Heart Flashcards
Which arteries deliver blood to the myocardium?
Coronary arteries
What delivers oxygen poor blood to the coronary sinus from the heart?
Cardiac veins
Why does the heart need no external nerves to beat?
The heart is made up of cardiomyocytes. Waves of excitation are sent from the SAN which allow the heart to beat. No external nerves are needed for the heart to beat. But vagus nerve and sympathetic cardiac nerves control the SAN.
How does the parasympathetic nervous system affect heart rate?
Decreases heart rate.
Parents want you to slow down while driving
Which nerve controls the parasympathetic heart rate ?
Vagus nerve
How does the sympathetic nervous system affect heart rate?
Increases heart rate
What nerve controls the sympathetic nervous system ?
Sympathetic cardiac nerves
What nerve controls the sympathetic nervous system ?
Sympathetic cardiac nerves
How many beats per minute is normal heart rate ?
60-100 beats per minute
What is Tachycardia?
Heart rate over 100 beats per minute. Tach = too fast
Bradycardia
Heart rate under 60 beats per minute
What is the function of the atrioventricular node?
Adds a brief delay between contraction of the atria and ventricles.
Describe the cardiac conduction system ?
SA node
Atrioventricular node
Bundle of his
Left and Right bundles
Purkinje fibers = coordinate ventricular contraction
Where are the purkinje fibers found?
Walls of the ventricles
Another name for systole?
Ventricular contraction
Another name for diastole?
Ventricular relaxation
At what point is the pressure in the arteries the lowest?
ventricular relaxation. When blood is coming out of the atria into the ventricles.
At what point is the pressure in the arteries the lowest?
ventricular relaxation. When blood is coming out of the atria into the ventricles.
What causes the lub and dub sounds of the heart?
Closing of the atrioventricular or semilunar valves
What causes the ‘lub’ sound
Atrioventricular valve closing
What causes the ‘dub’ sound
Semilunar valve closing
Systole occurs between which sounds?
lub and dub
Diastole occurs between which sounds ?
dub and lub
What connects cardiomyocytes togther?
Intercalated discs
What are intercalated discs made up of ?
Desmosomes and Gap Junctions
Describe desmosomes?
small proteins that adhere cardiomyocytes together.
they look like stitches
Describe gap junctions?
protein tunnels that connect the cytoplasm of cardiomyocytes.
This allows the movement of ions between cardiomyocytes and allows action potantials to be sent between cells?
What is cardiac syncytium ?
The cardiac syncytium is a network of cardiomyocytes connected by intercalated discs that enable the rapid transmission of electrical impulses through the network, enabling the syncytium to act in a coordinated contraction of the myocardium
What to electrodes attached to the chest measure?
Depolarization
What does P wave represent ?
Atria depolarization
What does Q wave represent?
Depolarization through the interventricular septum
What does the R wave represent?
Depolarization through the ventricles
What does S wave represent ?
Completion of ventricular depolarisation
What does QRS complex represent?
Broad view of ventricular depolarisation.
What does T wave represent?
Ventricular repolarisation
Why cant you see atrial repolarization wave on a ECG?
There is no visible atrial repolarization wave because it’s hidden by the dominant QRS complex.
What is the stroke volume?
Volume of blood pumped from the heart with each beat. Typically refers to the volume of blood ejected from the left ventricle.
What equation do you use to work out the stroke volume ?
EDV - ESV = SV
(End - diastolic volume) - (End - systolic volume) = Stroke Volume
EDV - is the volume of blood after diastole
ESV - after systole a little blood is left in each ventricle which is called the ESV.
What does EDV - ESV = SV mean ?
Amount of blood before ventricular circulation - Amount if blood after ventricular circulation = blood pumped out at ventricular circulation
What does cardiac output tell us ?
Cardiac output: The volume of blood pumped by the heart in one minute
What is the equation for cardiac output ?
CO = HR x SV
Cardiac Output = Heart rate x stroke volume
Why is knowing the cardiac output important ?
Too high or low cardiac output can indicate heart problems.
What does TPR stand for and what does it mean ?
