Exam 1 - Cardiac Muscle & Heart Flashcards
Cardiac Muscle is composed of _______ which are _____ and under _______ control (autonomic nervous system). The majority of these are specialized for ______, there are however modified ______ whose main role is conduction.
Cardiac Muscle Myocytes Striated Involuntary Contraction Myocytes
Cell Size
Cardiac Myocytes in the atria are ____ than in the ventricle
- ______ Cells
- # of Nuclei/cell?
- cardiace myocytes do not fuse extensively as in skeletal muscle, therefore they normally have __ - ___ central nuclei
- Myofibrils
- banding is the same as in ______ muscle. Striations are less distinct than theres due to a _____ arrangement of myofibrils within the cells. - Organelles - these cells have many large _________. The sarcoplasmic reticulum is more ______ in arrangement and usually contacts the ___-_______ in a 1:1 relation called a ________. This junction of terminal cisternae with the ___-_____ is located at the _____ line.
Smaller
(1) Branching
(2) 1-2 (1-2)
(3) skeletal; variable
(4) mitochondria; variable; T-Tubule; DIAD; T-Tubule; Z
Specialized Intercellular Junctions
Cardiac muscle has relatively reduced intercellular fibers fro attaching to and coordination _______. To unify this, the cells have ______ _____ joining cells end to end ( _____ and _____ adherentes) in long chains and lateral regions of the
disk ( _____ _____), which allow neighboring celsl to communicate.
contraction
Intercalated Disks
Desmosomes
Fasciae Adherentes
Gap Junctions
T Tubulues located at ___ lines - like Amphibian _____ muscle
Specialized anchors for ____ that help connect adjacent cardiac myocytes
SR is less extensive and forms ______ with T Tubules
Z; Skeletal
Actin
Diads
Heart Wall Layers
1.
- ______
- ______ (& 2 sublayers of this)
2.
3.
- Endocardium
- Endothelium
- Subendothelium - Inner and Outer subendothelium
- Myocardium
- Epicardium
Heart Wall Layers
Endocardium
Completely lines the ____ surface of the heart (____, _____ and ______)
- Endothelium - Cell type?
- Subendothelium
- Inner Subendothelium: _____-______ connective tissue composed of ____, ____ fibers and occasional _____ muscle fibers.
- Outer Subendothelium: _______ connective tissue composed of _____, _____ fibers. This area may also have large amounts of ______ tissue, ____ and ______ vessels, and specialized conduction cells (_____ cells)
Inner; Atria; ventricles; valves
- Dense-Irregular; Collagen; Elastic Fibers; Smooth
- Loose; collagen; elastic; adipose; blood; lymph; Purkinje
Heart Wall Layers
Myocardium - is the _____ layer of the heart. In contains cardiac muscle, the cardiac skeleton and part of the conduction system (______ cells). The myocardium is thickest in the _____ (esp. the ____ ______ - more force is required to eject blood into the systemic circulation).
Ventricular myocardium is made up of _____ layers (superficial, middle and deep). In the superficial and depp layers myocytes are oriented from ____ to ____ - contraction of these cells results in ventricular shortening.
The myocytes in the middle layer circumscribe the lumen; contraction results in ______ of the ventricular lumen.
Atrial myocardium is _____ and has ____ layers (superficial and deep).
Thickest; Purkinje; Ventricle; Left ventricle
3; Base to Apex
Narrowing
Thinner; 2
Heart Wall Layers
Epicardium - ( ______ pericardium) is a ____ membrane (mesothelium) covering the _____ surface of the heart.
Visceral; Serous; External
Pericardial Sac
is the cavity between the ______ (____ pericardium) and the _____ pericardium, these 2 laers become continuous in the areas where large vessels exit/enter the heart. The pericardial sac contains _____ to reduce friction between these 2 layers.
Epicardium; Visceral; Parietal; Fluid
“Skeleton” of the Heart:
1.
2.
3.
Is a support system within the muscle framework. This area serves as a site for anchoring of the _____, _____ musculature, and _____ musculatures. The skeleton is composed of _____ _____ connective tissue and depending on species and age it may have some components of ____ and _____.
Pig & Cat = ____ ____ connective tissue
Dog = __________________________
Horse = _________ _______________
Large Ruminants = ______ ( “____ _____”) esp around the _______
- Membranous Septum
- Annulus
- Trigone
Valves, Atria, Ventricular, Fibrous Connective, Cartilage & Bone
Dense Irregular
Fibrocartilage
Hyaline Cartilage
Bone “Os Cordis” - Aorta
Components of the Skeleton of the Heart
- ______ _____ - fibrous rings surrounding the 4 valves of the heart
- ______ _______ - fibrous triangle beteween the valves
- _____ _____ - fibrous connective tissue in the interventricular septum
- Annuli Fibrosi
- Trigonum Fibrosum
- Septum Membranaceum
COMPARE
Cardiac Muscle Myocyte vs.Skeletal Muscle Myocyte
Size
Diameter
Do Fibers Branch?
