06/08/2023 Notes Flashcards
What division of the nervous system innervates the heart?
Autonomic nervous system
What is the coronary plexus?
Both the sympathetic and parasympathetic innervation of the heart
What carries out sympathetic innervation of the heart, and what does it do?
nerve fibers form T1-T5 increase the heart rate and force of contractions
What causes parasympathetic innervation of the heart?
The medulla through CN X decreases the heart rate but does not affect force of contractions
What do autonomic centers in the brainstem do for the heart?
Increase/decrease the heartbeat, but does NOT initiate the heartbeat
What is a cardiac cycle?
Inclusive period from the start of one heartbeat to the initiation of the next
What is systole?
Contraction of the heart that force blood into another chamber of blood vessel
What is diastole?
Relaxation of the heart that allows the chambers to fully fill with blood
At the beginning of the cardiac cycle, which chambers contract simultaneously?
Left and right atria
During atrial systole, what happens?
Blood returning from the superior/inferior vena cava and the coronary sinus (right atrium) and pulmonary veins (left atrium) is forced through the open AV valves into ventricles
Once atrial diastole occurs, what happens?
Both the left and right ventricles contract simultaneously
What happens to AV valves as the ventricle contract?
AV valves shut tight and blood pushes against the cusp to form a seal
What prevents the heart valves from everting?
Papillary muscles and chordae tenineae
When semilunar valves are forced open, where does blood travel?
Into the pulmonary trunk and aorta
During ventricle diastole, how does blood travel?
Blood flows passively from the atria to ventricles through open AV valves
During the last half of the cardiac cycle, what state are all four heart chambers in?
Diastole
Give a summary of blood flow during 1 cardiac cycle.
Pressure on the blood in heart chambers increase/decrease during contraction/relaxation;
Blood flows from veins continuously into both atria with low pressure;
Blood flows from atria to ventricles if AV valves are open;
Systole increases pressure on blood in ventricles and forced to enter arterial trunks
When does most ventricular filling of blood occur?
70% occurs when chambers are in diastole and atrial pressure is greater than ventricular pressure
What is brachycardia?
Abnormally slow heartbeat less than 50 bpm
What is athlete’s brachycardia?
A beneficial adaptation resulting from a muscular heart, healthy circulatory system, and excellent lung capacity
What is the foramen ovale?
A one-way flutter valve in the embryo that shunts blood from the right atrium to the left atrium through the septum primum to the rest of the body since the lungs are not functional
When a baby is born with functional lungs, what happens to the foramen ovale?
The septum primum is forced shut from blood at the left atrium to turn it into a closed interatrial septum; eventually the fossa ovalis forms
What are 2 other names for patent foramen ovale?
Perforated fossa ovalis or atrial septal defect
What is a patent foramen ovale?
When the septum primum does not fully fuse and blood flows directly from the right atrium to the left atrium and vice versa, which may lead to poor pulmonary circulation and undesired material to travel directly from venous circulation to arterial circulation
How much of the adult population suffers from perforated fossa ovalis?
30%
What are blood vessels analogous to?
Highway since they are an efficient mode of transportation for oxygen, carbon dioxide, nutrients, hormones, and waste products
Are blood vessels rigid and immobile?
No, they can pulsate and change shape in accordance to the body’s needs
What composes the systemic circulation?
Consists of left atrium, left ventricle, and all other named vessels that travel the body until it reaches the right atrium
What composes the pulmonary circualtion?
Right atrium, right ventricle, and all other named vessels until it reaches the left atrium
What are the 3 types of blood vessels?
Arteries, veins, and capillaries
What are arteries?
Blood vessels that carry blood FROM the heart and branch into smaller arteries and arterioles as they get further from the heart
What are veins?
Receives blood from venules and carry blood TO the heart and become larger as they get closer to the heart
What occurs in capillaries?
Exchange of nutrients and oxygen between tissue and muscles
What is an anastomosis?
A site where two or more arteries or veins merge together to supply the same body region
What do arterial anastomosis do?
Supply alternate blood routes to body tissues or organs
Do veins or arteries form more anastomosis?
Veins form more
What are end arteries?
Arteries that do not form anastomosis and result in only one pathway for blood to reach an organ
What are examples of end arteries?
Renal artery to kidney and splenic artery to spleen
What are companion vessels?
Arteries and veins that travel together and service the same body region
What are the three layers of blood vessel tunics?
Tunica Intima, Tunica Media, and Tunica Externa
What is the tunica intima?
The innermost layer of a blood vessel composed of endothelium and subendothelium with one-way valves in veins
What is the tunica media?
The middle layer of a blood vessel composed of circularly arranged layers of smooth muscle
What innervation controls vasodilation and vasoconstriction?
Sympathetic innervation
What blood vessels have a thick layer of tunica media?
Arteries
What is the tunica externa?
The outermost layer of a blood vessel wall
What blood vessel has a thick layer of tunica externa?
Veins
What type of fibers compose blood vessels tunics?
