Unit 2: Cardiovascular System Flashcards
1
Q
What is the Cardiovascular system
A
Heart + blood vessels
- transports blood throughout the body
2
Q
What is perfusion
A
- delivery of blood per time per gram of tissue
- mL/min/g
- adequate perfusion required to maintain healthy cells
- require healthy unblocked vessels
3
Q
Where is the heart located
A
within the thoracic cage (rib cage) - posterior to the sternum, ribs, and thoracic vertebrae - encloses heart and lungs
- left of the midline and between the lungs within the mediastinum
4
Q
Where is the base of the heart
A
posterosuperior surface of the heart
5
Q
Where is the apex of the heart
A
inferior conical end
6
Q
What are the three layers of the pericardium?
A
Fibrous pericardium
Parietal layer of serous pericardium
Visceral layer of the serous pericardium (epicardium)
7
Q
What is the Fibrous pericardium
A
-dense irregular CT
- encloses the heart
- attaches diaphragm, aorta and pulmonary trunk
8
Q
What is the parietal layer
A
- simple squamous epithelium with underlying areolar CT
- attached to fibrous pericardium
9
Q
What is the Visceral layer
A
Simple squamous epithelium with underlying areolar CT
- attached directly to the heart
10
Q
What is the pericardial cavity
A
- space between serosal layers
- filled with serous fluid (reduced friction with every heartbeat)
11
Q
What are the 5 anatomical features of the heart
A
2 sides of the heart
Great vessels attached to the heart
2 sets of valves
12
Q
What are the 2 sides of the heart and what do they do
A
Allows for separation of deoxygenated and oxygenated blood
Left Side
- receives oxygenated blood from lungs
- pumps to body
Right Side
- receives deoxygenated blood from the body
- pumps to lungs
13
Q
What are the 4 chambers of the heart
A
2 atria - smaller superior chambers, send blood to ventricles
2 ventricles - larger inferior chambers - pump blood out of heart
14
Q
What are the 4 Great vessels
A
Vena Cava
Pulmonary Trunk
Pulmonary Veins
Aorta
15
Q
What is the Vena Cava
A
Superior and inferior
- drain deoxygenated blood into right atrium
16
Q
What is the pulmonary trunk
A
- receives deoxygenated blood from right ventricle
17
Q
What is the pulmonary veins
A
- drains oxygenated blood into left atrium
18
Q
What is the aorta
A
- receives oxygenated blood from left ventricle
19
Q
What is the atrioventricular valves
A
between atrium and ventricle
- prevent backflow in atria
20
Q
What is the semilunar valves
A
- between ventricles and arterial trunk
- prevent backflow into ventricles
21
Q
What is the pulmonary SL valve
A
between right ventricle and pulmonary trunk
22
Q
what is the Aortic SL valve
A
between the left ventricle and aorta
23
Q
What is Pulmonary circulation
A
Movement of blood to and from lungs
Overview:
- deoxygenated blood transported from right side of heart (pulmonary trunk)
- gas exchange in lungs
- oxygenated blood transported through vessels to left side of heart (pulmonary veins)
24
Q
What is systemic circulation
A
blood to and from tissues
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)
25
What is the sulci
grooves on the surface of the heart
separate chambers
26
What is the coronary sulcus
separate atria from the ventricles
- extends around circumference of the heart
27
Interventricular sulcus
separate ventricles
- anterior interventricular sulcus (anterior - front side)
- posterior interventricular sulcus (posterior - back side)
28
Internal anatomy
walls of ventricles are thicker than walls of atria
- left ventricle wall 3x thicker than right wall
- needs to pump to entire systemic system (whereas the R only has to go to lungs)
29
What are the 3 layers of the heart
Epicardium
Myocardium
Endocardium
30
What is the epicardium
- outer layer
- = visceral layer of serous pericardium
- simple squamous epithelium and areolar CT
31
What is the Myocardium
- middle layer
- cardiac muscle (contracts)
32
What is the Endocardium
- inner layer
- simple squamous epithelium and areolar CT
- Continuous with lining of blood vessels
33
What is the septa
- separates left and right sides of the heart
34
Where are the pectinate muscles
- anterior wall and within auricle
function to increase the surface area of the atrial chambers by creating a ridged inner wall, allowing for greater blood volume to be held during atrial filling and contributing to efficient contraction when the atria squeeze to pump blood into the ventricles; essentially, they act like small internal "trabeculae" to maximize the atrial chamber's capacity without significantly increasing its mass.
