Blood, Blood Vessels, and Bone Marrow
Blood, Blood Vessels, and Bone Marrow 315
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This 4 page Class Notes was uploaded by Skye Sampels on Monday October 26, 2015. The Class Notes belongs to 315 at Washington State University taught by Dr. Johnson in Fall 2015. Since its upload, it has received 17 views. For similar materials see Gross and Microanatomy in Biology at Washington State University.
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Date Created: 10/26/15
l Blood Marrow amp Blood Vessels Exam 3 Bone Marrow amp Blood Cell Formation o Hematopoiesis process by which blood cells are formed gt 100 billion new blood cells formed each day gt bone marrow is located in all bones 0 Red Marrow actively generates new blood cells gt contains different stages of developing blood cells gt remains in proximal epiphyses girdles and all of axial skeleton gt infantschildren most bones contain red marrow 0 Tissue Framework gt reticular connective tissue 0 reticular bers support developing blood cells gt blood sinusoids large capillaries with open intercellular junctionswide open spaces 0 Yellow Marrow dormant 0 contains many fat cells 0 located in most of the long bones of adults in appendicular skeleton 0 Cell Lines in Blood Cell Formation o All blood cells originate in bone marrow 0 all originate from blood stem cells continually divide o hemopoietic stem cell most undifferentiated blood cell gt lymphoid stem cells give rise to lymphocytes gt myeloid stem cells give rise to all other types of blood cells besides lymphocytes 0 become committed to specific cells 0 Erythrocytes are formed from proerythroblasts o Megakaryocytes form from megakaryoblasts 0 Formation of leukocytes blood cell lines gt granulocytes form from myeloblasts gt monocytes form from monoblasts gt lymphocytes form directly from lymphoid stem cells Blood Vessels 0 Structure gt 3 layers tunics 0 Tunica intima composed of simple squamous epithelium endothelium o subendothelial layer thin later of loose connective tissue 1 mm in diameter 0 Tunica media primarily sheets of smooth muscle also collagen and elastin especially in larger vessels 0 Tunica externa composed of dense connective tissue 0 Lumencentral blood filled space of a vessel 0 Arteries carry blood away from the heart 0 Difference from Veins gt thicker tunica media smaller lumenvessel size ratio more smooth muscle andor elastin 0 Types gt Elastic Arteries largest 0 diameter 25cm 1 cm 0 includes aorta and major branches 0 quotconducting arteriesquot 0 high elastin content in tunica media stores energy for continuous ow of blood gt Muscular distributing Arteries 0 lie distal to elastic arteries 0 diameter 1cm O3mm 0 includes most of the named arteries 0 thick tunica mediavessel size 0 unique features include 0 internal and external elastic laminae gt Arterioles smallest 0 tunica media contains smooth muscl 0 diameter 03mm 10micrometers 0 larger arterioles contain all 3 tunics 0 diameter of lumen can change 0 contraction of smooth muscle causes vasoconstriction o relaxation vasodiation 0 diameter of arterioles controlled by 0 local factors in the tissues 0 sympathetic nervous system 0 Capillaries smallest blood vessels the site of exchange of molecules between blood and tissue uid 0 Diameter 8 1 0 micrometers gt red blood cells pass through single le very narrow o Site Specific functions of the capillaries gt ungs oxygen enters blood C02 leaves gt small intestines receive digested nutrients gt endocrine glands pick up hormones gt kidneys removal of nitrogenous wastes 0 Structure gt endothelial cells held together by tight junctions and desmosomes gt outer tunic absent gt intercellular clefts gaps of un joined membrane between tight junctions overlap 0 small molecules can enter and exit gt pericytes supporting cells gt Two types of capillary 0 continuous most common 0 fensetrated have openings in endothelial cell membranes 0 Routes of Capillary Permeability gt 1 Direct Diffusion lipid soluble molecules gt 2 through intercellular clefts I 1 Continuous Capillaries 393 39 Red blood cell in lumen Inlercellular cleft Endothellal cell I u gt 3 through fenestrations if present 5283333 x v cm gt 4 through cytoplasmic vesicles pinocytosis quotgmwmggggk 13212 o Sinusoids gt wide leaky cpillaries found in some organs 2 Fenestrated capillaries 0 fenestrated 0 intercellular clefts are open 0 exchange of large substances gt occur in bone marrow spleen and liver o larger diametertwisted course 39 nucleus Basement membrane Pinocytotic vesicles Red blood cell ln lumen lnlercellular cle Tight junction Endothellal 5 cell Pericyte Endothelial lt SINUSOIDS cell intercellular cleft Tight junction Incomplete Nucleus of c basement membrane endothelial cell 0 Capillary Beds network of capillaries running through tissues gt Metarteriole and Thoroughfare Channels gt Precapillary sphinters bands of smooth muscle 0 reg ow of blood to tissue gt Metabolically inactive tissues have reduced blood ow through capillary beds gt Some tissues lack or have sparse capillary beds 0 epithelia and cartilage avascular 0 cornea and lens of eye nutrients from aqueous humor 0 tendons and ligaments poorly vacularized V o nutrients from connective tissues Thoroughfare channel b 4 7 HI 7 I x l L If a ltf 39 Terminal 13 039 Postcapillary arteriole venule b SBhinctors closed Termlnal rf 39 I I a 9quot quot9quot When sphincters are closed blood does not pass through a Sphinctors open true capillaries bypasses Inactive tissues 0 Veins carry blood toward the heart 0 Difference from arteries gt thinner walls larger lumenvessel size ratio thicker tunica externa 0 blood pressure is much lower than in arteries 0 smallest veins are called venules gt diameters from 8100 micrometers gt the smallest venules are called postcapillary venules o Venules join to form veins 0 tunica externa is the thickest tunic in veins gt little smooth muscle in tunica media mostly collagen o Mechanisms to Counteract Low Venous Pressure 0 muscles press against thin walled veins 0 Vascular Anatomoses l gt vessels interconnect to form vascular anatomoses gt organs receive blood from more than one arterial Valve open source gt neighboring arteries from arterial anastomoses 0 provide collateral channels gt veins anastomose more frequently than arteries 0 Vasa Vasorum gt tunica externa of large vessels have tiny arteries capillaries and veins gt vasa vasorum quotvessels of vesselsquot 0 nourish outer region of large vessels gt inner half of large vessels receive nutrients from luminal blood 0 quotGreat Vesselsquot of Circulation gt includes 0 aorta and major branches 0 pulmonary trunkpulmonary arteries amp veins 0 inferior vena cava blood returning to heart from lower body 0 superior vena cava blood returning to heart from head upper body gt 1 One way valves in some veins 0 particularly in limbs gt 2 Skeletal muscle pump v C Contracted skeletal muscle Direction of blood ow