Heart Physiology Flashcards
What three layers compose the heart wall?
Epicardium- Outside
Myocardium- Middle
Endocardium- Inner
The epicardium is a ________ membrane overlying a layer of ________ tissue.
Serous
Areolar
What kind of cells compose the serous membrane of the epicardium?
Simple squamous
The surface of the epicardium is ________.
Slippery
This epicardium also has ______ tissue to protect the _______ vessels.
Fatty
Coronary
This layer composes the bulk of the heart wall
Myocardium
What composes the “fibrinous skeleton” of myocardium?
A meshwork of collagenous and elastic fibers
What are the three functions of the “fibrinous skeleton” of the myocardium?
- Provide structural support
- Limits the routes that electrical signals can travel
- Pushes blood up from the apex to the base “squeezing” blood up, allowing blood to exit at the base of the heart
What is the innermost layer of the heart wall?
Endocardium
What tissue types is the endocardium made from?
Endothelium (simple squamous epithelium) overlying a thin layer of connective tissue.
The endocardium is continuous with the ________ of blood vessels.
Endothelium
What are the trabeculae carneae?
Irregular ridges of muscle in the ventricles
“Crossbars of flesh”
What covers the trabeculae carneae and pectinate muscles?
Endocardium
What are the pectinate muscles?
Ridges of muscle in the anterior wall of the right atrium (and its auricle), and auricle of left atrium.
Not found anywhere else in the left atrium, or on posterior wall of right atrium
What is the pericardium? What two layers is it made from?
Two protective layers surrounding the heart, a double-walled sac
Fibrous pericardium
Serous Pericardium
Where is the fibrous pericardium? What is it made from?
Outside. Tough, inelastic, dense fibrous CT
What are the three functions of the fibrous pericardium?
Protects the heart (like sclera protects the eye)
Anchors the heart to its surrounding structures, like the diaphragm or great vessels
Prevents the heart from overfilling with blood
What is the serous pericardium, in general?
Internal, made of 2 layers
In general, thin, slippery membrane, more delicate
What two layers make the serous pericardium?
Parietal Layer of the serous pericardium
Visceral layer of the serous pericardium (AKA epicardium)
The parietal layer of the serous pericardium is attached to…
Fibrous pericardium
What, and how much, fills the gap between the parietal and visceral layers of the serous pericardium?
Pericardial fluid. 5-30ml
What does pericardial fluid do?
Reduces friction, making the layers slippery
From inside to out, name the layers of the heart wall
Endocardium Myocardium Epicardium/ visceral layer of serous pericardium Pericardial fluid Parietal layer of the serous pericardium Fibrous layer of pericardium
What is pericarditis? Definition and what’s happening
Inflammation of pericardium
Hinders production of serous fluid
Roughens serous membrane surfaces which hurts, friction pain with each heartbeat
What is cardiac tamponade?
Compression of heart by an abnormal accumulation of fluid in pericardial sac
Cardiac tamponade interferes with ______ filling, so it _______ the heart.
Ventricular
Compresses
What is the Tx for cardiac tampinade?
Insert a syringe into the pericardial cavity to remove fluid
What is RHD? How does it develop?
Rheumatic Heart Disease
May develop after strep throat if not resolved well. Heart valves are damaged, but are repaired with more fiber, which causes scarring. Can reemerge if patient has strep again.
What is ischemic heart tissue? What can cause it?
Tissue that isn’t receiving enough oxygen, inadequate blood flow or a blockage of a coronary artery
How do I tell if there’s ischemia on an EKG?
ST elevation
What procedure can be done to test for ischemia? Why?
A stress test
At rest can appear normal, but it shows during exercise
What is angina pectoris? At the cellular level?
Thoracic pain caused by fleeting deficiency of blood flow (O2) to the myocardium. So increase in lactic acid production as heart goes into anaerobic fermentation, which stimulates pain receptors in the heart.
Where is pain felt with angina pectoris? How can it be treated?
Substernal pain, radiating to the left shoulder. Treat with sublingual nitroglycerin, a vasodilator
What is an MI?
Myocardial Infarction- If anaerobic respiration occurs for more than a few minutes then cell death (necrosis) occurs
MI’s are called _____ _____, and __% of patients die before being seen medically.
heart attacks
25%
Can cardiocytes heal? What develops from their death?
No.
Scar tissue
How do I see an MI on an EKG?
Enhanced Q wave or elevated ST segment
What is Creatine phosphokinase?
An enzyme whose levels increase in blood
Cardiocytes break down and release this enzyme to blood, levels ↑ 3-6 hours after MI, returning to normal 3 days after
What is troponin I?
Protein released by dead or damged heart cell in blood
This is an extremely sensitive test, released days or weeks after an MI, therefore allows a longer timefrsme to diagnose an MI
