exam 1 ap 2

syncope

"Passing out", loss of consciousness or fainting

viscous

(adj.) having a gelatinous or gluey quality, lacking in easy movement or fluidity

Hardening of Arteries

- "Hardening of the arteries" (loss of elasticity) seriously hampers the body's ability to increase blood flow to meet metabolic demands.

Filtration

- Filtration is the movement of fluid through the walls of the capillary into the interstitial fluid.

tunica externa

- Outer lining of elastic & collagen fibers

clot retration

- Pulls torn edges of vessel closer togethe

Reabsorption

- Reabsorption is the movement of fluid from the interstitial fluid back into the capillary.

Renin

- Renin is released by kidneys when blood volume falls or blood flow decreases. - It is subsequently converted into the active hormone angiotensin II which raises BP by vasoconstriction and by stimulating secretion of aldosterone from the adrenal glands.

Pulmonary Circulation

- The pulmonary circulation leaves the right heart to allow blood to be re-oxygenated and to off-load CO2.

Systemic Circulation

- The systemic circulation leaves the left side of the heart to supply the coronary, cerebral, renal, digestive and hepatic circulations (among others). The bronchial circulation provides oxygenated blood to the lungs, not the pulmonary circulation, which oxygenates blood!

cardiac tamonade

-Blood rapidly collects in pericardial sac, compresses myocardium because the pericardium does not stretch, and prevents ventricles from filling

thrombophlebitis?

-Vein occlusion/inflammation ("-phlebitis") due to a thrombus ("thrombo-"

cardiac arrhythmias

-ventricular arrhythmias, a fib, conduction disturbanc

blood flow through the heart

1-Superior & Inferior Vena Cava, 2-Rt Atrium, 3-Tricuspid Valve, 4- Rt Ventricle, 5-Pulmonary Valve, 6-Pulmonary Artery, 7- Lungs-pick up oxygen, 8-Pulmonary Veins, 9- Lt Atrium, 10- Mitral Valve (Bicuspid), 11-Lt Ventricle, 12- Aortic Valve, 13-Aorta, 14- Body

end diastolic volume

130 The amount of blood in the ventricle immediately before a cardiac contraction begins; used as a measurement of diastolic function.

platelets

150,000-400,000 Blood clotting

AT WHAT MAP LEVEL DOES CEREBRAL EDEMA START

160

arterial anastomoses

2 arteries merge. provide collateral (alt) routes of blood supply to a tissue. common around jts where movement may temporarily compress an artery and obstruct one pathway.

how much o2 is normal used in normal day

25%

heart wall how many layer

3 layers

end systolic volume

50 Heart Cycle: amount of blood in the ventricle after systole usually 50 mL

AT WHAT LEVEL DOES SYNOPE COMMONLY OCCUR

60

pseudopods

A "false foot" or temporary bulge of cytoplasm used for feeding and movement in some protozoans.

albumin 60

A blood protein produced by the liver. Albumin helps to mantain blood osmotic pressure (oncotic pressure) 60

connective tissue

A body tissue that provides support for the body and connects all of its parts

basophil

A circulating leukocyte that produces histamine.

lymphocyte

A class of white blood cells that consist of small and large lymphocytes. The small lymphocytes bear variable cell-surface receptors for antigen and are responsible for adaptive immune responses. There are two main classes of small lymphocyte—B lymphocytes (B cells) and T lymphocytes (T cells). Large granular lymphocytes are natural killer (NK) cells, lymphocytes of innate immunity.

embolus

A clot that breaks lose and travels through the bloodstream.

cardiac cycle

A complete heartbeat consisting of contraction and relaxation of both atria and both ventricles

hypovolemic shock

A condition in which low blood volume, due to massive internal or external bleeding or extensive loss of body water, results in inadequate perfusion.

anemia

A condition in which the blood is deficient in red blood cells, in hemoglobin, or in total volume.

hemoglobin

A four-subunit protein found in red blood cells that binds oxygen. Each subunit contains a heme group, a large multi-ring molecule with an iron atom at its center. One hemoglobin molecule can bind four oxygen molecules in a cooperative manner.

heart

A hollow, muscular organ that pumps blood throughout the body.

