Transcript Tutorial June 25 - University of British Columbia

Tutorial June 25
Bio 155
Blood
• Cellular component:
1) RBC
2) WBC
3) Platelet
• Rh Factor
• A woman is at risk when she has a negative Rh factor and
her partner has a positive Rh factor. This combination can
produce a child who is Rh positive.
• While the mother's and baby's blood systems are separate
there are times when the blood from the baby can enter
into the mother's system. This can cause the mother to
create antibodies against the Rh factor, thus treating an Rh
positive baby like an intruder in her body. If this happens
the mother is said to be sensitized.
• A sensitized mother's body will make antibodies. These
antibodies will then attack an Rh positive baby's blood,
causing it to breaking down the red blood cells of the baby
and anemia will develop. In severe cases this hemolytic
disease can cause illness, brain damage and even death.
Capillary Network:
• Blood flows from
arterioles through
metarterioles, then
through capillary
network
• Venules drain network
• Smooth muscle in
arterioles,
metarterioles,
precapillary sphincters
regulates blood flow
Capillary Exchange and
Interstitial Fluid Volume Regulation
• 1) Blood pressure, 2) capillary permeability,
and 3) osmosis affect movement of fluid from
capillaries
• A net movement of fluid occurs from blood
into tissues. Fluid gained by tissues is removed
by lymphatic system.
Fluid Exchange Across
Capillary Walls
CHP vs OP
• Capillaries are where fluids, gasses, nutrients, and wastes
are exchanged between the blood and body tissues by
diffusion.
• Fluid exchange is controlled by blood pressure within the
capillary vessel (hydrostatic pressure)(pumping action of
the heart) and osmotic pressure of the blood within the
vessel.
• The osmotic pressure is produced by high concentrations of
salts and plasma proteins in the blood.
• The capillary walls allow water and small solutes to pass
between its pores but does not allow proteins to pass
through.
Fluid Exchange Across
Capillary Walls
Movement of Fluid In and Out
• As blood enters the capillary bed on the arteriole end, the blood pressure
in the capillary vessel (hydrostatic pressure,HP) > the osmotic pressure of
the blood in the vessel. The net result is that fluid moves from the vessel
to the body tissue ( OUT).
• At the middle of the capillary bed, blood pressure (HP)in the vessel = the
osmotic pressure of the blood in the vessel. The net result is that fluid
passes equally between the capillary vessel and the body tissue. Gasses,
nutrients, and wastes are also exchanged at this point.
• On the venule end of the capillary bed, blood pressure in the vessel(HP)
< the osmotic pressure of the blood in the vessel. The net result is that
fluid, carbon dioxide and wastes are drawn from the body tissue into the
capillary vessel (IN).
Important Facts
• 24 L/Day is being filtered
• 20.4 L/Day is being reabsorbed
• 3.6 L/Day goes to lymphatic system and is
returned to the venous system
Blockage of a major lymph vessels in
leg
• The fluid lost from the capillary will not be
able to be returned to the venous system via
the lymphatic system.
• Edema (Excess fluid in the tissue)
• Increase in size Elephantiasis
protein leaking out of capillary?
• Osmotic pressure decreases
• So fluid has less chance of re-entering the
capillary at venule end
• Reabsorption rate decreases
• Excess fluid in the tissue
• Edema
Pressure and Resistance
 Blood pressure
averages 100 mm Hg in
aorta and drops to 0
mm Hg in the right
atrium
 Greatest drop in
pressure occurs in
arterioles which
regulate blood flow
through tissues
 No large fluctuations in
capillaries and veins
Blood Volume
–Most in the veins
–Smaller volumes in arteries and
capillaries
Fetal circulation:
Foramen Ovale
• a hole between the left and right atria (upper
chambers) of the heart
• A foramen ovale allows blood to go around the
lungs. A baby's lungs are not used when it grows in
the womb, so the hole does not cause problems in
an unborn infant.
• Normally this opening closes at birth. When the
lungs become functional at birth, the pulmonary
pressure decreases and the left atrial pressure
exceeds that of the right. This forces the septum
primum against the septum secundum, functionally
closing the foramen ovale.
Ductus Arteriosus
• a short broad vessel in the fetus that connects
the pulmonary artery with the aorta and
conducts most of the blood directly from the
right ventricle to the aorta bypassing the
lungs.
• If it does not close leads to pulmonary
hypertension and possibly congestive heart
failure
Ductus Venosus
• the vascular channel joining the umbilical
vein with the inferior vena cava.
• it allows oxygenated blood from the placenta
to bypass the liver.
• It closes shortly after birth as pulmonary
circulation is established and as the vessels in
the umbilical cord collapse and become
occluded.