Physiology - Vessels

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Physiology - Vessels
2011-03-04 02:17:56

Lymphatic System:
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  1. Lymphatic System:
    returns fluid and proteins to circulatory system, picks up fat absorbed and tersfers it to the cirulatory system, serves as a filter for pathogens
  2. Edema:
    • has 2 causes: inadequate drainage of lymph, or filtration is far greater than absorption
    • -disruption of the balance between filtration and absorption causes and increase in hydrostatic pressure, a Decrease in plasma protein concentration, and an Increase in interstitial proteins
  3. Regulation of Systemic Blood PressureLearning Objectives
    • 1. Describe the activity of baroreceptors
    • 2. Explain the baroreceptor reflex to various stimuli
  4. Components of the baroreceptor reflex:
    • stimulus:change in blood pressure
    • sensory receptor: carotid artery and the aortic baroreceptors
    • integrating center: medularry cardio vascular control center
    • efferent path: parasympathetic and sympathetic neural pathways
    • effector:
    • PARA: SA node, SYMP: SA node, ventricles, veins, arterioles
  5. The baroreceptor reflex: the response to increased blood pressure
    • stimulus: increase in blood pressure
    • receptor: firing of baro receptors in carotid arteries and aorta afferent pathway: sensory neurons
    • integrating centre: cardiovascular control center in the medulla oblongata
    • efferent pathway: either decreased sympathetic out put or increased parasympathetic output
    • efferent pathway: either decreased sympathetic out put or increased parasympathetic output
    • tissue response: vaso dialation, decreased force of contraction, decreased heart rate
    • this all leads to decreased blood pressure
  6. The baroreceptor reflex: the response to orthostatic hypotension
    • stimulus: decreased mean arterial pressure upon standing
    • receptor: firing of carotid and aortic baroreceptors
    • afferent pathway: sensory neurons
    • integrating centre:cardiovascular control center in the medulla oblongata
    • efferent pathway: either increased sympathetic out put or decreased parasympathetic output
    • effector:articular smooth muscle, ventricular myocardium, SA node
    • tissue response: vasoconstriction, increased force of contraction, increased heart rate
    • system response: increased peripheral resistance, and increased cardiac out put
    • this all leads to increased blood pressure
  7. Cardiovascular Disease: Atherosclerosis and Hypertension Learning Objectives:
    • 1. Identify risk factors for cardiovascular disease
    • 2. Describe the basic events of atherosclerosis
    • 3. Define hypertension and differences between systolic and diastolic hypertension
    • 4. Distinguish between primary and secondary hypertension
  8. CVD: Risk Factors
    • Controllable: smoking, obesity, sedentary lifestyle, untreated hypertension
    • Uncontrollable: sex, age, family history
    • genetics are uncontrollable but modifiable lifestyle
    • blood lipids lead to atherosclerosis ( HDL-C versus LDL-C)
    • Diabetes mellitus: metabolic disorder contributes to developement of atherosclerosis
  9. LDL and Plaque:
  10. Definition of Hypertension:
    • generally defined as blood pressure > 140/90
    • chronically elevated
    • need to differentiate physiological from pathophysiological
    • BP may be transiently elevated in normal people
    • exercise/stress/ “White Coat” syndrome
    • higher
    • BP = more likely to be pathophysiological/ more likely to require
    • treatment
  11. Hypertension
    • is very common (35-50% of Canadian adult population affected) and increases in occurence with age, with significant morbidity and mortality.
    • Uintreated HTN shortens life by 10-20 years and over 50% will develope end organ damage despite treatment. The symptoms (fatigue, blurred vision, headache) are often clinically silent and will often go untreated as patients feel well despite HTN. Those who do detect it may have issues of compliance with their treatment.
    • The risk of developing cardiovascular disease doubles with each 20/10 mm Hg increase in blood pressure
    • Essential hypertension has no clear cause other than hereditary
    • Carotid and aortic baroreceptors adapt
    • • Risk factor for atherosclerosis
    • • Heart muscle hypertrophies
    • • Pulmonary edema
    • • Congestive heart failure
    • • Treatment: Calcium channel blockers, diuretics, betablocking drugs, and ACE inhibitors
    • predominantly an increase in systolic pressure
    • associated with: wide pulse pressure / increased stroke volume
    • predominantly an increase in diastolic pressure
    • associated with: usually reflects elevated TPR / rarely occurs without elevated systolic pressure
  14. Classification of Hypertension - PRIMARY (essential
    • - most common
    • - no clearly defined cause
    • - majority of hypertensive patients (90-95%)
    • ~35-50% of Canadian population affected
    • - unknown cause but genetic susceptibility
    • - salt sensitivity? (only60% are)
    • arteriolar constriction can lead to increased TPR (leading to increased systolic pressure and increased diastolic pressure), decreased renal blood flow, or increased renin, angiotensin, and aldosterone (which can further lead to increased arteriolar constriction.
  15. Classification of Hypertension SECONDARY
    • - occurs secondary to a disease
    • - more likely if onset of ↑BP occurs at <25 or >50 years old
    • - usually a symptom of another condition/disease
    • - ~5-10% of all cases of hypertension
    • causes:
    • • renal disease most common: ~3-5% of all cases of hypertension (nephrosclerosis)
    • • endocrine diseases hyper
    • aldosterone secretion – leads to increased blood volume
    • pheochromocytoma- catecholamine secreting tumour
  16. - OTHER
    • - malignant hypertension
    • - hypertension associated to pregnancy
  17. Prolonged hypertension can lead to:
    • - damage to retinal blood
    • vessels (blindness)
    • - damage to arterial walls
    • (atherosclerosis)
    • - damage to cerebral
    • arteries (stroke)
    • - damage to renal blood
    • vessels (kidney failure)
    • - increased work load of
    • heart
    • • hypertrophy
    • • heart failure