Flow of blood through capillary beds

A microcirculation of interwoven networks of capillaries, consisting of: Vascular shunts - metarteriole-thoroughfare channel connecting an arteriole directly with a postcapillary venule True capillaries - 10 to 100 per capillary bed, capillaries branch off the metarteriole and return to the thoroughfare channel at the distal end of the bed Precapillary sphincter Cuff of smooth muscle that surrounds each true capillary Regulates blood flow into the capillary Blood flow is regulated by vasomotor nerves and local chemical conditions, so it can either bypass or flood the capillary be

electrocardiogram (ECG or EKG)

A recording of the electrical activity of the heart

anaphylactic shock

A severe reaction that occurs when an allergen is introduced to the bloodstream of an allergic individual. Characterized by bronchoconstriction, labored breathing, widespread vasodilation, circulatory shock, and sometimes sudden death. released of histamine cause the vasodilation

pressure point

A site on the body where an artery lies close to the surface of the skin and can be compressed against an underlying bone to control bleeding.

sinoartrial node

A small mass of tissue that is made up of Purkinje fibers, ganglion cells, and nerve fibers, that is embedded in the musculature of the right atrium, and that originates the impulses stimulating the heartbeat -- called also S-A node, sinus node.pacemaker of the heart

homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

neutrophil

A type of white blood cell that engulfs invading microbes and contributes to the nonspecific defenses of the body against disease.

monocyte

A type of white blood cell that transforms into macrophages, extends pseudopods, and engulfs huge numbers of microbes over a long period of time

vasodilation

A widening of the diameter of a blood vessel.

leukopenia

Abnormally low white blood cell count

preload

Amount of blood returned left ventricle from the x systemic circulation

heparin

An anticoagulant that acts to inhibit a number of coagulation factors, especially factor Xa. Heparin is formed in the liver

hypoxic

An oxygen deficiency (related to the pulse oximetry vital sign) (PE Respiratory/Chest)

desmosomes

Anchoring junctions that prevents cells subjected to mechanical stress from being pulled apart; button like thickenings of adjacent plasma membranes connected by fine protein filaments

aneurysm

Ballooning of a weakened portion of an arterial wall

precapillary sphincter

Blood flow through a capillary is most directly regulated by the

pulmonary circulation

Blood flow through a network of vessels between the heart and the lungs for the oxygenation of blood and the removal of carbon dioxide.

BP

Blood pressure is a measure of the force (measured in mmHg) exerted in the lumen of the blood vessels.

cardiovascular system

Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood.

hemogloblinuria

Can occur simultaneously in urine samples

capillary pressures

Capillary hydrostatic pressure, interstitial hydrostatic pressure, capillary oncotic pressure and interstitial oncotic pressure

mediastinum

Centrally located space between the lungs

left atrium

Chamber that receives oxygenated blood from the pulmonary veins and pumps it into systemic circulation.

serum

Clear fluid portion of blood that remains after coagulation

cbc

Complete blood cell count

vascular murmur

Condition that originated in the blood vessels as a result of turbulent blood flow

Continuous Capillaries

Continuous capillaries are the most common with endothelial cells forming a continuous tube, interrupted only by small intercellular clefts.

pericardium

Double-layered membrane surrounding the heart.

What are the 3 types of arteries

Elastic, muscular, and arterioles

Fenestrated Capillaries

Fenestrated capillaries (fenestra = windows), found in the kidneys, villi of small intestines, and endocrine glands are much more porous.are pores formed with in the endothelieum of the vessel this allows a greater permeability to fluid and small solute are found in the liver, bone marrow, lymphoid tissue, and endocrine.

plasma

Fluid portion of blood

angiogenesis

Formation of new blood vessels

macrophages

Found within the lymph nodes, they are phagocytes that destroy bacteria, cancer cells, and other foreign matter in the lymphatic stream.

Return blood from veins to the heart against gravity

Gravity is an ever-present force against which the limb's venous system is designed to compete in the upright position. If the valves fail, it is gravity that causes any blood that has been shifted upwards to fall back again and this has various effects

myocardial infarction

Hear attack occurs due to lack of blood flow through the coronary arteries to the heart muscle

cardiac reflexes

Heart Rate: Baroreceptors and chemoreceptors are monitored by the cardiac centers in the brain and adjust the heart's activity accordingly (low blood pressure or low oxygen signals the heart to work harder)

stoke volume

Heart: amount of blood ejected with each myocardial contraction EDV- ES

visceral pericardium

Innermost layer of the serous membrane around the heart

Composition of the tunica media

Location: the middle layer function: vasoconstrictions and vasodilations ROles of vasoconstrictions decrease the blood flow and dilation increase the blood flow

Mean arterial pressure

MAP = cardiac output x total peripheral resistanc (MAP) mean between systolic and diastolic pressures, which propel the blood to the tissue

globulins 35

Match the following plasma proteins with the correct function

parietal pericardium

Middle layer of the heart

DIFFUSION

Movement of molecules from an area of higher concentration to an area of lower concentration.