Elastic and collagen fibers
How are arteries able to remain patent (open) and spring back to their shape?
Arteries have high layers of elastic and collagen fibers in all their tunics
What happens to the shape of veins when there are no blood within them?
Vein walls collapse
The lumen is smaller in which blood vessel?
Arteries
What layers of blood wall tunica are found in capillaries?
Only the tunica intima, but capillaires contain a basement membrane and endothelium
Why are basement membranes important in capillaries?
Allow for exchange of nutrients between blood vessels and interstitial fluid (fluid surrounding tissue cells)
What do arteries do?
Arteries in systemic circulation carry oxygenated blood to the body’s tissues
What are the three types of arteries?
Elastic arteries, muscular arteries, and arterioles
Describe some characteristics of elastic arteries
Largest arteries with diameters ranging from 1-2.5 cm, and contain a large proportion of elastic fibers through all 3 tunics (especially in tunica media)
Why is it important for elastic arteries to have high levels of elastic fibers?
Allows arteries to stretch when left ventricle pumps blood into them, and allows them to withstand the strong pulsations and reduce the force of pulsations so that the pressure of arterial blood equalizes
What are some elastic arteries? (6)
Aorta, pulmonary, brachiocephalic, common carotid, subclavian, and common iliac
Describe muscular arteries
Muscular arteries have a diameter of 3mm-1cm and have elastic fibers confined to laminar rings found between the tunica intima and media, and between the tunica media and externa; also have a large tunica media with multiple layers of smooth muscles and consist of most named arteries
Describe arterioles
Smallest arteries with diameters ranging from 10 micrometers-3mm and contain less than 6 layers of smooth muscle in tunica media; large arterioles may have all 3 tunics while the smallest have less; arterioles are responsible for increasing/decreasing arterial blood pressure and regulates blood flow through capillaries
What are capillaries?
Smallest blood vessels (diameter between 8-10 micrometers) that connect venules and arterioles together that mainly consist of the tunica intima and a basement membrane
WWhat is sickle cell disease?
Inheritance of hemoglobin-S which causes blockages and infarctions in body organs
What are the functional units of the cardiovascular system?
Capillaries
What are the most common types of capillaries?
Continuous capillaries
What are fenestrated capillaries?
Capillaries with fenestrations within each epithelial cell and are found where a great deal of fluid transport occurs between blood and interstital fluid
Where can fenestrated capillaries be found?
Intestines, kidneys, and endocrine glands
What are sinusoids?
Wider and larger capillaries with openings that allow for transport of larger material like proteins or cells
Where can sinusoids be found?
In blood marrow, spleen, anterior pituitary, and liver
What do veins do?
Drain capillaries and return blood to the heart
When the body is at rest, how much blood is found in the veins?
60%
Veins function as blood _____.
Reservoirs
What do systemic veins do?
Carry deoxygenated blood to the right atrium of the heart
What do pulmonary veins do?
Carry oxygenated blood to the left atrium of the heart
After blood has travelled from the left atrium, to arteries, and then to capillaries, how much blood pressure is left in veins?
Very little blood pressure
Smaller and medium sized veins travel with what type of arteries?
Muscular arteries
Large veins travel with what type of arteries?
Elastic arteries
Since veins have low blood pressure, how does blood manage to return to the heart?
One-way valves formed by the tunica intima found in the vein help prevent backflow of blood, and the skeletal muscle pump squeeze veins as they contract
What does being active do for blood flow?
Improve blood flow in veins
What creates blood pressure?
Rhythmic pumping of blood through the heart produces a rhythmic pulsation of blood through the arteries
What is used to measure blood pressure?
Sphygmomanometer
How does a sphygmomanometer measure blood pressure?
Compresses the brachial artery; a stethoscope is used to listen to the vein as pressure is lessened and blood flow occurs
What is the initial measurement of a sphygmomanometer?
Systolic blood pressure that corresponds with highest pressure in brachial artery
When the pressure of a sphygmomanometer is reduced so that arterial blood flow is no longer obstructed, what is measured?
Diastolic blood pressure (lowest pressure in brachial artery)
How is blood pressure written?
In a ratio with systolic over diastolitc
What is the normal blood pressure in a healthy person?
120/80
Where is blood pressure the highest?
In the left ventricles and arteries closest to the heart
What is the level of blood pressure as it leaves arterioles and enters capillaries?
40 mm/Hg
What is the level of blood pressure as it travels from capillaries to venules?
20 mm/Hg
What is the level of blood pressure as it travels from venules and veins to the vena cava into the right atrium?
0 mm/Hg
What are 6 factors that affect blood pressure, and how do they affect (increase/decrease) blood pressure?
Increase in blood volume INCREASES bp
Increase in cardiac input INCREASES bp
Vasoconstriction INCREASES bp
Overweight/poor health INCREASE bp
Cocaine (potent vasoconstrictor) INCREASES bp
Vasodilation DECREASES bp
