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60-year-old woman experienced myocardial infarction (Background (Heart…
60-year-old woman experienced myocardial infarction
Downstream effects
permanent damage to papillary muscle of left ventricle
failure of mitral valve closure
Inteferes with blood flow
Cause pressure to build up in lungs
Leads to pulmonary edema
When one ventricle pumps more blood than the other, the imbalance can result in edema
Fluid buildup strains the right side of the heart
leads to right heart failure
Depresses pumping efficiency
Noncontractile fibrous (scar) tissue replaces the dead heart cells
Treatment
Receive aspirin and other medications to prevent unwanted blood clotting in the coronary arteries
Oxygen to breathe, pain medication, beta-blockers to reduce the heart's demand for oxygen, nitroglycerine to help blood flow in the heart muscle cells, and a cholesterol-lowering statin drug
Reperfusion therapy if possible
Required lifestyle changes
Exercising regularly
Eating healthy
Maintain healthy weight
No tobacco use
Controlling blood pressure
Controlling DM II
Lowering LDL chlesterol
Myocardial infarction
Also known as a heart attack
If left untreated
Pulmonary hypertension
Heart failure
Heart enlargement
Atrial fibrillation
Blood clots
Possible affects on other body systems
Increased heart rate due to increased sympathetic nervous system activity
Increased blood pressure due to sympathetic nervous system activity
Increased blood volume and blood pressure due to secretion on antidiuretic hormone in response to sympathetic nervous system activity, causes fluid retention in the kidneys
Salt and fluid retention by the kidneys caused as a result of reduced blood flow to the kidneys, which ultimately leads to the secretion of aldosterone
Aldosterone is a hormone that stimulates absorption of sodium by the kidneys, regulates the balance of salt and water in the bloodstream
Heart muscle remodeling caused by chronically high levels of a number of hormones including catecholamines, renin, angiotensin, and aldosterone
Decreased muscle strength due to skeletal muscle atrophy resulting from reduced perfusion
Impaired liver function and jaundice caused by severe liver congestion
Shortness of breath
Upstream causes
DM II
Obesity
Blocked coronary arteries or extremely slow blood flow
Slow blood flow can happen when the heart is beating very fast or has low blood pressure
Formation of a blood clot
Usually forms inside a coronary artery that has been narrowed by fatty deposits built up along the inside walls of blood vessels
Blockage can cause arrhythmias
Swelling in lower extremities
Other possibilities of myocardial infarction
Overactive thyroids
History of drug or alcohol abuse
Lung or heart infection
Anemia
Family history of coronary artery disease
High blood pressure
Smoking
Physical inactivity
Medications
Congenital heart disease
Low level of HDL
High level of blood cholesterol
Diet
Background
Heart
Hollow, four-chambered organ at center of cardiovascular system
Three significant anatomic features
Great vessels lead to and from
One large artery leads away from each ventricle (total of 2)
Pulmonary trunk
Leads away from right ventricle
Splits into right and left pulmonary arteries
Carries deoxygenated blood to lungs for oxygenation
Aorta
Leads away from left ventricle
Carries oxygenated blood to rest of body
Large veins deliver blood to heart
Superior and inferior vena cava
Bring deoxygenated blood from body to the right atrium
Pulmonary veins
Bring oxygenated blood from lungs to left atrium
Two sets of valves
Ensure one-way flow of blood; keeps blood from flowing back into a chamber
Atrioventricular valves
Located between atria and ventricles
Right AV valve (tricuspid valve)
Located between right atrium and right ventricle
Left AV valve (bicuspid/mitral valve)
Located between left atrium and left ventricle
Semilunar valves
Located between each ventricle and it is associated arterial trunk
Loos like crescent moons in picture
Pulmonary semilunar valve
Between right ventricle and pulmonary trunk
Aortic semilunar valve
Between left ventricle and aorta
Two-pump structure
One on right side, one on left side
Right side receives deoxygenated blood from the body and pumps it to the lungs to become oxygenated
Left side receives oxygenated blood from lungs and pumps out to body
Each side has one atrium to receive blood
Directly inferior to each atrium is a ventricle
Pumps the blood back out of the heart
Four chambers: right atrium. right ventricle, left atrium, left ventricle
Blood is received in atrium and then travels inferiorly to ventricles, before being pumped back out of heart
Left atrium
Has pectinate muscles in auricle
Pulmonary veins open into this chamber
Left atrioventricular opening separates left atrium from left ventricle and contains left AV valve
Right ventricle
Papillary muscles
Three cone-shaped muscle projections that extend from internal wall
Anchor thin collagen strands called chordae tendineae that attach to the right AV valve
Ventricle narrows and smoothens out at superior end, leading to pulmonary semilunar valve and pulmonary trunk
Internal wall has large, smooth, irregular muscular ridges called trabeculae carneae
Right atrium
Oval depression called fossa ovalis where fetal foramen ovale used to be
Coronary sinus
Hole where blood that has drained from the heart wall enters the right atrium
Found immediately inferior to the fossa ovalis
Has muscular ridges, pectinate muscles, on anterior wall and auricle
Inferior and superior vena cavae open into this chamber
Internal wall is smooth on posterior surface
Right atrioventricular opening separates right atrium from right ventricle and contains right AV valve
Left ventricle
Two papillary muscles anchored by chordae tendineae
Superior end leads to aortic semilunar valve and aorta
Also has trabeculae carneae
Heart Anatomy
Arteries and veins that serve the heart cells are housed in grooves on its superficial surface
Coronary sulcus
Groove that wraps all the way around the heart, separating atria from ventricles
Interventricular sulci
Grooves between left and right ventricles
Anterior interventricular sulcus
located on the anterior surface of heart
Posterior interventricular sulcus
