Circulation and Respiration

A&P Fall 2025

What is the purpose of heart valves?

Ensuring one way flow

Atrioventricular Valves

Located between atria and ventricles

What are the two atrioventricular valves?

Tricuspid Valve (right side) and the Bicuspid Valve/Mitral Valve (left side)

Semilunar valves

Located between ventricles and arteries

What are the two semilunar valves?

Aortic valve and pulmonary valve

What causes a heart murmur?

A valve not functioning correctly allows blood to flow backward instead of being flushed out

Arteriosclerosis

Narrowing of blood vessel by built up plaque

Does heart tissue regenerate?

NO; this compromises heart

Why is it important for an artery’s wall to have a smooth surface?

To allow for good blood flow

What is the Widow maker Heart Attack?

Condition in which the left anterior descending artery (LAD) is blocked. VERY DANGEROUS; a sudden heart attack will occur

What is a stint in a blood vessel?

A mesh like structure surgically implanted into artery that is on track to be blocked. The mesh is blown up, pushing away clogging substances and is left behind the support the artery.

Pericardium

The membranous fluid filled sac that encases the heart. 

What is the purpose of the pericardium?

Serving as a buffer for the heart when it rubs against other organs

What is one issue the pericardium may experience?

If the bacteria gets into the pericardium, it may fill with fluid which puts too much pressure on the heart and prevents it from pumping properly.

What is an ERYTHROCYTE?

A red blood cell (RBC)

How do RBCs appear?

Oval shaped with a central dip (biconclave disk)

What are some important features of an RBC?

Lack of a nucleus, short lifespan, inability to reproduce

What protein/iron compound is found in RBCs?

Hemoglobin

What is Erythropoetin (EPO)

A hormone made and secreted by kidneys to stimulate production of RBCs

What is erythropoesis?

The process of RBC production

How do RBCs flow through a capillary?

Single-file

What is the diameter of an RBC?

7.5 microns (smaller than a capillary)

What is the diameter of a capillary?

8 microns

What is the smallest blood vessel in the body?

Capillaries

What is the purpose of the spleen?

Removing old RBCs, storing healthy RBCs, platelets, and lymphocytes

What are hemopoietic tissues?

Tissues that produce new RBCs by erythropoesis (Ex: Red Bone Marrow)

What is the appropriate amount of RBCs/cubic meter?

7-10 million

A count of less than 7-10 million RBCs/cubic meter is considered:

ANEMIA

What are some good sources of iron?

Leafy greens and red beef

Each hemoglobin has:

4 globins (2 alpha + 2 beta) which each carry an oxygen that attach to their iron

How are RBCs so effective at carrying Oxygen?

1 RBC = 200-300 million hemoglobins = 4 globins = 4 atoms of Oxygen

Which part of the globin carries oxygen?

Iron (Fe²⁺)

What is the heme portion of hemoglobin?

A porphorin ring that contains an iron

Each globin ALWAYS has:

A heme and an iron

What state must Iron be in so Oxygen can attach to it?

Fe²⁺ (ferrous state)

Why is carbon monoxide poisoning so dangerous?

CO₂ binds to hemoglobin 60x more, starving cells of oxygen.

How does Kidney disease affect RBC production?

If kidneys aren’t functioning, erythropoetin is not being produced, so RBCs are not produced, leading to anemia

What is the ONLY place in the body where veins carry blood that ix oxygenated?

Pulmonary veins

Why is the left side of the heart thicker?

More force is needed to get blood from the heart to the rest of the body

Hemolysis

Bursting of the RBC

What kind of product is Heme?

Waste product

What is the process of conversions in Hemolysis?

Non-iron heme is converted to bilverdin (green) → bilirubin (yellow/orange) → Urobilinogen→ some absorbed back into blood but most excreted in feces after turning into stercobilin (brown)

What is the process of steps in RBC production (erythropoesis)

Stem cell → comitted cell → early erythroblast → late erythroblast → normoblast → reticulocyte → erythrocyte

What is a stem cell (hemocytoblast)

Precursor to RBC that may differentiate to a different cell type; has nucleus, serves as immune cell

What is a committed cell (proerythroblast)

1st stage of erythropoiesis: cannot turn into anything but RBC

What occurs in an early erythroblast (2nd stage)?

