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Chapter 20
El Corazón:
The Heart
Anatomía y
Sistema de
Conducción
Lecture Presentation by
Lee Ann Frederick
University of Texas at Arlington
© 2015 Pearson Education, Inc.
Introducción al Sistema Cardiovascular
• Objetivos
• 20-1 Describir la anatomía del corazón;
incluyendo: vascularización externa e interna, el
pericardio, las camaras y válvulas the anatomy of
the heart
• 20-2 Explicar los eventos en el potencial de
acción en el músculo cardiaco, incluyendo la
importancia del calcio.
• 20-3 Describir el sistema de conducción del
corazón repasando los principales eventos
electricos asociados al electrocardiograma normal
© 2015 Pearson Education, Inc.
Introducción al Sistema Cardiovascular
• Dos Circuitos Cardiovaculares principales:
• El Circuito Pulmonar
• Desde y hacia los pulmones para intercambio de
gases
• El Circuito Sistémico
• Desde y hacia el resto del cuerpo
• La sangre alternates entre ambos circuidos:
• Corazón Pulmones Corazón Cuerpo
Corazón
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Introducción al Sistema Cardiovascular
• Tipos de Vasos Sanguíneos
1.
Arterias
• Eferentes – sacan sangre fuera del corazón
2.
Venas
• Aferentes – llevan sangre hacia el corazón
3.
Capilares
•
•
•
•
Red de vasos entre arterias y venas
Interconección
Vasos de intercambio, microscópicos, paredes finas
Facilitan el intercambio entre sangre y tejidos:
• Gases, nutrientes, desechos, hormonas…
© 2015 Pearson Education, Inc.
Figure 20-1 An Overview of the Cardiovascular System.
PULMONARY CIRCUIT
Pulmonary arteries
Pulmonary veins
Capillaries
in lungs
Right
atrium
Right
ventricle
Capillaries
in trunk
and lower
limbs
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SYSTEMIC CIRCUIT
Systemic arteries
Systemic veins
Capillaries
in head,
neck, upper
limbs
Left
atrium
Left
ventricle
20-1 Anatomía del Corazón
• Musculo hueco con 4 cámaras
1. Atrio Derecho
• Recibe sangre desde el circuito sistémico (cuerpo)
2. Ventrículo Derecho
• Envía sangre hacia el circuito pulmonar
(pulmones)
3. Atrio Izquierdo
• Recibe sangre desde el circuito pulmonar
4. Ventreiculo Iquierdo
• Envia sangre hacia el circuito sistémico
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20-1 Anatomía del Corazón
• El Corazón
• Rodeado por el saco pericárdico
• Ubicado en el mediastino
• entre las dos cavidades pleurales
•
•
•
•
Cercano a la pared anterior
Inmediatamente posterior al esternón
Venas y arterias grandes en la base
Las puntiagudo el ápice
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Figure 20-2a The Location of the Heart in the Thoracic Cavity.
Trachea
First rib (cut)
Thyroid
gland
Base of
heart
Right lung
Left lung
Parietal
pericardium
(cut)
Apex of
heart
Diaphragm
a An anterior view of the chest, showing the
position of the heart and major blood vessels
relative to the ribs, lungs, and diaphragm.
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
• El Pericardio
• Cubierta doble de la cavidad pericárdica
• Visceral
• Capa interna de la cavidad pericárdica
• Contacto directo con el miocardio
• Parietal
• Capa externa de la cavidad pericardica
• Cavidad pericárdica - contiene fluido pericárdico
• entre las capas visceral y parietal
• Forman el saco paricárdico
• Tejido conectivo fibroso
• Rodea y estabiliza al corazón
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Figure 20-2b The Location of the Heart in the Thoracic Cavity.
Posterior
mediastinum
Aorta (arch
segment removed)
Esophagus
Left pulmonary artery
Right pleural cavity
Right
Left pleural
cavity
Left
lung
lung
Bronchus of lung
Left pulmonary
vein
Right pulmonary
artery
Pulmonary trunk
Aortic
arch
Right pulmonary
vein
Left atrium
Left ventricle
Superior vena cava
Pericardial cavity
Right atrium
Epicardium
Right ventricle
Anterior mediastinum
Pericardial sac
Sternum
b A superior view of the organs in the mediastinum; portions of the lungs have been removed to reveal
blood vessels and airways. The heart is located in the anterior part of the mediastinum, immediately
posterior to the sternum.
© 2015 Pearson Education, Inc.
Figure 20-2c The Location of the Heart in the Thoracic Cavity.
Base of
heart
Cut edge of
parietal pericardium
Wrist (corresponds
to base of heart)
Fibrous tissue of
pericardial sac
Inner wall (corresponds
to epicardium)
Parietal pericardium
Areolar tissue
Mesothelium
Fibrous
attachment to
diaphragm
Air space (corresponds
to pericardial cavity)
Cut edge of epicardium
Outer wall (corresponds
to parietal pericardium)
Apex of heart
Balloon
c The relationship between the heart and the pericardial cavity; compare with the fist-and-balloon example.
