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Four structures make up the core of the electrical conduction system of the heart:
- Sinoatrial (SA) node
- Atrioventricular (AV) node
- AV bundle (bundle of His)
- Subendocardial branches (Purkinje fibers)
Electrocardiogram, written and spoken
- written - ECG
- spoken - EKG
Intrinsic SA (Sinoatrial) rate in BPM
Abnormal ectopic pacemaker rates
If the SA node fails for any reason and AV (Atrioventricular) node takes over:
Plasma membrane of a striated muscle cell (including cardiac)
Meaning "joined cells", the connections of individual heart muscle cells via intercalated disks results in a continuous and electrically coupled impulse of myocardial tissue.
NOTE: Heart muscle "cannot summate to produce tetanus and thus do not fatigue".
Depolarization of the atria causes what ECG wave?
Repolarization of the atria and depolarization of the ventricles causes what ECG wave?
Repolarization of the ventricles causes what ECG wave?
Describe the ECG U wave, if present
Sometimes, an additional U wave may be seen in the electrocardiogram. The U wave, when visible, appears as a tiny "hump" at the end of the T wave. The U wave results from late repolarization of Subendocardial branches (Purkinje fibers) in the papillary muscle of the ventricular myocardium. If not too big, U waves are usually considered to be normal. Sometimes, however, U waves can be a sign of hypokalemia (low blood potassium) or too much digoxin (a heart medication).
Name the 5 phase of a complete cardiac cycle
- Atrial systole
- Isovolumetric ventricular contraction
- Isovolumetric ventricular relaxation
- Passive ventricular filling
At what ECG wave does the first heart sound (LUBB) appear?
Starts at R and ends just past S
At what ECG wave does the second heart sound (DUBB) appear?
Starts at the end of T
What causes the LUBB heart sound?
- The first or systolic sound
- is a contraction of the ventricles and vibrations from the closing of the Atrioventricular or cuspid valves.
- It is longer and lower than the DUBB sound.
What causes the DUBB heart sound?
- The second or diastolic sound
- is caused by vibrations from the closing semilunar valves.
- It is shorter and sharper than the LUBB sound.
What do abnormal heart sounds mean, e.g. a murmur?
Any deviation from the normal is an indication of an improperly functioning valve. A "swishing" sound may mean an incomplete closing of the value (valvular insufficiency) or a stenosis (constriction or narrowing).
What is the pressure called that is needed for blood to flow through tissue and what does it mean?
Perfusion pressure, which means "flow through"
How are blood volume and arterial pressure related?
Pressure increases with increases in volume and vice versa.
Two factors that affect arterial blood volume?
Cardiac output and peripheral resistance.
Resting cardiac output in ml/min?
Define CO (cardiac output) in terms of volume/minute
= SV (stroke volume)
X HR (heart rate)
This volume of blood is also known as the "systolic discharge".
How do CO (cardiac output) and PR (peripheral resistance) affect arterial BP?
Pressure increases in direct relationship with increases in volume, so as CO increases, volume will increase, and as PR (in the arterioles) increases, the amount of blood leaving the arteries is REDUCED, thus increasing the volume REMAINING inside, and increasing arterial BP.
Relate, i.e. increases/decreases: SV, HR, CO, arterial blood volume (ABV), and BP
As SV or HR change, so to do CO, ABV and BP tend in the same direction.
The reason for tend is because the book wanted to point out that the relationship only works if the are no other changes in a conflicting direction.
Formula for EF% (ejection fraction)...
SV (stroke volume)
/ EDV (end diastolic volume)
Nervous System Division Review:
- Somatic - under your control
Autonomic - NOT under your control
- Somatic Sensory - afferent
- Somatic Motor = efferent
- Visceral Sensory - afferent
- Sympathetic - efferent - "Fight or Flight"
- Parasympathetic - efferent - "Rest and Repair"
Neurological factors thats affect heart rate
Ratio of sympathetic and parasympathetic nerve impulses (autonomic) conducted to the SA node.
