DeWitt Ch. 2 Embryology & EKG Ch 1 Flashcards
This is an extensive review for TEST 1 (540 cards)
1
Q
What are the two layers of cells that form the heart before week 3?
A
Inner, thinner layer and outer, thicker layer
2
Q
What forms during week 3 as heart tubes fuse?
A
Single endocardial heart tube
3
Q
Which aortic arch forms the definitive aortic arch?
A
Left 4th arch
4
Q
What structures are derived from the sinus venosus?
A
- SVC
- IVC
- Pulmonary veins
- CS
- Oblique vein of LV
- Posterior portion of RA & LA
5
Q
What is the heart’s developmental milestone during week 4?
A
Heart begins to beat
6
Q
What is the term for the loop formed during the heart’s development?
A
Bulboventricular loop
7
Q
What is present when the septum primum grows from the wall of the primitive atrium?
A
Endocardial cushions
8
Q
What closes when the septum primum reaches the endocardial cushions?
A
Ostium primum
9
Q
What forms the RVOT & LVOT?
A
mid-portion of the bulbus cordis called the conus cordis connects the primative RV with the truncus arteriosus which ULTIMATELY will form the RVOT & LVOT
10
Q
At what week does the septum secundum cease to grow?
A
Week 6
11
Q
What increases the LAP at birth?
A
Increased pulmonary resistance
12
Q
What is the only vessel to carry enriched blood with O2 saturation ~ 80%?
A
Umbilical vein
13
Q
Fill in the blank: The _______ delivers O2 and nutrients to the fetus.
A
Placenta
14
Q
What are the two shunts that allow blood to bypass the lungs in fetal circulation?
A
- Foramen Ovale (FO)
- Ductus Arteriosus (DA)
15
Q
What is a PFO?
A
Patent Foramen Ovale
16
Q
What is a PDA?
A
Patent Ductus Arteriosus
17
Q
What does the fetal circulatory pattern mix?
A
O2 enriched and O2 depleted blood
18
Q
What is the only great vessel leaving the heart during development?
A
Truncus arteriosus
19
Q
How many pairs of aortic arches are there?
A
Six pairs
20
Q
What are the major structures that develop from the truncus arteriosus?
A
- Aorta
- Main pulmonary artery
21
Q
What is the primary function of the placenta in fetal circulation?
A
Exchanges O2, CO2, nutrients, and waste
22
Q
What happens to the foramen ovale at birth?
A
Closes due to increased left atrial pressure
23
Q
What does the ductus venosus connect?
A
Umbilical vein to IVC
24
Q
Trace a drop of blood starting and ending at the placenta.
A
Placenta -> Umbilical vein -> Ductus venosus -> IVC -> RA -> FO -> LA -> LV -> AO -> Body
25
Week 3
26
What is the structure of the heart prior to week 3 of embryonic development?
A pair of tubes on either side of the midline
## Footnote
This structure is the earliest form of the heart in embryonic development.
27
How many layers of cells are present in the heart prior to week 3?
2 layers of cells
## Footnote
The heart consists of an inner, thinner layer and an outer, thicker layer.
28
What are the characteristics of the inner layer of cells in the heart prior to week 3?
Thinner
## Footnote
This layer is crucial for the initial formation of the heart structure.
29
What are the characteristics of the outer layer of cells in the heart prior to week 3?
Thicker
## Footnote
This layer provides structural support to the developing heart.
30
What is the heart tube formed from during the folding process?
Single endocardial heart tube
## Footnote
The heart tubes initially form in the midline and fuse during development.
31
What structures does the sinus venosus give rise to?
* SVC
* IVC
* Pulmonary veins
* CS
* Oblique vein of LV
* Posterior portion of RA & LA
## Footnote
The sinus venosus is located at the caudal end of the developing heart.
32
What does the primitive atrium develop into?
RA & LA
## Footnote
The primitive atrium is part of the early heart structure.
33
What is the function of the atrioventricular sulcus?
Divides primitive atrium & primitive ventricle
## Footnote
This sulcus is an important anatomical feature in heart development.
34
What does the primitive ventricle become?
* Apical portion of LV
* Inlet portion of RV
## Footnote
The primitive ventricle is crucial in forming the left and right ventricles.
35
What does the interventricular sulcus divide?
Primitive ventricle & bulbus cordis
## Footnote
This sulcus is important for the separation of heart chambers.
36
What structures are derived from the bulbus cordis?
* Apical portion of RV
* RVOT
* LVOT
* AO
* Main PA
## Footnote
The bulbus cordis is a significant part of the heart's development.
37
What does the left 4th arch develop into?
Definitive AO arch
## Footnote
The aortic arch system is essential for proper circulation.
38
What does the distal left 6th arch become?
DA
## Footnote
The distal left sixth aortic arch contributes to the development of the ductus arteriosus.
39
What additional structures are formed from the aortic arches?
* Proximal portions of RPA & LPA
* Innominate artery
* Right subclavian artery
* Common carotid arteries
## Footnote
These structures are vital for systemic and pulmonary circulation.
40
True or False: Some aortic arches disappear by birth.
True
## Footnote
During development, not all aortic arches persist into birth.
41
Week 4
42
What happens to the bilateral heart tubes by week 4 of embryonic development?
They completely fuse to form a single tube
## Footnote
This marks a significant step in heart development.
43
What is one of the first systems to function in the embryo?
The heart
## Footnote
The heart begins to beat early in development.
44
What shape does the heart tube take as it grows?
S-shaped loop
## Footnote
This folding is typically to the right, known as d-looping.
45
What is formed during the heart's development after the s-shaped loop?
Bulboventricular loop
## Footnote
This structure will later find its correct anatomical position within the chest.
46
What two major structures does the truncus arteriosus give rise to?
Ascending aorta and pulmonary trunk
## Footnote
These are critical for circulation.
47
What does the bulbus cordis represent in the developing heart?
Left ventricular outflow tract (LVOT) and right ventricular outflow tract (RVOT)
## Footnote
This area contributes to the formation of the ventricles.
48
What does the primitive ventricle develop into?
Trabeculated right and left ventricles
## Footnote
Trabeculation is important for efficient contraction.
49
What does the sinus venosus become in the mature heart?
Posterior portion of the right atrium and coronary sinus
## Footnote
This structure plays a role in venous return.
50
What are endocardial cushions responsible for?
Forming the valves of the heart
## Footnote
They play a crucial role in separating the heart chambers.
51
What is a primary birth defect associated with abnormal heart tube rotation?
L-Loop instead of D-Loop
## Footnote
This defect occurs when the heart tube rotates in the wrong direction.
52
What structure appears from the wall of the primitive atrium during heart development?
Septum primum
## Footnote
This structure is essential for the formation of atrial septation.
53
What remains after the septum primum grows?
Ostium primum
## Footnote
This is an important feature for blood flow during early development.
54
How do the sinus venosus and primitive atrium communicate?
Via the sinoatrial orifice
## Footnote
This communication is vital for proper heart function.
55
What occurs as the endocardial cushions grow within the atrioventricular canal?
Separation into left and right sided orifices
## Footnote
This leads to the formation of the mitral valve (MV) and tricuspid valve (TV).
56
What appears as a small ridge on the floor of the primitive ventricle?
Ventricular septum
## Footnote
This structure is crucial for separating the ventricles.
57
What is the truncus arteriosus in the context of heart development?
A common arterial trunk that eventually separates into aorta and pulmonary artery
## Footnote
Its proper development is critical for normal circulation.
58
What happens during week 5 of embryonic development in terms of septum primum?
Septum primum reaches endocardial cushions and closes ostium primum
## Footnote
This marks a critical step in the formation of the atrial septum.
59
What develops within the septum primum after it reaches the endocardial cushions?
Perforations develop within septum primum, leading to ostium secundum
## Footnote
This allows blood flow between the atria.
60
Week 5
61
What is the role of septum secundum during week 5?
Septum secundum develops
## Footnote
It is crucial for the separation of the right and left atria.
62
Where does the sinoatrial orifice communicate after it has shifted?
Sinoatrial orifice communicates with right atrium
## Footnote
This is important for normal heart rhythm.
63
What are the components that flank the sinoatrial orifice?
Right and left venous valves
## Footnote
They help guide blood flow into the right atrium.
64
What happens to the left venous valve during the growth of the septum secundum?
Left venous valve and septum spurium fuse with septum secundum
## Footnote
This is part of the structural development of the heart.
65
What is the primitive atrium?
The primitive atrium is one chamber
## Footnote
It is the original structure before further differentiation.
66
What is the foramen primum?
The opening that remains during the growth of septum primum
## Footnote
It is eventually closed as the heart develops.
