Circulatory system

Main blood vessel flow summary

-Arteries carry blood away from heart toward capillaries -Veins carry blood toward the heart away from capillaries -Capillaries carry blood from tiny arterioles into tiny venules -The aorta carries blood out of the left ventricle of the heart -Venae cavae return blood to the right atrium after systemic circulation

Angina Pectoris

-pain caused when myocardium is deprived of oxygen -it is often a warning that coronary artery is blocked and no longer funtioning correctly

pulmonary circulation

-right ventricle to the lungs- -(low in oxygen)

"dup"

-semilunar valves closing when ventricles relax (diastole) -the pause between the lub and the dup is shorter than between the dup and the next lub

tunica intima

-single layer of squamous epithelial cells called endothelium -lining this inner surface of the entire circulatory system (inside layer)

when the heart beats what contracts first?

-the atria contract first -this atrial systole forces blood into the ventricles

coronary arteries

-the first branches of the aorta -in both coronary thrombosis and coronary embolism, a blood clot plugs a coronary artery

blood flow through the heart

-the heart acts as 2 seperate pumps -the right atrium and ventricle perform a task quite different from the left atrium and ventricle

"lub"

-the lub is caused by closure of the AV valves as ventricles contract (systole) -this closure prevents blood from rushing back into the atria during ventricular contraction -the "lub", first sound, is longer and lower in pitch

once atria is filled what contracts?

-the ventricles then contract -this ventricular systole forces blood out of the heart

cardiac output

-volume of blood pumped by one ventricle per minute -this averages about 5 L in a normal, resting adult

Right and Left Coronary Arteries

-what takes your blood into your heart

Heart action

the heart serves as a muscular pumping device for distributing blood to all parts of the body

Heart sounds

the heart sounds are rythmical and repetitive and are often described as "lub dup"

ventricle systole

the ventricles fill and contract simultaneously

stroke volume

the volume of blood pumped out by a ventricle with each heartbeat

diastolic pressure

Between each beat (contraction), the heart relaxes

Foods that Influence Blood Pressure

-"Yes" foods - apples, avocado, bananas, broccoli, fish, grapes, oats, orange juice, water -"No" foods - high salt foods, medium salt foods, saturated fat, hydrogenated oils, partially hydrogenated vegetables oils

how is blood pressure written?

-Blood pressure is written as a fraction -Systolic is the numerator (top) and diastolic is the denominator (bottom) -It is recorded in millimeters of mercury (mm Hg)

Arteries and Arterioles function:

-Distribute blood from the heart to capillaries all throughout the body -Help to maintain arteriole blood pressure at a normal level by constriciting and dilating

Several factors impact blood pressure: -Heart rate - direct relationship with BP

-Faster heart rate = higher blood pressure -However, if stroke volume decreases as ventricles are contracting faster, they have less time to fill so they are pumping less blood -This demonstrates an inverse relationship

Capillaries function:

-Function as exchange vessels

pulse points In the head and neck:

-In front of the ear over the superficial temporal artery -On the neck over the common carotid artery -Below the corner of the mouth over the facial artery

pulse points In the upper limb:

-In the armpit over the axillary artery -At the bend of the elbow along the medial side over the brachial artery -On the wrist over the radial artery

Several factors impact blood pressure: -Blood viscosity - direct relationship with BP

-Less viscosity (thickness) = lower blood pressure

Myocardial Infarction (MI)

-MI is common cause of death during middle and late adulthood -recovery is possible if the amount of tissue death is small enough that undamaged muscle can still pump

3 distinctive waves in ECG

-P wave -QRS complex -T wave

Impulse generators:

-Sinoatrial node-aka SA node/pacemaker -atrioventricle node-aka AV node -AV bundle-aka bundle of his -Purkinje fibers

Several factors impact blood pressure: -Strength of heart contractions - direct relationship with BP

-Stronger contraction = higher blood pressure

Blood Pressure

The force exerted on your blood vessel wall as blood flows through the body

A pulse can be detected best at?

