serves as collateral circuits.

Fenestrated capillaries

- are also composed of a complete, continuous lining of endothelial cells, and a complete basement membrane. However, small regions of the endothelial cells (typically 10 to 100 nanometer in diameter) are extremely thin; these thin areas are called fenestrations (or pores).

fenestrations

- are small enough to prevent formed elements from passing through the wall, yet large enough to allow movement of some smaller plasma proteins.

Elastic arteries

- are the largest arteries, with diameters ranging from 2.5 to 1 centimeter. They are also called conducting arteries because they conduct blood--- from the heart to the smaller muscular arteries. These arteries have a large proportion of elastic fibers throughout all three tunics, especially in the tunica media. The abundant elastic fibers allow the artery to stretch and accommodate the blood when a heart ventricle ejects blood into it during ventricular systole (contraction) and then recoil, which helps propel the blood through the arteries during ventricular diastole (relaxation).

Continuous capillaries

- are the most common type of capillary. The endothelial cells form a complete, continuous lining around the lumen that rests on a complete basement membrane.

arterioles

- are the smallest arteries, with diameters ranging from 0.3 millimeters to 10 micrometers. In general, ________________________ have fewer than six layers of smooth muscle in their tunica media. Larger ________________ have all three tunics, whereas the smallest _________________ may have a thin layer of endothelium surrounded by a single layer of smooth muscle cells. Smooth muscle in the arterioles usually is at least slightly constricted (just as your skeletal muscles often are in a partial state of contraction)

Arteries walls characteristics

- tend to have a round lumen and relatively thick wall. - The tunica interna of ___________ is rippled and possesses an internal elastic membrane. - have a thick tunica media dominated by smooth muscle and elastic fibers. - possess an external elastic membrane within its tunica media. - have a tunica externa made of collagen and elastin fibers with a nervi vasorum and vasa vasorum present.

Blood velocity

- the rate of blood flow through a blood vessel. - is inversely proportional to the cross-sectional surface area of the vessels; the more surface area - the more friction - the slower blood flows. - Even though individual capillaries are small, there are so many of them they collectively have a very high surface area. - Capillaries have the highest cross-sectional area and blood traveling through them is therefore very slow. - Arteries and veins are larger with high individual surface area but they are far less numerous than capillaries so collectively they generate less cross-sectional surface area so blood moves through them faster.

Muscular arteries

- typically have diameters ranging from 1 centimeter to 0.3 millimeters. These medium-sized arteries are also called distributing arteries because they distribute blood to specific body regions and organs..They have a proportionally thicker tunica media, with multiple layers of smooth muscle cells. Unlike in elastic arteries, the elastic fibers in ________________________________ are confined to two circumscribed sheets: The internal elastic lamina, and the external elastic lamina.

What are the 3 tunics of blood vessels?

-Tunica intima, interna -Tunica media -Tunica externa, adventitia

As an artery increases:

-decrease in the amount of muscle fibers -increase in the amount of smooth muscle

How many capillaries grouped together is considered a capillary bed?

10-100

Portal system

2 consecutive beds before returning to heart

Veins carry what percentage of blood when at rest?

60 percent

vasomotor tone

A slightly constricted state is called ___________________________________________and is regulated by the vasomotor center in the brainstem. Arterioles have a significant role in regulating systemic blood pressure and blood flow to different areas of the body.

What is the hepatic portal system?

A venous network that drains the GI tract and shunts the blood to the liver of processing and absorption of transported materials

lungs

ACE (angiotensin-converting enzyme)

Functions of endothelium

Acts as a selectively permeable barrier and secretes chemicals that stimulate dilation or constriction

Blood viscosity

Amount of Formed elements within blood (blood thickness)

Function of Tunica externa

Anchors the vessel and provides passage for small nerves, lymphatic vessels

Liver

Angiotensinogen

Conducting (elastic/large) arteries are found in

Aorta, common carotid, subclavian, pulmonary trunk and common iliac arteries

Hemorrhoids

Are Dilated veins in anus, which can cause pain & are easy to rupture(cause bleeding)

Capillaries

Are the smallest vessels within the circulatory system. Connects the smallest(Resistant) arteries to the veins. This is where diffusion of gases & nutrients occurs between blood & interstitial fluid.

Systolic pressure

BP during ventricular contraction. In BP test it's the first heart beat sound heard. Normal range 120

Distolic pressure

BP during ventricular relaxation. Is the sound BP test heard when releasing the pressure. Normal range 80

aneurysm

Ballooning of a weakened arterial wall, resulting from sudden pressure increase

How is blood flow affected by constriction of precapillary sphincters

Blood flow is reduced and it diverts blood to other tissues

Blood Hydrostatic Pressure

Blood pressure the force exerted per unit area by the blood as it presses on vessel wall Promotes filtration

Vascular length resistance

Blood pressure & flow decrease with distance (increases friction). Longer the length = more resistance/friction

Veins

Blood vessels that drain capillaries and return blood to the heart Pressure is much lower than in arteries At rest, old about 60% of the body's blood. Thus, unction as blood reservoirs.