Pericarditis - inflamación
Cardiac tamponade – acumulación de líquido
Pericardioscentesis – extracción del líquido
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20-1 Anatomía del Corazón
• Anatomía Superficial
• Atrios – paredes finas
• Apándice de piel expandible, aurícula
• Surcos
• Coronario – divide los atrios y los ventriculos
• Surco Anterior inter-ventricular
• Surco Posterior inter-ventricular
• Separan los ventrículos
• Contienen vasos sanguíneos del músculo
cardiáco
© 2015 Pearson Education, Inc.
Figure 20-3a The Position and Superficial Anatomy of the Heart.
Base of heart
1
2
3
4
5
6
7
8
9
10
1
Ribs
2
3
4
5
6
7
8
9
10
a Heart position relative to the rib cage.
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Apex of
heart
Figure 20-3b The Position and Superficial Anatomy of the Heart.
Left subclavian artery
Left common
carotid artery
Arch of aorta
Ligamentum
arteriosum
Brachiocephalic
trunk
Descending
aorta
Ascending
aorta
Left pulmonary
artery
Superior
vena cava
Auricle
of right
atrium
Pulmonary
trunk
Right
atrium
Auricle of
left atrium
Right
ventricle
Fat and
vessels in
coronary
sulcus
Fat and vessels
in anterior
interventricular
sulcus
Left
ventricle
b Major anatomical features on the anterior surface.
© 2015 Pearson Education, Inc.
Figure 20-3c The Position and Superficial Anatomy of the Heart.
Left subclavian artery
Left common carotid
artery
Ligamentum
arteriosum
Brachiocephalic trunk
Left pulmonary
artery
Ascending
aorta
Pulmonary
trunk
Superior
vena cava
Auricle of left atrium
Auricle of
right atrium
Left coronary artery
(LCA)
Right atrium
Anterior
interventricular
sulcus
Right
coronary
artery
Coronary sulcus
Marginal branch
of right coronary artery
Right
ventricle
Left
ventricle
Anterior
interventricular
branch of LCA
c Anterior surface of the heart, cadaver dissection.
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Figure 20-3d The Position and Superficial Anatomy of the Heart.
Arch of aorta
Left pulmonary artery
Right pulmonary
artery
Left pulmonary veins
Fat and vessels
in coronary
sulcus
Superior
vena cava
Left
atrium
Coronary
sinus
Right
atrium
Left
ventricle
Right
ventricle
Right
pulmonary
veins
(superior
and inferior)
Inferior
vena cava
Fat and vessels in posterior
interventricular sulcus
d Major landmarks on the posterior surface. Coronary
arteries (which supply the heart itself) are shown in
red; coronary veins are shown in blue.
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
La Pared del Corazón – Tres capas
•Epicardio (Externa, membrana serosa)
• Pericardio visceral
• Cubre el corazón directamente
•Miocardio (Medial, muscular)
• Capas concentricas de tejido muscular cardiaco
• El Atrial rodea vasos sanguíneos grandes
• El ventricular forma un espiral
•Endocardio (Interna)
• Epitelio escamoso simple
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Figure 20-4a The Heart Wall.
Myocardium
(cardiac muscle tissue)
Cardiac muscle cells
Connective tissues
Pericardial
cavity
Parietal
pericardium
Dense fibrous layer
Areolar tissue
Mesothelium
Artery
Vein
Endocardium
Endothelium
Areolar tissue
Epicardium
(visceral
pericardium)
Mesothelium
Areolar tissue
The Heart Wall
1. Epicardio
2. Miocardio
3. Endocardio
© 2015 Pearson Education, Inc.
a A diagrammatic section through the heart
wall, showing the relative positions of the
epicardium, myocardium, and endocardium.
The proportions are not to scale; the
thickness of the myocardial wall has been
greatly reduced.
Figure 20-4b The Heart Wall.
Atrial
musculature
Ventricular
musculature
b Cardiac muscle tissue forms
- concentric layers that wrap around the atria or
- spiral within the walls of the ventricles.
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
• Tejido muscular cardiaco
• Discos intercalados
•
•
•
•
Interconenctan células del músculo cardiaco
Fijas por desmosomas
Unidas por uniones gap
Transfieren la fuerza de la contracción de una
célula a otra
• Propagan el potencial de acción
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Figure 20-5a Cardiac Muscle Cells.
Cardiac muscle
cell
Mitochondria
Intercalated
disc (sectioned)
Nucleus
Cardiac muscle
cell (sectioned)
Bundles of
myofibrils
a Cardiac muscle cells
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Intercalated
discs
Figure 20-5b Cardiac Muscle Cells.
Intercalated disc
Gap junction
Z-lines bound to
opposing plasma
membranes
Desmosomes
b Structure of an intercalated disc
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Figure 20-5c Cardiac Muscle Cells.
Intercalated
discs
Cardiac muscle tissue
c Cardiac muscle tissue
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LM x 575
20-1 Anatomía del Corazón
• Características de Células Musculares Cardiacas
1.
2.
3.
4.
Pequeñas
Un sólo núcleo, central
Interconecciones ramificadas entre células
Discos intercalados
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Table 20-1 Structural and Functional Differences between Cardiac Muscle
Cells and Skeletal Muscle Fibers.