Total Peripheral Resistance and it means the total resistance blood faces while flowing through vasculature ( veins / arteries / capillaries).
What does vasoconstriction do to TPR?
Increases TPR
What does vasodilation do to TPR?
Decreases TPR
What does SBP stand for and what does it mean ?
Systolic blood pressure (SBP): Highest pressure in your arteries
What does DBP stand for and what does it mean ?
Diastolic blood pressure (DBP) : Lowest pressure in your arteries
How is blood pressure often written ?
120/80 mm Hg
The number at the top is systolic blood pressure
The number at the bottom is your diastolic blood pressure
mm Hg means millimeters of mercury
What does Map stand for and what is its equation ?
Mean Arterial Pressure
MAP is a better indicator of blood pressure than SBP or DBP.
MAP = CO x TPR
What are the two equations for finding out MAP ?
MAP = CO x TPR
MAP = (SV x HR) x TPR
What is the name of the technique used to measure blood pressure using a blood pressure cuff?
Auscultation
What is another name for blood pressure cuff?
Sphygmomanometer
What are the 3 tissue layer of a vein or an artery?
tunica intima
tunica media
tunica externa
Describe tunica intima layer of a vessel?
Tunica intima is made up of a single layer of endothelial cells ( simple squamous epithelium) which line the lumen of the vessel.
It reduces the amount of friction the blood experiences when flowing through the vessel.
Describe the tunica media layer of a vessel ?
Tunica media can change the size of a blood vessel, so how much blood can go through a vessel. So tunica media can cause vasodilation or vasoconstriction of the blood vessel.
Tunica media is made up of smooth muscle cells and elastic fibers.
Describe the tunica externa layer of a vessel?
The tunica externa layer is the outer layer of a blood vessel. Its made up of:
- connective tissue
- collagen
- elastin
- nerve fibers ( the tunica externa has nerves which communicate with the tunica media and stimulate vasodilation or vasoconstriction ).
What makes tunica media layer of a blood vessel highly elastic ?
Thick tunica media
High amounts of elastin
Why are arterioles called resistance vessels ?
Blood can experience a lot of resistance when travelling through arterioles.
Where does blood travel at a lower pressure arteries or arterioles ?
Arterioles
How might arterioles assist in thermoregulation ?
On a cold day - vasoconstriction
On a hot day - vasodilation
What are capillaries made up of ?
Only made up of tunica intima ( endothelial cells) & basement membrane
What are the three types of capillaries ?
Can you describe each ?
- Continuous: these capillaries are made up of only tunica intima and have a water tight barrier.
-Fenestrated: In some capillaries they utilize fenestrations ( pores/holes) which allow for larger nutrients to pass into or out of the capillaries.
- Sinusoid: Sinusoid capillaries have even larger pores for more diffusion
What does fenestra mean ?
pores
What is the area around the capillaries called ?
interstitial space
What is capillary Hydrostatic Pressure and what does it do ?
Capillary hydrostatic pressure means that as blood moves along the capillary, fluid moves out through its pores and into the interstitial space. This allows nutrients to be brought to tissues.
What is capillary Hydrostatic Pressure opposed by ?
Interstitial Fluid Hydrostatic Pressure (IFHP)
Which force is greater Capillary Hydrostatic Pressure (CHP) or Interstitial Fluid Hydrostatic Pressure (IFHP) ?
Capillary hydrostatic pressure is a greater force than interstitial hydrostatic pressure.
What is Plasma osmotic pressure and how does it work ?
Plasma osmotic pressure pulls plasma back into the capillary.
It happens because of high oncotic pressure in the vessel. There is low osmotic pressure in the capillary at this point. Water flows into the capillary and takes proteins with it.
What pressure pushes fluid out of the capillaries at the arterial end ?
And what pressure opposes this ?
Hydrostatic pressure pushes fluid out of the capillaries at the arterial end.
Interstitial fluid hydrostatic pressure opposes this
What pressure pulls plasma back into the capillaries ?
And what opposes this?
Osmotic pressure pulls fluid back into the capillaries at the venule end.
Interstitial fluid osmotic pressure
What are known as capacitance vessels ?
