Test 2 Anatomy and Physiology
Major Types of Blood Vessels
Aorta, Arteries, Arterioles, Capillaries, Venules, Veins, Superior Vena Cava, Inferior Vena Cava
Carry blood away from the heart
Carry oxygenated except for pulmonary circulation and umbilical vessels of fetus.
Direct contact with tissue cells
Directly serve cellular needs
known as exchange vessels
Composed of simple squamous epithelium
Carry blood towards the heart
Carry deoxygenated except for pulmonary circulation and umbilical vessels of fetus.
Recovers excess tissue fluid that leaks from circulation and returns fluid (lymph) to blood.
Three layers of Blood Vessels
Tunica intima: Innermost layer that is in " intimate" contact with blood
Tunica Media: Middle layer composed of smooth muscle of elastic CT
Tunica Externa: Outermost layer
Simple Squamous ET
flat and slick surface to reduces friction
(Thickest in Arteries)
Sympathetic vasomotor nerve fibers innervate smooth muscle
controls vasoconstriction or vasodilation
Increase Sympathetic stimulation Increase constriction (vasoconstriction)
Decrease sympathetic stimulation decrease constriction (vasodilation)
lumen diameter decrease as smooth muscle contracts; less blood delivered decrease blood flow
Lumen diameter increase as smooth muscle relaxes; more blood delivered increase blood flow.
Circulation (where blood goes)
Also called Tunica adventitia
composed mostly of loose collagen fibers that protect and reinforce BV wall
BVs to nourish BV wall; system of tiny blood vessels to nourish outermost external layer of BV wall; whereas, the lumen of BV obtain nutrients directly from blood in lumen.
located near heart, conduct blood away from heart and called conducting arteries
Act as pressure reservoirs by expanding during systole and recoiling during diastole
Why aterioclerosis is so dangerous?
Because affected blood vessels do not smooth out BP
Arterioles smooth muscle contracts
Lumen diameter is constricted (increase resistance) and capillary bed served is bypassed
Arterioles smooth muscle relaxes
Lumen diameter dilates blood vessel (decrease resistance ) and the capillary bed is perfused with increased blood flow.
Capillaries are called exchange vessels
Because gases, nutrients, wastes and hormones are exchanged between blood and interstitial fluid.
Example of highly vascularized tissue
Examples of poorly vascularized tissue
(slow to heel)
Examples of Avascular (no blood vessels) tissue
Cartilage, Epithelial Tissue, cornea, lens of eye
Allows passage of fluids and small solutes. Leakier capillaries have specialized passageways that increase fluid movement.
Three types of Capillaries
in the brain form the blood brain barrier because they lack intercellular clefts and are totally enclosed with continuous tight junctions
Have large pores that increase permeability
Found in areas involved involved in filtration as in the kidneys, absorption as in intestines, and in endocrine tissue for hormone secretion think "swiss cheese like holes"
Most Permeable and occur in limited locations
Found only in the liver, bone marrow, spleen, and adrenal medulla
blood flows through
Two types of vessels make up microcirculation in capillary beds
- Vascular shunt
- true capillaries
blood flow from arteriole to venule through the capillary bed
Metarteriole and the thoroughfare channel that connect arteriole with venule and blood bypasses the capillary bed
branch into 10 to 100 exchange vessels (capillary bed) and normally branch from metarteriole
Precapillary Sphincters open
blood flows into the true capillary
Precapillary Sphincters close
blood flows through metarteriole
During vigorous excerise
- Precapillary sphincters are open going to skeletal muscle
- Precapillary sphincters are closed going into the digestive system
Veins have a large diameter lumen that offer little resistance ; increase lumen diameter decrease resistance
What are examples of Venous Sinuses?
Coronary sinus of the heart
Dural sinuses of the brain
What are Varicose veins?
Dilated and painful veins due to incompetent (leaky) valves
Normally located in lower limbs
- Arteries=pressure reservoirs, conduits
- Arterioles=resistance vessels, control distribution
- Capillaries=exchange sites
- veins= blood reservoirs, conduits
What is blood flow?
volume of blood flowing through a vessel or an organ
varies based on need
what is blood pressure?
force of blood exerted on wall of blood vessel expressed in mm hg
Normal Adult: 120/80
Newborn Baby: 90/55
Three factors of resistance
- blood viscosity (thickness or stickiness)
- total blood vessel length
- blood vessel diameter
Viscosity effects resistance
increases blood viscosity increase resistance
increase BV increase resistance decrease blood flow
increase BV increase resistance decrease blood flow
decrease viscosity decrease resistance increase blood flow
Vessel length effect resistance
increase BV length increase resistance decrease blood flow
Vessel Diameter effects resistance
Greatest influence on resistance
Dilate BV: decrease resistance
Constrict BV: increase resistance
ex. Increase lumen decrease resistance
Mean Arterial Pressure= MAP
BP that propels blood through circulation and to tissues
Factors aiding in venous return to heart
- muscular pump
- respiratory pump
- Sympathetic venoconstriction
three main variable in regulating BP
- Cardiac output
- Peripheral Resistance
- Blood volume
increase sympathetic activity increase vasoconstriction increase BP
decrease symphathetic activity decrease vasoconstriction decrease BP
What happens when arterioles vasodilate?
decrease peripheral resistance decrease BP
What happens when veins vasodilate?
decrease venous return decrease CO decrease BP
Angiotensinogen+renin > Angiotensin1
local autoregulation to distribute blood to individual organs and tissue as needed.
involves sympathetic nervous system/ hormones to control blood flow through whole body to maintain BP and blood flow
Returns excess tissue fluid and proteins that have leaked from blood vessels back to blood.
Three major parts of the lymphatic system
- Network of lymphatic vessels
- lymph: fluid in lymphatic vessels
- lymph nodes: cleanse lymph
What are the structures of lymphatic system?
- lymph nodes
- other lymphoid tissues
Lymphatic capillaries are absent from
- bone marrow
How does leaked proteins in interstitial fluid get back into the blood?
proteins moved into permeable lymphatic capillaries because of higher IF pressure
what are lacteals?
specialized lymph capillaries present in small intestine mucosa
they digest fat and deliver fatty lymph to the left subclavian vein
pathway of lymph
- lymphatic capillaries
- lymphatic vessels
- lymphatic trunks
- lymphatic dunks
lymphoid cells consist of
- T cells
- B cells
- Dendritic cells
Lymphocytes mature into two main types
anything the body perceives as foreign and stimulates an immune response
Examples of Pathogenic antigens
- mismatched RBCs
- Cancer cells
how does t cell protect?
helper t cells : help in cloning
regulatory t cells: dampen immune response
cytotoxin t cell: attack and destroy infected cell
how does b cells protect?
plasma cells: secrete antibodies
antibodies bind to antigens in ECF
mark them for destruction by phagocytosis or other means