4. Cardiovascular System Flashcards
Perfusion Status
- Pulse
- BP
- Skin color
What underpins cardio measurements
- heart muscle contraction/relaxation
- blood vessel resistance
- blood volume
Location of heart
I’m the mediastinum
Heart Chambers
R/L Atrium
R/L Ventricle
Base vs. apex of the heart
Base is the top and Apex is the bottom for some reason
Inter-ventricular Septum
Middle wall of the heart between the ventricles
What are the atrioventricular valves?
Right: Tricuspid
Left: Bicuspid/mitral
What are the semilunar valves?
Right: pulmonary valve
Left: aortic valve
Where do coronary veins converge to from the myocardium?
Coronary sinus/Right atrium
The cardiac cycle
Full complex
- electrical events
- mechanical events
- pressure changes
- heart sounds
- volume changes
Cardiac conducting system
- intrinsic conduction system
- autorhythmic nodal cells
- pacemaker
Nodes of the heart
SA - Sinus
AV - Junctional
R/L Bundle Branches
Purkinje Fibers
Action Potentials of Autorhythmic Cells
-60mv: Na+ entry: slow depolarization (Pacemaker Potential) -40mv threshold potential -Ca2+ entry: fast depolarization to +mv (Action Potential) -K+ exit: repolarization back to -60mv
The 2 Cardiac Muscle Cells Involved Cardiac Contraction
- Conducting System
2. Contractile cells
Cardiac Muscle Cells
- Striated, one nucleus
- Branching Cells: joined by intercalated discs, communicate via gap junctions, quick cell-to-cell communication
Action potential of cardiac muscle (contractile) cells
Depolarization: From -90mv, Na+ influx shoots cell up to +30mv
Plateau Phase: due to Ca3+ influx through slow Ca2+ channels, this keeps the cell depolarized.
Repolarization: due to Ca2+ channels inactivating and K+ channels opening, this allows K+ efflux, which brings the membrane potential back to its resting voltage
Mechanical Events
- Atrial systole (contraction)
- Ventricular systole (contraction)
- Diastole (relaxation)
Heart Sounds
S1: AV valves (Lub)
S2: Semilunar Valves (Dub)
Stroke Volume
“Per stroke”
Amount of blood pumped out of ventricle (~70ml) in one beat
Cardiac Output
Amount of blood ejected from the left or right ventricle into the aorta or pulmonary trunk each minute
CO (mL/min) = SV (mL/beat) x HR
Regulation of stroke volume
- Preload
- Contractility
- Afterload (pressure to overcome ventricles to eject blood, e.g. ⬆️BP)
3 tunics of blood vessel
- Tunica internia
- Tunica media
- Tunica externia
Continues capillaries
Tightly bound, small gaps.
Skin, muscle
Fenestrated Capillaries
Larger pore, facilitated exchange (kidneys, small intestine)
Albumin
Protein in blood that takes/keeps water back into vessel (oncotic pressure)
Lymphatic vessels
Remove excess fluid
Factors in vascular/peripheral resistance
- Size of blood vessel lumen
- Blood viscosity
- Total blood vessel length
The higher the resistance the smaller the blood flow
Venous return
Return of blood through veins with help of valves, resp pump and skeletal muscle pump
Short-term control of BP
- Vasometer centre (medulla oblongata)
- Barotrceptors
- Chemical-hormonal
Long term control of BP
Renin-angiotensin-aldosterone system
Vasomotor center
Regulates blood vessel diameter
- Vasoconstriction: ⬆️BP
- Vasodilation: ⬇️BP
Sympathetic Nervous System: vasoconstriction
Baroreceptors Reflex
Pressure receptor
RAAS
Kidneys: Renin, released when lower blood volume is detected
Liver: Angiotensin, is converted by renin into A1
Lungs: Angiotensin converting enzyme (ACE), converts A1 to A2
Angiotensin 2
- Leads to vasoconstriction
- goes back to kidney to cause release of hormone, aldosterone, which causes retention of Na and H2O
- then goes to hypothalamus to cause thirst response
- then goes to posterior pituitary gland to cause a release of Antidiuretic hormone (ADH), causing production urine
Erythrocytes
Red Blood Cells
- Transport O2 & CO2
- Lack nucleus and most organelles to make space for hemoglobin (iron-containing oxygen-transport metalloprotein)