Blood viscosity & polycythemia

Blood viscosity is high (thick consistency)

Blood viscosity & Anemia

Blood viscosity is low. (Blood is a thin consistency)

Capillaries

Body's MOST IMPORTANT blood vessel Renew and refresh interstitial fluid by: Delivering O2 and nutrients & Removing CO2 and nitrogenous wastes Smallest of all blood vessels Diameter only slightly larger than an erythrocyte Wall consists solely of the tunica intima (a single layer of endothelial cells) Only type of blood vessel where metabolic exchange can occur between blood and cells outside of the bloodstream Form capillary beds Branches from the metarteriole that begin with a ring of smooth muscle on their walls are called true capillaries

Arteries

Branch, Diverge, Fork Carry blood away from the heart and become progressively smaller as they branch and finally result in capillaries

Bulk Flow Reabsorption

Bulk flow into blood Venous end of capillary

tunica intima

Capillaries are unique in that they contain only the _________________________ composed of an endothelium and its underlying basement membrane; there is no subendothelial layer. Having only the _____________________ allows for rapid gas and nutrient exchange between the blood in capillaries and the tissues.

capillary bed

Capillaries do not function independently; rather, a group of capillaries (10 to 100) function

Where does diffusion of gases & nutrients between blood & interstitial fluid occur?

Capillary

Arteries

Carries blood away from the heart & are red in colors because of the high amount of oxygen concentration

Arteries

Carries blood away from the heart to capillaries thicker tunica media narrower lumen more elastic and collagen fibers more resilient and resistant to changes in blood pressure than veins remains open fast blood velocity

Veins

Carries blood back to the heart from organs & limbs. It appears blue because lacking oxygen

Veins

Carry blood from capillaries to heart thicker tunica externa wider lumen less elastic and collagen fibers wall of vein collapses if no blood in it valves present fast blood velocity

Tunica Intima

Composed of an endothelium (simple squamous epithelium lining the inside of the arteries and veins) and a subendothelial layer of areolar connective tissue

Tunic media

Comprised of circularly arranged smooth muscle. Sympathetic input causes this smooth muscle to contract resulting in vasoconstriction. Parasympathetic input results in vasodilation.

Ductus Venosus

Connect umbilical vein & will send blood to the left part of heart. After birth will become the ligamentum VENOSUM

Tunica externa

Connective tissue helps anchor the blood vessel to an organ Larger blood vessels vascularized by smaller arteries called vasa vasorum which runs through

Ductus Arteriosus

Connects blood from the pulmonary trunk to the aorta. After birth it will become the ligamentum ARTERIOSUM

What are the 3 types of capillaries

Continuous Fenestrations (pores) Sinusoid

Types of Capillaries

Continuous, Fenestrated, Sinusoid

vasoconstriction

Contraction of smooth muscle in the tunica media results in _____________________________________, or narrowing of the blood vessel lumen.

Length versus diameter vessels

Differences in diameter have much more significant effects on resistance than do differences in length. If two vessels are equal in diameter but one is twice as long as the other, the longer vessel offers twice as much resistance to blood flow. But for two vessels of equal length, one twice the diameter of the other, the narrower one offers 16 times as much resistance to blood flow. For this reason, the brain typical initiates changes in blood vessel diameter (by *vasoconstriction* and *vasodilation*) to regulate blood pressure. However, abnormal narrowing of a vessel due to a plaque buildup (as with *atherosclerosis*) leads to hypertension and increased risk of heart attack (*myocardial* *infarction*) and stroke (*cerebral* *vascular accident*).

Varicose veins

Dilated veins that are usually visible.

Four Routes of Capillary Permeability

Direct diffusion through endothelial cell membrane: CO2 and O2 Intercellular clefts: Transport most small molecules Cytoplasmic vesicles (caveolae): Large molecules such as small proteins Fenestrations: Small molecules

Sinusoid

Discontinuous capillaries Enlarged capillary that serves as a blood channel red bone marrow liver and spleen endocrine glands

Capillary Permeability

Endothelial cells held together mostly by tight junctions Tight junctions block passage of small molecule but do not surround entire cell So there are gaps of unjoined membrane called intercellular clefts where small molecules enter and exit capillary Pericytes strengthen capillary

Fenestrated Capillaries

Endothelial cells possess small "holes" to allow fluid exchange between blood and interstitial fluid

Increase venus return by

Exercising

Vascular resistance

Friction between blood & vessel walls & is determined by 2 factors Vessel length & Vessels diameter (radius)

Fenestrations (pores) capillary

Has an incomplete basement lining. This capillary allows a passive or active secretion/execration materials/fluids e.g. Choroid plexus(secretes CSF)

Sinusoid Capillaries

Have big gaps between endothelial cells that promotes transport of large molecules and cells to and from the blood

Where would you find the portal system

Hypothalamus and anterior pituitary Kidney Intestines to liver

Reactive hyperemia

If blood supply cut off then restored, flow increases above normal. This may be due to the accumulation of metabolites during the period of ischemia. When the skin flushes after coming from the cold. Occurs in the forearm if a BP cuff is inflated for too long

Metabolic theory of autoregulation

If tissue is inadequately perfused, waste accumulate, stimulating vasodilation which increases perfusion Blood stream delievers oxygen and removes metabolites When wastes are removed, vessels constrict

Net filtration pressure step 3:

In the middle of the capillary bed CHP and BCOP are equal so that NFP = Zero. This means there is no net movement and materials are moving in and out equally.

The effect of age in BP level usually

Increase level with age

Macrophage (phagocytes)

Is a bacteria found in the sinusoid capillaries that are scavenges for waste through out the blood system.

