Final (rest of information) Flashcards
Blood vessels go into…
capillary beds then into the venous system, where most blood volume is (60%)
All vessels consist of what?
A lumen (central blood containing space, blood vessels are tubes), walls of all vessels minus capillaries have three layers
3 layers of blood vessels:
Tunica intima: innermost layer, made of endothelium and subendothelial layer
Tunica media: middle layer composed of smooth muscle and sheets of elastin, bulkiest layers responsible for maintaining blood flow/pressure
Tunica Externa: outermost later, composed of loose collagen fibers, infiltrated with nerve fibers
What is the vaso vasorum?
conceptually similar to the conary blood supply, small blood vessels that feed larger blood vessels and remove waste
Flow of blood?
Arteries- Capillaries- Veins
3 groups of arteries?
Elastic, Muscular, Arterioles
Elastic arteries? (big)
Thick-walled, low-resistance lumen, found in the aorta, inactive in vasoconstriction, pressure reservoirs that expand/recoil as blood leaves heart
Muscular arteries? (medium)
delivering blood to organs
Thickest tunia media with more smooth muscle, less elastic tissue, Active in vasoconstriction
Arterioles? (small)
Larger contain all 3 tunics, small are single layer of smooth muscle
Control flow into capillary beds via vasodilation/constriction, change diameters change resistance to blood flow
What are capillaries?
walls thin tunica intima, one cell forms entire circumference
Functions: exchange gases, nutrient, waste, etc. between blood and interstitual fluid
What stabilizes capillaries?
Pericytes: spider-shaped stem cells help stablize capillary walls, control permeability
How are capillaries joined?
endothelial cells joined by tight junctions with intercellular clefts
3 kinds of capillaries?
Continuous, fenestrated, sinusoidal
Continuous capillaries? (least permeable)
Abundant in skin, muscles, and lungs, often have pericytes, Pinocytotic vesicles ferry fluid
Brain capillary lack intercellular clefts, and only have tight junctions
Fenestrated capillary? (medium permeable)
Occur in areas of filtration or absorptions (kidney, small intestine)
Holes that tunnel through endothelial cells
Usually covered by a thin diaphragm made of glycoproteins
Sinusoidal capillaries (most permeable)
In the liver, bone marrow, spleen
Large intercellular clefts, incomplete basement membrane, irregularly shaped
Blood flows slowly
What are capillary beds?
where arterioles and venules meet, referred to as the microcirculation
2 features of capillaries in serous intestine?
Vascular shunt: channel that connects arteriole with venule, bypasses capillaries
Precapillary sphincter: cuff of smooth muscle surrounding capillary that branches off metarteriole, acts as valve regulating blood flow to capillary bed
Defintion of veins
Carry blood toward the heart, beginning when capillary beds unite and merge into larger veins
Have tunics but thinner walls with large lumens
Definiton of venules
Capillaries unite to form postcapillary venules
Endothelium, few pericytes, very porous
Large venues have layers of smooth muscle cells
How is blood pressure maintained?
Blood pressure is lower than in arteries, large diameter lumens offer resistance, venous valves prevent backflow, Skeletal Muscles help blood flow through veins, and pulsing of nearby arteries
What are anastomoses?
Interconnections of blood vessels, provide alternate pathways
What are the 3 sources of blood flow resistance?
Blood viscosity- higher viscosity= more resistance
Total blood vessel length- longer= more resistance
Blood vessel diameter- thinner= more resistance, the greatest impact on resistance,
Blood flow proportional?
Blood flow (F) is directly proportional to blood pressure gradient (P), as P increases blood flow speed up
Blood flow inversely proportional to peripheral resistance (R) F= DeltaP/ R
Change in pressure…
drives blood flow, resistance opposes flow
As we move through the circulatory system…
Mean pressure falls
2 factors that regulate blood pressure in arteries
The elasticity of arteries close to the heart
The volume of blood forced into them at any time
Normal blood pressure?
Systolic pressure is normally less than 120 mm Hg, and Diastolic pressure is normally less than 80 mm Hg
Regulation of blood pressure in capillaries?
Ranges from 35 mm Hg to 17 mm Hg, low pressure is desirable because high BP ruptures capillaries
Regulation of BP in veins?
Small pressure gradient ( 15 mm Hg), low pressure due to effects of peripheral resistance, low pressure of venous side requires adaptations to help with venous return
4 factors that promote blood flow?
Skeletal muscle, repiratory system, smooth muscle, valves
3 factors to regulate blood pressure?
CO, PR, blood volume
Short term reg: neural control
Control BP by regulating resistance/ CO
MAP maintained by altering BV diamteter
Vasometer center sends impulses via. sympathetic to BV (causes vasometer tone)
Barorecptors give negative input, decreases BP
Chemoreceptors check for drop in O2 or increase in Co2, send signals to get blood to lungs
Regulated by brain centers (medulla, cerebral cortex, hypothalamus)
Short-term reg: hormonal control
Epinephrine/ norepinephrine increase CO and vasoconstriction, ADH and Angiotensin 2 stimulate vasoconstriction, ANP decreases BP and generlized vasodilation
Long term reg: hormonal/ renal control
Nor(epinephrine) increases heart contractility. via. Cyclic AMP second messanger
Direct hormonal mechanism in kidney?
