The Circulatory System Flashcards
Vaso que llega al corazón
Vena
Todos llegan al corazón, no se llaman venas ya que no transportan sangre, transportan linfa que al final desemboca en el sistema venoso
Vasos linfáticos
Dos tipos de sistema circulatorio
Sistema circulatorio menor
Sistema circulatorio mayor
Es la que existe entre el corazón y los pulmones, cuando se lleva la sangre a oxigenar
Circulación menor
Vaso que sale del corazón
Arteria
es la que existe entre el corazón y el resto del cuerpo y sus sistemas
Circulación mayor o periférico
Tres capas del corazón
Epicardio
Miocardio
Endocardio
La mas externa , llamado pericardio visceral, formada por tejido conectivo laxo, presenta fibras de colageno es el sitio donde se acumula el tejido adiposo que recubre al corazón,que puede ser muy extenso
Epicardio
Es propiamente el músculo encargado de la contracción y bombeo del corazón , formada por las células de músculo estriado cardiaco, en haces de fibras en forma de espiral.
Miocardio
Capa mas interna, está formado por un epitelio de tipo plano simple sobre una lamina basal, asentados ambos sobre una capa subendotelial de fibras de colagena, fibroblastos y algunas fibras escasas del músculo liso
Endocardio
La víscera cardiaca se encuentra dentro de una bolsa conocida como…, parietal formado por células mesoteliales y tejido conectivo,
Pericardio
El pericardio en su interior cuenta con
Abundante tejido adiposo, y pequeñas cantidades de líquido para lubricar al corazón durante su movimiento
Estructura funcional mas importante del sistema circulatorio
Capilar
Diámetro del capilar
5-7 micrómetros, que el eritrocito tiene mayor contacto con la pared vascular y aquí libera oxigeno y recoge el dióxido y monóxido de carbono.
Máximo Diámetro de la aorta
3 centímetros
Órgano formado por fibras elásticas , en su interior esta revestido por un epitelio plano simple, endotelio
Aorta
La capa elástica se va perdiendo conforme se aleja del corazón y son sustituidos por
Músculo liso el cual va a regular la presión dentro del vaso
Son un tipo de capilar que tiene tres características
Células endoteliales discontinuas
Células endoteliales suelen estar fenestradas
Hay macrofagos en contacto con la luz al mismo nivel que las células endoteliales
Sinusoides
Los vasos sanguíneos están formados por 3 capas
Túnica intima
Túnica media
Túnica adventicia
Capa cuyos componentes son un revestimiento de endotelio especializado, tejido conectivo subendotelial y una lamina generalmente fenestrada de tejido elástico
Túnica intima
Capa formada por células de músculo liso acomodados en forma espiral o circular y fibras reticulares y elásticas dispersas
Túnica media
Capa formada por una lamina elástica externa irregular y tejido conectivo elástico y fibras de colagena distribuidas principalmente en forma longitudinal
Túnica adventicia
Son vasos sanguíneos revestidos por un endotelio , por donde las células linfoides , pueden escurrirse por un proceso llamado transmigración, no se observa capa elástica pero si un sistema de fibras elásticas a lo largo de su pared, muchas cuentan con válvulas que son proyecciones de la capa intima y toman forma bicuspidea
Venas
Proceso por donde las células linfoides(celulas blancas de la sangre) pueden escurrirse y pasar al tejido para llevar acabo su función
Transmigración y diapedesis
Características de las arterias
Forma redondeada, menos deformada Pared gruesa Capa intima arrugada Tiene tres capas(túnica media prominente) Cuenta con una lamina interna elástica
Características de las venas
Plana Pared delgada Capa intima lisa No se pueden diferenciar las tres capas No tiene elástica interna
Vaso principal
La aorta
La manera de distinguirlos es que son en realidad un espacio en blanco con una célula basofila y alargada en un extremo
Capilares
Adult total vessels length is estimated at between
100,000 and 150,000 kilimeters
Propel blood through the system
Heart
Series of vessels efferent from the heart that become smaller as they branch into various organs, carry blood to the tissue
Arteries
The smallest vessels , are sites of O2,CO2, nutrients, and waste product exchange between blood and tissue
Capillaries
Complex network of thin, anastomosing tubules called
Microvasculature
Propel blood to the pulmonary and systemic circulation
Right and left ventricles
When the body is at rest ..% of the blood moves through the systemic circulation
70%
When the body is at rest ..% of the blood moves through the pulmonary circulation
18%
When the body is at rest ..% of the blood moves through the heart
12%
Myocardium is much thicker in the wall of the ventricles, particularly
The left