Endocrine control regulation BP & blood flow

Is a direct long term changes e.g. Any hormone (ADH)

Comparison/structure of vein

Lumen: Shaped is irregularly Thickness of Wall: Walls are Thin Internal Elastic Membrane: Not visible Thickest Coast (layer): Tunic adventitia (external) Valve: Has valves which prevent black flow of blood that is caused by gravity. Isn't a smooth muscle. This vessel's diameter is larger than arteries This vessel expands easier at low pressure(capacitance vessel)

Muscle Arteries

Medium diameter arteries Possess two concentric rings of elastic fibers in between the three tunics: Internal elastic lamina, External elastic lamina Proportionately thicker tunica media

Capillaries

Microscopic, pourrons vessels. Site of exchange of substances between blood and tissues only contains tunica intima no subendonthelial layer thin barrier allows for rapid gas and nutrient exchange smallest blood vessels only simple squamous cells 60,000 miles of capillaries greatest cross sectional area and slowest blood flow slow blood velocity

Tunica Media

Middle layer of blood vessel wall smooth muscle cells elastic fibers vasoconstriction(narrowing) vasodilation(widens)

Venous anastomosis

Most common One vein empties directly into another, which provides several alternative routes of drainage from an organ. Reason vein blockage is less serious than arterial blockage

Continuous Capillaries

Most common type, endothelial cells form a continuous and complete lining (no physical holes) aided by the presence of tight junctions

Why are 3/4 of body's capillaries shut down

Most control of flow involves constriction of arterioles that are upstream from the capillaries.

arterioles

Most named arteries (e.g., the brachial, anterior tibial, coronary, and inferior mesenteric arteries) are examples of muscular arteries. Muscular arteries branch into ________________________.

Vascular Anastomoses

Neighboring arteries often communicate with one another Alternate pathways for blood flow These collateral channels can maintain adequate blood supply when one branch is occluded Coronary artery can be 90% before myocardial infarction Veins anastomose much more readily than arteries

Capillary Beds

Network of capillaries running throughout most tissues Tissues with capillaries said to be vascularized Each bed is fed by a metarteriole whose proximal end is surrounded by smooth muscles while the distal end, called the thoroughfare channel lacks smooth muscles.

neural regulation

Neurotransmitter binding [Ca2+] in sarcoplasm; either graded (local) potential or action potential; Response depends on neurotransmitter released and type of receptor molecules

Net filtration pressure step 1:

On the arterial end of the capillary bed, CHP is greater than BCOP so that NFP is positive. The positive number indicates a net movement of materials out of the bloodstream (such as water, nutrients, and oxygen).

Net filtration pressure step 2:

On the venous end of the capillary bed, CHP has dropped while BCOP has remained relatively constant. The net effect is that BCOP is now greater than CHP and NFP is negative. The negative number indicates a net movement of materials into the bloodstream (such as water, wastes, and carbon dioxide).

General Arterial Flow Out of the Heart

Oxygenated blood is pumped out of left ventricle into Ascending Aorta in to the Aortic Arch. Ascending aorta gives off two branches: Left coronary artery (A) & Right coronary artery (B) Aortic arch gives off three branches: Brachiocephalic trunk (C) which bifurcates into right common carotid (D) and right subclavian (E) arteries Left common carotid artery (F) Left subclavian artery (G) Descending thoracic aorta follows the aortic arch and gives off several branches to the thoracic wall It is renamed the descending abdominal aorta when it passes inferior and posterior to the diaphragm At the fourth lumbar vertebra, the aorta bifurcates into left and right common iliac arteries The common iliac arteries further divide into internal and external iliac arteries

Vasomotion

Precapillary sphincters go through cycles of contracting and relaxing at a rate of about 5 to 10 cycles per minute

How is blood flow controlled within the capillary beds

Precapillary sphincters relax to allow the capillaries to become perfused with blood, contractions limits the entry of blood

interstitial fluid hydrostatic pressure

Pressure that would push fluid into vessel Usually assumed to be zero so basically no pressure

What do endothelium do when tissues around the vessel are inflamed

Produce cell-adhesion molecules that induce leukocytes to adhere to the surface. This causes leukocytes to congregate in tissues where their defensive actions are needed

capillary blood colloid osmotic pressure (BCOP)

Puts fluids back into the capillary e.g. reabsorption At the end of the venous capillary

Blood viscosity

RBC count and albumin concentrations ELEVATE viscosity the most Increased viscosity with polycythemia and deydration slow flow

vasodilation

Relaxation of the smooth muscle causes _____________________________________, or widening of the blood vessel lumen.

Kidney

Renin

1- Liver continuously produces angiotensinogen 2- Kidneys detect low blood pressure and release renin 3- Renin converts angiotensinogen into angiotensin I 4- ACE (found in lungs) converts angiotensin I into angiotensin II 5- Angiotensin II increases BP by vasoconstriction, stimulating thirst center, and decreasing urine

Renin-Angiotensin System

What is pulmonary circulation?

Responsible for carrying deoxygenated blood from the right side of the heart to the lungs, and then returning the newly oxygenated blood to the left side of the heart

Coronary circuit blood flow

Rest: 250 mL/min light exercise: 350 mL/min Heavy exercise: 750 mL/min

brain blood flow

Rest: 750 ml/min light exercise: 750 ml/min Heavy exercise:750 ml/min

Arteriole

Smallest arteries Less than 6 cell layers of smooth muscle in their tunica media Sympathetic innervation to the muscle fiber cells of the tunica media causes vasoconstriction resulting in elevation of blood pressure Parasympathetic innervation causes vasodilation and a lowering of blood pressure

Venule

Smallest veins Companion vessels with arterioles Smallest ones are located at the distal end of a capillary bed and are called postcapillary venules Diapedesis occurs through the walls of the postcapillary Merge to form veins

How to prevent excessive blood pressure

Strech and recoil during the cardiac cycle. This prevents the flow and stop and the stress on the small vessels

Function of Tunica media

Strengthens vessels and prevents blood pressure from rupturing them. Regulates the diameter of the blood vessel.