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
• Anatomía y Organización Interna
• Septo interatrial separa atrios
• Septo Interventricular separa ventriculos
• Válvulas Atrioventriculares (AV)
• Conectan Atrios con Ventrículos
• Plieques de tejido fibroso que se extienden en los
huecos entre atrios y ventrículos
• Permiten el flujo de sangre, normalmente, en una
dirección
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20-1 Anatomía del Corazón
• Atrio Derecho (AD)
• Vena Cava Superior (VCS)
• Trae sangre de la cabeza, el cuello, pecho y
extremidades superiores
• Vena Cava Inferior (VCI)
• Recibe sangre desde el tronco, visceras y
extremidades inferiores
• Seno Coronario (SC)
• Venas cardiacas regresan sangre a este y este
drena en el atrio derecho
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20-1 Anatomía del Corazón
• Atrio Derecho (AD)
• Foramen oval
• Abertura en el septo interatrial presente antes de
nacer
• Connecta los dos atrios
• Se cierra al nacer y se queda como la fosa oval
• Músculos Pectinados
• Poseen bordes musculares prominentes
• En la superficie de la pared atrial anterior
• En la superficie del atrio derecho
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Figure 20-6a The Sectional Anatomy of the Heart.
Left common carotid artery
Left subclavian artery
Brachiocephalic
trunk
Superior
vena cava
Ligamentum arteriosum
Pulmonary trunk
Aortic arch
Pulmonary valve
Right
pulmonary
arteries
Left pulmonary
arteries
Ascending aorta
Fossa ovalis
Opening of
coronary sinus
Right atrium
Pectinate muscles
Left
atrium
Left pulmonary
veins
Interatrial septum
Aortic valve
Cusp of left AV
(mitral) valve
Conus arteriosus
Left ventricle
Cusp of right AV
(tricuspid) valve
Chordae tendineae
Papillary muscles
Right ventricle
Interventricular
septum
Trabeculae
carneae
Inferior vena cava
Moderator band
Descending aorta
a A diagrammatic frontal section through the heart, showing
major landmarks and the path of blood flow (marked by
arrows) through the atria, ventricles, and associated vessels.
© 2015 Pearson Education, Inc.
Figure 20-6c The Sectional Anatomy of the Heart.
Left subclavian artery
Left common carotid artery
Brachiocephalic trunk
Superior vena cava
Ascending aorta
Pulmonary
trunk
Cusp of
pulmonary valve
Auricle of left atrium
Right atrium
Cusp of left AV
(bicuspid) valve
Chordae tendineae
Cusps of right AV
(tricuspid) valve
Papillary muscles
Left ventricle
Trabeculae carneae
Right ventricle
c Anterior view of a frontally sectioned
heart showing internal features and valves.
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Interventricular
septum
20-1 Anatomía del Corazón
• El Ventrículo Derecho (VD)
• Bordes libres unidos a cuerdas tendinosas de
los músculos papilares del ventrícuo
• Previenen el que las válvulas abran en la
direccion opuesta
• Válvula AV Derecha
•
•
•
•
Tricúspide
Abre de atrio a ventrículo derecho
Tres picos
Evita el flujo retrógrado de sangre
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20-1 Anatomía del Corazón
• Ventrículo Derecho (VD)
• Carnosidad Trabecular
• Bordes musculares en la superficie interna de los
ventrículos
• Incluyen la banda moderadora
• Contiene partes del Sistema de Conducción
• Coordina las contracciones de células musculares
cardiacas
© 2015 Pearson Education, Inc.
Figure 20-6b The Sectional Anatomy of the Heart.
Chordae tendineae
Papillary muscles
b The papillary muscles and chordae
tendineae support the right AV (tricuspid)
valve. The photograph was taken from
inside the right ventricle, looking toward
a light shining from the right atrium.
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
• Circulación Pulmonar
• Cono arterioso (extremo superior del ventrículo
derecho), va hacia el tronco pulmonar
• Tronco pulmonar se divide en arterias
pulmonares derecha e izquierda
• Sangre fluye desde el VD hacia el TP a través de
la válvula semilunar pulmonar (SLP)
• Tiene tres picos semilunares
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20-1 Anatomía del Corazón
• Atrio Izquierdo (AI)
• La sangre llega desde las venas pulmonares
derecha e izquierda
• Sangre pasa por la válvula AV izquierda
• Una valvula de dos picos, bicúspide o mitral
• Sangre pasa al ventrículo izquierdo (VI)
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20-1 Anatomía del Corazón
• Ventrículo Izquierdo (VI)
•
•
•
•
Recoge el mismo volumen que el derecho
Es mas grande, músculo mas grueso
Es mas potente
Internamente es similar al derecho, sin banda
moderadora
• Circulación Sistémica
• La sangre que sale del VI a travás de la VSA hacia
la Aorta Ascendente (AA
• AA se convierte enel Arco Aórtico y luego en AD
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Figure 20-6c The Sectional Anatomy of the Heart.
Left subclavian artery
Left common carotid artery
Brachiocephalic trunk
Superior vena cava
Ascending aorta
Pulmonary
trunk
Cusp of
pulmonary valve
Auricle of left atrium
Right atrium
Cusp of left AV
(bicuspid) valve
Chordae tendineae
Cusps of right AV
(tricuspid) valve
Papillary muscles
Left ventricle
Trabeculae carneae
Right ventricle
c Anterior view of a frontally sectioned
heart showing internal features and valves.
