A&P II Quiz #5

What is the cardiac cycle?

The different phases going on the heart to get blood to move through the heart and get ejected

Is the cardiac cycle continuous or not?

It’s continuous

What happens to pressure when the volume increases in the same space?

Pressure increases

How does fluid move in relation to pressure?

From high pressure to low pressure

What are the 3 main events of the cardiac cycle?

1) Atrial systole

2) Ventricle systole

3) Ventricle diastole

What happens during atrial systole?

Blood is ejected from the atria

What happens during ventricle systole?

The ventricles eject blood

What happens during ventricle diastole?

The ventricles fill with blood

What does systole refer to?

The pressure in chambers of the heart when blood is being ejected

What does diastole refer to?

The pressure in the chambers of the heart when they’re relaxed and filling

How do the ventricles initially fill?

Passive filling

To what percentage do the ventricles fill with passive filling?

To 80%

What happens when the ventricles are 80% full?

The pressure gradient between the atria and ventricles nears equilibrium

What happens when the ventricles reach 80% full?

* The ventricles stop passively filling with blood
* The atria contract to fully fill the ventricles

When does atrial systole begin?

When the ventricles are 80% full

What happens once the atria contract and fully fill the ventricles?

The atrioventricular valves shut to prevent back flow

Why do the atrioventricular valves have to shut after atrial contraction?

Because the ventricles now have greater pressure than the atria

What intrinsic conducting cells cause atrial systole?

The SA node

What is the goal of ventricle systole?

To get blood out of the ventricles into the arteries

Does the pressure in the ventricles need to be greater or less than the pressure in the arteries to eject blood?

The pressure needs to be greater

What happens in early ventricular systole to increase the pressure in the ventricles?

Isovolumetric contraction

What happens during isovolumetric contraction?

The ventricles contract without blood leaving the ventricles

What intrinsic conducting cells cause the isovolumetric contraction of the ventricles?

The AV node sends the signal down the Bundle of His to make it happen

What does end-diastolic volume refer to?

The volume of blood in the ventricles when they’re done filling with blood and the atrioventricular valves are shut

What happens during late ventricular systole?

The ejection of blood from the ventricles to the arteries

When do semilunar valves open?

When pressure in the ventricles is greater than the pressure in the arteries

* After the isovolumetric contraction

What happens to the semilunar valves the moment the blood leaves the ventricles?

The semilunar valves shut

Why do the semilunar valves shut once blood is ejected from the ventricles?

To prevent backflow

* The arteries have greater pressure than the ventricles then

Which valves are open or closed at the end of ventricular systole?

Both the atrioventricular and semilunar valves are shut

What begins at the start of ventricular diastole?

Isovolumetric relaxation

What happens in isometric relaxation?

The myocardium in the relaxes without blood entering

How does the pressure of the ventricles have to be in comparison to the pressure of the atria in order to passively fill?

The pressure of the ventricles has to be less than the pressure of the atria

What causes the atrioventricular valves to open again?

Low pressure in the ventricles

What does the opening of the atrioventricular valves lead to?

Passive filling of the ventricles

When do the atria begin filling?

As soon as the atrioventricular valves shut during atrial systole

What are the 3 main function of blood?

1) Distribution of nutrients, gases, and hormones

2) Regulation of body temperature and pH

3) Protection

How does the blood regulate body temperature?

* If you’re hot, it takes heat produced by muscle contractions and circulates it to sweat glands that get rid of it
* If you’re cold, it takes heat produced by muscle contractions and circulates it to the vital organs

How does the blood protect the body?

White blood cells

What are the 4 components of whole blood?

1) Red blood cells

2) White blood cells

3) Platelets

4) Plasma

What are the 2 categories of the elements of whole blood?

1) Formed elements

2) Non-formed elements?

What components of blood are formed elements?

* Red blood cells
* White blood cells
* Platelets

What component of whole blood is a non-formed element?