External carotid

Supplies most external head structures

Edema

Swelling of fluid in the peripheral tissue usually happens because there is less formed elements in your blood e.g. Anemia

BP=

Systolic Pressure ...120 ———__normal range—— Distolic pressure... ..80

cardiovascular control centers

The _____________ are primarily located in the hypothalamus and require the stimulation of baroreceptors and chemoreceptors. The medulla oblongata can coordinate respiratory activities to enhance control.

tunica media

The ____________________ is the middle layer of the vessel wall. It is composed predominantly of circularly arranged layers of smooth muscle cells that are supported by elastic fibers.

tunica externa

The ________________________, or tunica adventitia, is the outermost layer of the blood vessel wall. It is composed of areolar connective tissue that contains elastic and collagen fibers. The _________________________ helps anchor the vessel to other structures. Very large blood vessels require their own blood supply to the ______________________ in the form of a network of small arteries called the vasa vasorum. The vasa vasorum extend through the ____________________________.

blood brain barrier

The _______________________________ is formed by modified continuous capillaries that have thickened basement membranes and no intercellular clefts. Substances can pass through endothelial cells only by regulated cellular processes. However, movement of nonpolar substances is not regulated by cells and so these nonpolar substances (e.g., nicotine, alcohol) may pass through the cells by simple diffusion and enter the brain.

internal elastic lamina

The ______________________________________ separates the tunica intima from the tunica media.

external elastic lamina

The _________________________________________ separates the tunica media from the tunica externa.

elastic arteries

The aorta, the pulmonary trunk, and brachiocephalic, common carotid, subclavian, and common iliac arteries---- are all some examples of _______________________________. These arteries branch into muscular arteries.

Tunica adventitia (tunic external)

This vessel wall is made up of aeroal tissue (LCT) & has the Vaso Vasorum.

tunica intima

The innermost layer of a blood vessel wall is the ______________________________, or tunica interna. It is composed of an endothelium ( a simple squamous epithelium) that faces the blood vessel lumen and a thin subendothelial layer made up areolar connective tissue. This layer provides a smooth surface as the blood moves through the lumen of the blood vessel. It is continuous with the endocardium, which is the inner lining of the heart.

Diapedesis

The migration of leukocytes from the bloodstream to the body

rouleau

The narrow vessel diameter means erythrocytes must travel in single file ( termed _______________) through each capillary. Capillaries consist solely of an endothelial layer resting on a basement membrane. The narrow vessel diameter and the thin wall are optimal for exchange of substances between blood and body tissues.

Tunica intima

This vessel wall is made up of simple squamous & contains an INTERNAL ELASTIC MEMBRANE.

Pulmonary circulation consists of vessels that take?

blood to the lungs for gas exchange

Blood Pressure

The pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure. The blood pressure in the circulation is principally due to the pumping action of the heart. Differences in mean blood pressure are responsible for blood flow from one location to another in the circulation. The rate of mean blood flow depends on both blood pressure and the resistance to flow presented by the blood vessels. Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Mean blood pressure drops over the whole circulation, although most of the fall occurs along the small arteries and arterioles.

How does capillary exchange occur

The process like diffusion, filtration, & reabsorption.

Perfusion

The specific amount of blood entering capillaries per unit time per gram of tissue (mL/min/g)

Increasing distance from left ventricle causes

The systemic blood pressure to decrease (venae cavae is the lowest)

Circulatory Shock

There are several recognized forms of shock which can occur with the failure to maintain blood pressure or blood flow: 1. Hypovolemic shock 2. Cardiogenic shock 3. Distributive shock 4. Obstructive shock

Muscular arteries

Thicker tunica media distributing arteries-distribute blood to specific body parts more smooth muscle than elastic fibers branch into arterioles

Why do veins have a greater capacity for blood containment than arteries

Thinner walls, flaccid, less muscular and elastic tissue Collapse when empty, expand easily Have steady blood flow Merge to form larger veins Low blood pressure

Continuous capillary

This capillary has a complete endothelial lining. Is usually found on the basement membrane & has no gabbed spaces between cellular layers. Is found in skeletal muscles

Umbilical Arteries

Will drain blood back from the the fetus to the mother. Looks blue because of low O2. After birth will turn into the MEDIAL UMBILICAL LIGAMENT

Smooth muscle, 3/4

___ layer constitutes about ___ of wall thickness

Capillaries connect

________ arteries to veins and are the site of nutrient and waste exchange. A capillary is a microscopic channel that supplies blood to the tissues themselves, a process called perfusion.

Large veins

________ include the superior and inferior venae cavae and their tributaries. All three vessel wall layers are present in all _____________. The slender tunica media is surrounded by a thick tunica externa composed of a mixture of collagen and elastin fibers. Some __________ are flattened with extremely thin walls. These are called *venous sinuses* and are found in the heart (coronary sinus) and the brain (dural sinuses).

Vessel diameter

_________ Friction also occurs between layers of fluid moving at different speeds. The layer of blood closest to the vessel wall is slowed down by friction with the endothelial surface. The adjacent layer of blood is slowed down by friction with the more superficial layer. As blood proceeds toward the capillaries, the diameter of arteries decreases markedly; as blood returns toward the heart, the diameter of veins increases. This gradually diminishes as the distance from the wall increases. In a small-diameter vessel, all the blood is slowed to some degree and therefore resistance is high. In a large diameter vessel the central region is unaffected by events at the periphery, so the resistance is relatively low.

Vessel length

_________ Friction occurs between the moving blood and the walls of the vessel. The longer the________, the greater the surface area in contact with the blood, and therefore the greater the resistance. The most dramatic changes in blood ___________ occur between birth and adulthood. Once the reach adulthood, ____________ is relatively constant.