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Interventricular
septum
20-1 Anatomía del Corazón
• Diferencias Estructurales entre los ventrículos
•
•
•
•
•
•
•
•
Derecho: envía sangre a circulación__________?
Pared mas fina que el izquierdo
Desarrolla menos presión que el izquierdo
En forma de saco, mas flexible,
Izquierdo
Es mas grueso, mas fuerte
Es redondo
Mas muscular
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Figure 20-7a Structural Differences between the Left and Right Ventricles.
Posterior
interventricular
sulcus
Left
ventricle
Right
ventricle
Fat in anterior
interventricular sulcus
a
© 2015 Pearson Education, Inc.
A diagrammatic sectional view through
the heart, showing the relative thicknesses
of the two ventricles. Notice the pouchlike
shape of the right ventricle and the greater
thickness of the left ventricle.
Figure 20-7b Structural Differences between the Left and Right Ventricles.
Right
ventricle
Left
ventricle
Dilated
Contracted
b Diagrammatic views of the
ventricles just before a
contraction (dilated) and just
after a contraction (contracted).
© 2015 Pearson Education, Inc.
20-1 Anatomía del Corazón
• Válvulas del Corazón
• Dos pares
• En una dirección
• Previenen el flujo retrógrado durante la
contracción
• Válvulas Atrioventriculares (AV: D e I)
• Entre atrios y ventrículos
• La presión sanguínea cierra los pliegues de las
válvulas durante contracción ventricular
• Los músculos papilares tensan las cuerdas
tendinosas lo que previene el que las válvulas se
mesan hacia el atrio
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20-1 Anatomía del Corazón
• Valvulas del corazón
• Válvulas Semilunares (SL:A y P)
• Pulmonar y aórticas
• Previenen el flujo retrógrado desde el tronco
pulmonar y la aorta hacia los ventrículos
• No tienen tejido muscular que apoye
• Tres picos como en un trípode
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20-1 Anatomía del Corazón
• Senos Aórticos
• En la base de la aorta
• Sacos que previenen el que los picos de las
válvula se peguen a la ahortar
• Punto donde se origina las arterias coronarias
derecha e izquierda
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Figure 20-8a Valves of the Heart (Part 1 of 2).
Transverse Sections, Superior View,
Atria and Vessels Removed
POSTERIOR
Cardiac
skeleton
Relaxed ventricles
RIGHT
VENTRICLE
Left AV (bicuspid)
valve (open)
LEFT
VENTRICLE
Right AV
(tricuspid)
valve (open)
Aortic valve
(closed)
ANTERIOR
a
Aortic valve closed
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Pulmonary
valve (closed)
When the ventricles are relaxed,
the AV valves are open and the
semilunar valves are closed. The
chordae tendineae are loose, and
the papillary muscles are relaxed.
Figure 20-8a Valves of the Heart (Part 2 of 2).
Frontal Sections through Left Atrium and Ventricle
Pulmonary
veins
Relaxed ventricles
LEFT
ATRIUM
Left AV (bicuspid)
valve (open)
Aortic valve
(closed)
Chordae
tendineae (loose)
Papillary muscles
(relaxed)
LEFT VENTRICLE
(relaxed and filling
with blood)
a
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When the ventricles are relaxed, the AV valves are open
and the semilunar valves are closed. The chordae
tendineae are loose, and the papillary muscles are relaxed.
Figure 20-8b Valves of the Heart (Part 1 of 2).
Contracting ventricles
Right AV
(tricuspid) valve
(closed)
RIGHT
VENTRICLE
Cardiac
skeleton
Left AV
(bicuspid) valve
(closed)
LEFT
VENTRICLE
Aortic valve
(open)
Pulmonary
valve (open)
b When the ventricles are contracting,
Aortic valve open
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the AV valves are closed and the
semilunar valves are open. In the
frontal section notice the attachment
of the left AV valve to the chordae
tendineae and papillary muscles.
Contracting ventricles
Figure 20-8b Valves of the Heart (Part 2 of 2).
Aorta
Aortic sinus
Aortic valve
(open)
LEFT
ATRIUM
Left AV (bicuspid)
valve (closed)
Chordae tendineae
(tense)
Papillary muscles
(contracted)
Left ventricle
(contracted)
b When the ventricles are contracting, the AV valves are
closed and the semilunar valves are open. In the frontal
section notice the attachment of the left AV valve to the
chordae tendineae and papillary muscles.