Neonatal Circulation After Birth

Neonatal Circulation After Birth • At birth, the neonate's lungs open and in just a few seconds, there is a massive drop in pulmonary vascular resistance. - Blood now entering the right heart now sees lower pressure looking into the lungs and has no "incentive" to flow through the foremen ovale or the ductus arteriosus. • Another change also occurs very rapidly - the umbilical cord is severed. - And so begins the adult pattern of blood flow. • Within hours, days, or weeks after birth, the umbilical vein atrophies to become the ligamentum teres. - The ductus venosus atrophies to become the ligamentum venosum. - The foramen ovale becomes the closed fossa ovale. - The ductus arteriosus atrophies to become the ligamentum arteriosum. - Umbilical arteries atrophy to become the medial umbilical ligaments.

colliod osmotic pressure

OPc - created by nondiffusible plasma proteins, which draw water toward themselves Effect of loss of osmotic pressure Kwashiorkor

prostacyclin

PGI2: prostaglandin vasodilator and inhibitor of platelet aggregation

interventricular septum

Partition that separates the right and left ventricles.

hemolysis

Performing venipuncture before alcohol is dry can result in what?

gap junctions

Points that provide cytoplasmic channels from one cell to another with special membrane proteins. Also called communicating junctions.

Hydrostatic pressure

Pressure exerted by a volume of fluid against a wall, membrane, or some other structure that encloses the fluid.

formed elements

Red Blood Cells, White Blood Cells and platelets

erythrocytes

Red blood cells

vasoconstriction

Reduces blood flow and heat transfer by decreasing the diameter of superficial blood vessels.

cardiogenic shock

Related to MI, serious arrhythmias, or heart failure. Decreased cardiac output. Heart can't pump, tissue perfusion ceases. Vitals: hypotension, urine output decreases, cold, clammy skin, poor peripheral pulses, pulmonary congestion, dyspnea, restless/confused

septic shock

Related to endotoxins released by bacteria, which cause vascular pooling, diminished venous return, and reduced CO

Sinusoids capillary

Sinusoids Blood flows sluggishly, allowing for modification in various ways Found in the liver, bone marrow, lymphoid tissue, and in some endocrine organs Highly modified, leaky, fenestrated capillaries with large lumens Allow large molecules (proteins and blood cells) to pass between the blood and surrounding tissues

Sinusoids

Sinusoids (capillaries) form very porous channels through which blood can percolate, e.g. in the liver and spleen.

vASA VASORUM

Small blood vessels in the tunica externa (adventitia) of a blood vessel that supply blood to the outer parts of the vessel wall are called

thrombus

Stationary blood clot

systemic circulations

Supplies tissues located in the body, EXCEPT heart and lungs

CEREBRAL EDEMA

Swelling of the brain.

Systemic Circulation - Arteries

Systemic Circulation - Arteries • Aorta (one) • Brachiocephalic (one) • Common Carotid • External Carotid • Internal Carotid • Subclavian • Axillary • Brachial • Radial • Ulnar • Bronchial (usually 3) • Renal • Iliac (common, internal, external) • Femoral • Popliteal

Systemic Circulation - Veins

Systemic Circulation - Veins • Vena Cava • Brachiocephalic (two) • External Jugular • Internal Jugular • Subclavian • Axillary • Brachial • Median Cubital • Iliac (common, internal, external) • Femoral • Popliteal • Saphenous • Hepatic portal

Blood Brain barrier

The brain is protected from harmful chemicals in the blood stream by thicker walls surrounding the brains blood vessels.

pulse pressure

The difference between systolic and diastolic pressure

venous pressure

The force exerted by the blood against the vein walls. Normal pressures are highest in the extremities 5-14 cm H2O in the arm and 6-8 cm H2O in the inferior vena cava

AFterload

The force or resistance against which the heart pumps.

tunica media

The middle and thickest layer of tissue of a blood vessel wall, composed of elastic tissue and smooth muscle cells that allow the vessel to expand or contract in response to changes in blood pressure and tissue demand.

pressure to get the fluid into the tissue from the capillary

The movement of fluid between capillaries and the interstitial fluid. Fluids flow out of a capillary at the upstream end near an arteriole and reenters a capillary downstream near a venule. The direction of fluid movement across the capillary wall at any point depends on the difference between two opposing forces: blood pressure and osmotic pressure.

fibrous pericardium

The outermost layer of the pericardium, which consists of inelastic dense irregular connective tissue, is called the

Systolic pressure

The pressure measured in the arteries during contraction of the ventricles (during systole).