Plasma

What is plasma composed of?

* Water
* Solutes
* Plasma proteins

Is plasma dynamic?

Yes

What does the composition of plasma dependent on?

What you eat and what can dissolve in water

What is another name for red blood cells?

Erythrocytes

What is another name for white blood cells?

Leukocytes

What is another name for platelets?

Thrombocytes

What is the most dense part of blood?

Erythrocytes

What is the least dense part of blood?

Plasma

What percentage of blood in a healthy person do erythrocytes make up?

About 45%

What percentage of blood in a healthy individual do leukocytes and thrombocytes make up?

About 1 %

What percentage of blood does plasma make up in a healthy individual?

About 55%

What is the hematocrit value?

The percentage of red blood cells in the blood

What does plasma composition depend on?

What your cells need

What are plasma proteins?

Proteins that are supposed to stay in the blood vessels

What does osmotic pressure do?

It prevents all the fluid from entering the blood

How do plasma proteins contribute to osmotic pressure?

They increase the pressure in the blood to stop a large pressure gradient from forming

Can some fluid still enter the blood?

Yes

* The blood can still gather waste, but not a lot of fluid

What is one of the main roles of the liver?

To make plasma proteins

Can plasma proteins be released for energy?

No

Are formed elements typical or atypical?

Atypical

How many of the formed elements are true cells?

Only 1 formed element is a true cell with a nucleus

Can the formed elements without a nucleus divide?

No

How long is the lifespan of formed elements?

Really short

* Usually just a couple of days

Are thrombocytes usually active or inactive?

Inactive

What activates thrombocytes?

Injury

What happens to thrombocytes when they’re activated?

They release chemicals and form strands of proteins

How are erythrocytes shaped?

They have a biconcave shape

* The center is depressed

What protein is in red blood cells?

Hemoglobin

About how many hemoglobin proteins are in 1 red blood cell?

About 1 billion

What is hemoglobin composed of?

4 heme with 1 iron each

What binds to iron?

Oxygen

What is the purpose of the biconcave shape of the red blood cells?

It makes the membrane distance to the hemoglobin smaller so the diffusion of oxygen to the tissues that need it is quicker

Why do red blood cells not have nuclei?

It would limit the amount of hemoglobin they could contain

Why can’t we just increase the number of red blood cells to get more hemoglobin instead of getting rid of the nuclei?

It would increase the viscosity of blood too much

When do red blood cells shed their nucleus?

Right before they mature

Why do red blood cells have a nucleus in the first place?

They need nuclei to produce hemoglobin

How does increased viscosity affect blood flow?

It decreases blood flow

What is polycythemia?

High red blood cell counts

What are 2 scenarios when polycythemia can occur?

* High altitude because there’s less atmospheric pressure to push oxygen into lungs so the kidney produces more red blood cells
* Blood doping

Why does polycythemia increase the risk for strokes?

It increases viscosity and decreases blood flow too much

Do erythrocytes have mitochondria?

No

Why don’t erythrocytes have mitochondria?

Mitochondria uses oxygen for cellular respiration which defeats the purpose of the red blood cells transporting oxygen

Other than hemoglobin, what is the only thing that red blood cells contain?

Enzymes that prevent oxygen from becoming free radicals

What are free radicals?

Potent substances that destroy things

How would free radicals affect red blood cells?

They would die

Why does hemoglobin have to be contained in red blood cells?

To decrease viscosity

* Free flowing hemoglobin in such high quantities would increase viscosity
* Also protects hemoglobin

What is oxyhemoglobin?

Oxygenated hemoglobin

What is deoxyhemoglobin?

Deoxygenated hemoglobin

What is carbaminohemoglobin?

Hemoglobin with carbon dioxide bound to it

What happens to hemoglobin when it releases oxygen?

It changes shape which allows carbon dioxide to bind to it

When does carbon dioxide bind to hemoglobin?

ONLY when it is deoxyhemoglobin