Heart and Circulation Flashcards
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What are the five functions of the circulatory system?
- Transport of O2 and CO2
- Regulate Temprature
- Transport of hormones
- Prevention of blood loss (closed system)
- Protection from disease-causing microbes and toxic substances (Pathogens)
Why is it important that the circulatory system remains a closed system?
- Maintain constant pressure
- Prevent blood loss
What is the difference between the pulmonary system and the systemic system?
The pulmonary system exists between the heart and lungs and the systemic system exists between the heart and body.
What three major components consist of the circulatory system?
- Heart
- Blood vessels (Arteries, Veins, Capillaries)
- Blood
What are the two major functions of the heart?
- Pumping blood - important for transport and filtering
- Keeping oxygenated blood from de-oxygenated blood - This way each cell gets oxygen-rich blood and de-oxygenated blood can become oxygenated
What is the purpose and location of the pericardium?
The pericardium is a membrane around the heart in between the heart and the lungs. This is to prevent friction between the heart and lungs.
What is the basic rundown of heart structures?
- 4 Chambers
a. Right Atrium
b. Right Ventricles
c. Left Atrium
d. Left Ventricle - Made up of specialized cardiac cells
Which side of the heart receives de-oxygenated blood and from where?
The right side receives the deoxygenated blood through the right atrium and then is transferred to the right atrium where through the pulmonary artery is pumped to the lungs. Blood is originally pumped into the right atrium through the superior and inferior vena cava. The superior vena cava brings blood from the head chest and arms whereas the inferior vena cava brings blood from the rest of the body.
Which side of the heart receives and distributes oxygenated blood?
The left side receives oxygenated blood from pulmonary veins into the left atrium, then is pumped by the left ventricle into the aorta.
What are the 5 different types of blood vessels and what are their functions?
- Arteries - Thick muscular blood vessels which take blood away from the heart.
- Veins - Blood vessels with one-way valves which prevent the backflow of blood. Contrary to arteries which rely on pulses from the heart to move blood, veins rely and suction in from the heart as well as the muscles around the veins. Take blood toward the heart.
- Cappilaries - Microscopic blood vessels that allow for the diffusion of Oxygen and Carbon Dioxide. Very low pressure and move slowly
- Arterioles - Small arteries which eventually turn into capillaries. Made of small muscles named precapillary sphincters which can regulate the flow of blood to the capillaries
- Venules - transition vessels between capillaries and veins
What is the difference between a vasodilator and Vasoconstrictor
Vasodilators are chemicals that are nerves that expand the width of vessels.
Vasoconstrictors however cause precappilary spincters to constrict.
Why is the ability to regulate the size of precapillary sphincters important?
Regulate blood pressure
What are the 3 types of valves found in the heart?
- Atrioventricular valves
composed of the tricuspid(right side) and bicuspid(left side). Regulate blood flow to ventricles from atriums and prevent backflow of blood into atrium during ventricular contraction. - Semilunar valves
Found at the entrance to major blood vessels. Smaller valves with no muscular attachments. Has THREE flaps.
What accessory structure is found at both atrioventricular valves?
Chordae tendinae - String-like structure that prevents blood backflow into the atrium during ventricular contraction.
What makes the “Lubb” “Dubb” sound in the heart?
The AV valves and semi-lunar valves closing make the “Lubb” and “Dubb” sound. When the AV valves close it makes the ‘lubb’ sound and when the semi-lunar valves close it makes the ‘dubb’ sound.
What initializes the heartbeat?
A bundle of specialized cells known as the sinoatrial node located in the right atrium initiates the heartbeat.
What effect do the sinoatrial node electrical impulses have?
The SA node’s electrical signals cause heart muscles to contract.
What are the steps involved in heart contraction?
- The SA node generates electrical impulses and causes both atriums to contract simultaneously
- As the atrium contracts the signal reaches the atrioventricular node (AV) node which transmits the signal through specialized cells called the bundle of HIS.
- The bundle of HIS divides into fast-conducting Purkinje fibers.