Veins
What hold more blood veins or arteries?
Veins
How do veins hold more blood than arteries ?
Veins have a relatively thin smooth muscle layer ( thin tunica media), so there is more space for a larger lumen, therefore they can hold more blood.
List blood vessels from those with the highest pressure to the lowest pressure ?
Aorta (highest blood pressure)
Elastic arteries
Muscular arteries
Arterioles
Capillaries
Venules
Medium and large veins
Vena cavae (lowest blood pressure)
What stops gravity pulling blood back down in the veins ?
Valves in the legs prevent the backflow of blood
What two pumps propel blood to go back to the heart in the veins ?
- Skeletal muscle pump
Blood is propelled back up towards the heart when our leg muscle sqeeze. - Respiratory Pump ( aka abdominothoracic pump)
When you inhale the diaphragm contracts and flattens pushing on your abdomen and increasing abdominal pressure. This squeezes the veins in your abdomen, increasing pressure and forcing blood upwards.
The decrease in thoracic pressure causes a negative pressure, which causes a negative vegetive force on the vena cava, which help propel blood back into the right atrium.
What two pumps propel blood to go back to the heart in the veins ?
- Skeletal muscle pump
Blood is propelled back up towards the heart when our leg muscle sqeeze. - Respiratory Pump ( aka abdominothoracic pump) - acts when you inhale
When you inhale the diaphragm contracts and flattens pushing on your abdomen and increasing abdominal pressure. This squeezes the veins in your abdomen, increasing pressure and forcing blood upwards.
The decrease in thoracic pressure causes a negative pressure, which causes a negative vegetive force on the vena cava, which help propel blood back into the right atrium.
What’s another word for respiratory pump ?
Abdominothoracic pump
What are the effects on abdominal and thoracic pressure when you inhale ?
- Increases abdominal pressure
- Decreases thoracic pressure
What is the hepatic portal system ?
Hepatic portal system: Shunts blood from the digestive tract (the esophagus, stomach, small and large intestine, pancreas, gallbladder, and spleen to the liver) to the liver, where it can be made safe for the rest of the body.
The reason we do this is because it would be very dangerous for organs such as the brain if we sent really concentrated blood to the brain.
What is a portal system ?
Why is a portal system important ?
Portal system: when blood is sent from:
capillary bed -> portal vein ->capillary bed
Portal system is important as it allows the shunting of concentrated blood from one area of the body to another.
What does the Hypophyseal Portal System do ?
Hypophyseal portal system: shunts hormones from the hypothalamus to the anterior pituitary gland (adenohypophysis).
This allows for rapid communication between the hypothalamus and pituitary gland as blood does not have to be pumped through the systemic circuit before reaching anterior pituitary. It also means we do not need lots of hormones in the systemic circuit which do not need to be there.
Why are portal systems considered to be venous systems ?
Portal venous systems are considered venous because the blood vessels that join the two capillary beds are either veins or venules
What mechanism does our body have to fix blood vessels if they get broken ?
Blood clotting cascade
What are platlets ?
Platelets (aka thrombocytes) are small, colorless cell fragments in our blood that form clots and stop or prevent bleeding.
What type of mechanism is the blood clotting cascade ?
Positive feedback mechanism
Describe the blood clotting cascade ?
- Tissue damage to a blood vessel exposes the collagen of blood vessels.
- Platelets interact with collagen and become activated
- Platelets aggregate at area of damage on blood vessel and form a PLATLET PLUG
- Activated platelets release THROMBOPLASTIN
- thromboplastin converts PROTHROMBIN (inactivated enzyme) to THROMBIN (activated enzyme).
- thrombin converts FIBRINOGEN to FIBRIN
- Fibrin polymerizes with other fibrin strands, to form a HEMOSTATIC PLUG ( blood clot)
What is the function of thromboplastin ?
Thromboplastin converts PROTHROMBIN to THROMBIN
What is the function of thrombin ?
Thrombin converts FIBRINOGEN to FIBRIN
What is another name for a blood clot?
Hemostatic plug
Name a clotting factor ?
Prothrombin
Whys is vitamin k important ?
