6. Orthostatic Hypotensionis caused by lying down and then quickly standing up. a. A sudden rush of blood out of the head causes this b. In order to compensate, baroreceptors decrease vagal inputs to increase blood pumping. B. Renal Mechanisms 1. The renal mechanism is an important long-term regulator of blood pressure control. 2. The renal hormone cascade serves to increase blood volume and blood pressure through vasoconstriction and the absorption of water.
2015 NITTANY NOTES ALL RIGHTS RESERVED ANY ATTEMPT TO REPRODUCE THESE NOTES IS PUNISHABLE BY LAWNittany NotesCheck outnittanynotes.com for Online notes!| 814-238-0623 Like us atFacebook.com/NittanyNotes BIOL 472.1Exam Pack #3 6 OF 41 STRAUSS ANNOUNCEMENTS: handout and problem sheet given in class ERRATA:none NOTES BEGIN: 10-28-15 W I. BLOOD PRESSURE A. Role of Venous Return 1. Frank Starling Lawstate that venous return is the major determining factor of cardiac out put. a. The heart pumps what it receives 2. There are 3 Factors:a. TheVenous Valvesi. The venous system is low pressure ii. The collapse of these valves results in Varicose Veins. b. The Skeletal Muscle Pumppumps blood as the body moves. i. Soldiers at attention of a tendency to faint, because their muscles aren’t moving and there is low venous return. c. The Thoarsic Pumpis controlled by inhalation. i. Inhalation creates a negative pressure and creates a vacuum which pulls blood up in the body. ii. Val Salva Maneuveris when the abdominal muscles contract when the glottis is closed; Occurs when you sometimes go to the bathroom. iii. Victorian women’s tight corsets reduced venous return because of a great increase in abdomen pressure. They could faint on command if they did the val salva maneuver. B. Role of Hormones1. Vasoconstrictorsinclude: a. Norephinephrinewhich is activated by the sympathetic nervous system. b. ADH(vasopressin), anti-diuretic hormone, increases water recovery that enables the recovery of body fluid such as blood. c. Indirect vasoconstriction occurs by increasing fluid volume. 2. The Renal Hormone Cascade (see fig 12-3 in handout) –MUST KNOW3. Endothelinsare potent vasoconstrictors that have local effects. 4. Vasodilatorsinclude EDRF or endothelium derived relaxing factor. a. EDRF = Nitric Oxide(NO) b. It acts via cGMP to relax smooth muscle. c. Arginineis a precursor.
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