How do we move blood in the body? 2/4

Today’s Goals (CH19): What are the major features of our pump called the heart?

How is the circulation divided into two loops with different pressure and degrees of hemoglobin oxygenation?

What are the characteristics of a single cardiac myocyte?

What are the three layers of the heart? How do the cardiac valves determine the direction

of blood flow in the heart? How dependent is the heart upon oxygen supplies? How does blood reach the different regions of the

heart? FIVE STEP cardiac cycle

Taking Tests and Getting a GradeA=+90%B=+80%C=+70%D=+60%F=-60% Most persons find that studying for AP 212 is different from AP 211Most persons find AP 212 requires less memorization and more applicationMost persons find that each hour of lecture requires 2-3 hours of study time put in as you go (not just before the test) to be in ballpark for a “B” or better.If your study methods worked, use them again. If they did not, reassess and try something else.Essay Hint #1: remember to answer only the question being asked.Essay Hint #2: be able to use specifics when you answer a general question.

What are some common plasma/blood electrolyte imbalances and the terminologies used to describe them?

Ion----[Plasma]---[ICF]----Deficiency Term-------Excess Term ↓↓ ↓↓ Na+--142-----------10------Hyponatremia---------Hypernatremia K+----5--------------141----Hypokalcemia----------Hyperkalcemia Ca++-5-------------<1------Hyopocalcemia--------Hypercalcemia Cl-----103-----------4--------Hypochloremia--------Hypochloremia PO4---4-------------75-------Hyperphosphatemia-

Hypophosphatemia

The plasma levels are often evaluated in a panel test:

Lipoproteins are large particles in the plasma that are specialized for carrying non-water soluble lipids.

Chylomicron: largest and synthesized by intestine Carry_____________from the _______to the ______________

Very Low Density Lipoprotein: VLDL: Big and synthesized by liver Carry______________from the _______to the ______________

Low Density Lipoprotein: LDL: VLDL-left over! Carry______________from the _______to the ______________

High Density Lipoprotein: HDL: smallest and synthesized by liver Carry______________from the _______to the ______________

HDL is called “Good Cholesterol” and LDL is called “Bad Cholesterol” Plasma cholesterol and coronary heart disease/stroke risk: Dietary influence: Genetic Influence:

Why do we often die of a heart attack a few hours after a fatty Christmas dinner? Look and see!

REVIEW: BLOOD CELLS HAVE AN ANTIGENIC PROPERTY CALLED BLOOD TYPE.

Agglutinogens: Polysaccharides on outside of RBC (antigens) Agglutinins: Plasma antibodies that seek non-native agglutinogens in

your blood Agglutination/hemolysis: This occurs when your antibodies observe

foreign antigens (foreign erythrocytes) in your blood and bind to these cells. Antibodies bound to foreign cells then bind other bound foreign cells and create clumps that clog capillaries and lead to cellular hemolysis, possible death from a bad transfusion.

Blood Banking/ABO designation refers to antiGENS found on your RBCs, so your blood destroys RBCs with other antigens.

Type-O Type-A Type-B Type-AB Transfusions- Blood or Plasma? Plasma transfusions:Long shelf-life but fewer risks/benefits!

IgG proteins and Rhesus designations- Rh+ or Rh- Hemolytic Disease of the Newborn (HDN)/Erythroblastosis fetalis First fetus gets off free! Following fetuses at risk of maternal Abs! HDN: Fetal lysis, Bilirubin, Liver function, and UV-phototherapy

Universal Donor is Type-O and has anti-A and B antibodies and cannot accept A, B or AB blood. Universal Recipient has Type AB antibodies on their erythrocytes and has NO antibodies for A or B, if they did they would destroy their own blood. They are the universal recipient Rh problems: second Rh+ fetus in an Rh- mother (first is usually ok because mother is not exposed to enough fetal blood (Rh+) to created antibodies to fetal Rh+ until parturition occurs (birth). Second birth is problematic because her body needs far less Rh+ to create a response form memory lymphocytes.

One more review: The shift in the oxygen binding curve to the right means less oxygen will be attached to the hemoglobins in an acidic region! So oxygen leaves the hemoglobin and can be delivered to where it is needed most! ↑Carbon dioxide and ↑Temperature have similar effects.

Lets Talk about your HEART!WHAT ARE THE PRIMARY ANATOMICAL FEATURES OF THE HEART?

Key Features: 4 chambers

Base (Top) vs. Apex (Bottom)

Sides: Anterior vs. Posterior vs. L/R Lateral

Location in pericardial sac and thoracic cavity

Cycles of Activity: Systole vs. Diastole

In Lab: Remember to identify the anterior surface by looking for the more prominent anterior interventricular sulcus (posterior sulcus is less prominent), then you also know left vs. right, anterior/posterior.

Why is blood flow in the body divided into two very different loops?

2 Pressure loops: Low mmHg vs. High mmHg

2 Anatomical loops: Pulmonary vs. Systemic

2 Oxygenation loops: Oxygenated vs Deoxygenated

Blood/body colors:Bright red vs Cyanotic

Blood Volumes in 2 circuits:Resistance vs. Capacitance

What is the expense of pressure? WORK!!!

WHAT ANATOMICAL CHARACTERISTICS OF CARDIAC MYOCYTES MAKE THEM UNIQUE?

Why do these cells function the way they do?

Intercalated discs

Striations

Mitochondria

Gap junctions

Why is the cardiac cell very different from smooth muscle or skeletal muscle cells?

