Week 8 // Heart Flashcards
heart is located inside these two things
answer is not thoracic cavity - more specific
Heart located in the mediastinum, behind sternum inside pericardial cavity
The heart is enclosed and held in place by this
pericardial cavity
The two layers of the pericardial cavity
Visceral layer of serous pericardium (towards heart)
Parietal layer of serous pericardium (towards chest)
Three layers of the heart wall (superficial to deep)
epicardium, myocardium, and endocardium
Peri, myo and endocarditis
Pericarditis – inflammation of pericardium
2 types: acute has no known cause, sometimes viral
and chronic begins gradually. Fluid increases between parietal and visceral layers in chronic swelling
Myocarditis – inflammation of myocardium
(usually viral) also… covid vaccine
Endocarditis – inflammation of endocarditis, usually bacterial and usually involves heart valves
Layers of the pericardium
The pericardium consists of an outer fibrous pericardium and an inner serous pericardium
Layers of the serous pericardium has 2 layers
Visceral
Parietal
What are the chambers of the heart?
The chambers of the heart include two upper atria and two lower ventricles
The superior vena cava comes from which portion of the heart?
The right atrium
What does the right atrium do?
The right atrium receives blood from the superior and inferior vena cava and the coronary sinus
What does the right ventricle do?
The right ventricle receives blood from the right atrium and sends blood to the lungs
Right A->V->
Left Atrium?
The left atrium receives blood from the pulmonary veins
Left Ventricle
The left Ventricle receives blood from the left atrium and sends blood all over the body (descending / ascending aorta)
Note that the wall of the left ventricle is much thicker than that of the right ventricle – why?
Right ventricle only needs to send blood to lung, relatively short distance. Left ventricle must send farther - pumps blood for all of the body
Vena cava (superior and inferior) - what do they do?
Vena cava (superior and inferior) collect blood full of carbon dioxide and send it to the heart so that it can be oxygenated
oxygen rich blood comes back into the heart in the
left atrium
oxygenated blood is sent the rest of the body from the
left ventricle
fibrous skeleton in the heart
The fibrous skeleton of the heart:
- Forms the foundation for which the heart valves attaches
- Serves as a point of insertion for cardiac muscle bundles
- Prevents over-stretching of the heart valves
- Acts as an electrical insulator
Heart valves
The valves of the heart open and close in response to pressure changes as the heart contracts and relaxes
Right and left atrioventricular valves
- Prevent back flow from the ventricles into the atria
Right and left semilunar valves
- Prevent back flow from the arteries into the ventricles
When one set of valves is open, the other set is
closed
flow of blood through heart and lungs from the vena cavas and the coronary sinus (veins) to the arteries
vena cava -> right atrium -> right ventricle -> pulmonary valve, pulmonary artery ->
pulmonary capillaries of LUNGS ->
pulmonary veins, left atrium, left ventricle, aorta and other arteries then veins then back to vena cava (etc.) again
Myocardial Ischemia
Reduced blood flow to the myocardium
Can cause hypoxia (reduced oxygen supply) and angina pectoris (severe pain in the chest) and pain in the neck, chin, left arm and elbow
Myocardial Infarction
(Also called Heart attack)
Infarction refers to death of tissues due to interrupted blood supply
Treatments include thrombolytic injection, coronary angioplasty or coronary artery bypass grafting
Heart Conduction system
Cardiac muscle cells are self-excitable, and therefore auto-rhythmic. (No stimulation from outside.)
Cardiac muscle cells repeatedly generate spontaneous action potentials that then trigger heart contractions
These cells form the conduction system, which is the route for propagating action potentials through the heart muscle
Artificial Pacemakers
Device that sends out small electrical currents to stimulate heart to contract
Includes a battery and pulse generator
Connected to 1 or 2 flexible leads threaded through superior vena cava and into chambers of the heart
Influences on the Conduction System - things setting heart’s pace
The auto-rhythmic fibers in the SA (sinuatrial) node are the natural pacemaker of the heart because they initiate action potentials most frequently
Signals from the nervous system and hormones (like epinephrine) can modify the heart rate and force of contraction but they do not set the fundamental rhythm
What is the Sinuatrial Node? *
The auto-rhythmic fibers in the SA (sinuatrial) node are the natural pacemaker of the heart because they initiate action potentials most frequently
How do hormones and nervous system affect heart?
Signals from the nervous system and hormones (like epinephrine) can modify the heart rate and force of contraction but they do not set the fundamental rhythm (which is controlled by the Sinuatrial Node)
Cardiac muscle generates _____ via anaerobic cellular respiration and creatine phosphate
ATP
What is an EKG or ECG?
An EKG (Electrocardiogram) is a recording of the electrical changes that accompany each heart beat
systole
contraction (systole)
diastole
relaxation (diastole)
One cardiac cycle consists of
One cardiac cycle consists of the contraction (systole) and relaxation (diastole) of both atria, rapidly followed by the systole and diastole of both ventricles
It includes: Electrical events Pressure changes Heart sounds Volume changes Mechanical events
Cardiac Output *
C O is the volume of blood ejected from the left or right ventricle into the aorta or pulmonary trunk each minute
Stroke volume
Stroke volume (SV) is the amount of blood pumped out of the ventricle in one beat C O (mL/min) = SV (mL/beat) × HR (beats/min)
Three factors regulate stroke volume:
Three factors regulate stroke volume:
Preload (before contraction, left ventricle - how much volume of blood inside the left ventricle.)
Contractility (how well valves close and open and how strong heart pumps)
Afterload (how much blood is left after pump, if too much, less stroke volume)
What factors regulate heart rate?
Sinuatrial Mode Plus: several factors regulate heart rate: Autonomic nervous system Hormones Ions Age Gender Physical fitness Temperature
Regular aerobic exercise can:
Increase cardiac output Increase HDL (high-density lipoproteins) Decrease triglycerides Improve lung function Decrease blood pressure Assist in weight control
Cardiomyoplasty
A large piece of the patient’s own skeletal muscle (left latissimus dorsi) is partially freed from connective tissue attachments and
wrapped around the heart, leaving the blood and nerve supply intact. An implanted pacemaker stimulates the skeletal muscle’s
motor neurons to cause contraction 10-20 times per minute, in synchrony with some of the heartbeats.
Skeletal muscle assist device
A piece of the patient’s own skeletal muscle is used to fashion a pouch inserted between the heart and aorta, functioning as a
booster heart. A pacemaker stimulates the muscle’s motor neurons to elicit contraction.
Ventricular assist device (VAD)
A mechanical pump helps a weakened ventricle pump
blood throughout the body so the heart does not have to work as hard
