Cardiovascular System: Heart Flashcards
1
Q
Perfusion
A
-delivery of blood per time per gram of tissue
-mL/min/g
-adequate perfusion required to maintain healthy cells
2
Q
Heart base
A
-posterosuperior surface of the heart
3
Q
Heart apex
A
-inferior conical end
4
Q
Pericardial cavity
A
-space between serosal layers
-filled with serous fluid
5
Q
Serous fluid
A
-reduces friction with every heartbeat
6
Q
Atria
A
-2 atria
-smaller superior chambers
7
Q
Ventricles
A
-2 ventricles
-larger inferior chambers
-pump blood out of heart
-pumps blood to the arterial trunks
-more muscular because they pump blood to farther places in the body
8
Q
Pulmonary circulation
A
-movement of blood to and from lungs
-transports blood to the lungs
-picks up O2 and releases CO2
9
Q
Pulmonary circulation: Overview
A
Overview:
-deoxygenated blood transported from right side of the heart
-pulmonary trunk
-gas exchange in lungs
-oxygenated blood transported through vessels to left side of heart
-pulmonary veins
10
Q
Systemic circulation
A
-transports blood to and from tissues in the body
-returning deoxygenated blood to right atrium then to the lungs to get oxygenated
11
Q
Systemic circulation: Overview
A
Overview:
-oxygenated blood leaves left side of heart
-aorta
-gas exchange at tissues
-deoxygenated blood returns to left side of heart
-superior and inferior vena cava
12
Q
Sulci
A
-grooves on the surface of the heart
-separate chambers
13
Q
Coronary sulcus
A
-separate atria
-extends around circumference of the heart
14
Q
Interventricular sulcus
A
-separate ventricles
15
Q
Anterior inter-ventricular sulcus
A
-anterior side
16
Q
Posterior sulcus
A
-posterior side
17
Q
Septa
A
-separates left and right sides of the heart
18
Q
Functional end arteries
A
-blockage of coronary arteries leads to insufficient flow to the heart wall
-cannot for anastomoses due to size (to small)
-blood vessels that supply a particular area and have minimal or no collateral circulation
19
Q
Anastomoses
A
-connections between vessels allowing blood to arrive by more than one route
20
Q
Coronary heart disease
A
-buildup of plaque in coronary arteries
-reduces blood flow to heart
muscle
21
Q
Angina pectoris
A
-heart pain during strenuous activity
-due to lack of oxygen and blood
22
Q
Myocardial infraction
A
-heart attack
-sudden and complete blockage of coronary artery
-heart muscle deprived of oxygen
-possible tissue death
23
Q
Cardiac muscle cells
A
-found in the myocardium
-short, branched and striated
-max overlap of actin and myosin occurs increasing stretch => more cross bridge cycling => more forceful contraction
24
Q
Sarcolemma
A
-plasma membrane in muscle cells
-forms T-tubules
25
T-tubules
-extend to the sarcoplasmic reticulum
-invaginations that go from the plasma membrane down into the cell
26
Sarcoplasmic reticulum
-around outside of muscle fiber
27
Myofibrils
-made up of sarcomeres
28
Myofilaments
-protein filaments that make up the structure of the myofibrils in muscle fibers
29
Sarcomeres
-made up of myofilaments (actin and myosin)
30
Desmosomes
-mechanically joining cells (hold cells together) with protein filaments
-prevent from pulling apart
31
Gap junctions
-electrically joins cells
-function as a pore
-electrically joins cells by allowing ion flow
-allows each chamber to function as a unit
32
Myoglobin
-bind oxygen
-act as a reservoir for when we need more oxygen
33
Creatine kinase
-allows for quick generation of ATP
-releasing ATP from creatine itself
34
Conduction system
-specialized cells within the heart located within the endocardium
-DO NOT CONTRACT
-initiate and conduct electrical signals
-activity influenced by autonomic nervous system
35
Conduction Process
Synovial node
1. AP starts at SA node
2. AP spreads through stria
3. Reaches AV node
4. Atria contract together
-AP travels through AV bundle to Purkinje fibers:
AV node -> AV bundle -> Purkinje fibers
AV node
5. AP delayed at AV node
6. Fibrous skeleton prevents AP from spreading
7. Ventricles fill before they contract
-AP spreads to cardiac muscle fibers in ventricles:
-fast propagation
-cells of 2 ventricles contract nearly simultaneously
36
Sinoatrial (SA) node
-initiates the heart beats
-often called “pacemaker”
-posterior wall of right atrium
37
SA nodal cells
-initiate heartbeat
-spontaneously depolarize
-can reach threshold without stimulation
-auto rhythmicity
RMP of SA nodal cells:
--60 mV
-Na+/K+ pumps, Ca2+ pumps, leak channels
-voltage gated channels
-not stable which lead to auto rhythmicity
38
Atrioventricular (AV) node
-delays transmission
-floor of right atrium
39
Atrioventricular (AV) bundle
-connects with Purkinje fibers
-extends from AV node
40
Purkinje fibers
-functions to spread impulse of contraction to ventricles
-extends from AV bundles
41
Cardiac center
-in medulla oblongata
-receives signals from baroreceptors and chemoreceptors
-sends signals via sympathetic and parasympathetic pathways
-modifies heart rate and force of contraction
42
Cardioinhibitory center
Parasympathetic innervation:
-results in decreased heart rate