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20-1 Anatomía del Corazón
• Tejidos conectivo y el Esqueleto Cardiaco
• Fibras de tejido conectivo
1. Apoyo físico a las fibras musculares cardiacas
2. Distribuyen la fuerza de la contracción
3. Añaden fuerza y previenen la sobreexpansión del
músculo
4. Proveen elasticidad que ayuda al corazón a
regresar al tamaño y forma original, luego de la
contracción
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20-1 Anatomía del Corazón
• El Esqueleto Cardiaco
• Cuatro bandas de tejido conectivo que rodean:
• Las válvulas del corazón
• La base del tronco pulmonar y la aorta
• Estabilizan las válvulas
• Aisla o separa eléctricamente las células
ventriculares de las atriales
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20-1 Anatomía del Corazón
• Suplido de sangre al corazón
• Circulación coronaria
• Suple sangre al tejido muscular del corazón
• Arterias coronarias y venas cardiacas
• Arterias coronarias
•
•
•
•
Izquierda y Derecha
Se originas en los senos aorticos
Expuestas a altas presiones
Rebote elastico entre contracciones empuja la
sangre a traves de las arterias coronarias
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20-1 Anatomía del Corazón
• Arteria Coronaria Derecha
• Suple sangre a:
•
•
•
•
Ario derecho
Partes de ambos ventrículos
Celulas de los Nodos SA y AV
Superficie del ventriculo derecho por las arterias
marginales
• Arteria interventricular posterior
• Arteria Coronaria Izquierda
• SuppSuple sangre:
• Atrio y ventrículo izquierdo
• Septo interventricular
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20-1 Anatomía del Corazón
• Arteria Coronaria se divide en dos ramas:
1. Arteria circumfleja
2. Arteria interventricular anterior
• Anastomosis arterial
•
•
•
Conección entre vasos
Artero arterial – arterias interventriculares
anterior y posterior
Estabiliza el suplido de sangre al corazón
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20-1 Anatomía del Corazón
• Venas cardiacas
• Gran vena cardiaca
• Drena sangre del area de la arteria
interventricular anterior
• Drena en el seno coronario
• Venas cardiacas anteriores
• Drena en el atrio derecho
• Venas cardiaca posterior, cardiaca mediana y
cardiaca pequeña :
• Drenan en la gran vena cardiaca y en el seno
coronario
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Figure 20-9a The Coronary Circulation.
Aortic
arch
Ascending
aorta
Right
coronary
artery
Left coronary
artery
Pulmonary
trunk
Circumflex
artery
Anterior
interventricular
artery
Atrial
arteries
Great
cardiac
vein
Anterior
cardiac
veins
Small
cardiac vein
Marginal
artery
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a Coronary vessels supplying
and draining the anterior
surface of the heart.
Figure 20-9b The Coronary Circulation.
Coronary sinus
Circumflex artery
Great cardiac vein
Marginal artery
Posterior
interventricular
artery
Posterior
cardiac
vein
Small
cardiac
vein
Left
ventricle
Right
coronary
artery
Middle cardiac vein
Marginal artery
b Coronary vessels supplying and draining
the posterior surface of the heart.
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Figure 20-9c The Coronary Circulation.
Auricle of
left atrium
Left pulmonary
veins
Left pulmonary
artery
Right
pulmonary
artery
Circumflex
artery
Superior
vena cava
Great cardiac
vein
Marginal
artery
Right
pulmonary
veins
Posterior
cardiac vein
Left atrium
Right atrium
Inferior
vena cava
Coronary sinus
Middle cardiac vein
Right ventricle
Posterior interventricular artery
c A posterior view of the heart; the vessels have
been injected with colored latex (liquid rubber).
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Figure 20-10 Heart Disease and Heart Attacks (Part 2 of 4).
Narrowing of Artery
Normal Artery
Tunica
externa
Lipid deposit
of plaque
Tunica
media
Cross section
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Cross section
20-1 Anatomy of the Heart – Asignado
• Heart Disease – Coronary Artery Disease
• Coronary artery disease (CAD)
• Areas of partial or complete blockage of coronary
circulation
• Cardiac muscle cells need a constant supply of
oxygen and nutrients
• Reduction in blood flow to heart muscle produces a
corresponding reduction in cardiac performance
• Reduced circulatory supply, coronary ischemia,
results from partial or complete blockage of
coronary arteries
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Usual cause is formation of a fatty deposit, or
atherosclerotic plaque, in the wall of a coronary
vessel
• The plaque, or an associated thrombus (clot),
then narrows the passageway and reduces blood
flow
• Spasms in smooth muscles of vessel wall can
further decrease or stop blood flow
• One of the first symptoms of CAD is commonly
angina pectoris
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Angina pectoris
• In its most common form, a temporary ischemia
develops when the workload of the heart increases
• Although the individual may feel comfortable at
rest, exertion or emotional stress can produce a
sensation of pressure, chest constriction, and pain
that may radiate from the sternal area to the arms,
back, and neck
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Myocardial infarction (MI), or heart attack
• Part of the coronary circulation becomes blocked,
and cardiac muscle cells die from lack of oxygen
• The death of affected tissue creates a
nonfunctional area known as an infarct
• Heart attacks most commonly result from severe
coronary artery disease (CAD)
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Myocardial infarction (MI), or heart attack
• Consequences depend on the site and nature of
the circulatory blockage
• If it occurs near the start of one of the coronary
arteries:
• The damage will be widespread and the heart
may stop beating
• If the blockage involves one of the smaller arterial
branches:
• The individual may survive the immediate crisis
but may have many complications such as
reduced contractility and cardiac arrhythmias
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Myocardial infarction (MI), or heart attack