WHAT IS THE SIGNIFICANCE OF HAVING THE WALL OF THE HEART DIVIDED INTO THREE DISTINCT LAYERS?

1) Endocardium: prevent clotting/infection

2) Myocardium: force generation

3) Epicardium: parietal vs. visceral

Ischemia: local hypoxia/injury Infarct: cell death Post Infarct: tissues consist mostly of non-contractile collagen

deposited by fibroblasts (Scar Tissue)!What keeps the heart from smashing/bruising itself to pieces? Fat: Fluid: What protects the heart from the outside?

If excess fluids accumulate in the pericardial cavity and put pressure on the heart, it cannot be filled with venous return.

HOW DO THE HEART VALVES ENSURE ONE-WAY FLOW OF BLOOD? WHY IS THIS CRITICAL?

Blood flow through valves requires a pressure gradient.Two sets of Atrioventricular valves:

Right AV vs. Left AV Tricuspid vs. Bicuspid (mitral)

Two sets of Semilunar valves: Pulmonic vs. Aortic

DISEASE: Valvular stenosis vs. Mitral valve prolapse

Streptococcal infection in childhood? Why at the valves?Thrombosis formation: Why at the valves?

Why does cardiac work increase dramatically when the valves of the heart fail?

Can you name all the structures of the heart that blood would move across in moving from the vena cava to the aorta? Can you also describe the degree of oxygenation at these points?

RIGHT AV ValveLT AV Valve

APEX

BASE

WHY IS CIRCULATION THROUGH THE HEART SO VERY COSTLY FOR THE BODY? THE STATISTICS:

1) About 5% of CARDIAC OUTPUT goes right back into heart. The more blood you move, the more energy you USE!

2) Your heart USES about 10% of the oxygen consumed by the body! (This is called a HIGH extraction ratio)

3) The cardiac tissues mostly desaturate (remove oxygen from) the hemoglobin in the blood that passes thorough it! Does this leave much oxygen in reserve? How do you supply more oxygen?

4) Cardiac metabolism is mostly aerobic (mitochondria), why?5) Anaerobic Metabolism in the heart is mostly a back-up and

works largely via lactic acid and lactate dehydrogenase (LDH)

Blood and O2 are only pumped to cardiac cells during diastole (cardiac period of rest or quiescence).

Your heart never “rests” longer than about 0.5-0.75 second!VIP: What happens to the time available for blood flow into the

heart when it spends more time contracted, as happens when the heart beats very rapidly (tachycardia)?

WHAT ARE THE PRIMARY VESSELS SUPPLYING BLOOD TO THE HEART?

Two Major Coronary Arteries Supply the Heart! Left Coronary Artery (the “Widow Maker”?)splits

Left Anterior Descending or Circumflex Artery Right Coronary ArteryPosterior Interventricular Artery

How do you predict the risk of a heart attack in any one part of the heart?

5) Does the region receive blood flow from a single artery?4) Does the region receive blood from 2 or more arteries3) Is the ventricular wall thick of thin?2) Are coronary arteries occluded by a thrombosis/plaque?#1) Most important question: HOW MUCH WORK IS

THE HEART DOING?

Heart Attack (Infarct) is relatively rare in the atria because of their low work load!

(In the figure, dotted line means posterior aspect of heart).

An obstruction (thrombosis) of an artery can prevent oxygen delivery to dependent tissues!

Some regions of cardiac tissue can be perfused with blood from two or three coronary arteries! (“collateral flow”)

i.e. Apex (bottom): infarct here is rare because these tissues are perfused with blood originating from the LAD and right posterior descending!

i.e. Left lateral aspect of left ventricle: only gets perfussion form one artery: circumflex! HIGH RISK for thrombosis!

Why do more anastomoses/collateral flow improve your chances for heart attack survival?

Venous drainage during diastole occurs via the great cardiac veins, with some blood entering coronary sinus.

Fetal Adaptations: Ductus arteriosus and Foramen ovale

What purpose do these fetal structures provide?

Your heart pumps blood using a five step Cardiac Cycle:

Remember the two equal cycles: Pulmonary AND Systemic

1) Diastolic Filling of Atria and Ventricles (V. Diastole) Semilunars are closed and AV valves are open!

2) Atrial Systole (VIP: occurs towards the end of V. Diastole) Ventricles are primed with atrial blood (“topped off”) Semilunar valves closed

3) Isovolumetric Ventricular Contraction (V. Systole) Semilunar valves remain closed, AV valve flaps are

close by back flow of blood into atria when the ventricular pressure begins to increase.

Pressure is generated until Ventricular mmHg > Arterial mmHg

4) Ventricular Ejection (V. Systole) When Vent P > Arterial P, semilunars open and blood can

exit the ventricle Volume of blood ejected from ventricle is dependent on

magnitude of pressure gradient Semilunar valves must open before ejection can begin!

5) Isovolumetric Ventricular Relaxation (V. Diastole) End of contraction, semilunars close when VentP< Arterial

P AV valves open and diastolic filling begins next cycle

Remember the two ventricles BOTH do these activities at about same time with the same volumes at two different pressures!

While “Atrial” Systole does occur, it is not as clinically important because the atria only do about 5% of the work done by the ventricles, so they just don’t use as much ATP or need as much oxygen.

Remember that the AV and semilular valves close to prevent flow of blood from high to low pressure back into the atria or ventricles!