- sympathetic (fight/flight)
: distal end of cardiac nerve
- Action: stimulatory
- Mode: release of norepenepherine
- Parasympathetic (rest/repair)
: chiefly by vagus nerve
- Action: inhibitory
- Mode: release of acetylecholine
Describe anatomy of cardiac pressoreflexes
Barroreceptors in the aortic arch and carotid sinuses send signals to the cardioregulatory centers of the medula oblongata via the Vagus (cranial nerve X) and Nerve of Hering (branch of cranial nerve IX) respectively.
A negative feedback loop there sends control impulses via ratio of sympatheic and parasympathetic action.
These are "carotid sinus reflex" and "aortic reflex" feedback loops.
(SG1) Name the four chambers of the heart:
- left and right atria, or recieving chambers
- left and right ventricles, or major pumping chambers
(SG1) What are the characteristics and functions of four chambers of the heart:
left and right atria are thin-walled pumps, which take blood input from veins: pulmonary, oxygen-rich to the left, and vena cavas and coronary sinus, oxygen-poor to the right. 20% of this blood is "pumped" into the ventricles, while 80% flows due to gravity.
left and right ventricles, are major (left) systemic and (right) pulmonary pumping chambers, with the walls of the left venticle being significantly thicker than the right because of the distance the left has to pump through.
The left ventricle recieves blood through the mitral or bicuspid valve and outputs it to the aorta via the aortic semilunar valve, while the right recieves blood through the tricuspid valve and outputs it to the pulmonary trunk via the pulmonary semilunar valve.
Name the four tissue types and what type is blood>
epithelial, connective, muscle and bone. Blood is CONNECTIVE
Components of blood plasma?
- ~55% (46-63%) is non living plasma
- 91% water
- 7% plasma proteins
- Albumins 57%
- Globulins 38%
- Fibrinogen 4%
- Prothrombin 1%
- 1% other solutes
- enzymes, ions nutrients, waste products, and gasses
Components of blood formed elements?
(counts are per cubic millimeter
- ~45% (37-54%) is living cells
- 99.9% RBC, 4.2-6.2 million eruthrocytes
- <0.1% WBC, 5000-9000 leukocytes
- <0.1% WBC, 140-340k platekets
Components of WBC?
- NEVER LET MONKEYS EAT BANANAS
- Neutrophils 60-70%
- Lymphocytes 20-25%
- Monocytes 3- 8%
- Eisinophils 2- 4%
- Basophils 0.5-1%
Name the three parts of the cardiovascular system.
(SG2) Morphology of RBC?
- About 7.5 um in diameter
- Biconcave - very lare surface area to volume
- No nucleus, ribosomes or mitochondria
- One-third of the cell volume is the red protein pigment: hemoglobin
- Can fit through capillaries often smaller in diameter than 7.5 um
- Flexibility through stretchable fibers of protein spectrin
- Circulating life: 105-120 days
- Each RBC has 200-300 million molecules of hemoglobin and 95% of the dry weight of each cell
(SG2) Physiology of RBC?
- Each hemoglobin molecule is made up of 4 globin protein chains, each with a "red pigment" heme group with one iron atom
- Each of the 4 iron atom can combine with an oxygen molecule to form a reversible reactant oxyhemoglobin
- Each globin can form a reversible reactant with carbon dioxide to for carbaminohemoglobin
- Additionally RBCs contain an enzyme carbonic anhydrase (CA), which catalyzes a reaction that joins carbon dioxide and water to form carbonic acid. This then dissociates to bicarbonate ions and hydrogen ios, which diffuse out of the RBC to be excreted or used to buffer the bloods pH.
(SG2) Relate anemia to hemoglobin content
Normal men have 14-16 g of hemoglobin per 100 ml of blood, while women have 12-14 g. Anyone with less than 10g/100ml is diagnosed as having anemia.
- All formed blood elements are generated from adult blood-forming stem cells known as hematopoietic stem cells, which are called hemocytoblasts.
- Maturation from these nucleated cells begins in the red bone marrow.