Diastolic pressure

The pressure measured in the arteries while the ventricles are relaxed (during diastole).

angiogram

The radiographic visualization of blood vessels after the injection of radiopaque substance.

hematocrit

The ratio of the total RBC (red blood cell) volume to the toal blood valume and expressed as a percentage

intercalated disk

These structures branch and connect cardiac cells. They contain specialized gap junctions and coordinate muscle contractions.

myocardium

Thick middle muscle layer of the heart the muscular middle layer. This is the contractile element of the heart

Venous system

Venous System Venules Are formed when capillary beds unite Allow fluids and WBCs to pass from the bloodstream to tissues Postcapillary venules - smallest venules, composed of endothelium and a few pericytes Large venules have one or two layers smooth muscle (tunica media) Veins Are formed when venules converge Composed of three tunics, with a thin tunica media and a thick tunica externa consisting of collagen fibers and elastic networks Capacitance vessels (blood reservoirs) which contain 65% of the blood supply Veins have much lower blood pressure and thinner walls than arteries To return blood to the heart, veins have special adaptations Large-diameter lumens, which offer little resistance to flow Valves (resembling semilunar valves), which prevent backflow of blood (varicose veins) Venous sinuses - specialized, flattened veins with extremely thin walls (e.g., coronary sinus of the heart and dural sinuses of the brain)

eosinophil

What IgE-mediated cell secretes major basic protein and has elevated levels in the blood during asthma and parasitic infections?

korotkoff

What are the sounds a health care professional listens for during a manual blood pressure reading called?

right coronary artery

What artery supplies the right atrium, right ventricle, sinoatrial and atrioventricular nodes?

continuous capillary

Which capillary is least permeable and most common? also makes up blood brain barrier. allows limits passage of fluid. the blood brain barrier is the special

leukocytes

White blood cells

automated implantable cardioverter defibrillator

a double-action pacemaker that regulates the heartbeats and acts as an automatic defibrillator

fibrinogen 4

a protein in blood plasma that is necessary for the clotting of blood.

jaundice

a state of feeling in which views are prejudiced or judgment is distorted, as by envy or resentment; yellowing of skin and whiteness of eyes from certain illnesses.

Heart size

about the size of your clenched fist, it is hollow weight less then a pound

asystole

absence of contractions of the heart

artrial reflexes

adjucts the heart rate

diuretic

administered to stimulate the kidneys to increase the secretion of urine to rid the body of excess sodium and water

polycythemia

an abnormal increase in the number of red cells in the blood due to excess production of these cells by the bone marrow

artificial pacemaker

an electrical device that is implanted into the heart to treat problems with heart conduction

HYPEREMIA

an excess of blood in an area

average speed of blood in the aorta, capillaries, and veins

aorta-40 to50 cap0.03 veins 10-30

platelet plugs

are formed when exposed collagen fibers in a broken blood vessel come in contact with platelets.

PMI location

at the left 4th or 5th ICS, 7-9cm lateral to the midsternal line. Midclavicular line at the 4th or 5th ICS

coronary artery disease

atherosclerosis of the coronary arteries that reduces the blood supply to the heart muscle

laminar flow

blood flows in concentric circles with the slowest flow in the area of greater resistance, near the vessels wall and the fastest flow in the center

hematuria

blood in the urine

sphygmomanometer

blood pressure cuff

general function of the arteries

carried blood away from the heart to the peripherial capillaries

pulmonary trunk

carries blood from right ventricle to pulmonary arteries

general function of the veins

carry blood from the peripherial capillaries to the heart

pulmonary arteries

carry deoxygenated blood out of the right ventricle and into the lungs

angina pectoris

chest pain, which may radiate to the left arm and jaw, that occurs when there is an insufficient supply of blood to the heart muscle

pericardial cavity

contains the heart,contains about 10-20 of fluids, he

automated external defibrillator

designed for use by nonprofessionals in emergency situations when defibrillation is required

fibrinolysis

destruction of fibers

cardiac reserve

difference between resting and maximal CO

general functions of the capillaries

exchanges 02 and co2 and waste

cardiac arrest

failure of the ventricles of the heart to contract (usually caused by ventricular fibrillation) with consequent absence of the heart beat leading to oxygen lack and eventually to death

Arterial blood pressure

force exerted on the walls of an artery by pulsing blood under pressure of heart

hematopoiesis

formation of blood cells

Composition of the tunica externa

function: nevers and fiber location the outer layer

coronary sulcus

groove that marks border between atria and ventricles

erthroproteins

growth factoe

rennin

helps to create Angiotensin II which acts as a vasoconstrictor, elevating blood pressure

regulartory proteins 1

hormones

phlebotomy

incision of a vein

pericarditis

inflammation of the pericardium

phlebitis

inflammation of the vein

tunica intima

innermost layer of an artery or vein

coagulations

involves a complex sequence of steps leading to the conversion of FIBRINOGEN to FIBRIN

turbuient blood flow

is due to currents not moving parallel to the long axis

pinpcytosis

is how large stuff get across the cap beds

viscosity

is influence to the extent by the number of RBC cells it contains

Compliance

is the digestibility of the vessels related to the thickness of the vessels

Post load

is the force the left ventricles must over come to expel its contents into the systemic circulations

vessels to the fastest to the slowest

large arteries to capillaries

pulmonary semilunar value

located between the right ventricle and the pulmonary artery

red bone marrow

located within the spongy bone, is hemopoietic tissue that manufactures red blood cells, hemoglobin, white blood cells, and thrombocytes