• A crisis often develops as a result of thrombus
formation at a plaque (the most common cause of
an MI), a condition called coronary thrombosis
• A vessel already narrowed by plaque formation
may also become blocked by a sudden spasm in
the smooth muscles of the vascular wall
• Individuals having an MI experience intense pain,
similar to that felt in angina, but persisting even at
rest
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Myocardial infarction (MI), or heart attack
• Pain does not always accompany a heart attack;
therefore, the condition may go undiagnosed and may
not be treated before a fatal MI occurs
• A myocardial infarction can usually be diagnosed with
an ECG and blood studies
• Damaged myocardial cells release enzymes into the
circulation, and these elevated enzymes can be
measured in diagnostic blood tests
• The enzymes include:
• Cardiac troponin T,
• Cardiac troponin I,
• A special form of creatinine phosphokinase, CK-MB
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• About 25 % of MI patients die before obtaining
medical assistance
• 65 % of MI deaths among those under age 50
occur within an hour after the initial infarction
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• Risk factor modification - Epigenesis
• Stop smoking
• High blood pressure treatment
• Dietary modification to lower cholesterol and
promote weight loss
• Stress reduction
• Increased physical activity (where appropriate)
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• Drug treatment
• Drugs that reduce coagulation and therefore the risk
of thrombosis, such as aspirin and coumadin
• Drugs that block sympathetic stimulation
(propranolol or metoprolol)
• Drugs that cause vasodilation, such as nitroglycerin
• Drugs that block calcium movement into the cardiac
and vascular smooth muscle cells (calcium channel
blockers)
• In a myocardial infarction, drugs to relieve pain,
fibrinolytic agents to help dissolve clots, and oxygen
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• Noninvasive surgery
• Atherectomy
• Blockage by a single, soft plaque may be
reduced with the aid of a long, slender catheter
inserted into a coronary artery to the plaque
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• Noninvasive surgery
• Balloon angioplasty
• The tip of the catheter contains an inflatable
balloon
• Once in position, the balloon is inflated, pressing
the plaque against the vessel walls
• Because plaques commonly redevelop after
angioplasty, a fine tubular wire mesh called a
stent may be inserted into the vessel, holding it
open
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20-1 Anatomy of the Heart - Asignado
• Heart Disease – Coronary Artery Disease
• Treatment of CAD and myocardial infarction
• Coronary artery bypass graft (CABG)
• In a coronary artery bypass graft, a small section is
removed from either a small artery or a peripheral
vein and is used to create a detour around the
obstructed portion of a coronary artery
• The procedures are named according to the number
of vessels repaired, so we speak of single, double,
triple, or quadruple coronary bypasses
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Figure 20-10 Heart Disease and Heart Attacks (Part 1 of 4).
Normal Heart
A color-enhanced digital
subtraction angiography (DSA)
scan of a normal heart.
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Figure 20-10 Heart Disease and Heart Attacks (Part 3 of 4).
Occluded
Coronary
Artery
Damaged
Heart
Muscle
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20-2 Sistema de Conducción
• Palpitación cardiaca o latido
• Una contracción simple del corazón
• El corazón se contrae en serie
• Atrios primero
• Ventrículos luego
• Fisiología Cardiaca
• Dos tipos de células en el músculo cardiaco
1. Sistema de conducción
• Controla y coordina las contracciones
2. Células contráctiles
• Se contraen para bombear la sangre
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20-2 Sistema de Conducción
• Ciclo cardiaco • Comienza con un potencial de acción
• En el Nodo SA
• Este potencial de accion es transmitido por el
sistema de conducción
• Produce potenciales de acción en las células
contráctiles (musculares)
• Electrocardiograma (ECG or EKG)
• Registro gráfico de los eventos eléctricos que
ocurren durante un ciclo cardiaco
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20-2 Sistema de Conducción
• El Sistema de conducción
• Sistema de células musculares
• Especializado en
• Iniciar
• Distribuir
• Impulsos eléctricos que estimulan la contracción
• Automaticidad
• Principal característica del tejido muscular cardiaco
• Automático
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20-2 Sistema de Conducción
• Estructuras que componen el Sistema de
Conducción
• Nodo Senoatrial (SA) –
• En la pared del atrio derecho – origina
• Nodo Atrioventricular (AV) –
• En la unión entre los atrios y ventrículos
• Células conductoras –
• A través del miocardio
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20-2 Sistema de Conducción
• Células condutoras
• Conectan los nodos SA y AV
• Distribuyen el estímulo a traves del miocardio
• En el atrio
• Vias internodales
• En los ventriculos
• Haces AV
• Ramas
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20-2 Sistema de Conducción
• Prepotencial
• Potencial marcapaso
• Potencial de reposo de las células conductoras
• El Nodo SA se depolariza primero
• Estableciendo la frecuencia, el paso
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Figure 20-11a The Conducting System of the Heart.
Sinoatrial
(SA) node
Internodal
pathways
Atrioventricular
(AV) node
AV bundle
Bundle
branches
Purkinje
fibers
a Components of the
conducting system.
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Figure 20-11b The Conducting System of the Heart.
+20 mV
0 mV
−20 mV
Threshold
−40 mV
−60 mV
Prepotential
0
0.8
Time (sec)
1.6
b Changes in the membrane potential of a pacemaker
cell in the SA node that is establishing a heart rate
of 72 beats per minute. Note the presence of a
prepotential, a gradual spontaneous depolarization.