Blood flow (F)

_________ also called *tissue* *perfusion*, is defined as the volume of blood flowing through a vessel, an organ, or the entire circulation. - Systemic tissue perfusion occurs along the following path: left ventricle of the heart aorta, elastic and muscular arteries, arterioles, capillaries, venules, small veins, medium-sized veins, large veins, and finally superior and inferior vena cava to the right atrium of the heart. - The cardiovascular centers make extensive adjustments to cardiac output and blood distribution during changes in physical activity.

Venules

_________ drains capillary beds into veins. These are extremely porous and are often more similar in structure and function to capillaries than to veins. Many _________ possess only endothelium and pericytes while others may have scanty tunica media and a thin tunica externa.

blood pressure (BP)

_________ is defined as the amount of force per unit area exerted on the wall of a blood vessel by the blood contained within it. Pressure is measured in mmHg. - In general terms, *blood flow (F)* is directly proportional to the blood pressure (increased pressure results in increased flow), and inversely proportional to peripheral resistance (increased resistance results in decreased flow).

Anti-diuretic hormone (ADH)

_________ is secreted by the pituitary gland.__________enhances water reabsorption in the kidney so that urine output is reduced and blood volume rises. Increased blood volume increases blood pressure.

Cardiogenic shock

_________ results from the inability of the heart to maintain cardiac output. Most often, it results from a myocardial infarction (heart attack), but it may also be caused by arrhythmias, valve disorders, cardiomyopathies, cardiac failure, or simply insufficient flow of blood through the cardiac vessels. Treatment involves repairing the damage to the heart or its vessels to resolve the underlying cause, rather than treating _____________directly.

Hypovolemic shock

____________ in adults is typically caused by hemorrhage, although in children it may be caused by fluid losses related to severe vomiting or diarrhea. Other causes for __________ include extensive burns, exposure to some toxins, and excessive urine loss related to diabetes insipidus or ketoacidosis. Typically, patients present with a rapid, almost tachycardic heart rate; a weak pulse often described as "thread;" cool, clammy skin, particularly in the extremities, due to restricted peripheral blood flow; rapid, shallow breathing; hypothermia; thirst; and dry mouth. Treatments generally involve providing intravenous fluids to restore the patient to normal function and various drugs such as dopamine, epinephrine, and norepinephrine to raise blood pressure.

Filtration

____________ refers to the movement of materials OUT of the bloodstream while *reabsorption* refers to the movement of materials INTO the bloodstream.

Distributive shock (vascular shock)

______________ occurs when arterioles lose their normal muscular tone and dilate dramatically. A common cause is *sepsis* (or septicemia), also called "blood poisoning," which is a widespread bacterial infection that results in an organismal-level inflammatory response known as septic shock. Neurogenic shock is a form of vascular shock that occurs with cranial or spinal injuries that damage the cardiovascular centers in the medulla oblongata or the nervous fibers originating from this region. Anaphylactic shock is a severe allergic response that causes the widespread release of histamines, triggering vasodilation throughout the body.

Sinusoids

_________________, or discontinuous capillaries, have an incomplete lining of the endothelial cells with large opening or gaps, and the basement membrane is either discontinuous or absent. These openings allow for transport of large substances (formed elements, large plasma proteins), as well as plasma between the blood and tissues. _____________________ are found in bone marrow for entrance of formed elements into the circulation, the liver and spleen for removing aged erythrocytes from circulation, and some endocrine glands for facilitating the movement of hormone molecules into the blood.

Obstructive shock

__________________, as the name would suggest, occurs when a significant portion of the vascular system is blocked. It is not always recognized as a distinct condition and may be grouped with cardiogenic shock. The most common cause is a pulmonary embolism, a clot that lodges in the pulmonary vessels and interrupts blood flow. Other causes include stenosis of the aortic valve; cardiac tamponade, in which excess fluid in the pericardial cavity interferes with the ability of the heart to fully relax and fill with blood (resulting in decreased preload); and a pneumothorax, in which an excessive amount of air is present in the thoracic cavity, outside of the lungs, which interferes with venous return, pulmonary function, and delivery of oxygen to the tissues.

Arteries

___________________ may be classified into three basic types: elastic arteries, muscular arteries, and arterioles.

Compliance

__________is the ability of any vessel to expand to accommodate increased content. A metal pipe, for example, is not compliant, whereas a balloon is. Veins are more compliant than arteries and can expand to hold more blood resulting in less pressure. When vascular disease causes stiffening of arteries (as with *arteriosclerosis*), _________ is reduced and resistance to blood flow is increased. The result is higher pressure within the vessel and reduced blood flow.

What do capillaries only consist of?

a basement membrane and edothelium

Continuous capillary

a capillary with an intact endothelium that forms a tube interrupted only by intercellular clefts; found in most capillaries plasma and its contents pass through

Fenestrated Capillary

a capillary with small pores in its endothelium found in the kidneys, small intestine, choroid plexuses of the ventricles in the brain, endocrine glands large amounts of materials are filtered released or absorbed eye

The heart and blood vessels form what?

a closed loop

blood brain barrier

a continuous capillaries that have thickened basement membrane and no intercellular clefts, substances can only move through endothelial cells by facilitaed diffusion or active transport

Renin Angiotensin II

a drop in blood pressure or blood volume is detected by *baroreceptors* of the kidney. Renin is released and activates angiotensin I (already in the bloodstream) and is converted to the activated angiotensin II, a potent vasoconstrictor. This increases peripheral resistance and blood pressure rises. Plus, angiotensin stimulates the release of other hormones.

Lumen

a hollow passageway through which blood flows

Nitric oxide

a potent vasodilator which reduces peripheral resistance which in turn, reduces blood pressure.

