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BMS1021 lectures 17 to 32 (Metabolism (Blood and respiratory pigments…
BMS1021 lectures 17 to 32
Metabolism
Energy
If the
products of a reaction have a higher energy
content (free energy) than the reactants, then energy has to be put into the system to drive the reaction (pushing it uphill)
ENDOTHERMIC or ENDERGONIC
Positive
change in GIbbs Free Energy
If the
products of a reaction have a lower energy content
(free energy) than the reactants, then energy can be obtained from the system as the reaction takes place (flowing downhill)
EXOTHERMIC or EXERGONIC
Negative
change in Gibbs Free Energy
ATP hydrolysis yields -30.5 kJmol-1 of energy
Glycolysis and the Citric Acid Cycle
1
glucose
molecule yields 2
pyruvate
molecules
In;
2 ATP
Out:
4 ATP
2 NADH
Net:
**- 2 ATP
2 NADH**
anaerobic convert NADH back to NAD+ using enzyme
ethanol
or
lactate
aerobic
citric acid cycle
For every one pyruvate
**- 4 NADH
1 FADH2
1 ATP**
Metabolic regulation;
cells are in permanent metabolic disequilibrium by a constant transfer of products to the next reaction
negative
feedback; excess product
blocks
a step
positive
feedback; excess product
stimulates
a step
Enzyme regulation
Changing the activity of enzymes (allosteric regulation)
multi sub-unit proteins
Changing the activity of enzymes (competitive regulation)
can eventually be overcome by high substrate concentrations
Changing the number of enzymes (gene expression)
alcohol dehydrogenase in the liver
Compartmentalisation (specific localisation of enzymes in compartments of the cell)
oxidative phosphorylation
Temperature regulation
life strategies
poikilotherm; body temperature varies
homeotherm; body temperature is stable
endotherm; primary source of body heat is metabolic
Thermal neutral zone:
the range of ambient temperatures in which no extra metabolic work needs to be done to maintain temperature.
Don't have to do extra work to stay warm or keep cool.
ectotherm; primary source of body heat is environmental
Gas exchange and tissue
respiratory surfaces show increased area and reduced thickness
respiration on
land
is far easier than in water
respiration in water uses 20% of energy for gas exchange
oxygen diffuses much better through air than through water
Blood and respiratory pigments
functions
hydraulic
coagulation
transport
maintenance
composition
white blood cells
hematocrit
red blood cells (erthrocytes)
lack mitochondria and a nucleus and about 7-8um in size in mammals
plamsa
CARBON DIOXIDE TRANSPORT and DISSOCIATION
respiratory pigments
BOHR shift; effect of pH on O2 association
heme has a lower affinity for O2 at a lower pH
https://www.youtube.com/watch?v=QP8ImP6NCk8
Immunology
'The immune system doesn't know who the enemy is'
Innate immunity
very fast response minutes to hours
Inbuilt and do not develop or mature with exposure
External defenses
Mucous membranes
Secretions
Skin
Lysozyme in tears
Commensals (good bacteria)
Internal defenses
Antimicrobial proteins
Inflammatory response
Phagocytic cells; macrophages and neutrophils (the most abundant white blood cell)
Macrophages
found in large number in tissues
Granulocytes
not found in tissue until recruited and short lived
Basophils
Eosinophils
attack in great numbers to kill worms
Neutrophils
Natural killer cells (NK) only lymphocyte at the moment that is known as part of the inate immune system
Pattern recognition receptors
(PRR) recognise things on the pathogen but not on our own cells (PAMPs) this process is enhanced by a component in the blood called
complement
Adaptive immunity
Matures only after exposure to pathogens in many days and weeks
Specificity and memory are two hallmarks of adaptive immunity.
Types of responses
Humoral response (antibodies)
Cell-mediated response (cytotoxic lymphocytes)
Dendritic
Cells
central to switching on the adaptive immune system by presenting peptides called MHC
A.
show
B.
'shake hands'
C.
shoot cytokines into the T cell
in the lymph node
Lymphocytes; have from the beginning of life
B (make antibody as blood components)
to become antibody producing factories they need help from the T cell
the B cell receptor called immunoglobulin
IgA secreted across mucosal surfaces
IgG can bind very strongly and good toxin
IgM good a coating pathogen and stimulating phagocytosis
IgE - beneath skin
T (kill specific cells as cellular components)
created in the thymus
The only cell that can activate a T cell is a dendritic cell
CD4 T cells
(helper T cell) tells the B cell what to do and tells the
cytotoxic T cell
what to do
MHC class II
CD8 T cell
MHC class I
MHC
MHC class I is expressed on the surface of every single cell and is recognised by CD8 T cells to kill the cell
MHC class II is only on the surface of antigen presenting cells recognised by CD4 T cells to help the other cells
Vaccinations;
cause an immune response without making us sick.
Attenuated
Killed
Components
Toxins of pathogen
Examples:
Diptheria
Polio
Measles
Small Pox
presentation in lymph node by dendritic cell
activation of helper T cell
activation of antigen presenting B cell