- As the signal reaches the Purkinje fibers the ventricles contract.
What is the difference between Systole and Diastole?
Systole is when the ventricles contract and Diastole is when the atriums relax and drain into the ventricles.
During Systole what do the AV valves do?
The AV valves close making the ‘lubb’ sound.
What happens during Diastole?
The Semi-lunar valves close and the AV valves open. The semi-lunar valve closing makes the ‘dubb’ sound.
How is heart rate set?
The SA node sets the heart rate.
What are Bradycardia and, Tachycardia examples of?
These two are examples of different resting heart rates both of which are the extremes on the spectrum.
What is bradycardia?
Bradycardia is when a resting heart rate is <50 beats per/minute this could be bad if the body doesn’t not receive enough blood flow.
What is tachycardia?
This is when the resting heart rate exceeds 100 beats per minute. This could be bad as it could mean that the chambers may not fully fill with blood.
How is heartrate changed?
The heart rate is regulated by a feedback system including a monitor which detects change, a control center which sends out orders, and a regulator which brings about a change.
What is the difference between sympathetic and parasympathetic nerves?
Sympathetic nerves increase heart rate whereas parasympathetic nerves decrease heart rate.
What are some other factors which could increase heart rate?
- An increase in temperature
- An increase in the hormone epinephrine(adrenaline)
- Different chemicals such as carbon monoxide and alcohol.
How does CO2 affect heart rate and how is detected and changed?
If an increased amount of CO2 is detected chemoreceptors(monitor)in the Aorta and carotid arteries detect the change and send a nerve signal to the medulla oblongata(control center). The medulla oblongata send out sympathetic nerve impulses causing the heart to increase heart rate. The inverse happens if CO2 levels drop.
What is the purpose of an ECG?
An ECG is used to measure the change in electrical impulses produced as the heart relaxes and contracts.
In order an ECG has 5 steps: PQRST. What happens at each of these steps?
P - Small voltage increase as atriums contract
Q, R, S complex - Spike in electrical activity as ventricles contract.
T - Small spike in electrical activity as ventricles relax.
Why are you unable to see atrial relaxation on an ECG?
This is because the ventricular contraction is much greater electrically and happens at the same time.
What is blood pressure and why is it important?
Blood pressure measured in mm/Hg (mercury) is the force that blood exerts against blood vessel walls as it is pumped from the left ventricle. It is important as it maintains an efficient closed system.
Why is mm/Hg used instead of another value?
This is because mm/hg is a smaller unit. This is good because the pressure involved aren’t as large as a tire for example which would use pascals/inch^2
What causes pressure to increase in the Aorta and Pulmonary arteries?
Ventricular contraction forces blood into the aorta and pulmonary arteries.
What causes pressure to drop in the vessels?
Ventricular relaxation.
What medical device is used to measure blood pressure?
A sphygmomanometer is used to measure blood pressure.
What arms is a sphygmomanometer used on and why?
The left arm. This is because it is closest to the heart.
What form is blood pressure given in?
Fraction form: Systolic/Diastolic
What is the average blood pressure of a healthy young person?
120/80
What is more dangerous? High systolic pressure or high diastolic pressure? Why?
Diastolic pressure. This is because high pressure against vessels could lead to an increased risk of vessel rupturing.
If heart rate increases and more blood is being pumped per minute what happens to the pressure in the vessels?
Pressure increases.
What are the five factors that affect blood pressure?
- Volume of blood. Decreased blood = decreased pressure
- Heart rate. Increased heart rate = increased pressure.
- Size of arteries. Increased diameter = decreased pressure
- Elasticity of arteries. Less elastic more rigid = increased blood pressure
- Viscosity of blood. Increased viscosity = increased blood pressure
What could lead to less elastic arteries?
- Age
- Atherosclerosis
What effect do vasoconstrictors and vasodilators have on blood pressure?
Vasodilators decrease blood pressure and vasoconstrictors increase blood pressure.
How is high blood pressure regulated?
