❤️pt. 2 Flashcards
Systemic
Carries blood to and from the body
Blood flow through the ❤️
1) The blood first enters the right atrium from the superior and inferior vena cava.
2) It then flows through the tricuspid valve into the right ventricle.
3) The blood then moves through the pulmonary valve into the pulmonary artery.
4) The pulmonary artery carries blood to the lungs where it takes up oxygen.
5) Oxygenated blood returns to the heart through the pulmonary vein into the left atrium.
6)The blood then moves through the mitral valve into the left ventricle.
7)The left ventricle then pumps the blood through the aortic valve into the aorta.
8)From the aorta, the blood is transported through the network of blood vessels, delivering oxygen and nutrients to tissues and taking carbon dioxide and wastes from tissues.
9)Deoxygenated blood returns to the heart via the superior and inferior vena cava, and the cycle begins again.
Blood follow through the body
1)Oxygenated blood from the left side of the heart gets pumped out of the aorta, the largest vessel of the body. The aorta extends from the left ventricle of the heart down into the abdomen.
2)Blood then flows through arteries that branch off from the aorta. These arteries deliver blood to different areas of the body.
3)Arteries then split into smaller vessels known as arterioles, which then carry blood to the smallest vessels in the body—the capillaries.
4)The capillaries deliver oxygen and nutrients to the tissues of your body and simultaneously remove carbon dioxide to be eliminated in the lungs.
5)Deoxygenated blood from the capillaries then flows back to the heart through small vessels known as venules.
6)The venules then gradually merge to form veins.
7)Blood enters back into the heart via large veins known as the superior and inferior vena cava.
8)Blood is then pumped through the right side of the heart, into the lungs to get oxygen, and back into the left side of the heart.
Right atrium collects blood from
Systemic circuit
Left atrium collects blood from
Pulmonary circuit
Right ventricle pumps blood to
Pulmonary circuit
Left ventricle pumps blood to
Systemic circuit
Right AV valve
■ Also called tricuspid valve
■ Has 3 cusps
AV valves
Between atria and ventricles
■ Blood pressure closes valve cusps during ventricular contraction
■ Papillary muscles tense chordae tendineae:
■ prevent valves from swinging into atria during ventricular contraction
Left AV valve
“Mitral”/“bicuspid valve”
2 cusps
Pulmonary semilunar valve
heart valve that controls the flow of oxygen-poor blood from the right ventricle to the lungs
Opens when pressure in right ventricle greater than pressure in pulmonary artery
Aortic semilunar valve
regulate blood flow from the left ventricle of the heart into the aorta, while preventing blood from flowing backward
-opens when left ventricle contracts
-closes when left ventricle relaxes
Aortic sinuses
-origin of left and right coronary arteries
-blood can only flow into coronary arteries in diastole
-when the aortic valve is closed because valves block off coronary vessels during systoli
Fibrous skeleton
-4 bands around ❤️ valves and bases of pulmonary trunk and aorta
-stabilize valves
-electrically isolate ventricular cells from atrial cells
Cardiac muscle struture
Striated, short, branch, 1 or 2 nuclei per cell
Cardiac muscle: contracts as a unit
Yes, gap junctions create a functional syncytium
Na+ rush from cell to cell via gap junctions➡️enter cell➡️depolarization➡️trigger AP➡️ contraction
T tubules of cardiac muscle
Few and wide
Cardiac muscle: sacroplasmic reticulum
Less elaborate; no terminal cisterns
Cardiac muscle: source of Ca2+ for contraction
Sarcoplasmic reticulum and ECF
Cardiac muscle: Ca2+ binds to troponin?
Yes
Cardiac muscle: pacemaker cells present?
Yes
Cardiac muscle: tetanus possible?