Located on posterior surface of heart
Anterior features
Right atrium and right ventricle are prominent in anterior view
Aorta and pulmonary trunk are also seen in anterior view
Right auricle
Noticeable, wrinkles flap-like extension over right atrium
Left auricle
Flap-like extension over left atrium
Posterior features
Left atrium and left ventricle are prominent in posterior view
Superior and inferior vena cava and pulmonary arteries are visible
Posterior interventricular sulcus and part of coronary sulcus which houses the coronary sinus are also visible
Layers
Myocardium
Made of cardiac muscle, which contracts to generate force needed to pump blood out of the heart
Ventricular myocardium can change in thickness as we age or in response to conditions such as hardening of the systemic arteries
Middle layer of heart wall
Endocardium
Internal surface of heart and external surface of heart valves
Made of simple squamous epithelium and underlying layer of areolar connective tissue
Continuous with inner lining of blood vessels
Epicardium
Outermost layer (visceral pericardium)
Thickens as we age as more adipose tissue is addeed
Serious membrane made of simple squamous epithelium attached to underlying areolar connective tissue
Heart Valves
Atrioventricular valves
Right AV valve has 3 cusps; left has 2
Cusps extend into ventricles when valve is open, allowing blood to "fall in" to ventricle from atrium
As ventricles contract, blood is pushed back up, closing the cusps
Chordae tendineae secure the cusps to the ventricle wall, preventing them from being inverted and opening into the atria, which would allow blood to seep back the wrong directions
Semilunar valves
Right and left semilunar valves each have 3 cusps
No papillary muscles or chordae tendineae are associated with these cusps
When ventricles contracts, the blood is forced into the arterial trunk through the closed valves opening them
When the ventricles relax, the blood being pumped through the arterial trunks falls back down a little bit and in doing so, closes the semilunar valves, preventing backflow into the ventricles
Pulmonary circulation
Circulation of blood from right side of heart, through lungs, and back to heart's left side
Systemic circulation
Oxygenated blood from left side of heart through arteries to cells of body, to capillaries for substance exchange with cells, through veins and back to the heart
Pathway of blood through the heart
Starting with deoxygenated blood leaving capillaries after exchange with cells
Veins of body-> superior and inferior vena cava-> right atrium-> right ventricle-> pulmonary trunk-> right and left pulmonary arteries-> pulmonary capillaries in lungs-> right and left pulmonary arteries-> left atrium-> left ventricle->aorta->arteries of body-> capillaries for substance exchange
Ventricular balance
equal amounts of blood are pumped out of each ventricle during circulation
Microscopic structure of cardiac muscle
General structure of cardiac muscle
Cardiac muscle is made of short, branched cells that contain one or two nuclei
Cells are supported by an endomysium, and areolar connective tissue outer wrapping
Intracellular structures of cardiac cell
There is one T-tubule per sarcomere
SR surrounds bundles of myofilaments called myofibrils
The sarcolemma is the plasma membrane that invaginates, forming T-tubules that extend into the sarcoplasmic reticulum
Myofilaments are arranged into sarcomeres, giving cardiac muscle its striated appearance
Maximum overlap of thin and thick filaments occurs when cardiac muscle is stretched when blood is added to heart chamber, which allows for a powerful contraction
Sarcolemma of muscle cells has a lot of folds which means 2 cells can connect and still leave room between them allowing for communication between the cells
2 distinct structural features
Desmosomes
Protein filaments anchoring cells to one another
Keeps muscle cells from separating with heart beats
Gap junctions
Provide an easy passageway for ions to flow between cells
Allow an action potential to travel along the sarcolemma of one cardiac muscle cell seamlessly to the sarcolemma of another, resulting in a synchronized contraction in a particular chamber
Protein pores between cells
Functional syncytium
Refers to each heart chamber pumping as a separate single functional unit
Heart rate
Increase or decrease in heart rate is dependent upon chronotropic agents that influence the conduction system by stimulating SA node to change firing rate or AV node to alter amount of delay
Stroke volume
Increase or decrease is due to changes in myocardium, also sometimes due to resistance in arteries
Cardiac output
Directly related to both heart rate and stroke volume; hard to say how the cardiac output will be affected. If heart rate and stroke volume change in opposite directions of each other
Preload
Stretch of the heart wall due to the load the cardiac muscle is subjected to before shortening
Afterload
Usually only causes a situation in older people as atherosclerosis develops, with plaque accumulating inside blood vessels
Represents pressure that must be exceeded before blood is ejected from the chambers
Smaller arterial lumen causes greater resistance for passing blood, and stroke volume decreases
Resistance in the arteries to the ejection of blood from the heart
Mean arterial pressure
The average arterial pressure throughout one cardiac cycle, systole, and diastole
MAP is influenced by cardiac output and systemic vascular resistance
Peripheral resistance
Resistance of the arteries to blood flow
As the arteries constrict, the resistance increases and as they dilate, resistance decreases
Normal sounds of the heart
Often described as lub-dup are associated with the heart valves closing
Relationship between heart function and blood pressure
As the blood travels through the arteries it pushes against the sides of the blood vessels
As the heart squeezes and pushes your blood through your arteries, the blood pressure goes up
As the heart relaxes, blood pressure decreases
Relationship between heart function and respiratory rate
Breathing rate affects the heart rate
Breathing cycles and heartbeat can become synchronized
Breathing and blood circulation help deliver oxygen rich blood to organs and tissues