certain pulse points

since the direction of blood flow must be directed and controlled,what structures are responsible for this?

the AV and SL valves make this happen

QRS complex

***associated with depolarization of the ventricles

Tunica adventitia

- outer layer made of connective tissue fibers, which reinforce the wall to keep it from bursting under pressure

New US guidelines say the risk of cardiovascular disease begins at

115/75 mm Hg

Normal Blood Pressure for 17 year old males is

118/67

Hypertension

140/90 and above

Hypotension

90/60 and below

tunica media

middle layer of smooth muscle tissue and elastic fibrous tissue, which is much thicker in arteries than in veins

Conduction system of the heart

The network of nervous tissue that transmits the electric impulses needed for a heartbeat.

systolic pressure

When the heart contracts it sends a surge of blood through the blood vessels and pressure increases

When taking a pulse, you feel:

an artery expanding and then recoiling alternately

dotors may treat this by implanting?

an artificial pacemaker

artificial pacemaker

an electricle device that stimulates regular ventricular systole

to sustain life the heart must pump blood on a regular ongoing basis

as a result the heart muscle requires a constant supply of blood with nutrients and oxygen to function

T wave

associated with repolarization of the ventricles (relaxing

re-polarization

begins just before relaxation phase of cardiac muscle activity

blood vessel structure

both arteries and veins consist of 3 layers (coats)

Precapillary sphincters

control the entrances to capillaries and determine into which capillary blood will flow

coronary circulation

delivery of good blood to the heart and bad blood back to the venous system

P wave

depolarization of the atria

depolarization

electrical activity that triggers contraction of heart muscles

blood flow through the heart

even though right and left atria and right and left ventricles contract together, the right and left sides still act as seperate pumps

systole

heart contraction

diastole

heart relaxation

Microscopic Capillaries have one single layer

-Capillaries are extremely thin and not visible to the naked eye -Their membranes have only the tunica intima layer which allows substances such as glucose, oxygen, and wastes to easily pass through

Veins and Venules function:

-Collect blood from capillaries and return it to the heart -Serve as blood reservoirs because they can expand to hold a larger volume of blood or constrict to hold a smaller volume

Several factors impact blood pressure: -Blood volume - direct relationship with BP

-Higher blood volume = higher blood pressure -The diameter of arteries plays an important role in determining blood volume

pulse points In the lower limb:

-In the groin over the femoral artery -Behind the knee over the popliteal artery -On the front surface of the foot over the dorsalis pedis artery

Blood Pressure Lowering Tactics

-Stop smoking -Reduce weight -Reduce salt and protein intake -No caffeine -Suffificent rest / no oversleeping

Semilunar valves

-The valves in the heart that separate the ventricles from the arteries. -The pulmonary semilunar valve separates the right ventricle from the pulmonary artery -the aortic semilunar valve separates left ventricle from the aorta. -These valves close at the end of systole, preventing the backflow of blood from arteries to ventricles, and producing the second heart sound.

Artery

-a blood vessel that carries blood away from the heart -largest artery is aorta -arteries subdivide and become progressively smaller arterioles -arterioles control the flow into microscopic exchange vessels called cappillaries

Electrocardiogram

-commonly known as ECG -, the graphic record/representation of the heart's electrical activity

cardiac cycle

-each complete heartbeat -includes atrial and ventricular systole and diastole -each cycle takes about .8 seconds to complete -this is if the heart is beating at an average rate of ~72 beats per minute

Venules

-each join with other venules and increase in size becoming veins -the largest veins are the superios and inferior vena cava

Impulse generators in the heart

-four structures embedded in the heart wall generate speciallized impulses to specific locations within the heart -they ensure the atria and ventricles contract efficiently

impulse conduction:

-impulse conduction normally starts in the SA node (pace maker) -then it spreads in all directions through the atria causing atria fibers to contract -when impulses reach AV node, it relays them through the AV bundle and purkinje fibers to the ventricles causing them to contract -therefore, normally a ventricular beat follows each atrial beat (endocarditis or MI can damage the conduction system and disrupt the heart rythm)

deprived of oxygen, heart muscles cells dies this leads to?