Composition of the tunica intima

location: the layer that lines the lumen function: move blood why is it smooth: minimize frictions and to prevent blood from clotting

lymphatic vessel

lymph flows from the lymphatic capillaries into these progressively larger vessels, which are located deeper within the tissues

carotid sinus massage

massaging the carotid artery at the bifircation can slow the heart rate

normotensive

normal blood pressure

pressure to get the fluid out of the tissue from the capillary

oncotic pressure Oncotic pressure, or colloid osmotic pressure, is a form of osmotic pressure exerted by proteins in a blood vessel's plasma (blood/liquid) that usually tends to pull water into the circulatory system. Source: Boundless. "Capillary Dynamics."

left coronary artery

one of two arteries from the aorta that nourish the heart; (runs from left side of heart then divides into the circumflex and left anterior descending branches)

epicardium

outer layer of the heart

intermittent claudication

pain in the leg muscles that occurs during exercise and is relieved by rest

thrill

palpable vibration on the chest wall accompanying severe heart murmur

diapedesis

passage of blood cells (especially white blood cells) through intact capillary walls and into the surrounding tissue

white coat hypertension

phenomenon in which patients exhibit elevated blood pressure in the hospital or doctor's office but not in their everyday lives

leukocytosis

physiologic increase in white blood cells (greater than 10,000/mL)

anticoagulants

prevent formation of blood clots

venipuncture

puncture of a vein to remove blood, instill a medication, or start an intravenous infusion.

coronary ischemia

reduce supply blood to the heart

arterial puncture

reserved for checking the efficiency of gas exchange at the lungs. samples are generally drawn from the radial artery at the wrist or the brachial artery at the elbow

Vascular shock

results from extreme vasodilation and decreased peripheral resistance

pericardial friction rub

scraping or grating noise heard on auscultation of the heart; suggestive of pericarditis

hemocytoblast

stem cells that give rise to all the formed elements of the blood

right atrium

store deoxygenated blood The chamber of the heart, where deoxygenated blood is received from the vena cava and then sent to the right ventricle.

hematology

study of blood

cardiology

study of the heart

facts of blood

temp; 100,4 total volume

places to check pulses

temporal,facial,common caroitd, brachial, radial, femeral, pepliteap, posterior tribal, dorsails pedis

cardiomegaly

the abnormal enlargement of the heart

endocardium

the inner lining of the heart

erythropoiesis

the process y which new blood cell are made

values of veins

they get block

TPA

tissue plasminogen activator

general function of the lumen OF BLOOD vessels

to transport blood throughout the body to allow exchange of substances(resp. gases, nutrients, waste products) between the blood of capillaries & body's cells

functions of blood

transport oxygen, fight infection, regulate temp & maintain acid balance

shunt.

tube implanted in the body to redirect the flow of a fluid

autorythmic cells

unstable resting potential called pacemaker potential or prepotentials due to slow Na channel

sclerotherapy

use of sclerosing agents in treating diseases (e.g., injection of a saline solution into a dilated blood vessel tumor in the skin, resulting in hardening of the tissue within and eventual sloughing away of the lesion)

artithrombin III

use to break clots

Short term blood pressure control

vasoconstriction, vasorelaxation, heart rate, cardiac out put

Raynaud's phenomenon

vasospastic disorder decreasing blood supply to areas like finger

marginaton

vessal wa;;

plasma

water 92 protein 7 other 1

arterial end-out and venous end-in

where materials leave the blood

whole blood cells

whole cell

Peripheral Circulation

• A measure of peripheral circulation can be done by checking the pulse. The pulse is a result of the alternate expansion and recoil of elastic arteries after each systole. - It is strongest in arteries closest to the heart and becomes weaker further out. - Normally the pulse is the same as the heart rate. • Blood pressure is the pressure in arteries generated by the left ventricle during systole and the pressure remaining in the arteries when the ventricle is in diastole.

Alterations of Blood Pressure

• About 50 million Americans have hypertension (HTN). - It is the most common disorder affecting the CV system and is a major cause of atherosclerotic vascular disease (ASVD), heart failure, kidney disease and stroke.