67
What results from the resorption of septum primum tissue?
The foramen secundum is formed
## Footnote
This allows for continued fetal blood flow.
68
What is the consequence of errors in the formation of the atrial septum?
Results in PFO/ASD
## Footnote
These conditions can lead to various clinical implications.
69
Name the types of Atrial Septal Defects (ASDs).
* Superior vena cava ASD
* Secundum ASD
* Primum ASD
* IVC ASD
* Coronary sinus ASD
## Footnote
Each type is based on its location within the atrial septum.
70
What is noted about the most common types of ASD?
The most common are PFO or secundum ASD
## Footnote
These are frequently encountered in clinical practice.
71
What forms the newly developed bulboventricular loop?
RV and LV originate as trabecular expansions
## Footnote
This is a significant step in ventricular development.
72
How are the ventricles separated externally?
By the interventricular sulcus
## Footnote
This structure is important for heart anatomy.
73
What structure separates the ventricles internally?
Bulboventricular flange
## Footnote
It plays a key role in chamber formation.
74
What is the role of trabecular expansion from the bulbus cordis?
It contributes to the apical portion of the RV
## Footnote
This is essential for proper ventricular function.
75
What does the conus portion of the bulbus cordis develop into?
Right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT)
## Footnote
These are critical for directing blood flow.
76
What does the trabecular expansion from the primitive ventricle form?
Apical portion of the LV
## Footnote
This is part of the overall ventricular architecture.
77
When does the trabecular interventricular septum (IVS) form?
As ventricles grow until late in the 7th week
## Footnote
Growth stops once ventricular walls are no longer expanding.
78
How does the primitive atrium communicate with the LV?
Via the atrioventricular canal and primitive ventricle
## Footnote
This is a temporary arrangement before full separation occurs.
79
What shifts to the right to allow communication with the RV?
Atrioventricular canal
## Footnote
This is a critical adjustment in heart development.
80
What are the two routes for LV to communicate with RV before full separation?
* Primary interventricular foramen
* Secondary interventricular foramen
## Footnote
These routes facilitate blood flow during development.
81
What characterizes the membranous portion of the IVS?
It is thinner and more prone to malformations
## Footnote
This area is often involved in ventricular septal defects (VSDs).
82
What is the structure of the inlet IVS?
Located at the level of the atrioventricular canal
## Footnote
It plays a role in the separation of the ventricles.
83
What are the three components of the IVS?
* Muscular toward apex
* Inlet
* Infundibular (outlet)
## Footnote
Each component has a specific role in ventricular function.
84
What is the significance of the muscular portion of the IVS?
It is a proliferation of cells from the apex toward the endocardial cushion
## Footnote
This is essential for the structural integrity of the heart.
85
Where can VSDs occur along the IVS?
VSDs can be anywhere along the IVS
## Footnote
There can be multiple defects present.
86
Week 6
87
What happens to the septum secundum in week 6 of embryology?
Septum secundum ceases to grow and forms the foramen ovale (FO)
## Footnote
The foramen ovale is an opening in the septum between the right and left atria.
88
What occurs with the endocardial cushions during week 6?
Superior and inferior endocardial cushions fuse
## Footnote
This fusion is crucial for the formation of the heart's atrioventricular septum.
89
What is formed during week 6 in relation to the heart valves?
Atrioventricular valve cusps form
## Footnote
These cusps are essential for the proper functioning of the heart valves.
90
How does the right atrium communicate with the right ventricle during week 6?
Right atrium communicates with right ventricle
## Footnote
This communication is facilitated by the development of the tricuspid valve.
91
How does the left atrium communicate with the left ventricle during week 6?
Left atrium communicates with left ventricle
## Footnote
This communication is facilitated by the development of the mitral valve.
92
Week 7
93
What acts as a flap at the foramen ovale (FO) and controls blood flow between atria?
Remnant of septum primum
## Footnote
The septum primum is a structure in the heart that plays a crucial role in fetal circulation.
94
What happens at birth that forces the septum primum against the septum secundum?
Increase in left atrial pressure (LAP)
## Footnote
This pressure change is crucial for the closure of the foramen ovale.
95
What do the septum primum and septum secundum together form?
Interatrial septum (IAS)
## Footnote
The IAS separates the left and right atria in the heart.
96
What structure is formed during the final step of ventricular septation?
Membranous septum
## Footnote
This septum separates the left and right ventricles completely.
97
What develops within the truncus arteriosus to divide the lumen into two separate arteries?
Bulbar ridges
## Footnote
These ridges grow toward each other and fuse in the middle.
98
What is the outcome of the spiral growth in the truncus arteriosus?
Alignment of the pulmonary artery (PA) and aorta (Ao) with the appropriate ventricle
## Footnote
This alignment is essential for proper heart function postnatally.
99
By the end of which week is major fetal heart development complete?
7th week
## Footnote
This marks the completion of the basic structure of the fetal heart.
100
What condition is caused by septation defects in the truncus arteriosus?
Persistent truncus arteriosus
## Footnote
This condition involves a failure to separate the aorta and pulmonary artery.
101
What malformation is associated with the disruption of septation and spiraling in the aorticopulmonary area?
Tetralogy of Fallot
## Footnote
This is a congenital heart defect that affects normal blood flow through the heart.
102
What is the result of spiraling defects in the great vessels?
D-transposition of the great vessels
## Footnote
This condition involves the aorta and pulmonary artery being switched.
103
What week is this?
Week 3
104
What week is this?
Week 5
105
What week is this?
Week 4
106
What week is this?
Week 7
107
What week is this?
Week 4
108
What week is this?
Week 5
109
What week is this?
Week 7
110
What week is this?
Prior to Week 3
111
What week is this?
Week 5
112
Fetal Circulation
113
What is the primary function of the placenta in fetal circulation?
Delivers O2 & nutrients and removes waste products
## Footnote
The placenta plays a crucial role in maintaining the fetus's needs by facilitating the exchange of gases and nutrients.
114
In fetal circulation, which side has a higher pressure?
Right side
## Footnote
The pressure difference between the right and left sides of the heart is significant in fetal circulation.
115
What physiological condition forces blood to bypass the lungs in fetal circulation?
Increased pulmonary resistance
## Footnote
This increased resistance is due to the non-functioning lungs in the fetus.
116
What are the names of the two shunts necessary in fetal circulation?
Foramen Ovale (FO) and Ductus Arteriosus (DA)
## Footnote
These shunts allow blood to bypass the lungs and direct it towards the systemic circulation.
117
Describe the fetal circulatory pattern.
Mixes O2 enriched & O2 depleted blood; begins & ends at placenta
## Footnote
This mixing occurs as the fetus receives oxygen and nutrients while simultaneously expelling waste.
118
How do the fetus and mother exchange gases and nutrients?
Through the placenta without their blood mixing
## Footnote
Exchange occurs via a network of capillaries, maintaining separate blood supplies.
119
What vessel carries O2 enriched blood from the placenta to the fetus?
Single umbilical vein
## Footnote
This vessel is essential for transporting oxygen and nutrients to the developing fetus.
120
What composition do all other fetal vessels carry?
Mixed blood composed of O2 enriched blood mixed with O2 depleted blood
## Footnote
This mixture is a result of the fetal circulatory system's structure and function.
121
What is the pathway of enriched blood from the placenta?
Placenta enriched blood → umbilical vein → portal system
## Footnote
This describes the initial transport of enriched blood from the placenta to the fetal circulation.
122
What happens to a small amount of enriched blood in the portal system?
It mixes with the liver’s depleted blood
## Footnote
This occurs as part of the fetal circulation process, where some blood is processed by the liver.
123
How does the majority of enriched blood reach the inferior vena cava (IVC)?
Majority of enriched blood → ductus venosus → IVC
## Footnote
The ductus venosus allows the majority of enriched blood to bypass the liver and flow directly into the IVC.
124
What is the composition of blood in the IVC?
Depleted blood in IVC mixes with enriched blood from ductus venosus
## Footnote
This mixing is crucial for the distribution of oxygenated blood in fetal circulation.
125
What is the route of enriched blood from the IVC to the right atrium (RA)?
IVC enriched blood → EV → RA
## Footnote
The inferior vena cava (IVC) carries enriched blood to the right atrium.
126
What occurs in the right atrium (RA) regarding blood mixing?
Small amount of enriched blood in RA mixes with depleted blood from SVC
## Footnote
This mixing occurs before blood moves to the right ventricle (RV).
127
What is the pathway of blood from the right atrium to the left atrium (LA)?
Majority of blood in RA → FO → LA
## Footnote
The foramen ovale (FO) allows blood to flow from the right atrium to the left atrium.