Capillary Hydrostatic Pressure (CHP)

a push out of the bloodstream generated by fluids within the vessel.

Blood Colloid Osmotic Pressure (BCOP)

a suction into the bloodstream generated by large immovable plasma proteins.

types of veins

a. Venules b. Medium-sized veins c. Large veins

Where would you expect to find an aneurysm

abdominal aorta, renal arteries and arterial circle at base of brain

Hypervolemia

abnormally high levels of fluid and blood within the body.

Hypovolemia

abnormally low levels of fluid and blood within the body

veins as blood reservoir

about 55% of blood is in blood reservoirs in veins, blood my be shifted from venous reservoirs into circulation

Primary role of chemoreflex

adjust respiration to changes in blood chemistry

BP tends to rise with

age

Large vein

aka Superior eg. Vene cava

Medium sized vein

aka inferior

arterial anatomosis

allow blood supply to reach target capillary bed even when there is a blockage in one of the arteries

What do capillaries do?

allow gas exchange between blood and body tissues

Capillary exchange

allows exchange of substances between blood and surrounding tissues Diffusion Vesicular transpot Bulk flow

Elastic arteries

also known as conducting vessels, found near the heart because they can withstand the highest blood pressures (aorta and its immediate branches); diameter = 2.5 cm to 1 cm; possesses large amounts of elastin fibers in the tunica media forming a "holey sheet" (like Swiss cheese); has substantial smooth muscle in the tunica media, however they have little ability to vasoconstrict.

Muscular Arteries

also known as distribution vessels; delivers blood to specific body organs (renal artery, mesenteric artery, gastric artery, etc.); diameter = 1 cm to .3 mm; the tunica media has relatively more smooth muscle and less elastin than elastic arteries; very active in vasoconstriction and are less distensible.

Arterioles

also known as resistance vessels; regulate blood flow into capillaries; diameter = .3 mm to 10 micrometers; the tunica media is almost entirely smooth muscle w/ little to no elastin fibers; tunica externa is poorly defined.

Arteries

always carry blood away from the heart to the capillaries, typically red on models because they generally carry oxygenated blood.

Veins

always return blood from capillaries to the heart; typically blue on models because they generally carry deoxygenated blood.

Blood flow

amount of blood flowing through an organ, tissue or blood vessel in a given time

What is the circle of Willis?

an anastomosis of arteries around the sellae turcica

What does the tunica externa do?

anchor the vessel to other tissues

Decrease viscosity with

anemia and hypoproteinemia

circulatory shock

any state of the body when the cardiac output is not sufficient to meet the metabolic demands of the body

Veins function as what?

blood reservoirs

examples of elastic arteries

aorta, pulmonary trunk, brachiocephalis, common carotid, subclavian, and common iliac

vagus nerve

aortic to cardiac center

Capillaries

are microscopic, relatively porous blood vessels for the exchange of substances between blood and tissues.

What is the tunica externa primarily composed of?

areolar connective tissue contains elastic and collagen fibers

NFP in capillary

arterial end of the capillary bed=Hydrostatic pressure is greater than COP=filtration venous end=COP is greater that Hydrostatic pressure=reabsorption

companion vessels

arteries and veins that supply the same body region and tend to lie next to one another

systemic circulation blood flow

arteries carry blood high in O2 veins carry blood low in O2

pulmonary circulation blood flow

arteries carry blood low in O2 veins carry blood high in O2

Capillaries connect what two structures in the body?

arterioles and venules

Arteriovenous anastomosis (shunt)

artery flows directly into vein, bypassing capillaires

Arteriosclerosis

artery stiffening due to deterioration of elastic tissues of artery walls

simple pathway

artery to arteriole to single capillary bed to venule to vein to heart, repeat

Companion vessels

artier and veins supply the same area

Medullary ischemic reflex

automatic response to a drop in perfusion of the brain Increases heart rate and contraction force Causes widespread vasoconstriction Raises BP and restores normal perfusion to the brain

Where do arteries convey blood?

away from the heart

cardiovascular center

baroreceptors send signal to

Why is the hepatic portal system needed?

because the GI tract absorbs digested nutrients, and these nutrients must be processed and/ or stored in the liver

Arteries______ until they feed into______

bifurcate; capillaries

portal system

blood flow through two capillary beds, with two capillary beds separated by a portal vien

Tissues of the inner half of the wall are though to be nourished by diffusion from ___

blood in the lumen

mesenteric veins do not enter vena cava

blood is filtered through liver and spleen first

BP determined by

cardiac output(blood flow of left ventricle), blood volume & peripheral resistance

Hypertension (High blood pressure)

can weaken arteries, cause aneurysms and promote atherosclerosis

What is the smallest blood vessel?

capillaries

What structure in the blood vessels contain only tunica interna?

capillaries

An example of closed sphincters

capillaries in skeletal muscles at rest

Stimulates most vessels to constrict, but dilates vessels in ____ to meet demands of exercise

cardiac muscle

reactive hyperemia

condition when local blood flow is restored, there is a marked increase in blood flow to the affected tissue

Tunica externa

consists of loose connective tissue that often merges with that of neighboring blood vessels, nerves or other organs.

