Blood Pressure 25. When is BP the highest naturally? What extrinsic factors migh
ID: 212765 • Letter: B
Question
Blood Pressure 25. When is BP the highest naturally? What extrinsic factors might influence it? 26. Describe hypotension & hypertension the different types & the causes of each. 27. What is resistance? 28. Describe 2 constant and 1 dynamic sources of resistance. 29. What is atherosclerosis? How does it affect resistance and blood flow? 30. What is an aneurysm? 31. Describe how the heart, blood vessels, kidneys and brain maintain BP. Be specific here-how does each factor affect BP (ie. How doe increasing CO affect 32. What is a baroreceptor? Where is it found? 33. Use the diagram for Maintaining Blood Pressure to understand the negative feedback mechanisms involved in maintaining BP. 34. What is a chemoreflex? How does it pertain to BP? 35. How do the following hormones affect BP? ANP, Angiotensin II, aldosterone, ADH, epinephrine & norepinephrine/ the tissues? of fluid flow (this may not be in black and white-thing about what the two terms 36. In what directions are the different materials exchanged between capillaries and 37. What is net filtration pressure? How does it determine the amount and direction mean and how materials cross a membrane) 38. What is edema? Describe the three major causes. 39. Describe Circulatory shock and the three types.Explanation / Answer
25.
Blood pressure indicates the pressure exerted by the circulating blood on the blood vessels. It is expressed in terms of systolic pressure that is maximum during one heart beat and diastolic pressure that is minimum in between two heart beats. The normal pressure is considered as 120 (systolic) /80 (diastolic) mmHg. In a day, blood pressure rises gradually and become maximum at the middle of the afternoon, then it goes down, and become lowest at the time of sleeping at night.
The extrinsic factors that might influence the blood pressure are (i) vasomotor nerves that regulate the vasoconstriction or vasodilation and (ii) the hormones such as adrenaline, vasopressin, angiotensin II.
26.
Hypotension: A systolic blood pressure of less than 90 mmHg and diastolic blood pressure less than 60 mmHg are considered as hypotension. Mainly two types of hypotension are reported. One is chronic asymptotic hypotension, which does not need any medication and it is considered as normal pressure. Other types of hypertension occurs due to sudden fall of blood pressure. There are three types of orthostatic hypotension;
Orthostatic hypotension: it is caused due to inability of the body to adjust the blood pressure or blood flow for the change in position.
Neurally mediated hypotension: it causes due to faulty brain signals
Severe hypotension linked to shock: due to shock, often blood pressure became so low, that adequate blood cannot be supplied to the vital organs like heart, brain, kidney etc.
Hypertension: Hypertension is considered when the normal blood pressure reaches at or above 140/90 mmHg. There are mainly two types of hypertension can be categorized. One is primary or essential hypertension and other called secondary hypertension. The exact causes for essential hypertension remain unclear, but it may be influenced by the nonspecific lifestyle (includes high salt diet, excess body weight, smoking, alcohol consumption etc.) and genetic factors. The secondary hypertension occurs due to diseased condition like chronic kidney disease, narrowing of the kidney arteries, or an endocrine disorder.
27. In context of blood pressure, resistance is the measure that slow or impede blood flow within the blood vessel. Resistance (R) is calculated as dividing the difference in pressure (P) by the blood flow.
R = P/ Blood flow
The resistance offered by the systematic circulation is called systematic vascular resistance (SVR) or total peripheral resistance (TPR) and the resistance offered by the pulmonary circulation is known as pulmonary vascular resistance.
28. According to Poiseuille’s equation
Blood flow = P r48
P represents the difference in pressure.
r is the radius of the vessel.
represents the viscosity of the blood.
represents the length of a blood vessel.
Therefore,
Resistance (R) = 8/r4
Here, the variable factors are radius, vessel length and viscosity.
Therefore, three constant parameters that always influenced the resistance are the radius of the vessel, vessel length and the viscosity of the blood.
In addition, neuronal and hormonal signals dynamically regulate resistance. For example binding of norepinephrine and epinephrine to the 1 receptor on vascular smooth muscles, cause either vasoconstriction or vasodilation respectively, which further causes alteration in resistance.