Layers of Tunics

• All blood and lymph vessels in the body share components of 3 basic layers or "tunics" which comprise the vessel wall : - Tunica interna (intima) - Tunica media - Tunica externa

Anastomosis

• An anastomosis is a union of vessels supplying blood to the same body tissue. Should a blood vessel become occluded, a vascular anastomosis provides collateral circulation (an alternative route) for blood to reach a tissue. smallest, not visible to unaided eyes flow to the capillary beds

Chemoreceptors

• Another type of sensory receptor important to the process of autoregulation of BP are the chemoreceptors. • Chemoreceptors are found in the carotid bodies (located close to baroreceptors of carotid sinus) and aortic bodies (located in the aortic arch). • When they detect hypoxia (low O2), hypercapnia (high CO2), or acidosis (high H+), they signal the cardiovascular centers. - They increase sympathetic stimulation increasing heart rate and respiratory rate, and vasoconstricting the vessels (arterioles and veins) to increase BP.

Antidiuretic hormone (ADH)

• Antidiuretic hormone (ADH) is released from the posterior pituitary gland in response to dehydration or decreased blood volume

Arterioles

• Arterioles deliver blood to capillaries and have the greatest collective influence on both local blood flow and on overall blood pressure. - They are the primary "adjustable nozzles" across which the greatest drop in pressure occurs.

Starling Forces

• As blood flows to the tissues of the body, hydrostatic and osmotic forces at the capillaries determine how much fluid leaves the arterial end of the capillary and how much is then reabsorbed at the venous end. These are called Starling Forces.

Atrial Naturetic Peptide (ANP)

• Atrial Naturetic Peptide (ANP) is a natural diuretic polypeptide hormone released by cells of the cardiac atria. - ANP participates in autoregulation by : ➢ Lowering blood pressure (it causes a direct vasodilation). ➢ Reducing blood volume (by promoting loss of salt and water as urine).

Venous Reserve

• Because systemic veins and venules contain a large percentage of the blood volume (about 64% at rest), they function as blood reservoirs from which blood can be diverted quickly if needed. - To counteract a drop in BP, stimulation of the sympathetic NS will cause venoconstriction, allowing a greater volume of blood to flow to skeletal muscles.

Blood Vessel Types

• Blood Vessel Types : - Arteries - carry blood away from the heart. ➢ Large elastic arteries (>1 cm); medium muscular arteries (0.1 - 10 mm); arterioles (< 0.1 mm). - Capillaries - site of nutrient and gas exchange. - Veins - carry blood towards the heart. ➢ Venules are small veins (< 0.1 mm).

Blood Flow

• Blood flow is the amount of blood which is actually reaching the end organs (tissues of the body).

Capillaries

• Capillaries are the only sites in the entire vasculature where gases, water and other nutrients are exchanged. • Capillaries are different from other vascular structures in that they are made of only a single endothelial cell sitting on a very thin basement membrane - there are no other tunics, layers or muscle. - The minimalist nature of capillaries allows them to be freely permeable to many substances (gases, fluids, and small ionic molecules). they are the smallest 6000 sq meters and composed of one endothelium.the blood brain barrier is special continuous capillary.

Cardiovascular Homeostasis

• Cardiovascular homeostasis is mainly dependent on blood flow ... but blood flow is hard to measure. - Clinically, we check blood pressure because it is easier to measure, and it is related to blood flow. - The relationship between blood flow, blood pressure, and peripheral resistance follows a simple formula called Ohms Law.

Epinephrine and norepinephrine

• Epinephrine and norepinephrine are also released from the adrenal medulla as an endocrine autoregulatory response to sympathetic stimulation. - They increase cardiac output by increasing rate and force of heart contractions.

Autoregulation

• Homeostasis in the body tissues requires the cardiovascular system to adjust pressure and resistance to maintain adequate blood flow to vital organs at all times - a process called autoregulation. • Autoregulation is controlled through negative feedback loops. • Autoregulation of blood pressure and blood flow is a complex interplay between : - The vascular system - The nervous system - The endocrine hormones and organs like the adrenal gland and the kidney - The heart

Hypertension

• Hypertension is defined as an elevated systolic blood pressure (SBP), an elevated diastolic blood pressure (DBP), or both. Depending on severity, it is classified as pre-hypertension, Stage 1 HTN, or stage 2 HTN.

Autoregulatory Response

• In an autoregulatory response, important differences exist between the pulmonary and systemic circulations: - Systemic blood vessel walls dilate in response to hypoxia (low O2) or acidosis to increase blood flow. - The walls of the pulmonary blood vessels constrict to a hypoxic or acidosis stimulus to ensure that most blood flow is diverted to better ventilated areas of the lung.

Increase Blood Flow

• In an effort to meet physiological demands, we can increase blood flow by : - Increasing BP - Decreasing systemic vascular resistance in the blood vessels • Usually our body will do both - when we exercise, for example.

