BIO 446L 1st Edition Lecture 21 Outline of Last Lecture I. Endocrine System continueda. Adrenal medullab. Pancreasi. Alpha, beta, delta, and peptide cellsii. Diabetesc. Thyroid glandd. Parathyroid glandII. Circulatory System 1—The hearta. Heart gross anatomyi. Atria and ventriclesii. Position and vesselsiii. Valvesb. Blood flowc. Conducting systemd. Innervation and blood supplye. Microscopic anatomyi. Heart wall layers and membranesOutline of Current Lecture I. Circulatory System 2- Blood Vesselsa. Vascular systemi. Right versus left side (pulmonary vs. systemic)b. Vascular tunicsc. Elastic and muscular arteriesd. Arterioles and capillariesi. Capillaries1. Capillary bedse. Venules and veinsCurrent LectureCirculatory system 2- blood vessels- Know the artery and vein names- Know branches of aortaThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Coronary arterieso Right subclavian artery Gives rise to carotid arteryo Left common carotid (head)o Right common carotid (arms)- The vascular systemo Right ventricular side goes to the lungs= pulmonary circulationo Left ventricle to aorta= systemic circulation At tissue level, blood is exchanged then returned to the hearto Vascular beds in parallel Blood in the right ventricle only goes to one vascular bed, the pulmonary Outflow from left ventricle goes to many vascular beds, head, upper limbs, digestive tract, hearto Blood flow starts in pulmonary artery or aorta (elastic arteries) then go to large muscular arteries then to arterioles, then to capillaries, then capillary beds (where O2, other gases, and nutrients are exchanged), then to venules, then veins, then the vena cava, and finally pulmonary veinso Flow happens because of the pressure gradient Therefore, lowest pressure gradient is at the veins (vena cava and pulmonary veins), as the gradient moves from high to low P- Vascular tunicso Blood vessels composed of tunics, vessel layerso Tunica intima= innermost layer Simple squamous epithelia= endothelium- Sits on basement membrane with loose connective tissue- Capillaries only have this layero Tunica media Separated from intima by connective tissue layer and elastic lamina- Elastic lamina has holes in it to receive nutrients and O2 Concentric smooth muscle layer and elastic fiber, type III collagen, peptidoglycan, glycoproteinso Adventitia Lots of elastic fibers, Type I collageno vasa vasorum external/alternative blood supply outside vessel- microcirculation—arteries and capillarieso small vessel circulationo arterioles—layer thickness is different 1-2 layers of smooth muscle- Adventitia layer is very thin Very sensitive to sympathetic outflow- Vessels will constrict/dilate Arterioles meta-arterioles (smooth muscle is more sparse) capillary sphincters (dilar and constrict to control and direct blood flow)- Capillary sphincters when constricted, bypass capillary bed and increase velocity of flow- When dilated, well-perforated blood flow through capillary bedo Capillaries Continuous= most numerous- Regulatory capillaries- Very tight junctions in epithelial layer- Pericytes= contractileo Help with moving across epithelia Transcytosis Fenestrated- Found where need to facilitate hormone transport (endocrine glands, kidneys)- Continuous epithelial cells- Pores, fenestrations in kidneys are not completely open Sinusoid- Very leaky, large, open fenestrations- Bigger than other capillaries - Noncontinuous epithelia- Found in bone marrow, liver, speen Differences in structural organization- Simple pathway- Arteriovenus shunt= anastomoseso Like capillary sphincter when constricted- Portal systemo Capillary bed venuole vein capillary bedo Venules Very thin walls Endothelial layer Pericytes Postcapillary venules= venules that come off capillary system take part in immune response- WBC migration from wall into tissue (squeeze between endothelial cells)o Veins At any time, most of the blood in the circulatory stem is in the
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