128
What happens to enriched blood in the left atrium (LA)?
Enriched blood in LA mixes with a small amount of blood returning from lungs
## Footnote
This is part of the fetal circulation where oxygenated blood is prepared for systemic circulation.
129
What is the final destination of enriched blood from the left ventricle (LV)?
Enriched blood enters AO (aorta)
## Footnote
The aorta distributes oxygen-rich blood to the brain and upper body.
130
Fill in the blank: The pathway of enriched blood is placenta enriched blood → umbilical vein → _______.
portal system
## Footnote
This is the first step in the fetal circulation process.
131
True or False: The ductus venosus allows most of the enriched blood to be processed by the liver.
False
## Footnote
The ductus venosus bypasses the liver for the majority of the enriched blood.
132
What is the pathway of depleted blood in fetal circulation?
Depleted blood travels from SVC to RA
133
In the right atrium (RA), how does depleted blood mix?
Depleted blood from SVC mixes with a small amount of enriched blood from IVC
134
What is the next step after the right atrium (RA) in fetal circulation?
Blood flows to the right ventricle (RV) and then to the pulmonary artery (PA)
135
What happens to a small amount of blood in the pulmonary artery (PA)?
It goes to the lungs and returns to the left atrium (LA) via pulmonary veins (PV)
136
What is the fate of the majority of blood in the pulmonary artery (PA)?
It goes to the ductus arteriosus (DA) and then to the aorta (AO)
137
How does depleted blood mix in the aorta (AO)?
Depleted blood from the DA mixes with enriched blood from the proximal AO
138
What arteries are supplied by the abdominal aorta after mixing?
Abdominal aorta, common iliac arteries, internal iliac arteries
139
What do the internal iliac arteries give rise to?
They give rise to 2 umbilical arteries
140
Where do the umbilical arteries carry blood to?
They carry blood to the placenta
141
What happens to O2 and CO2 levels when placental blood flow is interrupted?
O2 level decreases and CO2 level increases
142
What occurs during the newborn's first breath?
Lungs fill with air instead of fluid and body experiences higher levels of O2
143
What effect does increased pulmonary blood flow have on the left atrium?
Increases blood returning to LA and LAP increases
144
What anatomical structure closes due to increased left atrial pressure?
Foramen ovale (FO)
145
How quickly does the ductus arteriosus (DA) close after birth?
Almost immediately after birth
146
What causes the ductus arteriosus to close?
Muscular contraction (ligamentum arteriosum)
147
What happens to the umbilical arteries shortly after birth?
They close due to smooth muscle contraction
148
What is the timeline for the complete obliteration of the umbilical arteries?
2-3 months
149
What follows the closure of the umbilical arteries?
Closure of the umbilical vein and ductus venosus (ligamentum venosum)
150
What is the purpose of the delay in the closure of the umbilical vein and ductus venosus?
Allows time for any remaining blood in placenta to reach newborn before umbilical cord is cut
151
EKG Ch. 1
152
Where is the heart located?
Lies in the mediastinum between the lungs, about two thirds to the left of the midline of the sternum
153
What is the size of an adult heart compared to?
Roughly the size of the owner's fist
154
What are the surfaces of the heart?
* Anterior surface
* Inferior surface (diaphragmatic)
* Base
* Apex
155
What is the innermost layer of the heart called?
Endocardium
156
What are the three layers of the heart wall?
* Epicardium
* Myocardium
* Endocardium
157
What are the four chambers of the heart?
* Right atrium
* Left atrium
* Right ventricle
* Left ventricle
158
What is the function of the heart skeleton?
Provides secure attachments for heart valves and myocardium
159
What are the two types of heart valves?
* Atrioventricular (AV) valves
* Semilunar (SL) valves
160
What are the names of the atrioventricular valves?
* Tricuspid valve
* Mitral (bicuspid) valve
161
What is the function of the semilunar valves?
Prevent backflow of blood from the aorta and pulmonary arteries into the ventricles
162
What does acute coronary syndrome refer to?
Conditions caused by abruptly reduced coronary artery blood flow
163
What are the primary branches of the right coronary artery (RCA)?
* Right atrium
* Right ventricle
* Inferior surface of the left ventricle
* Posterior surface of the left ventricle
* Sinoatrial (SA) node
* AV bundle
164
What does the left main coronary artery supply?
* Left anterior descending artery (LAD)
* Circumflex artery (Cx)
165
What is angina pectoris?
Chest discomfort caused by myocardial ischemia
166
What neurotransmitters are involved in sympathetic stimulation?
* Norepinephrine
* Epinephrine
167
What is the primary neurotransmitter in parasympathetic stimulation?
Acetylcholine
168
What do baroreceptors detect?
Changes in blood pressure
169
What is a positive chronotropic effect?
An increase in heart rate
170
What is systole?
Period during which the chamber is contracting and blood is being ejected
171
What is diastole?
Period of relaxation during which the chamber is filling
172
What does ejection fraction measure?
Percentage of blood pumped out of a ventricle with each contraction
173
What factors determine cardiac output?
* Heart rate (HR)
* Myocardial contractility
* Preload
* Afterload
* Stroke volume
174
Fill in the blank: Preload is the force exerted by the walls of the ventricles at the end of _______.
diastole
175
What are the signs and symptoms of decreased cardiac output?
* Acute drop in blood pressure
* Acute changes in mental status
* Cold, clammy skin
* Color changes in the skin and mucous membranes
* Crackles (rales)
* Dyspnea
* Dysrhythmias
* Fatigue
* Orthopnea
* Restlessness
176
What is the heart classified as?
Hollow muscular organ
177
Where does the heart lie in the body?
In the space between the lungs (mediastinum) in the chest
178
Approximately how much of the heart lies to the left of the midline of the sternum?
About two thirds
179
What anatomical structures are located behind the heart?
Sternum and diaphragm
180
Between which ribs does the heart primarily lie?
Between the second through the sixth ribs
181
Fill in the blank: The heart sits behind the _______.
[sternum]
182
True or False: The entire heart lies to the left of the midline of the sternum.
False
183
What is the remaining third of the heart's location in relation to the sternum?
Lies to the right of the sternum
184
What is the approximate size of an adult heart?
About the size of the owner's fist
185
What factors influence heart size and weight?
* Age
* Body weight and build
* Physical exercise frequency
* Heart disease
186
What percentage of a man's body weight is the heart?
About 0.45%
187
What percentage of a woman's body weight is the heart?
About 0.40%
188
True or False: Heart size and weight are the same for all individuals.
False
189
Fill in the blank: The heart’s weight is about _______ of a man’s body weight.
0.45%
190
Fill in the blank: The heart’s weight is about _______ of a woman’s body weight.
0.40%
191
Which factor does NOT influence heart size and weight?
Height
192
What lies behind the sternum and costal cartilages?
Anterior surface of the heart
## Footnote
The anterior surface is mostly formed by the right atrium and right ventricle.
193
Which area of the heart lies most directly behind the sternum?
Right ventricle
## Footnote
The right ventricle is positioned due to the heart's slight tilt toward the left.
194
What is the inferior surface of the heart also called?
Diaphragmatic surface
## Footnote
This surface is primarily made up of the left ventricle.
195
What forms most of the heart's inferior surface?
Left ventricle
## Footnote
The inferior surface includes the right and left ventricles and a small portion of the right atrium.
196
What separates the right and left ventricles on the inferior surface?
Groove containing the posterior interventricular vessels
## Footnote
This groove helps to delineate the two ventricles.
197
What does the base of the heart consist of?
Left atrium, small portion of the right atrium, proximal portions of the superior and inferior venae cavae, and pulmonary veins
## Footnote
The base is the upper portion of the heart.
198
What forms the apex of the heart?
Tip of the left ventricle
## Footnote
The apex is the lower portion of the heart.
199
At what anatomical level is the apex of the heart positioned?
Level of the left fifth intercostal space at the midclavicular line
## Footnote
This positioning is important for clinical examinations.
200
Fill in the blank: The anterior surfaces of the right and left ventricles are separated by the _______.
Left anterior descending artery
## Footnote
This artery plays a crucial role in supplying blood to the heart muscle.
201
What is the pericardium?
A double-walled sac that encloses the heart and helps protect it from trauma and infection
202
What are the two layers of the pericardium?
Fibrous parietal pericardium and serous pericardium
203
What is the tough outer layer of the pericardium called?
Fibrous parietal pericardium
204
What does the parietal pericardium do?
Forms the outer layer of the pericardial sac
205
What is the visceral pericardium also known as?
Epicardium
206
What is contained within the pericardial space?
