Studied by 2 people
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?
Atrial systole
Ventricle systole
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?
Distribution of nutrients, gases, and hormones
Regulation of body temperature and pH
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?
Red blood cells
White blood cells
Platelets
Plasma
What are the 2 categories of the elements of whole blood?
Formed elements
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
Note
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