Blood Vessels basic vessel anatomy maintaining constant blood pressure aneurisms variations in circulatory pathways examples of portal systems blood supply to the brain

Tunica intima Tunica media Tunica externa endothelium BM smooth muscle collagen some elastin L. vein L. artery Tunica externa loose CT vasa vasorum Medium sized vein Medium sized artery venule arteriole capillary

To heart Valve open Vein Valve closed Contracted skeletal muscles Relaxed skeletal muscles

Precapillary sphincters Sphincters open Sphincters closed When are sphincters closed? Fingers? Muscles? Around gut? Sphincters open Sphincters closed

Hepatic portal system Portal system (2 capillary beds) IVC Hepatic sinusoids Gastric veins spleen pan Superior Mesenteric V Hepatic portal system

Portal system Arteriovenous anastomosis Arterial anastomoses Venous anastomoses Dark blue = portal light blue = systemic

Internal carotid Basilar Circle of Willis Vertebral Cerebrovascular Accident = CVA = stroke

Aneurysm: weak point in an artery or heart wall common in abdominal aorta renal arteries & brain

Cerebral vascular accident (CVA) = stroke

How to maintain constant blood pressure 1. Conducting arteries expand & recoil With increasing and decreasing pressure 2. measure pressure, adjust HR and dilate or constrict BV’s High BP Lower HR

Fig. 21.4(TE Art) Carotid body Baroreceptors Aortic body Baroreceptors Carotid sinus Baroreceptors Common carotid artery Aortic body Aortic arch Baroreceptors

Fig. 16.1(TE Art) Glossopharyngeal Nerve (CN IX) Baroreceptors sense increased blood pressure Vagus nerve (CN X) Heart rate decreases