35
What does the Right AV valve do
allows blood to flow from atria to ventricle when open
36
What is the trabeculae carneae
Irregular muscular ridges
37
What is papillary muscles
Cone-shaped projections
located within the heart ventricles that play a crucial role in preventing the atrioventricular (AV) valves from prolapsing by contracting and pulling on the chordae tendineae, thus ensuring proper blood flow by preventing backflow during ventricular contraction; essentially, they help the valves close tightly to maintain unidirectional blood flow through the heart
38
What is the Tendinous cords
Thin collagen fibers
- attached to right AV valve
39
Where does blood exit through to get to the pulmonary trunk
through the pulmonary SL valve
40
What do heart valves ensure
ensures one-way blood flow
AV valves : open when ventricles filling, close when ventricles contract
(force blood superiorly, papillary muscles and tendinous cords prevent inverting into atria)
41
What is the fibrous skeleton made of and where is it located
Dense irregular connective tissue (surrounds the heart)
42
What is the function of Fibrous skeleton
- Provides structural support
- forms fibrous rings to anchor valves
- Attachment of cardiac muscle
- electrical insulator (preventing ventricles from contracting at the same time as atria)
43
What are the three types of Coronary Vessels
Coronary Circulation (delivers blood to hearts thick wall)
Coronary Arteries (transports oxygenated blood to heart wall)
Coronary Veins (transports deoxygenated blood away from heart wall to right atrium)
44
Where are the right and left coronary arteries
they sit in coronary sulcus and branch off of the aorta
45
What are the branches of the right coronary artery
right marginal artery (supplies lateral border)
and the posterior interventricular artery (supplies posterior left and right ventricle)
46
What are the branches of the left coronary artery
Anterior interventricular artery (supplies anterior wall of LV and most of interventricular septum)
Circumflex artery (supplies left atrium and ventricle)
47
Where is the coronary sinus
Sits in posterior aspect of coronary sulcus
- receives blood from coronary veins and drains into right atrium
48
Where is the great cardiac vein
sits in anterior interventricular sulcus
49
Where is the middle cardiac vein
sits in posterior interventricular sulcus
50
Where is the small cardiac vein
sits next to marginal artery
51
What is the cardiac cycle
Events in the heart from the start of one heartbeat to the start of the next
52
what is systole
Contraction
increase in pressure
53
What is diastole
Relaxation
decrease in pressure
54
What is EDV
end diastolic volume
- volume of blood in one ventricle at end of ventricular diastole
(rest/filling)
55
What is SV
Stroke Volume
- volume of blood ejected from one ventricle during systole
(contraction)
56
What is ESV
End Systolic Volume
- volume of blood left in one ventricle after ventricular systole
(contraction/ejection)
57
SV = ? - ?
SV = EDV - ESV
58
What are the 5 phases of the cardiac cycle
1. Atrial relaxation and ventricular filling
2. Atrial contraction and ventricular filling
3. Isovolumic Contraction
4. Ventricular Ejection
5. Isovolumic Relaxation
59
What is a part of the atrial relaxation and ventricular filling of the cardiac cycle
- all heart chambers relaxed
- AV valves open (blood flows into ventricles)
- SL valves closed
60
What is a part of the atrial contraction and ventricular filling of the cardiac cycle
- SA node starts atrial excitation
- Atria contract
- Ventricles filled to EDV
- Atria relax
61
What is a part of the isovolumic contraction of the cardiac cycle
- purkinje fibers initiate ventricular excitation
- ventricles contract (increases pressure)
- AV valves close
- SL valves closed
62
What is a part of the ventricular ejection of the cardiac cycle
- ventricles continue to contract (pressure rises above arterial pressure)
- SL valves open
- ESV remains after ejection
63
What is a part of the isovolumic relaxation phase of the cardiac cycle
Ventricles relax
- pressure decreases
SL valves close
64
What is cardiac output
- amount of blood pumped by a single ventricle in one minute (L/min)
- measurement of the effectiveness of the cardiovascular system
65
How is cardiac output determined
CO = HR x SV
Determined by heart rate and stroke volume
66
what are variables that influence heart rate?
1. autonomic reflexes - baroreceptors and chemoreceptors - send signals to cardiac center
2. Chronotropic agents - Change HR - alters activity of nodal cells - ANS or hormones - + or -
67
What are autonomic reflexes
- control ANS through sympathetic and parasympathetic divisions
- baroreceptors and chemoreceptors send sensory information to cardiac center
- alters HR and SV
- Atrial Reflex
68
What is atrial reflex
- protects the heart from overfilling
- baroreceptors in atrial wall stimulated by increase in venous return
69
what are positive chronotropic agents
- cause 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)
70
what are negative chronotropic agents
- decrease heart rate
- parasympathetic activity
- neurons release acetylcholine
- this binds to muscarinic receptors
- opens K+ channels (K+ diffuses out of the cell)
- leads to hyperpolarization
- takes longer for SA node to reach threshold
71
What are variables that influence SV?