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20-2 Sistema de Conducción
• Frecuencia cardiaca
• El Nodo Sinoatrial (SA)
•
•
•
•
•
•
En la pared posterior del atrio derecho
Contiene las células marcapaso
Genera 80–100 potenciales de acción por minuto
Estimulación PS reduce la frecuencia
Conectado al nodo AV por vías internodales
Comienza la activación atrial (Paso 1)
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Figure 20-12 Impulse Conduction through the Heart (Part 1 of 5).
1
SA node activity and
atrial activation begin.
Time = 0
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SA
node
20-2 Sistema de Conducción
• El Nodo Atrioventricular (AV)
•
•
•
•
•
En el piso del atrio derecho
Recibe impulsos desde el Nodo SA (paso 2)
Retrasa el impulso (Paso 3)
Comienza la contracción atrial
AV node puede generar de 40–60potenciales de
acción por minuto
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Figure 20-12 Impulse Conduction through the Heart (Part 2 of 5).
2
Stimulus spreads across the
atrial surfaces and reaches
the AV node.
AV
node
Elapsed time = 50 msec
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Figure 20-12 Impulse Conduction through the Heart (Part 3 of 5).
3
There is a 100-msec delay
at the AV node. Atrial
contraction begins.
AV
bundle
Bundle
branches
Elapsed time = 150 msec
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20-2 Sistema de Conducción
• Has AV
• En el septo
• Acarrea el impulso hacia las ramas derecha e
izquierda
• Estas lo conducen hacia las fibras Purkinje (Pas 4)
• Acarrea el impulso hacia la banda moderadora
• Esta lo conduce hacia los músculos papilares
• Fibras de Purkinje
• Distribuyen el impulso a través de los ventrículos
(Paso 5)
• Termina la contracción atrial
• Comienza la contracción ventricular
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Figure 20-12 Impulse Conduction through the Heart (Part 4 of 5).
4
The impulse travels along the
interventricular septum within
the AV bundle and the bundle
branches to the Purkinje fibers
and, by the moderator band,
to the papillary muscles of the
right ventricle.
Moderator
band
Elapsed time = 175 msec
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Figure 20-12 Impulse Conduction through the Heart (Part 5 of 5).
5
The impulse is distributed by
Purkinje fibers and relayed
throughout the ventricular
myocardium. Atrial contraction
is completed, and ventricular
contraction begins.
Elapsed time = 225 msec
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Purkinje fibers
20-2 Sistema de Conducción
• Anomalías en la función del marcapaso
• Bradicardia – frecuencia cardiaca anormalmente
lenta
• Taquicardia – frecuencia cardiaca anormalmente
rápida
• Marcapaso Ectópico
• Células anormales
• Generan una frecuencia alta de potenciales de
acción
• Esquivan el sistema de conducción
• Afectan las contracciones ventriculares
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20-2 El Sistema de Conducción
• El Electrocariograma (ECG or EKG)
• Registro gráfico de los eventos eléctricos en el
corazón
• Se obtiene por la colocación de electrodos en
lugares especificos del cuerpo
• Patrones anormales significan daños o riesgos
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Figure 20-13a An Electrocardiogram.
a Electrode placement for
recording a standard ECG.
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20-2 El Sistema de Conducción
• Ondas características de un EKG
• Onda P (0.08 – 0.1 sec)
• Depolarización atrial
• Complejo QRS (0.08 – 0.1 sec)
• Depolarización de ventrículos
• Onda T
• Repolarizacón de ventrículos
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Figure 20-13b An Electrocardiogram.
800 msec
+1
R
P wave
(atria
depolarize)
R
T wave
(ventricles
repolarize)
P–R segment
S–T
segment
+0.5
0
Q S
P–R
interval
S–T
interval
Q–T
interval
b
Millivolts
QRS interval
(ventricles depolarize)
−0.5
An ECG printout is a strip of graph paper containing a record of the electrical events
monitored by the electrodes. The placement of electrodes on the body surface affects
the size and shape of the waves recorded. The example is a normal ECG; the enlarged
section indicates the major components of the ECG and the measurements most often
taken during clinical analysis.
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20-2 El Sistema de Conducción
• Intervalos de tiempo entre las ondas
• Intervalo P-R (0.12 – 0.20 sec)
• Se mide desde el comienzo de la depolarización
atrial
• Hasta el comienzo del complejo QRS
• Intervalo Q-T (0.4 – 0.43 sec)
• Desde el comienzo de la depolarización ventricular
• Hasta la repolarización ventricular
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Figure 20-14 Cardiac Arrhythmias (Part 1 of 2).
Premature Atrial Contractions (PACs)
P
P
P
Paroxysmal Atrial Tachycardia (PAR)
P
P
P
Atrial Fibrillation (AF)
P
P
P
Premature atrial contractions (PACs)
often occur in healthy individuals. In a PAC,
the normal atrial rhythm is momentarily
interrupted by a “surprise” atrial contraction.
Stress, caffeine, and various drugs may
increase the incidence of PACs, presumably
by increasing the permeabilities of the SA
pacemakers. The impulse spreads along the
conduction pathway, and a normal ventricular
contraction follows the atrial beat.
In paroxysmal (par-ok-SIZ-mal) atrial
tachycardia, or PAT, a premature atrial
contraction triggers a flurry of atrial activity.
The ventricles are still able to keep pace, and the
heart rate jumps to about 180 beats per minute.