- The differentiated daughter cell created via mitosis for erythrocytes is the proerythroblast.
- Development states progress until the cell no longer has a nucleus and is called a reticulocyte.
- The complete process takes about 4 days.
- RBC are created at a rate of 200 billion per day to replace worn out/damaged RBCs.
(SG4) Characteristics of the outermost layer of the heart.
- Fibrous Pericardium
- Attached to the diaphram and to the major blood vessels exiting the top of the heart.
(SG4) Layers of the Heart from outside to inside...
- Fibrous Pericardium
- Parietal layer of the serous pericardium
- Pericardial space filled with 10-15 ml of pericardial or serous fluid
- Epicardium or visceral layer of the serous pericardium
- Fatty connective tissue with coronary vessels
- Endocardium covering beamlike protrussions of the myocardium called trabeculae cardeae
(SG4) Characteristics of Fibrous pericardium
- Loose fitting
- Not attached to the heart, only to blood vessels exiting the heart.
(SG4) Function of the Serous pericardium
Consiting of the Parietal layer, attached to the fibrous pericardium, and the Visceral layer or Epicardium and the very important lubricating fluid in between them, they provide and environment wherein the heart can easily move with no danger from friction.
(SG4) Characteristics of the Endocardium
- Delicate layer of endothelium - simple squamous cells.
- Lines the heart and all of the blood vessels.
- Covers muscular projections of myocardium called trabeculae cardeae or "fleshy beams", which help to add force to the inwar contraction of the heart wall.
- Inward folds of endocardium make of the flaps or cusps of the heart valves.
(SG5) What are the wall layers commonly found in blood vessels and contrast this to capillaries.
- Elastic fibers
- Smooth muscle cells
- Arteries thicker than veins
- Missing in capillaries
- Collagen fibers
- Arteries thicker than veins
- Missing in capillaries
Capillaries have only an endothelial cell lining surrounded by a basement membrane.
(SG5) Name and describe the types of Capillaries
- Has "Pinocytic vessicles", which can transport subsytances rapidly.
- Has many "fenestrations" or pores.
- Many intercellular clefts (lrge gaps or openings), and an incomplete or missing basement membrane.
(SG6) Normal pattern of impulse conduction through the heart:
- Sinoatrial (SA) node - alone or with influence from syparthetic/parasympathetic
- Three internodal bundles, including an interatrial bundle to the left atrium
- Atrioventricular (AV) node - impulse SLOWS here to allow complete contraction of both atria
- AV bundle (bundle of His)
- Left and right AV bundle branches (septum)
- Subendocardial branches (Purkinje fibers) to lateral walls
(SG7) Map the flow of blood relative to the heart beginning with the return of deoxygenated blood
- Returns to Right Atrium via the superior and inferior Vena Cava, as well as the Coronary Sinus.
- Through AV Tricuspid Valve to Right Ventricle.
- Out the Pulmonary Semilunar Valve to the Pulmonary Trunk.
- To Lungs or Pulmonary Circuit.
- Returns to Left Atrium via the Left and Right Pulmonary veins.
- Through AV Mitral or Bicuspid Valve to Left Ventricle.
- Out the Aortic Semilunar Valve to the Ascending Aorta.
- To Body or Systemic Circuit.
(SG14) What did Starling find and how does it relate to Starling's law of the heart?
English physiologists Ernest Starling, expanding earlier work of Otto Frank (Frank-Starling), found that, within limits, i.e. normal conditions, the longer or more stretched myocardial fibers are at the beginning of a contraction, the stronger that contraction will be.
What influences how stretched these muscle fibers get is directly related to how much venous blood is returned to the ventricles, or venous return. The effect is that under normal conditions, the heart will pump out the amount of blood that is returned to it.
(SG14) What physiological factors affect the strength of a heartbeat besides Starling's law?
norepinephrin (NE) releasd by sympathetic fibers in the cardiac nerve and epinepherin released into the blood by the adrenal medulla can both increased the strength of contraction or contractility, of the heart