Cardio 1 histo (physio) Flashcards
There are 2 systems that are responsible for moving fluid around your body. They are separate but are connected components: The blood vascular component called the cardiovascular system, and the lymphatic vascular system which collects and returns excess ECF (lymph) to the blood vascular system. The cardiovascular system includes………….. circulation and …………… circulation.
pulmonary circulation
systemic circulation
The cardiovascular system includes the heart, Arteries (a series of………. vessels from the heart which carry blood to other organs), Capillaries (the smallest vessels, site of O2,CO2, nutrient and waste product exchange between blood and tissues), and veins.
efferent
What are the three layers of the heart? (from innermost to outermost)
Endocardium
Myocardium
Pericardium
…………..is also known as the visceral layer of pericardium.
EPICARDIUM
The outermost layer of epicardium is covered by simple squamous epithelium called……………
Deep to this is a fibrous elastic connective tissue.
mesothelium
Epicardium (the visceral layer of pericardium) contains the blood vessels and nerves that……… The epicardium is reflected on the great vessels entering and leaving the heart.
There is a potential space, the pericardial cavity which contains a serous (pericardial) fluid around the heart.
supply the heart
MYOCARDIUM is the most well developed layer, which consists of bundles of…………… that are attached to the thick collagenous connective tissue skeleton of the heart .
cardiac muscle
The myocardium consists of 3 cell types :
- ………….. cardiocytes, which contract to pump blood through the circulation.
- …………. cardiocytes, producing atrial natriuretic factor.
- ………….. cardiocytes, which are specialized to control rhythmic contraction of the heart.
Contractile
Myoendocrine
Nodal
Where are nodal cardiocytes located?
the sinoatrial node and the atrioventricular node.
Endocardium is the inner most layer and is composed of………………. endothelium as well as a…………… tissue .
simple squamous
sub endothelial fibroelastic connective
The endocardium participates in the formation of……………
heart valves
The…………………….. layer lies deep to the endocardial layer. It is comprised of collagenous and elastic fibers .
Small blood vessels and…………. fibers are found here .
This layer attaches to the endomysium of the cardiac muscle fibers.
Sub endocardial layer
Purkinje
Cardiac muscle cells (……………) are branched cylinders that are 85-100 µm long, 15 µm in diameter, and have what kind of nucleus?
cardiocytes
single centrally placed nucleus
What are the 4 differences to note about myocardium compared to skeletal muscle?
- The T TUBULES are found at the level of the Z DISC & are substantially LARGER than those of skeletal muscle found at the A-I junction.
- The sarcoplasmic reticulum is NOT AS EXTENSIVE as that of skeletal muscle.
- DIADS, (rather than triads seen in skeletal muscle) are typical in cardiocytes. A diad consists of a T tubule interacting with just one sarcoplasmic reticulum (instead of 2 as in skeletal muscle)
- Mitochondria are MORE ABUNDANT in the cardiac muscle and contain numerous cristae.
The cardiocytes are joined end to end by specialized junctional complexes called…………….
intercalated discs
Intercalated discs appear at varying intervals and have a STEP LIKE arrangement, with…………. components that run perpendicular to the long axis of the cell and…………….. components running parallel to the cardiocytes .
Transverse
longitudinal
The intercalated discs possess what 3 important specializations?
* These specializations allow the passage of ions to pass freely there by resulting in a wave of contraction that spreads through out the heart wall.
Desmosomes
Fascia adherens
Gap junctions
When stretched, cardiac muscle cells (myoendocrine cardiocytes) in the ATRIA secrete a potent polypeptide hormone called…………….. that stimulates diuresis and natriuresis .
Atrial cardiocytes contain membrane bound storage granules and a more highly developed Golgi apparatus and rER than their ventricular counterparts.
atrial natriuretic factor (ANF)
What does atrial natriuretic factor (ANF) do?
- prevents sodium and water reabsorption (therefore preventing hypervolemia and hypertension that can result in cardiac failure)
- relaxes the cardiovascular muscle by antagonizing the action of vasopressin and angiotensin II .
………………. is the principal mediator of ANF release as a prohormone . Once outside the atrial cell , the ANF prohormone undergoes a rapid enzymatic cleavage to produce the principal form of circulating ANF.
Increasing atrial pressure
When it comes to the fibrous skeleton of the heart,
………………………………. connective tissue with thick collagen fibers is present in these locations:
- around the bases of aorta, pulmonary artery and atrioventricular orifices.
- near the aortic valve cusp.
- at the upper portion of atrioventricular septum.
dense irregular collagenous
What are the functions of the fibrous skeleton of the heart?
- Structural support for the heart.
- Point of attachment for cardiac muscle.
- Structural discontinuity between the atrial and ventricular muscle, thus ensuring the contraction of atria and ventricles will not occur simultaneously.
CARDIAC VALVES have a core of…………. connective tissue with…………… covering both sides. The valves attach to the fibrous skeleton.
fibrous
endothelium
What are the components of the conduction system of the heart? (list in order)
Sinoatrial node (SA node) Atrioventricular node (AV node) AV bundle of His R & L bundle branches Purkinje fibers
Each wave of heart contraction is initiated in the myocardium. Contraction must begin in the atria and the atrial contraction must finish at what point?
Just before the beginning of ventricular contraction.
The cells in the AV node and internodal tract conduct impulses relatively……….
slowly
Purkinje fibers are a specialized population of cells found in the distal portions of the…….. nodes and continuing into the left and right bundle branches .
AV
What are the specialized functions of purkinje fibers?
Specialized for rapid impulse conduction. (Therefore they contain abundant glycogen)
Purkinje cells are found in what specific tissue layer?
The sub endothelial connective tissue of the ventricular walls.
What neural components innervate the heart?
Both parasympathetic and sympathetic neural components.
Ganglionic nerve cells and nerve fibers are present in the regions close to SA and AV nodes, where they affect…………………
heart rate and rhythm
Stimulation of the parasympathetic division (via the……………… nerve) slows the heart beat.
Vagus
Stimulation of the sympathetic nerve…………. activity of the pacemaker.
accelerates
Between the fibers of the myocardium are afferent free nerve endings that register pain, such as discomfort called………………., that occurs when partially occluded coronary arteries cause local oxygen deprivation
angina pectoris
…………….. is a functional syncytium of cardiac myocytes.
Myocardium