What is the most common type of capillary?

continuous

What are the 3 types of capillaries?

continuous cappilarries fenestrated capillaries sinusoids

types of capillaries

continuous, fenestrated, sinusoids

myogenic response

contraction and relaxation of smooth muscle in response to changes in stretch of blood vessel wall

Resistance (small) arteries/ arterioles (smallest arteries)

control amount of blood to various organs

Two purposes of vasoreflexes

control of BP routin blood from one body region to another

cardiac center

controls heart activity (cardiac output)

Vascular diameter(radius) resistance

controls resistance quickly by vasomotions which include Vasoconstriction = increase BP Vasodilatation= decrease BP

vasomotor center

controls vasoconstriction/dilation of blood vessels

Anastomosis

convergence point between two vessels other than capillaries

Artery

convey blood away from the heart

Arteries

convey blood away from the heart to the capillaries.

glossopharyngeal nerve

corotid to cardiac center

Pressure and flow __ with distance

decline

Vasodilatation

decrease BP

Pulmonary arteries carry what type of blood to the lungs?

deoxygenated

cardiac output, resistance, blood volume

dependent variables of blood pressure

MAP

diastolic pressure = 1/3pulse pressure

Pulse pressure

difference between systolic and diastolic pressure

Vigorous exercise ___ artieries in lings, heart and muscles and ___ in kidneys and DI

dilates; constricts

Function of distributing arteries

distributes blood to specific organs

What are some symptoms of venous pooling

dizziness, syncope(shaking), & or shock. These venous pooling usually occurs because of prolong standing & other actives.

Veins

drain blood from the capillaries, transporting it back to the heart.

Veins drain what and return where?

drain-capillaries return to -heart

hepatic portal system

drains deoxygenated but nutrient-filled blood to the liver allows liver to process first

hepatic vein

drains from liver to inferior vena cava

hepatic portal vein

drains into liver

Capillary hydrostatic pressure (CHP)

drives fluid out of of capillary e.g. Filtration is which at the end of the arterial capillary

ligamentum arteriosum

ductus arteriosus becomes

ligamentum venosum

ductus venosum becomes

Sympathetic motor tone

vasocontricted- decreases blood flow vasodilated-increase blood flow

What are the 3 basic types of arteries?

elastic muscular arterioles

types of arteries

elastic, muscular, arterioles

vesicular transport

endothelial cells use pinocytosis to form fluid-filled vesicles, which are then transported to the other side of the cell and released by exocytosis

What are capillaries made of

endothelium and basal limina

Cusps of the valves pull apart in ____, further weakening vessels

enlarged superficial veins

What is the tunica intima composed of?

enothelieum and subendothelial layer

At rest, total flow is rather constant and is ___ to the cardiac output

equal (5.25 L/min)

What does the circle of Willis do?

equalizes blood pressure in the brain -provide collateral channels should a blood vessel be blocked

total cross sectional area

estimated lumen diameter across the total number of a given type of vessel

angiotensin II, alddosterone, ADH, norepinephrine

examples of local vasoconstrictors

ANP and epinephrine

examples of local vasodilators

Capillaries

exchange substances between blood and tissue

Capillaries

exchange vessels; site where gasses nutrients, wastes and hormones pass between the blood and tissue fluid.

Systemic circulation consists of blood vessels that?

extend to and from the body tissues

Sinusoidal Capillaries

least common of the three; leaky capillaries because tight junctions are rare and *intercellular clefts* are abundant. Commonly found in areas where cells must leave circulation and move to the tissues such as bone marrow, liver, and lymph organs. *Kupffer cells* are specialized phagocytic cells found in the sinusoidal capillaries of the liver. They act as macrophages that extend into the lumen of the capillary to capture prey.

Where do pulmonary veins carry oxygenated blood?

left atrium of the heart

The pulmonary trunk bifurcated into a?

left pulmonary artery and right pulmonary artery to the lungs

The greater the resistance, the ___ the flow

less

continuous capillary

lining of endothelial cells is complete around lumen; basement membrane is complete; intercellular clefts between endothelial cells; most capillaries

sinusoid

lining of endothelial cells is incomplete around lumen; basement membrane is incomplete or absent; red bone marrow, liver, spleen, anterior pituitary, adrenal, and parathyroid

3 ways of controlling vasomotor activity

local, neural and hormonal

Baroreceptors

located in the *carotid sinuses*, aorta, and right atrium; detect changes in blood pressure. When the baroreceptors detect an increase in blood pressure, they send a signal to the hypothalamus which in turn, triggers vasodilation, a decrease in heart rate, and a reduction in cardiac output. When they detect a decrease in blood pressure, they send a signal to the hypothalamus which in turn, triggers vasoconstriction, an increase in heart rate, and an increase in cardiac output.

Chemoreceptors

located in the carotid sinuses and aortic arch; detect changes in blood composition. When the chemoreceptors detect an increase in carbon dioxide or a decrease in oxygen concentration or pH, they stimulate mechanisms such as vasoconstriction or increased cardiac output and blood pressure.

carotid sinus, aortic arch, and right atrium

location of baroreceptors

aortic bodies and carotid body

location of peripheral chemoreceptors

Role of Lymphatic System

lymph vessels reabsorb excess fluid, filter it, and return it to the venous circulation

splenic, inferior mesenteric, and superior mesenteric veins

main blood vessels draing hepatic portal system

left gastric, splenic, and common hepatic arteries

main branches exiting the celiac trunk

baroreceptors

measures stretch of blood vessels

The heart is the _________

mechanical pump

muscular arteries

medium-sized arteries, distributing arteries, proportionately thicker tunica media with multiple layers of smooth muscle cells

tunica media

middle layer of vessel wall, smooth muscle cells (letter C)

Tunica media

middle layer which functions in *vasodilation* and *vasoconstriction*; composed mostly of smooth muscle, collagen, and elastin fibers. Large arteries also possess an external elastic membrane.

