The Heart Flashcards
What are the major divisions of the heart?
Pulmonary circuit
Systemic circuit
The pulmonary circuit carries blood to the ________ for gas exchange and returns it to the ________
Lungs
Heart
Blood travels from the _____ side of heart to _______ ________ to pulmonary ________ to _______ to _______ veins to heart.
Right
Pulmonary trunk
Pulmonary arteries
Lungs
Pulmonary veins
What is the function of the systemic circuit?
Supplies blood to every organ of the body
Path of the systemic circuit: ______ side of the heart to_______ to _________ arteries to tissues of body to ______ _______ to heart
Left
Aorta
Systemic
Vena Cava
Where is the heart located?
Lies in the thoracic cavity within the mediastinum
What is the apex of the heart?
The apex is the “unstable” part of the heart that rests on the diaphragm, below the base
What is the mediastinum?
This is the center of the chest
Describe the base of the heart.
The base of the heart is laterally, inclined to the right
It is the broader section of the heart
Describe the position of the heart.
The base points towards the right shoulder
More than half of the heart is to the left of the median plane
Describe the size and shape of the heart
The heart is approximately the size of a fist
The heart what is about 300 g in adults
What is the pericardium?
This is a membrane that surrounds the heart
What are the two types of pericardium?
Fibrous pericardium
Serous pericardium
What are the two divisions of the serous pericardium?
Parietal layer
Visceral layer
What is another name for the visceral layer of the serous pericardium?
The epicardium
What are the three layers of the heart wall?
Epicardium
Myocardium
Endocardium
What is the epicardium?
The outermost layer of the heart wall
Describe the epicardial membrane
It is a serous membrane
Consist of a simple squamous epithelium over lying thin loose connective tissue
What is the myocardium?
This is the middle layer of the heart wall
Describe the myocardial membrane
It is the primary cardiac muscle
It is the thickest layer of the heart wall
It performs the work of the heart
What is the endocardium?
This is the inner layer of the heart wall
Describe the endocardial membrane
lines the heart chambers
folds to create heart valves
Continuous with blood vessel endothelium
How many chambers does the heart have? Name them.
Four Chambers:
Two superior atria
Two inferior ventricles
What is the function of the heart valves?
They ensure blood flows, one way in the heart
Name the two classification of the heart valves
Atrioventricular valves
Semilunar valves
Name the two types of atrioventricular valves
Tricuspid valve or right atrioventricular valve
Mitral valve or left atrioventricular valve
What is the function of the tendinous cords?
The connect the AV valves to the papillary muscle
What is the function of the papillary muscle?
The tense when the miocardia contracts and prevent prolapsing of the AV valves
Describe the flow of blood through the chambers of the heart
Right atrium from superior and inferior vena cava
From right atrium to AV valve to right ventricle
Contraction of right ventricle opens pulmonary valve
Blood flows through pulmonary valve into pulmonary trunk
Blood distributed by right and left pulmonary arteries to lungs , unloads CO2 and Loads O2.
From lungs via pulmonary vein to left atrium
From left atrium through left AV valve to left ventricle
Contraction of left ventricle (happens with step 3) opens aortic valve
Blood flows through aortic valve into ascending aorta
Blood in aorta distributed to every organ in the body
Blood returns to right atrium via vena cava
What is coronary circulation?
This refers to the blood vessels of the heart wall that provide the heart with nutrients
What are the main vessels of the heart wall?
Left coronary artery
Right coronary artery
Cardiac veins
Describe coronary circulation
Left ventricle
aorta
coronary arteries
coronary capillaries
coronary veins
coronary sinus
right atrium
Describe the cardiac muscle structure
Consist of cardio myocytes
striated muscle tissue
Inter-calated discs
Describe cardio myocytes
muscle cells of the heart
Single centrally placed nucleus, some more
Sarco plasmic reticulum is less developed than in skeletal muscle, no terminal cisterns
Larger T tubules than in skeletal muscle, they admit calcium ions from EC fluid to activate contraction
Joined by intercalated discs
99% contractile cells
1% autorhythmic cells
What does the term myogenic mean in terms of the heartbeat?
The signal originates in the heart itself
What is the heart described as auto rhythmic?
It doesn’t depend on the nervous system for it’s rhythm
How does the heart generate its own rhythm?
It has its own built-in pacemaker, and electrical system
What are the intercalated discs in cardio myocytes?
These are thick connections that join cardio myocytes to each other.
They have a complex step like structure with three distinct features, not found in skeletal muscles
What are the three distinct features of inter-calated discs?
Interdigitating folds
Mechanical junctions
Electrical junctions
What is one major difference between skeletal muscle and cardiac muscle, in terms of healing?
Skeletal muscle contain satellite cells that divide and replace that muscle fibers to an extent these are not found in cardiac muscle
Cardiac muscle has a limited capacity for mitosis and regeneration
Heals mainly by scarring (fibrosis)
Cardiac muscle depends on what type of respiration to make ATP?
Aerobic respiration
Very vulnerable to oxygen deficiency
Does not make use of oxygen debt mechanism or anaerobic fermentation, so not prone to fatigue