Serous fluid
207
What is the typical volume of serous fluid in the pericardial space?
About 20 mL
208
What is the function of the serous fluid in the pericardial space?
Acts as a lubricant, preventing friction as the heart beats
209
What structures does the fibrous parietal pericardium anchor the heart to?
Sternum and diaphragm
210
Fill in the blank: The inner layer of the pericardium consists of _______ layers.
Two
211
True or False: The visceral pericardium attaches directly to the heart's surface.
True
212
What separates the visceral and parietal layers of the serous pericardium?
Pericardial space
213
What color and consistency is the serous fluid in the pericardial space?
Pale yellow and transparent
214
What prevents excessive movement of the heart in the chest?
Anchoring by ligaments from the fibrous parietal pericardium
215
What is the innermost layer of the heart wall called?
Endocardium
## Footnote
The endocardium lines the heart’s inner chambers and is continuous with the innermost layer of vessels.
216
What are the three tissue layers of the heart wall?
* Endocardium
* Myocardium
* Epicardium
## Footnote
These layers work together to form the heart's structure and function.
217
What is the primary function of the myocardium?
Responsible for pumping action
## Footnote
The myocardium consists of cardiac muscle fibers that enable the heart to pump blood.
218
What percentage of the total left ventricular mass does the myocardium make up?
About 30%
## Footnote
This indicates the significant volume of muscle tissue involved in heart function.
219
What separates the muscle fibers in the myocardium?
Connective tissues
## Footnote
These connective tissues contain a rich supply of capillaries and nerve fibers.
220
What is the outermost layer of the heart called?
Epicardium
## Footnote
The epicardium contains blood capillaries, lymph capillaries, nerve fibers, and fat.
221
What structures are found on the epicardial surface of the heart?
Main coronary arteries
## Footnote
These arteries supply the heart's inner layers with oxygenated blood.
222
Fill in the blank: The innermost half of the myocardium is called the _______.
Subendocardial area
## Footnote
This area is crucial for the heart's function and is part of the myocardium.
223
Fill in the blank: The outermost half of the myocardium is called the _______.
Subepicardial area
## Footnote
This area is also part of the myocardium and plays a role in heart function.
224
What is ischemia?
Decreased supply of oxygenated blood
## Footnote
Ischemia can affect parts of the body, including the heart, leading to serious conditions.
225
Which area of the heart is at the greatest risk of ischemia?
Subendocardial area
## Footnote
This area has a high oxygen demand and is fed by the coronary arteries’ most distal branches.
226
What type of muscle fibers form the walls of the heart?
Cardiac muscle fibers
## Footnote
Cardiac muscle fibers are unique and differ from other muscle types.
227
What structures are responsible for the contraction of cardiac muscle fibers?
Myofibrils
## Footnote
Myofibrils are packed closely together within muscle fibers.
228
What protein molecules are involved in producing muscle contractions?
* Myosin
* Actin
## Footnote
These proteins interact to facilitate muscle contraction.
229
What are intercalated disks?
Junctions that connect adjacent cardiac muscle fibers
## Footnote
They allow for coordinated contraction of the heart.
230
What function do gap junctions serve in cardiac muscle?
Allow electrical impulses to move rapidly between fibers
## Footnote
Gap junctions are essential for synchronized heart contractions.
231
What is the composition of cardiac muscle fibers?
* Mitochondria
* Myofibrils
* Sarcomeres
* Myofilaments
## Footnote
These components work together to enable contraction and energy production.
232
What inhibits myosin-actin interactions in cardiac muscle?
* Tropomyosin
* Troponin
## Footnote
These proteins play a regulatory role in muscle contraction.
233
What happens to cardiac muscle fibers when one fiber is stimulated?
All fibers become stimulated
## Footnote
This phenomenon is due to the syncytium function of cardiac muscle.
234
Fill in the blank: Cardiac muscle fibers are typically _______.
branched
## Footnote
This branching allows for the unique connectivity of cardiac muscle.
235
True or False: Cardiac muscle fibers can function independently of each other.
False
## Footnote
Cardiac muscle fibers function as a syncytium, requiring coordination.
236
What are the energy-producing parts of cardiac muscle cells?
Mitochondria
## Footnote
Mitochondria are crucial for ATP production in muscle cells.
237
How many chambers does the heart have?
Four chambers
## Footnote
The heart consists of two atria and two ventricles.
238
What are the two upper chambers of the heart called?
Right and left atria
## Footnote
The singular term for atria is atrium.
239
What are the two lower chambers of the heart called?
Right and left ventricles
240
What is the function of the atria?
To receive blood
241
What does the right atrium receive blood from?
Superior vena cava, inferior vena cava, coronary sinus
## Footnote
The superior vena cava carries blood from the head and upper extremities, while the inferior vena cava carries blood from the lower body.
242
What does the left atrium receive blood from?
Lungs via right and left pulmonary veins
243
Why do the atria have thin walls?
They encounter little resistance when pumping blood to the ventricles
244
What is the function of the right ventricle?
Pumps blood through the blood vessels of the lungs
245
What is the function of the left ventricle?
Pumps blood out to the body
246
Why do the ventricles have a thicker myocardial layer than the atria?
They must pump blood either to the lungs or to the rest of the body
247
What is an auricle in relation to the heart?
An earlike flap that protrudes from each atrium
248
Fill in the blank: The heart has two upper chambers called the right and left _______.
atria
249
True or False: The left atrium receives deoxygenated blood.
False
## Footnote
The left atrium receives freshly oxygenated blood from the lungs.
250
What is the primary function of the heart skeleton?
Provides secure attachments for heart valves
## Footnote
The skeleton of the heart encircles all four valves and supports their rims.
251
What does the heart skeleton provide for the myocardium?
Attachment
## Footnote
The outside of the rings of the heart skeleton provides for the attachment of the myocardium.
252
What structures do the partitions (septa) in the heart separate?
Atria from the ventricles
## Footnote
The heart skeleton helps form the partitions that separate these chambers.
253
How many rings of thick connective tissue make up the heart skeleton?
Four
## Footnote
These rings surround the bases of the pulmonary trunk, the aorta, and the heart valves.
254
The inside of the rings of the heart skeleton provides secure attachments for what?
Heart valves
## Footnote
This secure attachment is crucial for the proper function of the heart valves.
255
Fill in the blank: The skeleton of the heart encircles all four _______.
Valves
## Footnote
Each valve's rim is supported by the fibrous structure of the heart skeleton.
256
True or False: The heart skeleton is made of muscle tissue.
False
## Footnote
The heart skeleton is composed of thick connective tissue, not muscle tissue.
257
How many valves are in the heart?
Four valves
258
What are the two types of atrioventricular (AV) valves in the heart?
Tricuspid valve, Mitral valve
259
What are the two types of semilunar (SL) valves in the heart?
Pulmonary valve, Aortic valve
260
What is the primary function of the heart valves?
Ensure blood flows in one direction through heart chambers
261
What do heart valves prevent?
Backflow of blood
262
True or False: The valves in the heart open and close randomly.
False
263
Fill in the blank: The heart valves assist in producing the _______ needed between the chambers.
Pressure gradient
264
What is the significance of the sequence in which the heart valves open and close?
It ensures a smooth flow of blood through the heart
265
List the two sets of valves in the heart.
* Atrioventricular (AV) valves
* Semilunar (SL) valves
266
What do Atrioventricular (AV) valves separate?
Atria from ventricles
267
What is the name of the AV valve that lies between the right atrium and the right ventricle?
Tricuspid valve
268
How many leaflets does the tricuspid valve have?
Three
269
What are chordae tendineae?
Thin strands of connective tissue
270
Where are chordae tendineae attached?
To the underside of the AV valves and to papillary muscles
271
What are papillary muscles?
Small mounds of myocardium projecting inward from the ventricular walls
272
What role do papillary muscles play in heart function?
They adjust tension on the chordae tendineae to prevent bulging into the atria
273
What is another name for the mitral valve?
Bicuspid valve
274
How many cusps does the mitral valve have?
Two
275
What is the function of the AV valves?
To open when a forward pressure gradient forces blood and to close when a backward pressure gradient occurs
276
What percentage of blood flows directly through the atria into the ventricles before atrial contraction?
80%
277
What is the term for the additional blood contributed by atrial contraction?
Atrial kick
278
What happens to the tricuspid and mitral valves during ventricular contraction?
They completely close when the pressure within the ventricles exceeds that of the atria
279
Fill in the blank: The mitral valve is named for its resemblance to a _______.
Miter
280
True or False: The AV valves require a significant amount of backflow to cause closure.