Gas and Nutrient Exchange

• In contrast to the bulk flow of fluids at the capillaries, the exchange of gases and small particles (like certain nutrients and wastes) is a purely passive diffusion process. - Gases and these other substances simply move into or out of the capillary down their concentration gradient.

Muscular Arteries

• Medium sized muscular (distributing) arteries have more smooth muscle in their tunica media. - Muscular arteries help maintain the proper vascular tone to ensure efficient blood flow to the distal tissue beds. - Examples include the brachial artery in the arm and radial artery in the forearm.

Results of Shock

• Most cases of shock call for the administration of extra fluids and emergency medications like epinephrine to help restore perfusion to the tissues. • If the body is not able to do this quickly, with or without outside help, organs will fail (kidney failure, liver failure, coma) and damage may become permanent.

Reabsorption vs. Filtration

• Normally there is nearly as much fluid reabsorbed as there is filtered. - At the arterial end, net pressure is outward at 10 mmHg and fluid leaves the capillary (filtration). - At the venous end, net pressure is inward at -9 mmHg (reabsorption). - On average, about 85% of fluid filtered is reabsorbed. • Fluid that is not reabsorbed (about 3L/ day for the entire body) enters the lymphatic vessels to be eventually returned to the blood.

Resistance

• Resistance is the sum of many factors which oppose the flow of blood.

Carotid Sinus Reflex

• Stimulation of the baroreceptors in the carotid sinus is called the carotid sinus reflex, and it helps normalize blood pressure in the brain. Stimulation of the aortic baroreceptors helps normalize the systemic BP. - When the blood pressure falls, baroreceptors are stretched less, and the input is sensed in the cardiovascular centers of the brain which respond with decreased parasympathetic and increased sympathetic stimulation. Blood pressure increases do the opposite.

The 4 types of shock

• The 4 basic types of shock are : - Hypovolemic shock, due to decreased blood volume. - Cardiogenic shock, due to poor heart function. - Obstructive shock, due to obstruction of blood flow. - Vascular shock, due to excess vasodilation - as seen in cases of a massive allergy (anaphylaxis) or sepsis. In the U.S., septic shock causes >100,000 deaths / yr. and is the most common cause of death in hospital critical care units.

The Renin-angiotensin-aldosterone (RAA) system

• The Renin-angiotensin-aldosterone (RAA) system is an important endocrine component of autoregulation.

Blood Vessels

• The blood vessels of the body should not be thought of as mere "pipes" carrying blood - they are dynamic, interactive, essential components of the cardiovascular organ system.

The Three Types of Capillaries

• The body contains three types of capillaries : - Continuous capillaries are the most common with endothelial cells forming a continuous tube, interrupted only by small intercellular clefts. - Fenestrated capillaries (fenestra = windows), found in the kidneys, villi of small intestines, and endocrine glands are much more porous. - Sinusoids form very porous channels through which blood can percolate, e.g. in the liver and spleen.

Fetal Circulation

• The fetus has special circulatory requirements because their lungs, kidneys and GI tract are non-functional. • The fetus derives its oxygen and nutrients and eliminates wastes through the maternal blood supply by way of the placenta. Normally, there is no maternal / fetal mixing; the fetus is totally dependant on capillary exchange. • Oxygenated blood leaves the placenta through the umbilical vein. It then bypasses the liver via the ductus venosus and dumps into the inferior vena cava en route to the right heart. • This oxygen-rich blood then bypasses the lungs by traveling to the left heart through the foramen ovale. • Blood remaining in the right heart that manages to flow through the right ventricle meets with very high resistance from the closed and soggy lungs. • This blood is diverted into the left-sided circulation by passing through the ductus arteriosus before returning to the placenta via the umbilical arteries.

Factors of Peripheral Resistance

• The first two of these factors (viscosity and the length of blood vessels) are unchangeable from moment to moment. - The diameter, however, is readily adjusted if the body needs to change blood flow to a certain capillary bed. • Example : If the diameter of a blood vessel decreases by one-half, its resistance to blood flow increases 16 times!

Hepatic Portal System

• The hepatic portal system is designed to take nutrient- rich venous blood from the digestive tract capillaries, and transport it to the sinusoidal capillaries of the liver. - As it percolates through the liver sinusoids, the hepatocytes of the liver, acting as the chemical factories of the body, extract and add what they wish to maintain homeostasis (extracting sugars, fats, proteins when appropriate and then dumping them back into the circulation when necessary).

Elastic Arteries

• The largest arteries are the conducting arteries (elastic arteries), best exemplified by the garden hose-sized aorta. near the hearts - Their walls are thin compared to their overall size. - Elastic arteries perform the important function of storing mechanical energy during ventricular systole and then transmitting that energy to keep blood moving after the aortic and pulmonary valves close.

