Date post: | 24-Dec-2015 |
Category: |
Documents |
Upload: | noah-arnold |
View: | 215 times |
Download: | 2 times |
The mammalian circulatory system is a vast network of blood-filledvessels that delivers blood to every cell of the organism
The circulatory system is a mass flow system, moving bloodon mass from one part of an organism to another
The circulatory system is essential for ensuring that materials are transported between the various exchange surfaces of the organism
The capillaries of the blood system are the sites forexchange of materials between the blood and the tissues
The capillary networks surrounding the alveoli ofthe lungs are the sites at which gas exchange takes place
The capillary networks within the villi of the small intestinereceive and transport the digested food materials needed
by the cells of the organism
The circulatory systemis linked with exchange
surfaces
The Mammalian Circulatory SystemThe Mammalian Circulatory System
The heart, togetherwith the blood vessels and theblood that they contain forms
THE CIRCULATORY SYSTEM
R A L A
R V LV
C A P IL L A R IE SIN L U N G S
C A P IL L A R IE SA R O U N D
B O D Y T IS S U E S
The human heart,except during fetallife, is completelydivided into right
and left sidesThe heart has fourchambers with anupper and a lower chamber on each
sideThe upper chambers
are the right and left atria
(RA and LA), andthe lower chambers
are the ventricles(RV and LV)
Blood always entersthe heart along
veins, which deliverblood to the atria
Blood is pumpedaway from the
heart along arteries,which originate in
the ventricles
The LEFT SIDEof the heart
receivesOXYGENATED
BLOODfrom the lungs
and then deliversit to the body
tissues
The RIGHT SIDEof the heart
receivesDEOXYGENATED
BLOODfrom the body
tissues and then delivers it to the
lungs
LORD
The Human Circulatory System is a Double CirculationThe Human Circulatory System is a Double Circulation
Left side of the heart receives
Oxygenated blood and deliversit to the body tissues
Deoxygenated blood and delivers it to the lungs
Right side of the heart receives
R A L A
R V LV
C A P IL L A R IE SIN L U N G S
C A P IL L A R IE SA R O U N D
B O D Y T IS S U E S
The human circulation is a double circulation as there are two distinctcircuits along which blood flows
The heart pumpsoxygenated blood
TO the body tissuesand receives
deoxygenated bloodFROM the body
tissues
This circuit in whichblood flows from theheart TO the bodysystems and back
to the heart is calledTHE
SYSTEMICCIRCULATION
The heart pumpsdeoxygenated blood
TO the lungsand receives
oxygenated bloodFROM the lungs
This circuit in whichblood flows from theheart TO the lungs
and back to the heart is called
THEPULMONARY
CIRCULATION
The Human Circulatory System is a Double CirculationThe Human Circulatory System is a Double Circulation
lungs
head
liver
gut
kidneys
other bodyorgans
THE PULMONARY VEINdelivers oxygenated blood
from the lungs to the LEFTATRIUM of the heart
Smaller arteries branchfrom the AORTA in orderto deliver this oxygenated
blood into the various organs
The oxygenated blood enters the LEFT VENTRICLE,which pumps the blood
along the AORTA towardsthe body organs
The CORONARY ARTERIESdeliver oxygenated blood to
the heart muscle
The HEPATIC ARTERYdelivers oxygenated blood to
the liver
The RENAL ARTERIESdeliver oxygenated blood
to the kidneys
The CAROTID ARTERY delivers oxygenated blood
to the neck, head and brain
Veins carry deoxygenated bloodaway from the body organs. Theveins join to form two large veins
called the VENAE CAVAEThe VENAE CAVAE deliver
deoxygenated blood to the RIGHT ATRIUM
of the heart HEPATICVEIN
RENALVEIN
Deoxygenated bloodenters the right
ventricle from where it is pumped to the
lungs along the PULMONARY ARTERY
HEPATICPORTAL
VEIN
The liver receives bloodfrom BOTH the hepatic
artery AND theHEPATIC PORTAL
VEIN
The hepatic portal vein carries blood, rich in the products of digestion, from the gut to the liver
Naming The Blood VesselsNaming The Blood Vessels
The walls of the capillaries are only one cellthick and composed of flattened or squamous
epithelium called the endothelium
The endothelium rests on a basement membrane
Capillaries are referred to as the exchange vessels,since all the exchange of materials between the blood
and living cells takes place through their walls
The lumen of the capillary is just large enough forred cells to move along in single file
The human body contains about 40,000 kilometresof capillaries which is enough to circumscribe the
earth at the equator
Capillaries are so extensive that they permeate between and around all body cells
At the capillaries, metabolites such as oxygen and nutrients diffuse from the blood into the respiring
tissues. Metabolites such as carbon dioxide and other waste materials diffuse from the tissues into the blood
As blood in the capillaries is always moving, then steep concentration gradients for oxygen, carbon dioxide and nutrients will persist across the capillary walls
Capillaries and Metabolic ExchangeCapillaries and Metabolic Exchange
Most materials enter and leave the blood by diffusion
According to Fick’s Law...
Rate of diffusion =surface area x difference in concentration
thickness of exchange surface
The efficient rates of diffusion between the blood andbody cells occur as a result of:
• the large surface area presented by the capillaries
• the large differences in concentration of metabolites between the blood and the cells
• the thinness of the capillary walls
Capillaries and Metabolic ExchangeCapillaries and Metabolic Exchange
Capillary Cross Section
This cross-section of a capillary shows two endothelial cells formingthe wall around the lumen
Endothelial cells
LUMEN
The nucleus of one ofthe endothelial cells
(coloured red) is visiblewhilst the nucleusof the other cell is
located in a differentplane and hencenot visible withinthis thin section
The two epithelial cellsare separated fromone another by very
narrow gaps or capillary pores
through which mostsmall moleculescross the wall by
diffusionCapillary pore
Some larger moleculespass through the
endothelial cells by pinocytosis
The wall of thecapillary rests upon
a basement membrane
Capillaries and Metabolic ExchangeCapillaries and Metabolic Exchange
The cells of the body are bathed in a fluid called tissue fluid
Tissue fluid is essential for the efficient exchange of materials between the blood and the cells
Tissue fluid is formed at the arteriole end of the capillaries
CAPILLARY
TISSUE FLUID
Arteriole endof capillary
Venule endof capillary
BODYCELLS
Capillaries and Tissue Fluid FormationCapillaries and Tissue Fluid Formation
At the venule end of the capillary, the inward osmotic pull now exceedsthe outward hydrostatic pressure and some of the water re-enters the
capillary by osmosis
At the arteriole end of the capillary, the outward hydrostatic pressure isGREATER than the inward osmotic pull
Water, ions and small molecules are filtered out of the blood into the spaces between the cells - this is tissue fluid
The loss of fluid from the blood leads to a fall in hydrostatic pressure asthe blood approaches the venule end of the capillary
Tissue fluid is drained away from the cells by the lymphatic system and returnedto the circulation near the heart
CAPILLARY
TISSUE FLUID
Arteriole endof capillary
Venule endof capillary
BODYCELLS
Hydrostaticpressure
(kPa)
1.6
1.8
4.3
1.8
Summary of Tissue Fluid FormationSummary of Tissue Fluid Formation
small artery small veinlymphatic
cells
arteriole venule
capillaries tissue fluid
Tissue fluid is:• constantly being formed at the arteriole end of capillary beds• essential for the efficient exchange of materials between the blood and the cells• is constantly being drained away from the cells by lymph vessels