False
281
What happens to the pressure within the atrial chamber as it fills with blood?
It rises
282
What type of blood empties from the right atrium into the right ventricle?
Blood low in oxygen
283
What type of blood empties from the left atrium into the left ventricle?
Freshly oxygenated blood
284
What do the semilunar valves prevent?
Backflow of blood from the aorta and pulmonary arteries into the ventricles
285
Name the two types of semilunar valves.
* Pulmonic valve
* Aortic valve
286
What shape do the cusps of semilunar valves resemble?
Half moons
287
How many cusps do semilunar valves have?
Three
288
How do the openings of semilunar valves compare to atrioventricular (AV) valves?
Smaller
289
What is a key structural difference between semilunar valves and AV valves?
SL valves are not attached to chordae tendineae
290
When do the semilunar valves open?
When the ventricles contract
291
What type of blood flows through the pulmonic valve?
Blood low in oxygen
292
What happens to blood flow when the left ventricle contracts?
Freshly oxygenated blood flows through the aortic valve into the aorta
293
What triggers the closure of the semilunar valves?
Pressure in the pulmonary artery and aorta exceeds that of the ventricles
294
What causes heart sounds?
Vibrations in the heart’s tissues caused by the closing of the heart’s valves
295
What is the first heart sound known as?
S1
296
What reflects the start of ventricular contraction?
Closure of the tricuspid and mitral (AV) valves
297
Where is S1 heard loudest?
At the apex of the heart
298
What is the second heart sound known as?
S2
299
What reflects the start of ventricular relaxation?
Closure of the pulmonic and aortic (SL) valves
300
Where is S2 heard loudest?
At the base of the heart
301
What is a third heart sound called?
S3
302
What produces S3?
Ventricular filling
303
Is S3 considered normal in children and healthy young adults?
Yes
304
What is S3 generally associated with in individuals older than 40?
Heart failure
305
What is an S1–S2–S3 sequence called?
Ventricular gallop or gallop rhythm
306
How does the S1–S2–S3 sequence sound like?
Kentucky—Ken (S1)—tuck (S2)—y (S3)
307
What does coronary circulation consist of?
Coronary arteries and veins
308
What does the right coronary artery supply?
Right atrium, ventricle, and posterior aspect of the left ventricle
309
What are the branches of the left coronary artery?
Left anterior descending and circumflex arteries
310
What is the function of the coronary arteries?
Supplying blood to the heart
311
How do the coronary arteries encircle the myocardium?
Like a crown, or corona
312
Where do the main coronary arteries lie?
On the outer (epicardial) surface of the heart
313
What are epicardial coronary arteries?
Coronary arteries that run on the surface of the heart
314
What do coronary arteries branch into?
Progressively smaller vessels, arterioles, and then capillaries
315
What supplies the subendocardium with blood?
Branches of the main coronary arteries
316
What are 'feeder branches' in coronary circulation?
Branches that penetrate the heart's muscle mass
317
What characterizes the diameter of feeder branches?
Much narrower than main coronary arteries
318
What ensures the heart has an adequate blood supply?
Providing itself with a fresh supply of oxygenated blood
319
What are the two main vessels supplying oxygenated blood to the heart?
Right and left coronary arteries
320
True or False: The epicardium has a rich blood supply.
True
321
Fill in the blank: The coronary arteries are essential for supplying _______ to the heart.
blood
322
What are the first branches off the base of the aorta?
The right and left coronary arteries
## Footnote
These arteries are crucial for supplying blood to the heart muscle.
323
Where do the openings of the coronary arteries lie?
Just beyond the cusps of the aortic SL valve
## Footnote
This positioning is critical for effective blood flow during the cardiac cycle.
324
What happens to the coronary arteries during left ventricle contraction?
They are compressed, reducing blood flow to the tissues of the heart
## Footnote
This compression occurs during ventricular systole.
325
When do the coronary arteries fill with blood?
When the aortic valve is closed and the left ventricle is relaxed (diastole)
## Footnote
This phase allows for adequate perfusion of the heart muscle.
326
Name the three major epicardial coronary arteries.
The left anterior descending (LAD) artery, circumflex (Cx) artery, and right coronary artery (RCA)
## Footnote
Each of these arteries has specific areas of the heart that they supply.
327
What is the Right Coronary Artery (RCA)?
A major artery that supplies blood to the heart
328
Which structures are supplied by a branch of the RCA?
* Right atrium
* Right ventricle
* Inferior surface of the left ventricle in about 85% of individuals
* Posterior surface of the left ventricle in 85%
* Sinoatrial (SA) node in about 60%
* AV bundle in 85% to 90%
329
From where does the RCA originate?
The right side of the aorta
330
How does the RCA travel in relation to the heart?
Along the groove between the right atrium and the right ventricle
331
True or False: The RCA supplies the sinoatrial (SA) node in about 60% of individuals.
True
332
Fill in the blank: The RCA supplies the _______ surface of the left ventricle in about 85% of individuals.
inferior
333
What percentage of individuals does the RCA supply the posterior surface of the left ventricle?
85%
334
What percentage of individuals does the RCA supply the AV bundle?
85% to 90%
335
What is the first segment of the Left Coronary Artery (LCA) called?
The left main coronary artery
336
What does the Left Coronary Artery (LCA) supply?
Oxygenated blood
337
What are the two primary branches of the Left Coronary Artery (LCA)?
* Left anterior descending (LAD)
* Circumflex (Cx)
338
What is another name for the left anterior descending artery?
Anterior interventricular artery
339
Where does the Left Coronary Artery (LCA) originate?
From the aorta’s left side
340
What is the approximate diameter of the left main coronary artery?
About the diameter of a soda straw
341
How long is the left main coronary artery?
Less than 1 inch (2.5 cm) long
342
True or False: The left main coronary artery is larger than its primary branches.
True
343
Where does the Left Anterior Descending Artery (LAD) lie?
On the outer (i.e., epicardial) surface on the front of the heart
344
What is the significance of occlusion of the proximal LAD coronary artery?
Referred to as the 'widow maker' due to its association with sudden cardiac arrest when blocked
345
Along which groove does the LAD travel?
The anterior interventricular sulcus
346
What is the endpoint of the LAD in most patients?
Ends along the left ventricle’s inferior surface
347
In some patients, where does the LAD stop?
At or before the heart’s apex
348
What are the major branches of the LAD?
The septal and diagonal arteries
349
What areas does the LAD supply blood to? (List three)
* The anterior surface of the left ventricle
* Part of the lateral surface of the left ventricle
* The anterior two-thirds of the interventricular septum
350
What is the Circumflex Artery?
An artery that circles around the left side of the heart in a groove on the back of the heart called the coronary sulcus
## Footnote
It separates the left atrium from the left ventricle.
351
What structures does the Circumflex Artery supply blood to?
* The left atrium
* Part of the lateral surface of the left ventricle
* The inferior surface of the left ventricle in about 15% of individuals
* The posterior surface of the left ventricle in 15%
* The SA node in about 40%
* The AV bundle in 10% to 15%
## Footnote
These percentages indicate the variability in supply among different individuals.
352
The Circumflex Artery supplies blood to the SA node in what percentage of individuals?
About 40%
## Footnote
The SA node is crucial for heart rhythm regulation.
353
True or False: The Circumflex Artery supplies blood to the left atrium.
True
## Footnote
It is one of the key areas supplied by the Circumflex Artery.
354
Fill in the blank: The Circumflex Artery separates the left atrium from the left ventricle in a groove called the _______.
coronary sulcus
## Footnote
This groove is important for the positioning of the Circumflex Artery.
355
What part of the heart does the Circumflex Artery primarily circle around?
The left side of the heart
## Footnote
This positioning is crucial for its function.
356
What does acute coronary syndrome (ACS) refer to?
Distinct conditions caused by a similar sequence of pathologic events involving abruptly reduced coronary artery blood flow
## Footnote
This sequence results in conditions ranging from myocardial ischemia or injury to death of the heart muscle.
357
What is the usual cause of an acute coronary syndrome?
Rupture of an atherosclerotic plaque
358
Define arteriosclerosis.
Chronic disease of the arterial system characterized by abnormal thickening and hardening of vessel walls
359
What is atherosclerosis?
A form of arteriosclerosis characterized by thickening and hardening of vessel walls due to a buildup of fat-like deposits
360
What results from the buildup of fat-like deposits in arteries?
Decreased blood flow (ischemia)
361
What is angina pectoris?
Chest discomfort or other related symptoms caused by myocardial ischemia
362
What may result from a partial or intermittent blockage of a coronary artery?
No clinical symptoms, angina, heart attack (myocardial infarction), sudden death
363
True or False: Angina is a disease.