The Respiratory Pump

• The respiratory pump uses the negative pressures in the thoracic and abdominal cavities generated during inspiration to pull venous blood towards the heart.

Homeostasis and Shock

• The same negative feedback mechanism discussed in autoregulation of blood pressure / flow is activated to restore blood and nutrient flow in cases of shock. - Heart will respond with rate and force of contraction. - Selective tissue beds will vasoconstrict to shunt blood flow to those tissue most necessary to life (brain). - The other neural, hormonal, and chemical pathways will be recruited to restore balance. ➢ Heart rate & force increase ➢ Vasoconstriction or vasodilation depending on type of shock ➢ ADH released conserve water ➢ Renin released Angiotensin II ➢ Aldosterone released conserve Na+ ➢ ANP inhibited

The Skeletal Muscle Pump

• The skeletal muscle pump uses the action of muscles to milk blood in 1 direction (due to valves).

The Metarteriole-Capillary Junction

• The terminal end of an arteriole tapers toward the capillary junction to form a single metarteriole. - At the metarteriole-capillary junction, the distal most muscle cell forms the precapillary sphincter which monitors and regulates blood flow into the capillary bed.

Tunica Externa

• The tunica externa helps anchor vessel to surrounding tissue through use of elastic and collagen fibers.

Tunica Interna

• The tunica interna is the inner lining in direct contact with blood. - The epithelium of the intima is the same endothelium that makes up the endocardial lining of the heart. - It has an active role in vessel-related activities.

Tunica Media

• The tunica media is chiefly composed of smooth muscle that regulates the diameter of the vessel lumen.

The Vascular System

• The vascular system senses alterations of BP and blood flow and signals the cardiovascular centers in the brain. - The heart then appropriately modifies its rate and force of contraction. - Arterioles and the precapillary sphincters of the metarterioles adjust resistance at specific tissue beds. • For example, during emergencies, the autonomic nervous system will vasodilate the precapillary sphincters of metarterioles in the skeletal muscles, lungs, and brain, while constricting the precapillary sphincters found in tissues such as the skin, GI tract, and kidneys. - This sends the majority of the cardiac output (blood flow) to those organs important in a fight or flight response, while temporarily depriving (through vasoconstriction) the nonessential organs.

Venous Return

• The volume of blood returning through the veins to the right atrium must be the same amount of blood pumped into the arteries from the left ventricle - this is called the venous return. - Besides pressure, venous return is aided by the presence of venous valves, a skeletal muscle pump, and the action of breathing. • Although the venous circulation flows under much lower pressures than the arterial side, usually the small pressure differences (venule 16 mmHg to right atrium 0 mmHg), plus the aid of muscle and respiratory pumps is sufficient.

Baroreceptors

• Two of the most important control points are the pressure receptors (called baroreceptors) located in the arch of the aorta and the carotid sinus. • There are also baroreceptors in the kidney and the walls of the heart.

Two pressures promote filtration

• Two pressures promote filtration : - Blood hydrostatic pressure (BHP) generated by the pumping action of the heart - decreases from 35 to 16 from the arterial to the venous end of the capillary - Interstitial fluid osmotic pressure (IFOP), which is constant at about 1 mmHg.

Two pressures promote reabsorption

• Two pressures promote reabsorption : - Blood colloid osmotic pressure (BCOP) is due to the presence of plasma proteins too large to cross the capillary - averages 36 mmHg on both ends. - Interstitial fluid hydrostatic pressure (IFHP) is normally close to zero and becomes a significant factor only in states of edema.

Veins

• Veins have thinner walls, less muscle and elastic tissue, and are designed to operate at much lower pressures. - Intravenous pressure in venules (16 mmHg) is less than half that of arterioles (35 mmHg), and drops to just 1-2 mmHg in some larger veins. - Because intravenous pressure is so low, veins have valves to keep blood flowing in only 1 direction. ➢ When exposed to higher than normal pressures, veins can become incompetent (varicose veins).

Venules and Veins

• Venules and veins have much thinner walls than corresponding arterioles and arteries of similar size.

Peripheral Resistance

•As we have already seen, peripheral resistance is itself dependent on other factors like the viscosity of blood, the length of all the blood vessels in the body (body size), and the diameter of a vessel.

Hypotension

•Hypotension is defined as any blood pressure too low to allow sufficient blood flow (hypo-perfusion) to meet the body's metabolic demands (to maintain homeostasis). • Many persons, especially some thin, young women, have very low BP, yet experience no dizziness, fatigue, or other symptoms - they are not hypotensive, and in fact are probably very healthy (cardiovascular wise). • Hypotension leading to hypo-perfusion (pressure and flow are related) of critical organs results in shock.

heart location

•left of midline, posterior to the sternum and in the mediastinum (between the lungs)