Thompson LO'S (hypertension) Flashcards
pericardium
membrane that surrounds and protects heart
Layers of pericardium
- fibrous
- serous
fibrous pericardium
- superficial, tough, inelastic, dense irregular cardiac tissue
- anchors to mediastinum
Serous pericardium
- Deeper, thinner, more delicate and forms a double layer around the heart
- Outer parietal is fused to fibrous pericardium
- Inner visceral layer =epicardium that adheres tightly to heart wall
- Between the two is the pericardial cavity that contains pericardial fluid secreted by pericardial cells
Layers of heart
- epicardium
- myocardium
- endocardium
Epicardium
- Outer visceral layer of serous pericardium
- Inner layer of fibroelastic and adipose tissue
- Lined by squamous mesothelium
Myocardium
- Pumping action of heart
- Striated, involuntary cardiac muscle issue
- 95% of heart wall
Endocardium
- Squamous epithelium overlying connective tissu e
- Provides a smooth lining for the chambers of the heart and covers the valves of the heart
Left atrium
- forms most of base of heart
- Receives blood from lungs via pulmonary veins
- Pectinate muscles confined to auricle
- Bicuspid/mitral valve
Left ventricle
- trabeculae carneae and chordae tendineae that anchor cusps of bicuspid to papillary muscle
- Left ventricle to aorta
Right atrium
- Receives blood from superior and inferior vena cava and coronary sinus
- Pectinate muscles
- interatrial septum
- Tricuspid valve
Pectinate muscle
-muscles present in inner wall of left and right atria
Interatrial septum
- separates atria
- contains fossa ovalis (remnants of foreman ovale)
Right ventricle
- most anterior part of heart-
- Trabeculae carneae muscle ridges
- Separated from left ventricle by interventricular septum
- Blood passes through the pulmonary valve to the pulmonary trunk, which divides into the right and left pulmonary arteries that bring blood to the lungs
Coronary arteries
- Left main coronary artery
- Right coronary artery
Left main coronary artery
- circumflex
- left anterior descending
Circumflex
- left atrium, left ventricle
LAD
- right and left ventricles and interventricular septum
Right marginal artery
- Right ventricle and apex
Posterior descending artery/ posterior interventricular
-Right and left ventricles and interventricular septum
Right coronary artery
- Right atrium and right ventricle
Left marginal artery
-left ventricle
Blood vessel layers
- Tunica interna/intima
- Tunica media
- Tunica externa/adventitia
Tunica interna/intima
- squamous epithelium
- inner most layer
- in contact with blood
Tunica media
- smooth muscle
- Alpha and beta adrenergic receptors
- sympathetic nervous system mostly
Alpha receptor stimulation
- contraction of smooth muscle
Beta receptor stimulation
-Dilation of smooth muscle
Tunica externa/adventitia
- Elastic connective tissue (arteries) and collagen fibers (type I)
Arteries
- Thick walls to resist high pressure
- Rounder than veins
- Tunica media more muscle and elastic tissue than vein
- Smaller lumen to maintain high pressure
Types of arteries
- Large/elastic
- Medium/muscular
- Small artery/arterioles
Large/elastic artery
- Media is very thick, has collagen and elastin
- Aorta and branches, pulmonary trunk, common carotid, subclavian, verterbral and common iliac arteries under high pressure
Medium/muscular artery
- Large arteries branch into medium
- Larger quantity of smooth muscle in the intima
- Less elastin
- Less pressure
Small artery/arterioles
- Tunica media has far fewer muscle fibers
Veins
- thin walls
- Don’t retain shape
- Collapse easily
- Wider lumen lower presure
- Tunica media contain small amounts of smooth muscle
- Valves
- Tunica media thinner
Capillaries
- arterioles branch into capillaries
- fenestrated, discontinuous (sinusoids), continuous
Continuous capillaries
- most common
- found in skin, muscle, connective tissue, nervous and respiratory tissue
- cells close together with gap junctions
Fenestrated
- bowmans capsule, endocrine tissue and part of small intestine
- Rapid molecular exchange between lumen of capillary and tissues
Discontinuous capillaries/sinusoids
- bone marrow, liver and spleen
- no gap junctions between these cells and vessels allow for direct transportation from the vascular lumen to surrounding cell
Cardiac output
CO=SVXHR
Blood ejected by ventricles each minute (ml/min)
Stoke volume
- blood ejected from ventricle each cardiac cycle
- SV= EDV-ESV
Stroke volume influences
- Preload (starlings)
- Contractility
- Afterload
Preload
- initial stretching of cardia myocytes prior to contraction
Contractility
- ability of heart to eject a stroke volume at a given afterload and preload
Afterload
- force against which heart has to contract to eject blood
Starlings law of the heart
- increased filling pressure of the right heart results in increased cardiac output.
- Any increase in output of the right heart is quickly communicated to the left heart as an increased filling pressure.
Peripheral vascular resistance
- resistance of peripheral vasculature in the systemic circulation (not pulmonary)
Total peripheral resistance
- amount of force exerted on circulating blood throughout the circulatory system
systole
contraction of heart pumping blood out
Diastole
- heart relaxes after contraction
AV valves open
- atrial pressure higher than ventricular pressure
Semilunar valves open
- ventricular pressure higher then aortic and pulmonary pressure
Cardiac cycle phases
- Isovolumetric contraction
- Systolic ejection/rapid ventricular ejection
- Isovolumetric relaxation
- Passive (rapid) ventricular filling
- Active filling
Hypertension
persistent systolic blood pressure of greater than or equal to 140m Hg (>140) and/or diastolic blood pressure of greater than or equal to 90 mm Hg (>90)
Primary hypertension
Has no detectable cause (95% of cases)
Secondary hypertension
-due to a specific underlying issue (renal, endocrine, vascular diseases)
Accelerated hypertension
-a recent significant increase over baseline BP that is associated with target organ damage. Usually seen as vascular damage on funduscopic examination such as flame shaped hemorrhages or soft exudates but without papilledema
Secondary causes of hypertension
- Endocrine
- Adrenal
- Renal
- CVS
- Drugs
- Other
Pheochromocytoma
- benign tumor of chromaffin cells of the adrenal medulla which produces large amounts of NE/E –> increased vasoconstriction and cardia stimulation –> hypertension
Renal artery stenosis
- narrowing of one or more arteries of renal arteries preventing normal amounts of o2 rich blood from reaching kidneys
- Reduced GFR–> inability to excrete Na+ and water so fluid retained and blood volume and pressure cannot be reduced –> RAAS activated to increase BP