False
364
In which patients is angina most often observed?
Patients with coronary artery disease involving at least one coronary artery
365
What happens when myocardial ischemia or infarction is suspected?
Understanding coronary artery anatomy helps predict which coronary artery is blocked
366
What can prevent tissue death in cases of blocked coronary vessels?
Quickly restoring blood flow and oxygen to the injured area
367
What methods can restore blood flow in acute coronary syndrome?
Clot-busting drugs (fibrinolytics) or endovascular therapies
368
Fill in the blank: Angina occurs in persons with uncontrolled high blood pressure or _______.
[valvular heart disease]
369
What are the zones associated with a blocked coronary artery?
Zones of ischemia, injury, and infarction
370
What is myocardial infarction (MI)?
Heart attack
371
What are characteristic changes associated with the zones of ischemia, injury, and infarction?
Characteristic ECG changes
372
What do the coronary (cardiac) veins do?
They drain blood that has passed through the myocardial capillaries
373
Where does the coronary sinus lie?
In the groove (sulcus) that separates the atria from the ventricles
374
What is the largest vein that drains the heart?
The coronary sinus
375
Which veins drain into the coronary sinus?
* Great cardiac vein
* Middle cardiac vein
* Small cardiac vein
* A vein of the left atrium
* Left ventricle's posterior vein
376
Into which chamber does the coronary sinus drain?
The right atrium
377
True or False: The anterior cardiac veins join the coronary sinus.
False
378
Where do the anterior cardiac veins empty?
Directly into the right atrium
379
What are the primary neurotransmitters involved in sympathetic stimulation?
Norepinephrine, epinephrine
## Footnote
These neurotransmitters are crucial for the body's response during stress or emergencies.
380
What is the primary function of the sympathetic division?
To prepare the body for emergency or stressful situations
## Footnote
This preparation includes a variety of physiological changes to enhance survival.
381
What happens to the pupils during sympathetic stimulation?
Dilation of pupils
## Footnote
This allows more light to enter the eyes, improving vision in low light conditions.
382
What effect does sympathetic stimulation have on the bronchi?
Dilation of smooth muscles of bronchi
## Footnote
This improves oxygenation during stressful situations.
383
How does sympathetic stimulation affect heart rate?
Increased heart rate
## Footnote
This is part of the body's response to prepare for physical activity.
384
What is the effect of sympathetic stimulation on blood pressure?
Increased blood pressure
## Footnote
This helps ensure adequate blood flow to vital organs.
385
What happens to cardiac output during sympathetic stimulation?
Increased cardiac output
## Footnote
This is essential for meeting the body's heightened demands for oxygen and nutrients.
386
What is the effect on sweating during sympathetic stimulation?
Increased sweating
## Footnote
This helps regulate body temperature during stress.
387
What is mobilized to ensure an adequate supply of energy during sympathetic stimulation?
Stored energy such as glucose and fatty acids
## Footnote
This ensures that the brain and muscles have enough resources for heightened activity.
388
During sympathetic stimulation, where is blood shunted from?
From skin and blood vessels of internal organs
## Footnote
Blood is redirected to skeletal muscle to enhance physical performance.
389
Fill in the blank: Sympathetic stimulation results in ______ of smooth muscles of bronchi.
Dilation
## Footnote
This is crucial for improving oxygenation.
390
True or False: Sympathetic stimulation decreases heart rate.
False
## Footnote
Sympathetic stimulation increases heart rate to prepare the body for action.
391
What are the five main types of sympathetic receptors?
Alpha1, Alpha2, Beta1, Beta2, Beta3
392
Where are Alpha1 receptors located?
Eyes, blood vessels, bladder, male reproductive organs
393
What is the physiological action of stimulating Alpha1 receptors?
Constriction
394
Where are Alpha2 receptors found?
Digestive system, presynaptic nerve terminals in the peripheral nervous system
395
What happens when Alpha2 receptors are stimulated?
Decreased secretions, peristalsis, suppression of norepinephrine release
396
Where are Beta1 receptors located?
Heart, kidneys
397
What is the effect of stimulating Beta1 receptors in the heart?
Increased heart rate, contractility, irritability of cardiac cells
398
What does stimulation of Beta1 receptors in the kidneys promote?
Release of renin into the blood
399
What is the role of renin in the body?
Promotes the production of angiotensin, a potent vasoconstrictor
400
Where are Beta2 receptors found?
Bronchial smooth muscle, skeletal blood vessels, arterioles of the heart and lungs
401
What happens when Beta2 receptors are stimulated?
Dilation
402
Where are Beta3 receptors located?
Fat cells
403
What is the physiological action of stimulating Beta3 receptors?
Promotes the breakdown of fats and other lipids
404
What is the primary neurotransmitter involved in parasympathetic stimulation?
Acetylcholine
## Footnote
Acetylcholine (ACh) is released when parasympathetic nerves are stimulated.
405
What is the main effect of parasympathetic stimulation on the heart?
Slowing of heart rate
## Footnote
This effect is primarily due to the actions of acetylcholine on the heart.
406
Which nerve fibers supply the SA node, atrial muscle, and the heart’s AV bundle?
Parasympathetic (inhibitory) nerve fibers
## Footnote
These fibers are supplied by the vagus nerves.
407
What are the two main types of parasympathetic receptors?
* Nicotinic receptors
* Muscarinic receptors
## Footnote
Nicotinic receptors are located in skeletal muscle, while muscarinic receptors are found in smooth muscle.
408
What is the effect of parasympathetic stimulation on the SA node?
Slows the rate of discharge
## Footnote
This results in a decreased heart rate.
409
How does parasympathetic stimulation affect conduction through the AV node?
Slows conduction
## Footnote
This can lead to a delay in the electrical signals reaching the ventricles.
410
What effect does parasympathetic stimulation have on atrial contraction strength?
Decreases the strength of atrial contraction
## Footnote
This can affect the overall efficiency of the heart’s pumping action.
411
Fill in the blank: Atropine sulfate is used to _______ heart rate and AV conduction velocity.
increase
## Footnote
Atropine sulfate works by blocking the vagus nerve’s effects on the SA and AV nodes.
412
What is a possible effect of parasympathetic stimulation on ventricular contraction?
Can cause a small decrease in the force of ventricular contraction
## Footnote
This is generally less pronounced than effects on the atria.
413
What are baroreceptors?
Specialized nerve tissue that detects changes in blood pressure
## Footnote
Found in the internal carotid arteries and the aortic arch.
414
Where are baroreceptors located?
In the internal carotid arteries and the aortic arch
## Footnote
These are critical areas for blood pressure regulation.
415
What do baroreceptors detect?
Changes in blood pressure
## Footnote
They act as sensors for the cardiovascular system.
416
What happens when baroreceptors are stimulated?
They cause a reflex response in the sympathetic or parasympathetic divisions of the autonomic nervous system
## Footnote
This response helps regulate blood pressure.
417
What is the sympathetic response when blood pressure decreases?
Constricting peripheral blood vessels, increasing heart rate, increasing force of myocardial contraction
## Footnote
This response is known as sympathetic or adrenergic response.
418
What is the parasympathetic response when blood pressure increases?
Decrease sympathetic stimulation and increase parasympathetic response
## Footnote
This response is known as parasympathetic or cholinergic response.
419
What is the term for the adjustment of baroreceptors to a new normal blood pressure?
They adjust to a new normal after a few days of exposure
## Footnote
This reflects the body's ability to adapt to changes in blood pressure.
420
Fill in the blank: Baroreceptors are specialized nerve tissue found in the _______.
internal carotid arteries and aortic arch
421
True or False: Baroreceptors only respond to increased blood pressure.
False
## Footnote
Baroreceptors respond to both increases and decreases in blood pressure.
422
What are chemoreceptors?
Chemoreceptors are specialized cells that detect changes in the concentration of hydrogen ions (pH), oxygen, and carbon dioxide in the blood.
## Footnote
They play a crucial role in monitoring and regulating respiratory and cardiovascular functions.
423
Where are chemoreceptors located?
Chemoreceptors are located in the internal carotid arteries and the aortic arch.
## Footnote
These locations allow them to closely monitor blood composition as it is delivered to the brain and the rest of the body.
424
What changes do chemoreceptors respond to?
Chemoreceptors respond to changes in the concentration of:
* Hydrogen ions (pH)
* Oxygen
* Carbon dioxide
## Footnote
This detection is vital for maintaining homeostasis in the body.
425
What type of nervous system response can result from chemoreceptor activation?
The response can be sympathetic or parasympathetic.