During atrial fibrillation (fib-ri-LĀ-shun), the
impulses move over the atrial surface at rates
of perhaps 500 beats per minute. The atrial wall
quivers instead of producing an organized
contraction. The ventricular rate cannot follow
the atrial rate and may remain within normal
limits. Even though the atria are now
nonfunctional, their contribution to ventricular
end-diastolic volume (the maximum amount of
blood the ventricles can hold at the end of atrial
contraction) is so small that the condition may
go unnoticed in older individuals.
Frecuencia - /min, atrial o ventricular
Ondas/interalos – presentes, duración, +/-, forma, tamaños
Ritmo - atrial, ventricular, PVCs
Conducción – normal/bloqueos
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Figure 20-14 Cardiac Arrhythmias (Part 2 of 2).
Premature Ventricular Contractions (PVCs)
P
T
P
T
P
Ventricular Tachycardia (VT)
P
Ventricular Fibrillation (VF)
T
Premature ventricular contractions (PVCs)
occur when a Purkinje cell or ventricular
myocardial cell depolarizes to threshold and
triggers a premature contraction. Single PVCs
are common and not dangerous. The cell
responsible is called an ectopic pacemaker.
The frequency of PVCs can be increased by
exposure to epinephrine, to other stimulatory
drugs, or to ionic changes that depolarize
cardiac muscle plasma membranes.
Ventricular tachycardia is defined as four or
more PVCs without intervening normal beats. It
is also known as VT or V-tach. Multiple PVCs
and VT may indicate that serious cardiac
problems exist.
Ventricular fibrillation (VF) is
responsible for the condition known as
cardiac arrest. VF is rapidly fatal,
because the ventricles quiver and
stop pumping blood.
Frecuencia - /min, atrial o ventricular
Ondas/interalos – presentes, duración, +/-, forma, tamaños
Ritmo - atrial, ventricular, PVCs
Conducción – normal/bloqueos
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20-2 El Sistema de Conducción
• Células contráctiles
• Fibras de Purkinje –
• Distribuyen el potencial de acción/estímulo a las
celulas contráctiles
• Potencial de reposo
•
•
•
•
•
•
•
De las células ventriculares –90 mV
De las células atriales –80 mV
De las células nerviosas? De las células de músculo esqueletal?
Epitelio
En promedio
Rango
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Figure 20-15a The Action Potentials in Skeletal and Cardiac Muscle.
1
Rapid Depolarization
2
Cause: Na+ entry
Duration: 3–5 msec
Ends with: Closure of
voltage-gated fast
sodium channels
3
The Plateau
Cause: Ca2+ entry
Duration: ∼175 msec
Ends with: Closure
of slow calcium
channels
Repolarization
Cause: K+ loss
Duration: 75 msec
Ends with: Closure
of slow potassium
channels
+30
2
0
1
mV
3
Absolute refractory
−90
Relative
refractory
period
KEY
period
0
Stimulus
100
200
Time (msec)
a Events in an action potential in a ventricular
muscle cell.
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300
Absolute refractory
period
Relative refractory
period
Figure 20-15b The Action Potentials in Skeletal and Cardiac Muscle.
+30
Skeletal
muscle
Action
potential
0
Cardiac
muscle
+30
0
Action potential
mV
mV
−90
−85
Tension
Tension
Contraction
0
100
200
Contraction
300
0
Time (msec)
b Action potentials and twitch contractions in a
skeletal muscle (above) and cardiac muscle (below).
The shaded areas indicate the durations of the
absolute (blue) and relative (beige) refractory periods.
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100
200
300
Time (msec)
KEY
Absolute refractory
period
Relative refractory
period
20-2 El Sistema de Conducción
• Periodo Refractorio
• Absoluto
• Largo - células cardiacas NO responden
• Relativo
• Corto - respuesta depende del tamaño del estímulo
• Tiempo del periodo refractorio
• 250-300 msec
• Duración de el potencial de acción cardiaco en las
células ventriculares
• 30X mas largo que en musculoesqueletales
• Periodo refractorio largo previene/evita sumación,
tetanos y PLT:
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20-2 El Sistema de Conducción
• Que rol juega Calcio en las contracciones cardiacas?
• Ocurren
[Ca2+] alrededor de las miofribrillas
1. 20 % de los iones de Ca2+ son requeridos para la
contracción
• Ca2+ cruza la membrana durante la fase de plateau
2. Llegada del Ca2+ extracelular
• Gatilla la liberación de iones de Ca2+ desde las
reservas en el retículo sarcoplásmico (RS)
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20-2 El Sistema de Conducción
• El Rol de Calcio
• Según los canales de Ca2+ cierran
• El Ca2+ intracelular es absorbido por el RS
• O es bombeado fuera de la célula
• Tejido muscular cardiaco
• Muy sensitivo a cambios en las [Ca2+] extracelular
• Drogas juegan con canales y PLT con [Ca+2]
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20-2 El Sistema de Conducción
• De donde proviene la E para las contracciones?
• Es energía Aeróbica cardiaca
• Mitocondrias degradan ácidos grasos y glucosa
• Hgb matiene [oxígeno] circulante apropiada
• Las células cardiacas almacenan oxígeno en la
mioglobina
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