Flaps of connective tissue anchored in the heart’s dense connective tissue or cardiac skeleton
Valves
Cords that extended from the cusps of both atrioventricular valves and attach to papillary muscle
Chordae tendineae
Valves and cords are covered by the
Nonthrombogenic endothelium
Functions of cardiac skeleton
Anchoring and supporting the heart valves
Providing firm points of insertion for cardiac muscle
Helping coordinate the heartbeat by acting as electrical insulation between atria and ventricles
Located in the right atrial wall, also called pacemaker, is a 6 to 7mm3 mass of cardiac muscle cells with small size, fewer myofibrils and fewer typical intercalated disks
Sinoatrial SA node
Located in the floor of the right atrium, they stimulate depolarization
Atrioventricular AV node
The AV node is continuous with specialized bundles of cardiac muscle fibers the….,
AV bundles or His
The AV node is continuous with specialized bundles of cardiac muscle fibers the AV bundles (of His), that run along the interventricular septum to the apex of the heart, where they branch further as …., that extend into myocardium of the ventricles
Conducting (Purkinje) fibers
Subendocardial conducting network of myofibers usually called …
Purkinje fibers
These are pale staining fibers, larger than the adjacent contractile muscle fibers, with sparse, peripheral myofibrils and much glycogen
Purkinje fibers
Slow the heartbeat
Parasympathetic division (vagus nerve)
Accelerates activity of the pacemaker
Sympathetic nerve
Occurs when partially occluded coronary arteries cause local oxygen deprivation
Angina pectoris
Abnormalities in the structure of heart valves, produces An abnormal heart sound referred to as
Heart murmur
Wall of all blood vessels except capillaries contain
Smooth muscle
Connective tissue
Endothelium presents …, on which blood will not clot and actively secrets agents that control local clot formation
Nonthrombotic surface
Endothelium presents nonthrombotic surface on which blood will not clot and actively secrets agents that control local clot formation such as
Heparin
Tissue plasminogen activator
Von Willebrand factor
The endothelial cell regulate local vascular tone and blood flow by secreting various factors that stimulate smooth muscle contraction such as
Endothelin 1
Angiotensin converting enzyme ACE
The cell endothelial regulate local vascular tone and blood flow by secreting various factors that stimulate smooth muscle relaxation such as
Nitric oxide
Prostcyclin
Endothelium has several roles in inflammation and local immune responses, ….. Is expressed rapidly on the luminal surface when enlongated granules called Weibel Palade bodies fuse with the cell membrane
P selectin
Endothelium cells secret factors that affect the activity of local white blood cells during inflammation
Interleukins
Stimulate vasculogenesis
Vascular endothelial growth factor VEGF
Promote capillary sprouting and out growth from small existing vessels (angogenesis)
Vascular endothelial growth factor VEGF
Stimulates endothelial cells to recruit smooth muscle cells and fibroblasts to form the other tissues of the vascular wall
Angiopoietins
Release factors that initiate a cascade of events that produce fibrin from circulating plasma fibrinogen
Platelets
A fibrin framework quickly forms to stop blood loss from the damaged vessels
Thrombus
From large thrombi, solid masses may detach and be carried by the blood to obstruct distant vessels
Emboli
Individuals in the initial stages of medical conditions involving thrombus formation such as myocardial infarct, stroke, or pulmonary embolism are treated with
Tissue plasminogen activator or tPA , this is a serine protease that breaks down fibrin and quickly dissolves the clot
Are connected by gap junctions and permit vasoconstriction and vasodilatation
Smooth muscle cells
Are found in the subendotelial layer, between the smooth muscle layers and in the outer covering
Collagen fibers
Provide the resiliency required for the vascular wall to expand under pressure
Elastin fibers
Contribute to the physical and metabolic properties of the wall in different vessels affecting permeability
Proteoglycans
Hyaluronate
Consist of the endothelium and thin subendothelial layer of loose connective tissue
Intima
In arteries and large veins, the intima includes a limiting layer
The internal elastic lamina composed of elastin with holes allowing better diffusion of substances from blood deeper into the wall
Consist of concentric layers of helically arranged smooth muscle cells, interposed among the muscle fibers are amount of elastic lamellae , reticular fibers and proteoglycans produced by smooth muscle cells
Tunica media
In arteries the media have