## Footnote
These responses help regulate cardiovascular and respiratory functions based on the detected blood gas levels.
426
What does the term 'Chronotropic Effect' refer to?
A change in heart rate
## Footnote
The term is used in cardiology to describe how heart rate is influenced by various factors.
427
What is a positive chronotropic effect?
An increase in heart rate
## Footnote
This effect can be induced by factors such as sympathetic stimulation or certain medications.
428
What is a negative chronotropic effect?
A decrease in heart rate
## Footnote
This effect can occur due to parasympathetic stimulation or the use of specific drugs.
429
What does inotropic effect refer to?
A change in myocardial contractility
430
What is the result of a positive inotropic effect?
An increase in myocardial contractility
431
What is the result of a negative inotropic effect?
A decrease in myocardial contractility
432
vWhat does the term 'Dromotropic Effect' refer to?
A change in the speed of impulse conduction through the conduction system
433
What is the result of a positive dromotropic effect?
An increase in conduction velocity
434
What is the result of a negative dromotropic effect?
A decrease in conduction velocity
435
What does the pulmonary circulation route do?
Routes blood flow to and from the gas-exchange tissues of the lungs
## Footnote
It is responsible for oxygenating blood.
436
What does the systemic circulation route do?
Routes blood flow to and from the oxygen-consuming tissues of the body
## Footnote
It delivers oxygenated blood to organs.
437
What separates the right and left sides of the heart?
An internal wall of connective tissue called a septum
## Footnote
There are two types of septa: interatrial and interventricular.
438
What is the function of the interatrial septum?
Separates the right and left atria
## Footnote
It prevents mixing of oxygenated and deoxygenated blood.
439
What is the function of the interventricular septum?
Separates the right and left ventricles
## Footnote
It ensures that blood flows correctly through the heart.
440
How many functional pumps does the heart have?
Two functional pumps
## Footnote
The right atrium and ventricle form one pump; the left atrium and ventricle form the other.
441
What is the purpose of the right side of the heart?
Pumps unoxygenated blood from the body to the lungs
## Footnote
This process is part of pulmonary circulation.
442
What is the purpose of the left side of the heart?
Receives oxygenated blood from the lungs and pumps it to the body
## Footnote
This process is part of systemic circulation.
443
What vessels carry blood away from the heart?
Arteries, arterioles, and capillaries
## Footnote
These vessels distribute oxygenated blood to body tissues.
444
How is blood returned to the right side of the heart?
Through venules and veins
## Footnote
This process collects deoxygenated blood from the body.
445
What is the thickness of the left ventricle wall?
About 13 to 15 mm thick
## Footnote
This thickness allows it to generate high pressure to pump blood.
446
What is the thickness of the right ventricle wall?
About 3 to 5 mm thick
## Footnote
This thickness is sufficient for its lower pressure function.
447
True or False: The left ventricle is a low-pressure chamber.
False
## Footnote
The left ventricle is a high-pressure chamber.
448
Fill in the blank: The left ventricle must overcome a lot of _______ and resistance to pump blood.
Pressure
## Footnote
This is why its wall is thicker than the right ventricle.
449
What is the cardiac cycle?
A repetitive pumping process that includes all events associated with blood flow through the heart
## Footnote
The cardiac cycle consists of two phases for each heart chamber: systole and diastole.
450
Define systole.
Period during which the chamber is contracting and blood is being ejected
451
Define diastole.
Period of relaxation during which the chamber is filling
452
What happens during ventricular diastole?
The myocardium receives its fresh supply of oxygenated blood from the coronary arteries
453
What factors affect the cardiac cycle?
The cardiac muscle’s ability to contract and the condition of the heart’s conduction system
## Footnote
Abnormalities of the cardiac muscle, the valves, or the conduction system may affect the heart’s efficiency as a pump.
454
What occurs to the pressure in each chamber during the cardiac cycle?
Pressure rises in systole and falls in diastole
455
What is the role of the heart's valves?
Ensure that blood flows in the proper direction
456
How does blood flow between heart chambers?
From higher to lower pressure
457
What determines the pressure relationships during the cardiac cycle?
The careful timing of contractions
458
What provides the necessary timing of events between atrial and ventricular systole?
The heart’s conduction system
459
What occurs during atrial diastole?
Blood enters the right atrium, right atrium fills and distends, tricuspid valve opens, right ventricle fills, left atrium receives blood from pulmonary veins, mitral valve opens, blood flows into the left ventricle
## Footnote
Atrial diastole is the phase when the heart's atria fill with blood in preparation for contraction.
460
What is venous return?
The amount of blood flowing into the right heart from the systemic circulation
## Footnote
Venous return is crucial for maintaining cardiac output and ensuring the ventricles receive adequate blood volume.
461
What happens to the tricuspid valve during atrial diastole?
The tricuspid valve opens, allowing the right ventricle to fill
## Footnote
The tricuspid valve is located between the right atrium and right ventricle and opens in response to pressure changes.
462
What is the function of the mitral valve during atrial diastole?
The mitral valve opens as the left atrium fills, allowing blood to flow into the left ventricle
## Footnote
The mitral valve is crucial for preventing backflow of blood into the left atrium during ventricular contraction.
463
What is the atrial kick?
The contraction of the atria that forces additional blood into the ventricles
## Footnote
The atrial kick is important for ensuring the ventricles are completely filled with blood before they contract.
464
What percentage of ventricular filling occurs before atrial contraction?
80%
## Footnote
This indicates that most of the ventricular filling is passive, relying on blood flow from the atria.
465
What phase follows atrial systole?
Atrial diastole
## Footnote
Atrial diastole is the phase where the atria relax and fill with blood again.
466
Fill in the blank: The left atrium receives oxygenated blood from _______.
the four pulmonary veins
## Footnote
The pulmonary veins are responsible for returning oxygen-rich blood from the lungs to the heart.
467
True or False: The ventricles fill completely with blood during atrial systole.
True
## Footnote
Atrial systole ensures that the ventricles are filled to capacity before they contract.
468
What is ventricular systole?
Blood is propelled through the systemic and pulmonary circulation
## Footnote
It is the phase of the cardiac cycle when the ventricles contract.
469
What happens to the SL valves during ventricular systole?
They close
## Footnote
This closure prevents backflow of blood during ventricular contraction.
470
What occurs during ventricular diastole?
Ventricles begin to passively fill with blood
## Footnote
This phase follows the closure of the SL valves.
471
What initiates ventricular systole?
Atrial diastole begins
## Footnote
This indicates a sequence in the cardiac cycle.
472
What is the role of the tricuspid valve during right ventricular contraction?
It closes to prevent backflow of blood
## Footnote
This ensures unidirectional flow from the right ventricle to the pulmonary circulation.
473
What is the role of the mitral valve during left ventricular contraction?
It closes to prevent backflow of blood
## Footnote
This ensures that blood flows from the left ventricle into the aorta.
474
What happens to the heart after the SL valves close?
The heart begins a period of ventricular diastole
## Footnote
This marks the transition between contraction and relaxation phases.
475
What characterizes ventricular diastole?
The ventricles are relaxed and filling passively with blood
## Footnote
This phase prepares the heart for the next cycle.
476
What begins the cardiac cycle again after ventricular diastole?
Atrial systole and the completion of ventricular filling
## Footnote
This completes the cycle of heartbeats.
477
What occurs during atrial systole?
Atria contract, pushing blood through the open tricuspid and mitral valves into the ventricles. Semilunar valves are closed.
## Footnote
Atrial systole is the first phase of the cardiac cycle.
478
What happens at the beginning of ventricular systole?
Ventricles contract, increasing pressure within the ventricles. The tricuspid and mitral valves close, causing the first heart sound.
## Footnote
This phase marks the transition from atrial to ventricular contraction.
479
What is the significance of the period of rising pressure in the cardiac cycle?
Semilunar valves open when pressure in the ventricle exceeds that in the arteries. Blood spurts into the aorta and pulmonary arteries.
## Footnote
This phase allows for the ejection of blood from the heart.
480
What occurs at the beginning of ventricular diastole?
Pressure in the relaxing ventricles drops below that in the arteries. Semilunar valves snap shut, causing the second heart sound.
## Footnote
This phase indicates the end of ventricular contraction.
481
What happens during the period of falling pressure in the cardiac cycle?
Blood flows from veins into the relaxed atria. Tricuspid and mitral valves open when pressure in the ventricles falls below that in the atria.
## Footnote
This phase allows the heart to refill with blood.
482
What is blood pressure?
Force exerted by circulating blood volume on walls of arteries
483
What is the formula for calculating blood pressure?
BP = cardiac output (CO) × peripheral resistance (PR)
484
What does blood pressure reflect?