Baroreceptors(‘Baro’ = pressure) in the aorta and carotid arteries are sensitive to high blood pressure. If blood pressure is high the baroreceptors send a message to the medulla oblongata which sends out more parasympathetic and less sympathetic impulses. This results in arterial dilation and reduced cardiac output. This reduces blood pressure.
How is low blood pressure regulated?
The kidney also monitors blood pressure. If blood pressure is low the kindy releases rennin into the blood. Rennin causes the chemical angiotensin II to be produced which causes arteries to constrict and cause capillary beds to shut down. This increases blood pressure as blood has less space to occupy.
What is the regulation of blood pressure an example of?
A negative feedback loop
What is hypertension and why is it bad?
Hypertension is when blood pressure is equal to or greater than 140/90. This causes the heart to have to work harder and may become less efficient. This inefficiency is may result in a heart attack and stroke.
What is a stroke?
A ruptured blood vessel in the brain.
What are four things hypertension could be caused by?
- Atherosclerosis
- Genetics
- Impaired kidney function(can’t release rennin into blood to lower blood pressure)
- Stress
As internal temperature is crucial to the metabolic process to function: Enzyme activity etc, how does the heart affect temperature?
If the internal temperature is too high: Blood vessels dilate to increase blood flow thus there is increased heat loss through the skin.
If the internal temperature is too low: Blood vessels near the skin constrict reducing blood flow and heat loss
What is the other thing our body does to warm up?
Muscle contractions(shivering)
How is heat generated in the human body?
Cellular respiration
What is cardiac output?
The amount of blood pumped out of the heart each minute. Measured in the ml/min
What are two factors that affect cardiac output?
- Heart rate
- Stroke Volume
What is stroke volume?
Amount of blood pumped out of the heart each BEAT. Measured in ml
How do you calculate cardiac output?
Stroke Volume x Heart rate = Cardiac output
As stroke volume depends on how easily the blood fills and empties with blood, how easily the heart can fill with blood is dependent on what?
- Volume of blood returning to the heart
- Stretchiness of ventricles
How easily the heart empties depends on ….
- Strength of ventricular contraction
- Pressure exerted by artery walls
What are the three pathways blood travels by throughout the body?
- Pulmonary (Lungs)
- Systemic(body)
- Coronary(heart)
What is the purpose of the coronary pathway?
To provide oxygen to the heart
Why can’t the heart use blood from the chambers?
Because the walls are too thick for oxygen to diffuse effectively?
What type of blood vessels is used in the coronary pathway?
Capillaries which split off of the aorta are embedded into the heart walls.
What happens to the deoxygenated blood of the coronary capillaries?
Deoxygenated blood leaves the heart through the coronary veins and into the right VENTRICLES.
What is Atherosclerosis?
The thicking and hardening of blood vessels. Fatty deposits, calcium, and fibrous tissues create a plaque on the inside of arteries.
What is Arteriosclerosis?
A general term used to describe the thickening and hardening of arteries.
What is angina?
- Chest pain
- Blood clots
- Shortness of breath
- Heart attack
- Heart failure
How can you reduce developing arteriosclerosis?
- Not smoking
- Diet high in fruits and veggies
- Diet low in saturated fats
What are two treatments for arteriosclerosis?
- Angioplatsy - A Tube is inserted into a clogged artery and a balloon is inflated to open the artery. Sometimes a small metal tube called a stint is insterted to hold the vessel open and prevent blockage.
- Coronary bypass (more invasive) - Uses a healthy section of arterial vein to create a new path for blood
What is a heart mummer?
Misflow of blood in the heart - Valves (one or more) don’t open or close properly
What is the defect categorized as if you are born with the condition?
Congenital
What if you contract it later on?
Acquired
What is an aneurysm?
A fluid-filled bulge in the weakened wall of artery
What are varicose veins?
Weins in which valves do not close properly and blood pools in the legs.
Who is at greatest risk for varicose veins?
Someone who is overweight, not very active, women(more common than men), hereditary
What is an artificial pacemaker?
Uses batteries to send electrical signals to produce a coordinated signal to replace SA and VA nodes when they fail.
