End of CH21, beginning of CH22
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Why does CORONARY CIRCULATION have HIGH BP???!!
to ensure continuous blood flow to meet demands of active cardiac muscle tissue
What is the FUNCTION of CORONARY CIRCULATION?
- supplies blood to muscle tissue of heart
- THE HEART!!!
What happens in MAXIMUM EXERTION?
- Oxygen demand rises
- blood flow to <3 rises
Where do the CORONARY ARTERIES originate?!
@ base of ascending aorta
ATRIAL BRANCHES supply the WHAT?!
OHHHH! the R and L atria!!!
The VENTRICULAR BRANCHES take blood where?
What are ANASTOMOSES?
interconnections between arteries
Where does the GREAT CARDIAC VEIN deliver blood?
the coronary sinus
What is SYSTOLE?
- chamber ejects blood either to another chamber or an arterial trunk
What is DIASTOLE?
- chamber fills with blood and prepares for next cycle
What is the effect of NE RELEASE?
- increases HR and force of contractions
- with betareceptors
What is the effect of ACh RELEASE?
- decreses HRand force of contractions
- with muscarinic receptors
What are the LAYERS of BLOOD VESSELS?
Describe the INTIMA.
- endothelial lining
Describe the INTERNAL ELASTIC MEMBRANE.
- layer of elastic fibers
- in arteries!!
- on outside of intima
Describe the MEDIA.
has concentric sheets of smooth muscle
How is the MEDIA bound to the INTIMA?
by collagen fibers
What is the FUNCTION of the CONCENTRIC SMOOTH MUSCLES in the MEDIA?
- constrict to reduce diameter of vessels (which is sympathetic)
- relax to increase diameter of vessels (which is parasympathetic)
What is affected by changes in VESSEL DIAMETER??
BP andblood flow through tissue
Describe the EXTERNAL ELASTIC MEMBRANE.
band of elastic fibers between media and adventitia
Describe the ADVENTITIA.
- outer connective tissue sheath around vessel
- very thick
- mostly collagen, some elastic
Describe ELASTIC ARTERIES.
- large arteries
- transport a lot of blood
- ex) pulmonary trunk and aorta
Describe MUSCULAR ARTERIES.
- transport blood to skeletal muscles and internal organs
- medium sized
- ex) external carotid, brachial, and femoral arteries
- control blood flow between arteries and capillaries
- incomplete layers
- quick exchange
- slow blood flow
- endothelial tube with basal lamina
Why do CAPILLARIES have SLOW BLOOD FLOW?
to allow diffusion of material across capillary walls
What is unique about CAPILLARIES?
only blood vessel with walls that permit exchange between blood and surrounding interstitial fluid
Describe CONTINUOUS CAPILLARIES.
- complete endothelium
- connected by tight junctions and desmosomes
Describe FENESTRATED CAPILLARIES.
- has pores from incomplete endothelial lining
- permits rapid exchange of fluids
- ex) chorois plexus
- larger pores that fenestrated
- thinner basal lamina
- flattened and irregular
- found in) liver and bone marrow
What is the FUNCTION of a SINUSOID?
permit extensive exchange of fluids and large solutes
Why does blood move SLOWLY through SINUSOIDS?
to maximize time available for absorption and secretion across walls
What is a CAPILLARY BED?
interconnected unit of capillaries
Where do VEINS get blood from?
all tissues and organs and return it to the heart
Why is BP in VEINS lower?
- thinner walls
- less elastic
- smallest veins
- collect blood from capillaries
- media layer may not exist
Describe MEDIUM SIZED VEINS.
- thin media
- thick adventitia
What is an example of LARGE VEINS?
inferior and superior venae cavae
The BLOOD RESERVOIR =
- the venous system
- liver main part
change in volume
What is VASOCONSTRICTION?
when smooth muscles of walls contract and reduce volume of venus system
Where does the PULMONARY CIRCUIT start and finish?
pulmonary trunk to the entrance of the L atrium
What happens in the PULMONARY CIRCUIT?
- oxygen replenished
- carbon dioxide excreted
- oxygenated blood returns to <3 to go to systemic circuit
What are ALVEOLI?
- small air pockets
- walls thin enough for gas exchange between capillary blood and inspired air
Describe the PULMONARY VEINS.
cary oxygenated blood to L atrium
Where does the SYSTEMIC CIRCUIT start and finish?
aortic valve to R atrium
What happens in the SYSTEMIC CIRCUIT?
capillary beds in all parts of bot not supplied by pulmonary circuit are supplied
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