A thin external elastic lamina separating the externa tunic
Consist principally of type I collagen and elastic fibers , and is continuous with the stromal connective tissue
Adventitia
Arteries, venules, capillaries in the adventitia
Vasa vasorum
Have more vasa vasorum than arteries because carry desoxigenated blood
Large veins
The adventitia of larger vessels contains a network of autonomic nerves fibers …, which release the vasoconstrictor Norepinephrine
Vasomotor nerves
Examples of elastic arteries
Aorta, pulmonary artery and their largest branches
Also called conducting arteries
Elastic arteries
The most prominent feature of elastic arteries is the thick media each about
10 micrometers alternate with layers of smooth muscle fibers
Important function of elastic arteries
Making blood flow more uniform
Ventricular contraction
Systole
Verticles relax
Diastole
Disease of elastic arteries and large muscular arteries , initiated by damaged or dysfunctional endothelial cells oxidizing LDLs in the tunica intima induces adhesion and intima entry of monocytes/macrophage to remove the modify LDLs
Atherosclerosis
Lipid filled macrophage accumulate and produce a pathologic sign of early atherosclerosis called fatty streaks
Foam streaks
Fibro fatty plaques, Consisting of a gruel like mix of smooth muscle cells, collagen fibers, and lymphocytes with necrotic regions of lipid,debris and foem cells
Atheromas
Predisposing factors in atherosclerosis
Dyslipidemia
Hyperglycemia of diabetes
Hypertension
In elastic arteries atheromas produce localized destruction within the wall, weakening in and causing arterial bulges called
Aneurysms
Slight dilations of the bilateral internal carotid arteries where they branch from the elastic common carotid arteries, acts as baroreceptors
Carotid sinuses
At sinuses this layer is thinner allowing greater distention when blood pressure rises
Media layer
Contains many sensory nerve endings from craneal nerve IX(glosopharyngeal)
Adventitia
Monitors blood levels of CO2 and O2 as well as hydrogen concentration pH
Chemoreceptors
Chemoreceptors are found in
Carotid bodies
Aortic bodies located in the wall of the carotid sinuses and aortic archivo
Carotid bodies and aortic bodies are parts of the autonomic nervous system called
Paraganglia with rich capillary network
Paraganglia capillary network are surrounded by glomus type I cells filled with dense core vesicles containing
Dopamine
Acetylcholine
And others which are supported by small satélite type II cells
Appropriate ion channels in the glomus cell membranes respond to stimuli in
The arteria blood
Hypoxia low O2
Hypercapnia excess CO2
Acidosis
Glosopharyngeal nerve form sinapses with the glomus cells and signal brain center to initiate
Cardiovascular and respiratory adjustments that correct the condition
Distribute blood to the organs and help regulate blood pressure by contracting or relaxing smooth muscle in the media, the intima has a thin endothelial layer and prominent internal elastic lámina, media contains up to 40 layers of large smooth muscle and external elastic lámina, and adventitia only connective tissue with vasa vasorum and lymphatic capillaries
Muscle arteries
Outer diameter of muscle arteries
10 - 1 mm
Outer diameter of An small arteries
1.0- 1 mm
Intima layer only endothelium, 3-10 layers of smooth muscle in media and adventitia only connective tissue without vasa vasorum and his function is to distribute blood to arterioles adjusting flow with vasodilatation and constriction
Small arteries
Size of 1or 2,of media layers of smooth muscle indicating organ’s microvasculature where exchanges occurs, subendotelial layer thin, elastic lamina absent and media Consist of the circularly arranged smooth muscle cells
Arterioles
Arterioles outer diameter
Less than 0.1 mm
The major determinants of systemic blood pressure
Arterioles
Elevated blood pressure secundarily to renal or endocrine problems increase of arteriolar constriction
Hypertension
Microvascular pathways in which blood flows through two successive capillary bed separated by a portal vein
Portal system
Arterioles supplying a capillary bed typically form smaller branches called
Metarterioles in which smooth muscle cells are dispersed as bands that act as precapillary sphinters
Distal portion of metarteriole called…, lack smooth muscle and merges with poscapillary venules
Throughfare channel
Examples of portal system
Hypothalmic hypophyseal
Hepatic portal
The precapillary sphinters that contract and relax to control the entry of blood, a cycle with…..cylces per minute
5 to 10 cylces per minute
Diameter of a capillaries and their length
From 4 to 10 micrometers diameter
More than 50 micrometer
