Lecture 4 Flashcards
What are Blood Vessels for?
Delivery of Nutrients, Removal of Wastes
How do Blood Vessels deliver nutrients to tissues?
Microvascular exchange, a consequence of vessel permeability
Capillary Beds constitute highest?
Surface Area
Blood Velocity is lowest in?
Capillaries
Capillaries are known as?
Exchange Vessels
Most Blood Volume is in?
Veins
Veins are known as?
Capacitance Vessels
Arterioles are known as?
Resistance Vessels
What do Arterioles do?
-Regulate systemic vascular resistance (SVR)
-Control SVR and Blood Flow to tissues
Arterioles are mostly made of?
Smooth Muscle
Smooth muscle cells regulate Arteriole vessel?
Diameter, to keep vascular tone
Electromechanical Coupling is?
Neuron Response from Brain
Pharmacomechanical Coupling is?
From Drugs
Sympathetic NS?
-NE (Nerepinephrine) is neurotransmitter
-GPCR + IP3, release from SR
-Very common in system
-Vascular Smooth Muscle
Parasympathetic NS?
-Acetylcholine
-Bind to Muscarinic receptor (GPCR)
-cGMP dilates smooth muscle
Add NE, Endothelial Regulation of Arteriolar Tone?
Increased so Vessel Constricted
Add Acetylcholine, Endothelial Regulation of Arteriolar Tone?
It dilated
Cannot dilate if?
There is no Endothelial Cells
Autoregulation of Blood Flow (Myogenic Response)?
Vascular smooth muscle contracts in response to an increase in pressure, to prevent too much blood from rushing in (mostly in Arterioles)
Myogenic Response is due to?
Smooth Muscle Cells
Active Hyperemia?
Increased metabolic activity leading to vasodilation and increase blood flow (hyperemia) (ex. working out)
Reactive Hyperemia?
Ischemia also creates a buildup of metabolic waste products that induce reactive hyperemia once blood flow is reestablish (ex. tree falls on arm)
Ischemia?
An inadequate blood supply to an organ or part of body
Active Hyperemia with eating?
Resistance decreases so we can increase blood flow to the stomach to digest the food
Ischemia is a decrease in oxygen so you will have an?
Increase in Lactate, PC, and Adenosine and byproduct of using ATP and leads to Vasodilators
Autoregulation Metabolic Hypothesis?
Vasodilation Only (explains changes when blood flow is interrupted)
Flow-Induced Vasodilation?
Increase flow without changing Pressure (maintaining pressure)
Endothelial Regulation of Blood Flow?
Endothelium is a mechanosensor and stimulates vasodilation in response to an increase in flow by producing NO
Response to Pressure is Intrinsic to?
Vascular Smooth Muscle (Myogenic Response)
Response to flow is sensed by?
Endothelium
Blood Capillaries?
-Main Site for Exchange
-Single layer of endothelial cell
-Huge Surface Area
-Low flow velocity
-Cannot dilate
-Can’t control blood pressure
Are Blood Capillaries permeable?
Yes
Continuous Capillary?
-Similar to BBB (very strict)
-Cell-Cell Junctions
-Fluid and Proteins
Types of Capillaries?
-Continuous
-Fenestrated
-Sinusoidal
Fenestrated Capillary?
-Most common
-Very leaky
-Has holes
-Fenestrae
-Only fluid
Sinusoidal Capillary?
-No basement membrane
-Lot of big holes and gaps
-Caveolae
-Mostly in Spleen and Liver
-Capillaries are very open
4 R’s of Inflammation?
-Tumor= Swelling (increases permeability to leukocytes)
-Rubor= Redness (increases vasodilation and blood flow)
-Calor= Heat (increases vasodilation and blood flow)
-Dolor= Pain (swelling and histamines)
How Does Stuff Get Out of Capillaries?
-Convection
-Diffusion
Convection of Capillaries?
Like filtration (solutes follow water) based on high hydrostatic pressure in capillaries forces water across endothelium
2) Diffusion of Capillaries?
Like Osmosis (water follows solutes) solutes move across semi-permeable endothelium according to concentration gradient
Lymphatic System dumps into?
Left Subclavian Vein
Lymphatics do what with fluid?
Remove fluid
Removal of Excess Fluid from Tissues starts at?
Blind-ended sacs and pushes to lymph node
Lymphatic Vessels prevent?
Edema
Edema?
Build up of fluid in tissues
Largest lymphatic in the body?
Thoracic duct, empties all lymph into left subclavian vein
