blood physiology Flashcards
cellular components of blood
- RBCs (erythrocytes)
- WBCs (leucocytes)
- platelets (thrombocytes)
plasma is ___% water
98
plasma contains what
water, ions, plasma proteins (albumin, globulin, fibrinogen), clotting factors
serum
plasma without the clotting factors
blood transports what
Oxygen, carbon dioxide, nutrients,
hormones, waste products
blood functions
- transport
- homeostasis
- protection against infections
- blood clottings
functions of RBCs
- Oxygen (O2) transport
- Carbon dioxide (CO2) transport
- Buffer
gas diffusion
high pressure –> low pressure
Gas diffuses between terminal _____ due to difference in partial pressure
bronchioles and alveoli
The rate of gas diffusion depends on the
partial pressure of gases.
how are oxygen and carbon dioxide transported in blood
can both be dissolved in blood, or bound to haemoglobin.
In addition, the majority of carbon
dioxide is transported in the form of bicarbonate
Dissolved O2 concentration =
= (PO2) x (O2 solubility at body temperature)
henry’s law
the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas
Erythrocytes (red blood cells) contain lots of _____ molecules
haemoglobin
Each haemoglobin molecule contains ___ subunits
4
Each of the 4 subunits of hemoglobin is bound to a
heme molecule
Each heme molecule (on each of the subunit of hemoglobin) binds to an
O2 molecule
→ Each haemoglobin molecule can carry up to
4 molecules O2
hemoglobin binding O2 summary
- Erythrocytes (red blood cells) contain lots of haemoglobin molecules
- Each haemoglobin molecule contains 4 subunits
- Each subunit is bound to a heme molecule
- Each heme molecule binds to an O2 molecule
→ Each haemoglobin molecule can carry up to 4 molecules O2
More red blood cells = ____oxygen that can be transported
more
Oxyhaemoglobin (Hb−O2) is formed when
O2 binds to haemoglobin
Oxyhaemoglobin is what colour
bright red-coloured molecule and so Oxygenated blood is bright red
Hb + O2 ↔ Hb−O2
reversible; where is oxygen loaded and unloaded
- Oxygen is loaded onto RBCs at the lungs (high concentration of O2)
- Oxygen is unloaded at the tissues (low concentration of O2)
The affinity of haemoglobin to O2 ____ as more O2 is bound
increases
is the curve between PO2 and O2 saturation of Hb is linear
no– sigmoidal curve
When all four heme sites are occupied by O2, the haemoglobin is said to be
saturated
when one to three of the heme sites are occupied w O2 the hemoglobin is said to be
partially saturated
A haemoglobin saturation of 100 percent would mean
every single heme unit in all of the
erythrocytes of the body is bound to oxygen.
In a healthy individual with normal
haemoglobin levels, haemoglobin saturation generally ranges from
95 to 99 percent
gases will travel from an area of higher partial pressure, to an area of
lower partial pressure
the more oxygen binds to heme, the affinity
increases
as the partial pressure of oxygen increases, a ____ percentage of oxygen molecules are bound by heme
greater
at lower partial pressures of
oxygen, ____ oxygen molecules will be bound by heme
fewer
in the lungs, at higher partial pressures of oxygen, the PO2 can change without much change in the
O2 sat, or oxygen concentration
______ plays a major role in how much oxygen is bound to heme in the lungs, as well as how much the oxygen dissociates from heme at the body tissues
partial pressure of oxygen
Although we consider venous blood returning to the heart to be deoxygenated some oxygen is still bound to haemoglobin, what is this oxygen for
This is an oxygen reserve that can be accessed when the tissues suddenly demand more oxygen.
P_50
the PO2 at 50% Hb saturation
what does P_50 indicate
Indicates the general affinity of O2 for Hb