1. Venous return (volume of blood returned to the heart)
2. Inotropic agents (cause a change in SV)
3. Afterload (resistance in arteries)
72
What is venous return
- amount of blood returned to the heart
- determines the amount of blood in the ventricles prior to contraction (EDV)
- determines preload (stretch of heart wall prior before cardiac muscle shortens - contraction)
73
What is 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)
74
What does inotropic agents do
- Alter SV by changing force of contraction
- due to changes of Ca2+ in sarcoplasm (influences number of crossbridges
75
What are positive inotropic agents
- increase Ca2+ availability
- NE, EPI and thyroid hormone
76
What are negative inotropic agents
- Decrease Ca2+ availability
- Electrolyte imbalances (K+ and H+) and certain drugs
77
What is afterload
- resistance in arteries to ejection of blood by ventricles
- arterial pressure that must be exceeded before blood ejected
- PV > V trunk
78
What is atherosclerosis
- plaque in vessels (decrease in SV)
- Increases afterload (greater resistance)
79
What is the myocardium
- middle layer of internal heart wall
- contains cardiac muscle cells
80
Describe cardiac muscle cells
striated, short, branched
81
What is the sarcolemma
- plasma membrane forms T-tubules
- T-tubules extend to the sarcoplasmic reticulum
82
When does max overlap of thick and thin filaments occur?
when cardiac muscle is stretched (allows for more cross-bridges and more force)
83
What are the two intracellular structures
Desmosomes (mechanically join cells with protein filaments)
Gap junction (electrically join cells by allowing ion flow, allows each chamber to function as a unit)
84
High demand for energy for metabolism
-Extensive blood supply
-numerous mitochondria
-myoglobin (binds O2) and creatine kinase (ATP synthesis)
85
What are the different molecules as fuel
- fatty acids
-glucose
- lactic acid
-amino acids
-ketone bodies
86
What is the Conduction system
- specialized cells within the heart located in the endocardium
- do not contract
- initiate and conduct electrical signals
- activity influenced by autonomic nervous system
87
What are the 4 groups of cells for conduction systems
Sinoatrial (SA) node
Atrioventricular (AV) node
Atrioventricular (AV) bundle
Purkinje Fibers
88
What is the SA node
Initiates heartbeat - pacemaker
Posterior wall of right atrium
89
Where is the AV node
Floor of right atrium
90
Where is the AV bundle
Extends from AV node
91
Where are Purkinje fibers
Extends from AV bundles
92
What is the 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
93
What is the parasympathetic innervation
-rest and digest
- 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)
94
What is the Sympathetic system
- Results in increased heart rate and force
- receptors send info to cardioacceleratory center
- motor neurons extend to SA node, AV node, myocardium and coronary arteries
95
What are the 2 events to contract the heart:
Conduction system initiates an action potential
Cardiac muscle cells initiate action potential -leads to contraction
96
Explain the conduction system
SA nodal cells
-initiate heartbeat
-spontaneously depolarize
(Can reach threshold without stimulation - autorythmicity)
RMP of SA nodal i
97
Where does the AP start and spread in the conduction system?
AP starts at SA node
- AP spreads through atria
- reaches AV node
- atria contract together
- AP delayed at AV node
- Fibrous skeleton prevents AP from spreading
- ventricles fill before they contract
98
Where does the AP travel through in the conduction system
- AP travels through AV bundle to Purkinje fibers (AV node, AV bundle and the purkinje fibers)
- AP spreads to cardiac muscle fibers in ventricles
- Fast propagation
- Cells of 2 ventricles contract nearly simultaneously
99
What is the RMP of cardiac muscle cells and what is happening with the voltage gated channels
RMP of -90mV
Voltage gated channels closed at rest
Na+, Ca2+, K+
100
what is tetany
- sustained contraction without relaxation
- cannot occur in cardiac muscle cells
101
What is a refractory period
- Cardiac cells have long refractory period
- cell cannot fire a new impulse
- heart cell contracts and relaxes before it can be restimulated
102
What is an ECG/EKG
Electrocardiogram
- skin electrodes detect electrical signals of cardiac muscle cells
- common diagnostic tool
103
What does the P wave represent
Atrial depolarization
104
What does the QRS wave represent
Ventricular depolarization
- atria also repolarizing
105
What does the T wave represent
Ventricular repolarization
106
What does the P-Q segment represent
Atria contracting
107
What does S-T segment represent
Ventricles contracting
108
What number does cardiac muscle depolarize to? and what is the Resting membrane potential
The RMP is - 90mV
and it depolarizes to about +30mV
109
What is the depolarization phase
When there is an inflow of Na+
causing the muscle to become more +
110
What is the plateau stage
When there is a K+ outflow, and additionally and inward flow of Ca2+
- there is a slow decrease in the membrane potential
111
What is the Repolarizataion
there is a fast decrease in the membrane potential
- K+ flows continues to flow out of the cell, while the Ca2+ channel closes
*no inflow or outflow of Na+ or Ca2+ during this stage, and with the outflow of K+, the MP becomes more negative*