The mechanical activity of the heart
485
What is peripheral vascular resistance?
Resistance to the flow of blood determined by blood vessel diameter and tone of vascular musculature
486
What is the relationship between blood volume in arteries and arterial blood pressure?
The volume of blood in the arteries is directly related to arterial blood pressure
487
How does an increase in cardiac output (CO) affect blood pressure?
Typically results in an increase in blood pressure
488
How does an increase in peripheral resistance (PR) affect blood pressure?
Typically results in an increase in blood pressure
489
What happens to blood pressure if either cardiac output (CO) or peripheral resistance (PR) decreases?
Results in a decrease in blood pressure
490
What is meant by 'tone' in the context of vascular musculature?
The normal state of balanced tension in body tissues
491
True or False: Blood pressure is independent of peripheral resistance.
False
492
What is the relationship between arterial blood volume and blood pressure?
Arterial blood pressure is directly proportional to arterial blood volume
## Footnote
This means that as blood volume increases, blood pressure also increases.
493
How are cardiac output (CO) and peripheral resistance (PR) related to arterial blood volume?
Both CO and PR are directly proportional to arterial blood volume, but for opposite reasons
## Footnote
CO affects the blood entering the arteries, while PR affects the blood leaving the arteries.
494
What happens to arterial blood volume when cardiac output increases?
The amount of blood entering the arteries increases, which tends to increase the volume of blood in the arteries
## Footnote
This results in an increase in arterial blood pressure.
495
What effect does an increase in peripheral resistance have on arterial blood volume?
It decreases the amount of blood leaving the arteries, which tends to increase the amount of blood left in them
## Footnote
An increase in PR can also lead to an increase in arterial blood pressure.
496
If both cardiac output and peripheral resistance increase, what is the overall effect on arterial blood volume?
Both increases lead to an increase in arterial blood volume
## Footnote
This results in a subsequent increase in arterial blood pressure.
497
What is cardiac output?
Amount of blood pumped into the aorta each minute by the left ventricle
## Footnote
Cardiac output is an important measure of heart function and circulatory health.
498
What are the factors that determine cardiac output?
* HR (Heart Rate)
* Myocardial contractility
* Preload
* Afterload
## Footnote
These factors interact to influence the efficiency and effectiveness of the heart's pumping action.
499
What is stroke volume?
Amount of blood ejected from the left ventricle with each heartbeat
## Footnote
Stroke volume is a critical component of cardiac output.
500
How is cardiac output calculated?
Cardiac output (CO) is defined as stroke volume (SV) multiplied by heart rate (HR)
## Footnote
This formula emphasizes the relationship between the volume of blood pumped per heartbeat and the frequency of those heartbeats.
501
What is the definition of Ejection Fraction?
The percentage of blood pumped out of a ventricle with each contraction
## Footnote
Ejection fraction is a key indicator of heart function.
502
What is Ejection Fraction used to measure?
Ventricular function
## Footnote
It helps assess how well the heart is pumping.
503
What is considered a normal range for Ejection Fraction?
Between 50% and 65%
## Footnote
Values outside this range may indicate health issues.
504
What constitutes impaired ventricular function in terms of Ejection Fraction?
Ejection fraction is less than 40%
## Footnote
This indicates significant heart dysfunction.
505
What is stroke volume?
The amount of blood pumped by the heart in one contraction.
## Footnote
Stroke volume is a key indicator of cardiac function.
506
What determines stroke volume?
Stroke volume is determined by:
* The degree of ventricular filling when the heart is relaxed (preload)
* The pressure against which the ventricle must pump (afterload)
* The myocardium’s contractile state (contracting or relaxing)
## Footnote
These factors collectively influence the efficiency of the heart's pumping action.
507
Fill in the blank: Stroke volume is determined by the degree of ventricular filling when the heart is relaxed (_______).
preload
508
Fill in the blank: The pressure against which the ventricle must pump is known as _______.
afterload
509
True or False: Stroke volume is solely determined by preload.
False
## Footnote
Stroke volume is influenced by preload, afterload, and the contractile state of the myocardium.
510
What are the three main factors that influence stroke volume?
The three main factors are:
* Preload
* Afterload
* Myocardial contractility
## Footnote
Understanding these factors helps in assessing cardiac health.
511
What is preload?
The force exerted by the walls of the ventricles at the end of diastole.
## Footnote
Preload is also referred to as end-diastolic volume.
512
What influences preload?
The volume of blood returning to the heart (venous return).
## Footnote
Increased venous return raises preload, while decreased venous return lowers it.
513
According to the Frank-Starling law of the heart, what is the relationship between cardiac muscle stretch and contraction?
The greater the cardiac muscle stretch (within limits), the greater the resulting contraction.
## Footnote
This law explains how the heart adjusts its force of contraction based on the volume of blood filling the ventricles.
514
What happens to heart muscle fibers in response to increased preload?
Heart muscle fibers stretch in response to the increased volume before contracting.
## Footnote
This stretching allows the heart to eject the additional volume with increased force.
515
What is the effect of greater preload on stroke volume (SV)?
Greater preload leads to a greater force of ventricular contraction and increased stroke volume.
## Footnote
This results in increased cardiac output (CO).
516
Fill in the blank: Preload is also known as _______.
end-diastolic volume.
517
True or False: Less blood returning to the heart increases preload.
False.
## Footnote
Less blood returning decreases preload.
518
What is afterload?
The pressure or resistance against which the ventricles must pump to eject blood
519
What factors influence afterload?
* Arterial blood pressure
* Arterial distensibility
* Arterial resistance
520
True or False: Lower afterload makes it easier for the heart to eject blood.
True
521
What happens to the heart’s workload when afterload increases?
Increases the heart’s workload
522
Fill in the blank: Conditions that contribute to increased afterload include increased thickness of the blood (________) and high blood pressure.
viscosity
523
What is cardiac output?
The amount of blood pumped by the heart per minute
## Footnote
Cardiac output is influenced by heart rate and stroke volume.
524
What factors influence heart rate?
Multiple factors including autonomic nervous system activity, hormonal influences, and physical activity
## Footnote
These factors can increase or decrease heart rate.
525
What factors affect stroke volume?
Preload, afterload, and contractility
## Footnote
These factors determine the volume of blood ejected by the ventricles with each heartbeat.
526
How can cardiac output be increased?
By an increase in heart rate or stroke volume
## Footnote
Both mechanisms can enhance the volume of blood pumped by the heart.
527
What happens to the cardiac cycle when heart rate increases?
All phases of the cardiac cycle shorten
## Footnote
The most significant effect is on the relaxation phase.
528
What is the consequence of a shortened ventricular relaxation time?
Less time for ventricles to fill adequately with blood
## Footnote
This can lead to decreased blood flow and potential ischemia.
529
What are the effects of inadequate ventricular filling?
Reduced blood sent to coronary arteries and decreased cardiac output
## Footnote
This can lead to signs of myocardial ischemia.
530
True or False: An increase in heart rate always leads to an increase in cardiac output.
False
## Footnote
If the heart rate increases too much, it can lead to inadequate filling of the ventricles.
531
What is an acute drop in blood pressure a sign of?
Decreased cardiac output
## Footnote
Indicates a significant reduction in the heart's ability to pump blood effectively.
532
Which symptom involves sudden changes in awareness or cognitive function?
Acute changes in mental status
## Footnote
Can manifest as confusion, disorientation, or decreased responsiveness.
533
What skin condition is associated with decreased cardiac output?
Cold, clammy skin
## Footnote
Results from poor circulation and reduced blood flow to the skin.
534
What color changes may occur in the skin and mucous membranes due to decreased cardiac output?
Color changes in the skin and mucous membranes
## Footnote
May include pallor or cyanosis.
535
What respiratory sound is indicative of decreased cardiac output?
Crackles (rales)
## Footnote
Often associated with fluid in the lungs.
536
What term describes difficulty in breathing that may occur with decreased cardiac output?
Dyspnea
## Footnote
Can result from fluid accumulation or decreased oxygenation.
537
What is a potential cardiac rhythm issue linked to decreased cardiac output?
Dysrhythmias
## Footnote
Irregular heartbeats that can further compromise cardiac function.
538
What symptom reflects a general lack of energy due to decreased cardiac output?
Fatigue
## Footnote
Can significantly affect a person's daily activities.
539
What is the term for difficulty breathing while lying flat?
Orthopnea
## Footnote
Often indicates heart failure or severe respiratory issues.
540
What symptom may present as anxious behavior or agitation due to decreased cardiac output?
Restlessness
## Footnote
Can be a response to decreased oxygenation or perfusion.