-receptors to cardioinhibitory center to vagus nerve (CN X)
-right vagus nerve innervates SA node
-left vagus nerve innervates AV node
43
Cardio acceleratory center
Sympathetic innervation:
-results in increased heart rate and force
-receptors send info to cardio acceleratory center
-motor neurons extend to SA node, AV node, myocardium and coronary arteries
44
Auto-rhythmicity
-produces its own rhythmic electrical impulse without nervous stimulation
-do not have a stable resting membrane potential (RMP)
1. cation channels opening (sodium entering the cells)
2. opening of calcium channels (calcium entering the cells making it more positive)
3. opening of potassium channels (cell becomes more negative)
45
Tetany
-sustained contraction without relaxation
-cannot occur in cardiac muscle cells
46
Refractory period
-cardiac cells have long refractory period
-cell cannot form a new impulse
-heart cell contracts and relaxes before it can be restimulated
47
Electrocardiogram
-skin electrodes detect electrical signals of cardiac muscle cells
-common diagnostic tool
48
P wave
-atrial depolarization
49
QRS wave
-ventricular depolarization
-atria also repolarizing
50
T wave
-ventricular repolarization
51
P-Q segment
-atria contracting
52
S-T segment
-ventricles contracting
53
Cardiac cycle
-events in the heart from the start of one heartbeat to the start of the next
54
5 Phases of the Cardiac Cycle:
1. Atrial relaxation and ventricular filling
-all heart chambers relaxed
-AV valves open: blood flows into ventricles
-SL valves closed
2. Atrial contraction and ventricular filling
-SA node starts atrial excitation
-atria contract
-ventricles filled to EDV
-atria relax
3. Isovolumic contraction
-Purkinje fibers initiate ventricular excitation
-ventricles contract: increases pressure
-AV valves close
-SL valves closed
4. Ventricular ejection
-ventricles continue to contract
-pressure rises above arterial pressure
-SL valves open
-ESV remains after ejection
5. Isovolumic relaxation
-pressure decreases
-SL valves close
55
Systole
-contraction
-increase in pressure
56
Diastole
-relaxation
-decrease in pressure
57
Endo diastolic volume (EDV)
-volume of blood in one ventricle at end of ventricular diastole
-resting/filling
58
Stroke volume (SV)
-volume of blood ejected from one ventricle during systole
-contraction
59
Endo systolic volume (ESV)
-volume of blood left in one ventricle after ventricular systole
-contraction/ejection
-SV = EDV - ESV
60
Cardiac output
-amount of blood pumped by a single ventricle in one minute
-measured in liters per minute
-measurement of the effectiveness of the cardiovascular system
-determined by heart rate and stroke volume
-CO = HR x SV
61
Chronotropic agents
-change HR
-alter activity of nodal cells
-ANS or hormones
-positive or negative
62
Positive chronotropic agents
-causes increase in HR
-sympathetic stimulation
-NE near SA node
-adrenals release NE and epinephrine (EPI)
-NE and EPI bind to nodal cells and increase firing
-adrenergic receptors
63
Negative chronotropic agents
-decrease heart rate
-parasympathetic activity
-neurons release Ach
-bonds to muscarinic receptors
-open K+ channels
K+ diffuse out of the cell
-leads to hyperpolarization
-takes longer for SA node to reach threshold
64
Autonomic reflexes
-baroreceptors and chemoreceptors
-send signals to cardiac center
-controls ANS through sympathetic and parasympathetic divisions
-baroreceptors and chemoreceptors send sensory information to cardiac center
-alters HR and AV
65
Atrial reflex
-protects the heart from overfilling
-baroreceptors in arterial wall stimulated by increases in venous return
66
Venous return
-first variables that influences SV
-volume of blood returned to the heart
-determines the amount of blood in the ventricles prior to contraction (EDV)
-determines the preload
67
Frank-Starling Law
-as EDV increases, the greater stretch of heart wall results in more optimal overlap of thick and thin filaments
-heart contracts more forcefully when filled with more blood
-SV increases
68
Preload
-stretch of heart wall prior before cardiac muscle shortens (contraction)
69
Inotropic agents
-second variable that influences the SV
-cause a change in SV
-alter SV by changing force of contraction
-Due to changes of Ca+ in sarcoplasm
-influences number of crossbridge
70
Positive inotropic agents
-increases Ca+ availability
-increase the force of heart muscle contraction
-NE, EPI and thyroid hormone
71
Negative inotropic agents
-decrease Ca+ availability
-electrolyte imbalance (K+ and H+) and certain drugs
72
Afterload
-third variable that influences SV
-resistance in arteries to ejection of blood by ventricles
-arterial pressure that must be exceeded before blood ejected
73
Atherosclerosis
-plaque in vessels
-increases afterload
-greater resistance
74
Mediastinum
-heart is within the mediastinum
75
Percardium
-Layers that enclose the heart and vessels
76
Fibrous pericardium
-Dense irregular connective tissue
-Encloses the heart
-Attaches diaphragm, aorta and pulmonary trunk
77
Parietal layer of serous pericardium