Diastolic pressure

minimum arterial BP taken during ventricular relaxation between heart beats

Continuous Capillaries

most abundant; these capillaries possess an uninterrupted layer of squamous cells. The cells are connected by *tight junctions* and have few *intercellular clefts*. These are common in skin, muscle, and brain tissues.

examples of muscular arteries

most named arteries, brachial, anterior tibial, coronary, and inferior mesenteric arteries

Vessel radius

most significant influence over flow Only significant way of controlling resistance through vasoreflexes

venous return

movement of blood from capillaries back to the heart via the veins

Bulk Flow

movement of large amounts of fluid and their dissolved substances in one direction down a pressure gradient

diffusion

movement of substances from high concentration towards lower concentration

Blood Distribution at Rest

pulmonary circulation-18% Heart-12% Systemic circulation-70%

What can blood vessels also do?

pulsate change shape

Blood flow in the arteries is

pulsatile

facial artery

pulse location: anterior to angle of the mandible

superficial temporal artery

pulse location: anterior to ear

dorsalis pedis

pulse location: dorsal interspace between the first and second toes

femoral artery

pulse location: inferior to the inguinal ligament (groin)

common carotid artery

pulse location: lateral to the larynx and trachea

brachial artery

pulse location: medial surface of the arm, between axilla and antecubital

popliteal artery

pulse location: popliteal fossa

posterior tibial artery

pulse location: posteroinferior to the medial malleolus of the tibia

As skeletal muscles contract, veins are squeezed to help what?

pump blood back into the heart

small changes in blood vessel ___ can cause large changes in flow

radius

Medium-sized veins

range from 2 - 9 mm in diameter; the tunica media is thin and contains smooth muscle cells and collagen fibers. The thickest layer is the tunica externa, which contains smooth muscle cells and longitudinal bundles of elastic and collagen fibers. Valves, particularly within veins of the limbs, are common.

Blood flow velocity

rate of blood transported per unit time (cm/sec) blood always moves along a hydrostatic pressure gradient water flow in river-artery,capillary,vein

blood flow velocity

rate of blood transported per unit time and typically measured in centimeters per second

venous end

reabsorption in capillary bed

Why doe conducting arteries recoil diastole

recoil maintains pressure during relaxation and keeps blood flowing

Shunts occur in the fingers, palms, toes and ears, where they __

reduce heat loss in cold weather by allowing warm blood to bypass these exposed surfaces

Shock

reduction of effective circulating blood, blood pressure & cardiac output

inversely, up CS down BV

relationship between blood flow velocity and total cross sectional area

inversely related, increase one will decrease other

relationship between total blood flow and PR

directly related, increase one will increase the other

relationship between total blood flow and blood pressure

directly related, increase one will increase other

relationship between total blood flow and cardiac output

Systemic Venous Blood Reservo

relatively large blood volume in systemic veins allows them to function as blood reservoirs when more blood is needed-shifted from venous reservoirs into circulation through vasoconstriciton When less blood is needed at rest-from circulation back into venous reservoirs through vasodilation

Vasodialation

relaxation of the smooth muscle, allowing blood pressure to expand vessel

Peripheral resistance

resistance is the amount of opposition (or friction) blood encounters as it flows through the vessels. As resistance increases blood pressure increases. As resistance decreases blood pressure decreases.

peripheral resistance

resistance of arterial system

peripheral resistance (PR)

resistance of blood in the blood vessels

kidney blood flow

rest: 1100 mL/min light exercise: 900 mL/min heavy exercise: 600 mL/min

Skeletal muscles blood flow

rest: 1200 mL/min light exercise: 4500 mL/min heavy exercise: 12500 mL/min

Abdominal organs blood flow

rest: 1400 mL/min light exercise: 1100 mL/min heavy exercise: 600 mL/min

skin blood flow

rest: 500 mL/min light exercise: 1500 mL/min heavy exercise: 1900 mL/min

TOTAL body blood flow

rest: 5800 mL/min light exercise: 9500 mL/min heavy exercise: 17,500 mL/min

Other tissues blood flow

rest: 600 mL/min light exercise: 400 mL/min heavy exercise: 400 mL/min

What do blood vessels do?

transport oxygen nutrients waste products and form body tissues

True/ False: Blood vessels work contiuously and tandem with each other

true

True/False: blood pressure in veins is too low to overcome the forces of gravity

true

True/false: systolic blood pressure may increase with age

true

arteries

trunks are

Tunica externa

tunica adventitia outermost layer of blood vessel wall areolar connective tissue elastic and collagen fibers anchors vessel to other structures very large; vasa vasorum

Tunica Intima

tunica interna innermost layer of blood vessel simple squamous epithelium areolar connective tissue releases substances to regulate contraction and relaxation of smooth muscles within tunica media

What layer of the tunics is the innermost layer?

tunica intima

Structure of Vessel Walls

tunica intima, tunica media, tunica externa

You would expect to find a larger ___ in proportion to their lumen than large arteries and very little ____

tunica media, tunica externa

venous anatomosis

two or more veins draining the same body region

What is an anastomosis?

two or more vessels merge to supply the same body region

internal carotid arteries

two parallel arteries supply the circle of willis

arterial anastomosis

type of anastomosis is the circle of Willis

medial umbilical ligaments

umbilical arteries become

ligamentum teres

umbilical vein becomes

interstitial fluid colloid osmotic pressure

value is relatively low because few proteins are present in the interstitial fluid

Hemorrhoids

varicose veins of the anal canal

The tunica media controls what?

vasoconstriction and vasodialation

Epinephine and norepinephrine in most blood vessels

vasoconstriction- bind to alpha-adrenergic receptors

Angiotensin II

vasoconstrictor Raises BP Promotes Na and water retention by kidneys increases blood volume and pressure

Sleeping in an arm chair after a meanl____ in lower limbs, redirecting blood to intestinal arteries

vasoconstricts