Vitamin k is important for creating clotting factors such as prothrombin.
It is produced and modified by symbiotic bacteria in the large intestine and we also get some vitamin k from our diet.
Who may be at increased risk of vitamin K deficiency ?
Newborns
What makes up blood ?
Plasma (55%)
Leukocytes and platelets ( < 1% of total blood)
Erythrocytes ( 45%)
What does blood plasma contain ?
Contains water, protein, nutrients and hormones.
What is another name for leukocytes ?
White blood cells
Describe thrombocytes ( aka platelets )
Cell fragments that do not contain a nucleus ( anucleate)
They originate from megakaryocytes
Describe erythrocytes ?
Deliver oxygen
Anucleate
Flexible
Biconcave
Each red blood cell contains millions of hemoglobin molecules
Describe hemoglobin ?
Is a quaternary protein with 4 subunits
Each subunit is associated with a heme group
Each hemoglobin can carry 4 new oxygen molecules
Why are the antigens on erythrocytes important ?
They give us our blood types
Which antibodies does type AB blood have ?
None
Which antibodies does type O blood have ?
Antibody - A
Antibody - B
Which antibodies does type O red blood cells have ?
They have no antigens
What is Rh?
If a person has Rh what is it called ?
If a person doesn’t have Rh what is it called ?
Rhesus factor (Rh)
Red blood cells either have Rh or they don’t
Rh positive
Rh negative
How many blood types are there and what are they called?
A+ & A-
B+ & B-
AB+ & AB-
O+ & O-
What does the term agglutination mean ? ( blood transfucions)
If you get the wrong blood type transfused, antibodies from your body will clump together those erythrocytes which is called agglutination.
What does a universal donor mean and what is their blood type ?
Person who can donate to anyone.
Type O-
( O negative)
They dont have A or B antigens
What does universal acceptor mean ?
Person who can receive to anyone
AB +
What is the pathway of oxygen rich blood in fetal circulation?
Oxygen rich red blood cells first go from the
1. Placenta
2. Umbilical cord
3. Umbilical vein
4. Towards the liver ( a little blood goes to the liver )
5. However most bypasses the liver through a shunt called the DUCTUS VENOSUS
6. The oxygen rich blood from the ductus venosus mixes with the oxygen poor blood of the inferior vena cava. We get blood that is slightly oxygenated heading back to the right atrium.
7. Right atrium -> Forman ovale -> left atrium -> left ventricle -> pumped around body
Why is blood shunted away from the liver ? ( fetal circulation )
- The liver is not functional at this point
- The liver does not need this blood
What is the function of the umbilical vein ?
How many umbilical veins are there ?
Transports oxygen rich blood from the placenta to the fetus
1 umbilical vein
What is the function of the umbilical artery ?
Transports oxygen poor blood from the fetus back to the placenta
2 umbilical arteries
Why do we bypass the pulmonary circuit in the pathway of oxygen rich blood? (fetal circulation)
The lungs are not functional yet.
What is the pathway of oxygen-poor blood in fetal circulation?
- Oxygen poor blood comes from the superior vena cava
- Only a small volume mixes in the right atrium with the oxygen-rich blood from the inferior vena cava.
- The majority is pushed into the right ventricle
- From there the blood goes up the pulmonary trunk where it is diverted by a shunt called the DUCTUS ARTERIOSUS
- The blood then enters the descending aorta.
- Slightly oxygen rich and oxygen-poor blood mix in the descending aorta
which generates very slightly oxygen-rich tissues.
Eventually this returns to the placenta via the umbilical arteries.
Foetal circulation bypasses the pulmonary circuit, which shunts allow for this to occur?
- Foramen ovale
- Ductus Arteriosus
What physical principle allows the bypassing of the pulmonary circuit during foetal circulation ?
Difference in resistance / pressure
1. lungs arterioles & capillaries are very constricted - which causes high resistance / high pressure
2. Blood like water goes form an area of high resistance / high pressure to an area of lower resistance / lower pressure.
2. The blood pressure is much higher in the pulmonary arteries than the blood pressure in the descending aorta (lower bp), so the blood travels this way.