-leads to Myocardial Infarction

systemic circulation

-left ventricle to the body via the aorta -(high in oxygen)

Atrioventricle valves

-located between atria and ventricles -bicuspid valve on left side -tricuspid valve on right side -AV valves prevent backflow of the blood into the atria when ventricles contract -strong stringlike chordae tendinae attach AV valves to the heart walls

Capillary Beds

-location of the the exchange of nutrients and respiratory gases -blood is drained from the capillary beds and enters the small venules

***Fetal Circulation

1. Circulation in the body before birth differs from circulation after birth because the fetus must secure oxygen and food from maternal blood instead of from its own lungs and digestive organs 2. Three specialized blood vessels (within the umbilical cord) must carry the fetal blood to the placenta, where exchange occurs, and then return it to the fetal body -2 small umbilical arteries -1 larger umbilical vein 3.In fetal circulation, arteries carry oxygen-poor blood while veins carry oxygen-rich blood

***Pulmonary Circulation

1. In order for blood to come full circle and reach back to the left ventricle, it must first go through pulmonary circulation 2. Venous blood moves from the right atrium into the right ventricle 3. From here it goes to the pulmonary artery for transport to lung arterioles and capillaries (where exchange occurs) 4. Oxygenated blood then flows back through lung venules into 4 pulmonary veins and returns to the left atrium of the heart 5. From here, it enters the left ventricle to begin systemic circulation again

***Systemic Circulation

1. The left ventricle pumps blood into the aorta 2. From there, it flows into arteries that carry it into tissues and organs of the body 3. Within each structure, blood moves from arteries to arterioles to capillaries (where exchange occurs) 4. Next, blood flows out of each organ through venules and veins 5. Eventually, blood drains into the inferior and superior vena cava 6. These veins return blood to the right atrium to complete the cycle

***Hepatic Portal Circulation

1. Veins from the spleen, stomach, pancreas, gallbladder, and intestines do not pour directly into the inferior vena cava, instead they send their blood through to the liver through the hepatic portal vein 2. Blood then passes through the liver before reentering the regular venous system returning to the heart 3. In this process, blood passes through an additional capillary bed in the liver -This allows for the liver to store excess glucose from food, providing the blood leaving the liver with a normal blood glucose concentration -Liver cells also remove and detoxify poisonous substances that may be present in the blood

Normal Blood Pressure for 17 year old females

111/66

FETAL CIRCULATION (CONT'D):

4.Ductus venosus - a continuation of the umbilical vein which serves as a shunt, allowing most blood from the placenta to bypass the under-developed fetal liver and empty directly into the inferior vena cava 5.Two other structures allow most blood to bypass the developing lungs, which remiain collapsed until birth -Foramen ovale - shunts blood from the right atrium directly into the left atrium -Ductus arteriosus - connects the aorta and pulmonary artery 6.When a newborn takes its first deep breaths, the circulatory system is subject to increased pressure, and these structures collapse and become non-functional

what are changes in an ECG indicative of?

MI or Heart Disease

Normal Blood Pressure

Normal blood pressure is said to be 120/80 mm Hg, but new guidelines are saying this is the high end of normal (110/70 now)

path of blood flow through the heart

vena cava(blood low in oxygen) > right atrium > tricuspid valve > PULMONARY CIRCULATION: right ventricle > pulmonary valve > pulmonary artery > lung (where oxygen is added and carbon dioxide is lost) > pulmonary vein (oxygen rich blood) > left atrium > bicuspid valve > SYSTEMIC CIRCULARION: left ventricle > aortic valve > aorta > body

an example of "heart block"

when impulses are blocked from getting through to the ventricles, slowing the pace of the heart drastically

atrial systole

when the heart beats, atria contract simultaneously