-Simple squamous epithelium with underlying areolar
connective tissue
-Attached to fibrous pericardium
78
Visceral layer of serous pericardium
-Also called epicardium
-Simple squamous epithelium with underlying areolar connective tissue
-Attached directly to heart
79
Vena cava
-Superior and inferior
-Drain deoxygenated blood into right atrium
80
Superior vena cava
-drain deoxygenated blood into right atrium, drains blood from the areas superior to the heart (head, neck, upper limbs)
81
Inferior vena cava
-drain deoxygenated blood into right atrium, drains blood from areas that are inferior to the heart (abdomen and lower limbs)
82
Pulmonary trunk
-receives deoxygenated blood form right ventricle, sends blood to the lungs
83
Pulmonary veins
-drains oxygenated blood into left atrium, blood returning form the lungs that is getting ready to be pumped to the rest of the body
84
Aorta
-receives oxygenated blood from the left ventricle and sending it to the rest of the body
85
Atrioventricular (AV) valves
-between atrium and ventricles
-prevent backflow in atria
-when valves are closed blood cant flow backwards has to flow out the trunks
-open when ventricles are filling
-close when ventricles contract
-force blood to move superiorly and out of the heart
-papillary muscles and tendinous cords prevent inverting into atria
86
Pulmonary SL valve
-between right ventricle and pulmonary trunk
- where we are sending blood out to the lungs
87
Semilunar (SL) valves
-between ventricles and arterial trunk
-prevent backflow into ventricles
-open when ventricles contract
-blood forced into arterial trunks
-close when ventricles relax
-blood slides backwards and catches in cusps
-no tendinous cords, pulmonary trunks have blood that is sitting there so when ventricles are relaxed SL valves are closed because the blood comes back and gets caught in cusps
88
Aortic SL valves
-between left ventricle and aorta
89
Myocardium
-middle layer
-cardiac muscle -> contracts the heart
90
Endocardium
-inner layer
-simple squamous epithelium with areolar connective tissue
-continuous with the lining of blood vessels
91
Pectinate muscles
-anterior wall and within auricle
92
Trabeculae carneae
-irregular muscular ridges found within ventricles
93
Papillary muscles
-cone shaped projections, papillary = nipple like projections, usually have three in right ventricles, attached to and anchors tendinous cords
94
Tendinous cords
-thin collagen fibers, attached to right AV valve, stops valves from being able to be inverted (doesn’t allow backflow)
95
Fibrous skeleton
-dense irregular connective tissue that surrounds the internal heart
Functions:
-provides structural support
-forms fibrous rings to anchor valves
-attachment of cardiac muscle
-electrical insulator
-preventing ventricles from contracting at the same tine at atria
-want ventricles to contract slightly after the atria
96
Coronary arteries
-transport oxygenated blood to heart wall
-right and left: sit in coronary sinus, branch off aorta
97
Right marginal artery
-supplies lateral border, not in any of the sulcus
-branch off right coronary artery
98
Posterior interventricular artery
-supplies posterior left and right side of ventricle, within interventricular sulcus
-branch off right coronary artery
99
Anterior interventricular artery
-supplies anterior wall of left ventricle and most if the interventricular septum, within the anterior interventricular sulcus
-branch off left coronary artery
100
Circumflex artery
-supplies left atrium and ventricle, within coronary sulcus
-branches off left coronary artery
101
Coronary veins
-transports deoxygenated blood away from heart wall to right atrium
102
Coronary sinus
-sits posterior aspect of coronary sulcus, receives blood from coronary veins and drains into right atrium
103
Great cardiac vein
-sits in anterior interventricular sulcus
104
Middle cardiac vein
-sit in posterior interventricular sulcus
105
Small cardiac vein
-sit next to marginal artery
106
Right atrium
-receives blood returning form systemic circulation -> deoxygenated blood
-pectinate muscles: anterior wall and within auricle
-right AV valves: allows blood to flow from atria to ventricle when open, stops flow when it is closed
107
Left atrium
-receiving oxygenated blood from pulmonary veins
-left AV valves
108
Right ventricles
-receiving blood from the right atria and sends blood to lungs
-still deoxygenated
-sends blood up through pulmonary trunk
-ensure one-way blood flow
-trabeculae carneae: irregular muscular ridges found within ventricles
-papillary muscles: cone shaped projections, papillary = nipple like projections, usually have three in right ventricles, attached to and anchors tendinous cords
-tendinous cords: thin collagen fibers, attached to right AV valve, stops valves from being able to be inverted (doesn’t allow backflow)
-blood exits through pulmonary SV valve to pulmonary trunk
109
110
Left ventricles
-receiving blood from left atrium
-blood exits through aortic SL valve to aorta
-contain papillary muscles, tendinous cords and trabecula carneae
-ensure one-way blood flow