What has a higher pulmonary pressure, the foetus or adult?
Pulmonary arteries of a fetus have a much higher pressure than the pulmonary arteries of an adult.
Why does blood flow back to the placenta ?
Placenta has low resistance this is because capillaries and arteries in the placenta re under very low pressure. They are very dilated
This low resistance means a large portion of fetal blood enters the umbilical arteries into the placenta rather than going down the leg.
No matter the position of the fetus oxygen poor blood will be brought back to the placenta
Which vessel returns oxygen poor blood back to the placenta ?
Umbilical arteries
What can cross the placenta from mother to fetus ?
Oxygen and nutrients from the the mother
What CANNOT cross the placenta from moter to foetus ?
What CANNOT cross the placenta from mother to fetus ?
Red blood cells.
Maternal and fetal blood do not mix.
This means foetus and mother can have different blood types.
Which structure prevents the mixing of maternal and fetal blood?
Embryonic CHORION
Embryonic chorion makes it so that some things cannot be passed to the mother from the foetus and some things from the foetus cant be passed onto the mother.
What is Erythroblastosis Fetalis ?
This is when fetal and maternal blood mix.
How does Erythroblastosis harm the second fetus ( second baby) ?
Some antibodies are allowed to cross the placenta. Including antibodies against Rhesus factor and act the fotuses red blood cells. This means the fetus doesn’t have enough red blood cells and is anemic. In many cases this can result in the death of the fetus.
A fetus would be at risk of erythroblastosis fetalis in which of the following situations ? Assume that each second born was preceded by a RH ( +) first born ?
RH (+) second born & RH ( - ) mother
What is the fluid around the capillaries called?(lymph)
Interstitial fluid
Not all of the interstitial fluid is reabsorbed. What happens to this fluid? (lymph)
The fluid enters the LYPHATIC CAPILLARIES
What are the smallest structure of the lymphatic system called?
Lymph
How does the interstitial fluid get into the lymphatic capillaries ?
The lymphatic capillaries are very leaky. The osmotic pressure at our venule end of our capillary bed is plenty to push all of this interstitial fluid into our lymphatic capillary. Once the interstitial fluid has gone into our capillary, we call it lymph.
At what point do we call interstitial fluid, lymph?
Once the interstitial fluid has entered the lymphatic capillaries.
What is lymph made up of ?
combination of interstitial fluid, fat, proteins and even bacteria.
What determines the amount of lymph you will have in your capillaries?
The amount of lymph in the lymphatic capillaries is determined by how much of that plasma is brought back into the circulatory system at the venule end of the capillary bed.
If a capillary only takes up a small amount of fluid, then there will be a lot of lymph as the lymphatic capillaries have to pick up the slack.
What are lacteals ?
Lacteals : The lymphatic vessels of the small intestine which absorb digested fats.
What is a lymph node ?
Lymph nodes filter substances that travel through the lymphatic fluid, and they contain lymphocytes (white blood cells) that help the body fight infection and disease. There are hundreds of lymph nodes found throughout the body.
Is the lymphatic system fast moving or slow moving ?
Slow moving
What contain lymphocytes ?
Lymph nodes
What happens when the lymph returns back to the circulatory system?
When the lymph returns to the circulatory system it’s going to replace all the fluid that was lost at the capillaries.
Lymphatic vessels do not deliver lymph to the heart but instead deliver it to the circulatory veins.
Which veins does the throracic duct drain into?
The thoracic lymphatic duct drains into the left subclavian vein.
Lymphatic vessels do not deliver lymph to the heart but instead deliver it to the circulatory veins.
Which veins does the right lymphatic duct drain into?
The right lymphatic duct drains into the right subclavian vein.
Features of the lymphatic vessels ?
Lymphatic vessels are most similar to veins.
they have a small smooth muscle layer that helps push lymph via peristalsis.
Lymphatic system is a low pressure system.
Lymphatic vessels have valves to prevent the backflow of blood, they also utilize the skeletal muscle pump.
What duct collects lymph from the upper right half of the body ?
Right lymph duct
What duct collects lymph from the rest of your body ?
Thoracic duct.