Ribosome synthesis

What occurs in a late erythroblast and normoblast (3rd -4th stage)?

LOTS of hemoglobin is attained, organelles ejected

What occurs in a reticulocyte (5th stage)

Nucleus ejected (gives RBC “donut” shape). A reticulocyte is an immature RBC

What should a mature RBC be able to do?

Be ready to carry oxygen with mature hemoblobin

How many RBCs produced per second in a human?

2-3 million

What is Hypoxia?

Low Oxygen in blood

What does low oxygen in blood stimulate?

EPO secretion in kidneys

What may kidney removal cause?

Anemia

Which vitamin is essential to RBC production?

VITAMIN B 12

Why is Vitamin B12 important to RBC production?

It contains cobalt

What is the gastric intrinsic factor?

Carrier proteins made by the mucosal cells in stomach increase vitamin B 12 uptake. B 12 has cobalt which is necessary for erythropoesis

What can cause pernicious anemia?

Deficiency in cobalt, Vitamin B12, or inability to absorb either of these

Low iron causes

Anemia

Anemia involves

Blood loss, affected dietary intake, and tiredness

What is a leading cause of anemia (in women)?

Heavy menstruation; loss of RBCs lead to poor oxygen carrying capacity. 

Is it possible to overdose on iron?

YES

What are old RBCs destroyed by?

Macrophages in the liver, spleen, and red bone marrow

What is responsible for clearing our busted RBCs in the spleen?

White Blood Cells

How are weak RBCs weeded out?

While passing through capillaries, weak RBCs will burst (weaker membrane) as they squeeze into the membrane

When a RBC is destroyed, what happens to the iron?

It is reused; it attaches to transferrin and is stored in the liver or bone marrow to make more hemoglobin

What is the purpose of transferrin?

To bind to iron and take it to spleen or red bone marrow

Arteries

Carry oxygenated blood AWAY from heart

How does blood leave the left ventricle?

Large arteries

Arterioles

Highly muscular with little to no elastin, regulates blood flow to the very small capillary bed

Where is pressure the highest in the entire body?

At the arterial to capillary transition

Capillaries

Single layer of endothelial cells, site of gas, nutrient, and waste exchange between body and circulatory system. Groups are “capillary beds”

Right Atrium

1st step of blood flow: Receives blood (Low in O high in CO2) from venous system through cranial and caudal vena cava → pumps blood through tricuspid valve into right ventricle

Right Ventricle

2nd step of blood flow: Pumps blood (low in O high in CO2) through right pulmonary semilunar valve → pulmonary artery → lungs

Left Atrium

3rd Step of blood flow: Blood (high in O low in CO2) returns from lungs via pulmonary veins → pumped through mitral valve into left ventricle

Left Ventricle

4th Step of Blood flow: Blood (high in O low in CO2) pumped through aortic semilunar valve into the body

Endothelial Cells

Line blood vessels and inner lining of heart (endocardium), simple squamos

What % of blood is White Blood Cells (WBC)?

1%

What are the 3 subtypes of WBCs?

Neutrophils, basophils, eosinophils

What are some traits of WBCs?

They have a nucleus, produce antibodies, live 18-36 hours, and are the body’s first defense against invaders.

What is pus made of?

1:1 ratio of dead bacteria and dead WBCs

In a spun down sample of blood, what is the buffy coat?

White blood cells

What are eosinophils and basophils?

Granular leukocytes

What is netrophil?

A granular leukocyte

What are some traits of neutrophils?

Most common, stored in bone marrow, quickly responds by leaving blood stream and collecting at points of pathogen invasion and kills bacteria at 1:1 ratio (one dies for every one bacteria killed)

DIAPEDISIS

Ability of neutrophils to leave change shape, leave blood steam and go to site of infection

Eosinophil traits

Fewer, cannot leave blood stream, combat allergic reactions, and increase with parasitic factors

Basophil traits

Least common, creates histamine, serotonin, and heparin

Function of histamine

Forms a wall to prevent spread of infection