No
Cardiac muscle cell: supply of ATP
Aerobic only
Functions of intercalated discs
-maintain structure
-enhance molecular and electrical connections
-conduct APs
Right coronary artery supplies blood to:
■ Supplies blood to:
■ right side of ❤️
■ portions of both ventricles
■ cells of sinoatrial (SA) and atrioventricular nodes
■ marginal arteries (surface of right ventricle)
■ posterior interventricular artery
Left coronary artery
■ Supplies blood to:
■ left ventricle
■ left atrium
■ interventricular septum
■ 2 main branches:
■ circumflex artery
■ anterior interventricular artery
Blood flows into coronary arteries during:
Diastole
Sinoatrial node
❤️ pacemaker
-location: right atrium, where superior vena cava joins right atrium
-function: generates electrical signals that make atria contract, then passes signals to make ventricle contract (contracts both sides of the ❤️)
-innervation: ANS
Atrioventrical (AV) node
Location: right side of ❤️ at junction of atria and ventricles
Backup pacemaker if SA node fails
The AV node introduces a brief delay between the atria and ventricles contracting, which allows the atria to fully fill the ventricles with blood before the ventricles contract
Steps of AP propagation in the❤️
1)SA node
2)AV node
3) bundle of His
4) bundle branches
5) Purkinje fibers
6) ventricles
Prepotential
K+ leaks from cell➡️reploarization ➡️ AP
Papillary muscles
Play vital role in AV valve function and prevent ventricular distension
Attach to AV valve leaflets via chordae tendinae
Contract to prevent AV valves from inverting or prolapsing during ventricular contraction
W/ chordae tendinae- regulate closure of AV valve during contraction
P wave
Atrial depolarization, initiated by SA node
QRS complex
Ventricular depolarization begins at apex➡️QRS complex
Atrial repolarization occurs
T wave
Ventricular repolarization begins at apex➡️T wave
Cardiac AP: (rapid) depolarizarion
Due to Na+ influx through fast voltage-gated Na+ channels. (+) feedback cycle rapidly opens many Na+ channels, reversing membrane potential. Channel inactivation ends this phase
Cardiac AP: plateau phase
Due to Ca2+ influx through slow Ca2+ channels. Keeps the cell depolarized b/c most K+ channels are closed
Cardiac SA: repolarization
Due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which bring membrane potential back to resting voltage
Absolute refractory period
-long
-cardiac muscle cells cannot respond
-cannot be ➕to contract no matter how strong the ➕
-b/c it is still recovering from previous contraction- makes sure ❤️ can relax before beating again
Beginning of QRS to peak of T wave
Relative refractory period
-short
-response depends on degrees of stimulus
-sensitive to ➕, but requires more➕ than normal to trigger an AP
Last half of T wave (final repolarization phase)
Cardiac cycle phase 1: mid to late ventricular diastole
-blood from venous circulation is returning to the ❤️ and acculumates into atria
-w/o contraction 70-80% of blood passively flows into ventricles
-atrial pressure> ventricular pressure
-arterial pressure> ventricle pressure
-AV valves: open
-semilunar vale: closed
-EKG- P wave
Cardiac cycle phase 2: isovolumetric contraction/systole
-no blood enters or leaves ventricles when it’s contracting
-atrial pressure< ventricular pressure
-arterial pressure > ventricle pressure
-AV valves: closed (“LUB”) S1
-semilunar valves: closed
-EKG: QRS
Cardiac cycle phase 3: mid to late ventricular systole
-ventricular pressure continues to ⬆️➡️blood leaves ventricles➡️arteries (via semilunar valves)