Alters BV independently of hormones, increased BP/BV causes elim. of urine (BP lower)
decreased BP/BV causes kidneys to conserve water (BP rises)
Indirect mechanism in kidneys?
Renin released from renals, turns angiotensinogen to angiotensinogen I, angiotensinogen I converts to angiotensinogen II , which stiumlates ADH secretion, increasing BP
Hypertension vs Hypotension
Elevated arterial BP higher than 140/90
Low BP below 90/60
4 steps of tissue perfusion?
Delivery of O2/ nutrients to, removal of wastes, tissue cells
Gas exchange in lungs
Apsorption of nutrients in digestive tract
Urine formation in kidneys
Rate of flow is…
precisely regulated to provide proper function to a given tissue or organ
Tissue perfusion controlled…
extrinsically (whole body) and intrinsically (local)
Metabolic intrinsic controls?
Declining levels of O2, increasing metabolic products, Cause relaxation of arterioles and precapillary sphincters
Cause release of NO (balanced by endothelins), powerful vasodilator
Myogenic intrinsic controls?
Local vascular smooth muscle responds to changes in MAP to keep perfusion constant
Increased stretch: smooth muscle constricts, decreased blood flow
Reduced stretch: smooth muscle dilates, increased blood flow to tissue
Capillary exchange speed?
speed in inversely related to total # of cross sections, Slow capillary flow allows time for exchange between blood and tissues
What is capillary exchange?
Transport of gasses and soltues from blood to interstitual fluid
4 methods of capillary exchange
Diffuse directly through endothelial membranes
Pass through clefts
Pass through fenestrations
Active transport via. Pinocytotic vesicles
What is bulk fluid flow?
Fluid forced out clefts of capillaries at arterial end, most returns to blood at venous end
Bulk filud flow across capillary wals causes mixing between plasma/interstitial
Hydrostatic vs Osmotic pressure
Hydrostatic pressure- force of liquid on vessel wall
Colloid osmotic pressures- sucking pressure generate by non-diffusable proteins in vessels
What is net filtration pressure?
Forces acting on capillary bed
Flow out at arterial end (filtration)
Flow in at venous end (reabsorption)
What is the lymphatic system?
Returns insertional fluid and plasma back to blood through a network of drainage vessels (lymphatics), the base of the immune system
What is a lymph/ Lymph node?
Lymph- fluid in the vessel
Lymph node-cleanse lymph
Lymphatic capillaries?
One way (towards heart), similar to blood capillaries but more permeable due to overlapping endothelial cells (minivalves) which increase ECF volume when open
Where do they drain into?
Collecting lympatic vessels, trunks, ducts (similar structure to veins with more vavles and thinner walls)
Lymphangitis vs. Lympehdema
Lymphangitis: Inflammation of lymphatic vessels, become congested with blood and appear as red lines under skin
Lympehdema: Severe localized edema, caused by anything that prevents return of lymph to blood.
How is lymph propelled?
Low pressure system. milking action of skeletal muscle. pressure change, pulsation
Ducts drain into where?
Right lymphatic duct drains right upper arm, side of the head, thorax
The thoracic duct drains the rest of the body
Lymphoctyes?
T and B cells, protect against antigens, manage immune response, produce antibodies
Macrophage and dendritic cells?
Activate T cells, capture antigens, phagotize substances
What is lymphoid tissue?
Proliferation site for lymphocytes
Body organ: diffuse lymphoid tissue, loose arrangemnt of lymphoid cells and reticular fibers
Nodules: follicles, tight arrangment of lymphoid cells and retucylar fibers
Primary vs. secondary lymphoid organs?
Primary- where T and B cells mature (red bone marrow, thymus)
Secondary- where mature lymphocytes encounter antigen
lymph nodes in detail?
Cleanse lymph and act as filters, activate immune system (lymphocytes attact antigens)
Secondary lymphoid organs of the body with hundreds of nodes
Structure of lymph nodes?
Cortec- B and T cells
Medulla- B/Plasma and T cells
Sinuses- Macrophages
What are buboes?
inflamed lymph nodes that result when nodes are overwhelmed by what they are trying to destry
What is the spleen?
blood rich organ, site of lymphocyte proliferation and immune serveilance
3 functions of spleen?
Stores breakdown products of RBC, store blood platlets and monocytes, may be site of fetal erythrocyte production
What is MALT?
Mucosa-associated lymphoid tissue, protects body from pathogens (found in mucosa of repiratory tract, tonsils, appendix, etc)
What are tonsils?
Ring of lymphatic tissue around pharynx, bacetria enter crypts and are destroyed
What is Peyers Patch
Lymphoid follicles in wall of large intestine, destroy bacteria and generate memory lymphocytes
Appendix?
Offshoot of large intestine, destroy bacteria and generate memory lymphocytes
Thymus?
Lymhoid organ in neck, T cells mature here