Nucleus
A-I Bands?
Mitochondria
T Tubule Location
Diads/Triads
Junctions btwn cells?
COMPARE Cardiac Muscle Myocyte Skeletal Muscle Myocyte
Size Smaller (85-100 um Long) Larger (50 cm Long)
Diameter 10-20 um 50-100 um
Do Fibers Branch? Fibers DO branch Fibers DO NOT branch
Nucleus Central – 1-2/cell Peripheral – many/cell
A-I Bands? A-I bands present – indistinct A-I bands present, distinct
Mitochondria Many Fewer
T Tubule Location Z Line A-I Junction
Diads/Triads Diads = 1 T Tub + 1 SR Triads = 1 T Tub + 2 SR
Junctions btwn cells? Intercalated Discs No junction btwn cells
Valves of the heart are ______ folds with an ______ connective tissue core that ties into the “skeleton” of the heart.
They are composed of:
- Endothelium - Cell type?
- Central Layer - _______ connective tissue with _____ fibers
- _______ _____ extend from the _______ valves - this is a fibrous cord continuous with the central connective tissue of the valve and covered with _______. They help prevent the valves from _____ during contraction.
endocardial; inner
- Simple Squamous
- Colleganeous; elastic
- Chordae Tendinae; atrioventricular; Endothelium; Evulsion
Conduction System of the Heart
is composed of a series of cells specialized for ______. The wave of depolarization begins at the _____ nodal cells and extends through the ____ cardiac muscle cells. When depolarization reaches the ____ node there is a delay in progression when passing through the “skeleton” components of the heart.
Depolarization progresses rapidly through the ____ bundle, which is composed of the specialized impulse-conducting fibers ( ______ fibers) arranged in series.
Conduction; SA; Atrial; AV
AV; Purkinje
Conduction System of the Heart
Components:
1.
2.
3.
- SA Node
- AV Node
- AV bundle
SA Node
is the “_______” of the heart. It is located in the _____ ______. These nodal cells are _____, branching cardiav muscle fibers which depolarize/repolarize more rapildy than other cells allowing it to assume this role.
The cells have few ____ and _____ intercalated discs. Many autonomic nerve endings surround this area.
Parasympathetic terminals release _____ which decreses the rate of _____ and therefore ______ the heart rate
Sympathetic sibers release _____ which _______ the heart rate.
Pacemaker; Right Atrium; Small
Myofibrils; No
Acetylcholine; Depolarization; Decreases
Norepinephrine; Increases
AV Node
is made up of cells similiar in morphology to the ____ nodal cells.
These cells are continuous with ____ myocardial fibers and the cardiac muscle cells specialized for
conduction (_____ cells)
SA
Atrial
Purkinje
AV Bundle (Bundle of ____ )
has _____ impulse-conduction muscle fibers ( _____ cells) arranged in series. These cells have _____ myofibrils and _____ T Tubules. There are large ____ _____ between the cells; because of the close coupling of the cells they act as a tissue synctium allowing the action potential to spread electronically from cell to cell.
These conduction fibers connect with smaller transitional cells, which lack _____ ______.
His
Large; Purkinje; Few; No; Gap Junctions
Intercalated Disks
Purkinje Fibers
_____ Myocyte - Very large cell
_____ myofibrils (e.g. stain pale)
______, ______ and _____ disks are present
Modified
Few
Mitochondria, SR, Intercalated Disks
_Trabeculae Septomarginalis ( ______ band)_
Extension of ____ and _____ of _____ wall, carries impulse-conducting muscle fibers ( _____ cells) from the ________ septum to the lateral wall of the ventricle.
Flow of conduction/coordination of contraction - sequence
Atria contract following depolarization of _____ node (blood pushed into ventricles)
_______ Nodal Delay - which facilitates maximum ventricular filling before the intiation of contraction
______ ______ speed the impulses to apex and allow the wave of contraction to go from ____ to heart _____ (blood ejected from ventricles into pulmonary trunk and aorta)
Endocardium; Myocardium; Ventricular; Purkinje; Interventricular
SA
AV
AV Bundles; Apex; Base
Myogenesis/Hypertrophy/Repair
Myogenesis - Cardiac Muscle develops from ____ ____ surrounding the endocardial heart tube. Cells differentiate and grow into ____ cardiac muscle cells. After birth, cardiac muscle has _____ (or VERY ______ ) ability to regenerate.
Hypertrophy of individual muscle cells results in an _____ in ______ only.
Note: Damaged cardiac muscle is replaced with ____ _____.
Splanchnic Mesoderm; Single; No; Little
Increase; Size
Connective Tissue