-atrial pressure< ventricular pressure
-arteriole pressure< vent pressure
-AV valves: closed
-semilunar valves: open
-EKG: QRS
Cardiac cycle phase 4: isovolumetric relaxation
-no blood leaves ventricles when it is relaxing
-ventricle repolarizing➡️⬇️ventricular pressure
-atrial pressure< ventricular pressure
-arterial pressure> vent pressure
-AV valve: closed
-semilunar valve: closed (“DUB”) S2
-EKG: T Wave
❤️ failure
-lack of adequate blood flow to peripheral tissues and organs due to ventricular damage
-usually starts with LEFT VENTRICLE in response to high peripheral BP
-build up of afterload( pressure ❤️must overcome to pump blood out during systole) make it hard for ventricles to contract due to ⬆️pressure
⬆️BP➡️_afterload
⬆️afterload
Stroke volume
Amount of blood ejected from each ventricle w/ each cardiac cycle (ml)
SV= EDV(amount of blood in the ❤️s ventricles after they’ve filled w/ blood)-ESV(amount of blood in ventricles at the end of contraction phase)
Cardiac output
Amount of blood ❤️ pumps in 1 min
CO(ml/min)= HR (beats/min) x SV (ml/beat)
Autonomic innervation
-cardiac centers of medulla oblongata:
-cardiac celebratory center:
-controls sympathetic neurons
-uses NE to ➕ beta1 receptors to ⬆️HR
-⬆️rate of spontaneous depolarization in SA node
-⬆️contractility of atria and ventricles➡️⬆️SV
-cardioinhibitory center
-controls parasympathetic output
-uses AcH to ➕M2 receptors to ⬇️HR
-⬇️rate of spontaneous depolarization in SA node➡️⬇️HR
-vasomotor center in medulla
-responsible for control of BP
-sympathetic control
-uses NE to ➕Alpha1 receptors➡️vasoconstriction➡️⬆️BP
Preload
-amount of ventricular stretching at the end of diastole (⬆️heart fills during diastole➡️⬆️preload)
-directly proportional to EDV
-affects ability of muscle cells to produce tension (⬆️preload➡️⬆️contractility)
Frank-starling principle
⬆️EDV➡️⬆️SV
-greater the stretch of cardiac muscle, the greasier will be the forces of recoil
-length-tension relationship (⬆️length➡️⬆️tension it can generate)
Positive isotopic actions
Factors that ⬆️❤️ contractility
Ex. NE
Negative isotropic actions
Factors that ⬇️❤️ contractility
Ex. ACh
Stroke volume: 3 factors that effect stroke volume
Directly proportional:
1)contractility
2) proload
3) EDV
Inversely proportional:
1) afterload
2)ESV
Relationship between afterload and systemic arterial pressure
Directly proportional
Pressure in arteries⬆️➡️⬆️afterload in ❤️
Systemic arterial pressure
Force of blood against wall of body’s arteries
Systolic pressure/ diastolic pressure
120/80
Hormones that ⬆️HR/contractility
-epi
-NE
-glucagon
-thyroid hormone
Stretch/baroreceptors in the ❤️
-location: right atrium
-detect⬆️ in volume and BP returned to ❤️
-transmit signals to PNS via CN10➡️⬇️BP
Carotid reflex
⬆️BP in carotid artery➡️⬆️firing of baroreceptors w/ ⬆️afferent stimuli
1)vasomotor center:⬇️ amount of NE➡️vasodilation
2) CAC: ⬇️SNS➕(⬇️NE)➡️slow ❤️and ⬇️strength of contraction
3)CIC: ⬆️PNS ➕(⬆️ACh)
4)⬆️BP in carotid artery➡️ventricular cells release BNP➡️⬆️Na+ in urine➡️urine output
Aortic relex
When ⬆️BP in aorta
-➡️⬆️firing of baroreceptors W
1)vasomotor center: ⬇️ amount of NE ➡️vasodilation
2)CAC: ⬇️SNS (⬇️NE)➡️slow ❤️ and ⬇️strength of contraction
3)CIC: ⬆️PNS➕ (⬆️ACh to slow ❤️)
Right ❤️ (brainbridge)/ artial reflex
⬆️BP in vena cava and right atrium
1)CAC: ⬆️SNS➕ (⬆️NE)to ⬆️HR and ⬆️strength of contraction
2)CIC: ⬇️PNS➕(⬇️ACh)➡️⬆️➕of ❤️
3)ANP released by atrium➡️➕Na+ in urine➡️⬇️BP and ⬇️BV
⬆️HR helps move blood from right atrium➡️arteries➡️⬇️BP on venous side
