Nutrients of life
Nutrients of life
Components of food
What does our body take up to survive?
• We need a lot of water (it has no calories)
• Fibers are important (becteria in
intestines can degrade them → what is
produced from their metabolism ends up
in our body). Makes up important stuff
• Some minerals (Na, Ca, K) we need in
larger mounts
• Trace minerals like cugald, manganese ->
also requeired for us to function
• We can't generate carbohydrates, water or
proteins. We synthesis lipids ourselves.
Calories
How much energy does our body require to survive?
• Daily energy requirement (example):
• 70% resting daily energy expenditure ( ≈ proportional to lean body mass)
• 20% physical activity (e.g. standing, walking, and sports)
• 10% digestion
• Contributions of exercise can be much higher! Maintaining body temperature in
cold environment has a large influence
Dynamic equilibrium
Excretion
• What does our body excrete?
• Carbon dioxide (not saliva or gastric juice)
• Saliva is produced by glands in mouth. It helps with digestion, we swallow it
and it remains in our body (secretion of glands). (Same for gastric juice)
• Carbon dioxide is the only one that leaves our body.
• Excretion is removal of metabolic waste (or substances) from our body.
• Which organ system produces excretions?
• Excretory/ urinative system- itself it does
not make stuff
leave the body,
it's the kidney
that makes it
work and forms
the excretion
• Respiratory- CO2
• Integumentary (skin)- e.g. urea
Absorption
• Metabolism transforms nutrients/substances:
body load
Input vs output
• In between there is metabolism: convert a substance (X) into another (Y)
Total amount of Substance X in the body = Existing body load of X + Intake or
Metabolic production of X –Excretion or Metabolic removal of X
• This is relatively stable thanks to homeostasis
, Mass balance: Daily intake and output of
water (some of it is produced by metabolism)
We can’t know if our body is in equilibrium
with the environment
Metabolism and heat
Physiology is the dynamic study of life
• The equilibrium in our body requires a lot of effort (= dynamic equilibrium). It’s
a steady state equilibrium- we need to burn energy to mantain it.
• We have mass balance (taking in substances and through metabolism running
producing waste).
→ Humans are open systems. Our bodies exchange material and heat with our
environment. So we can't be in equilbrium with the environment (only when
we're dead)
Why does our body produce heat?
• We cannot stop producing heat. It's part of life
• We need to mantain our body temperature.
• Our brian produces heat.
• Physical activity causes heat production.
Heat is a byproduct of metabolism and work
• Resting metabolic rate can be measured by determining
heat production.
• Some biosynthesis reactions create substances that keep
higher level of energy; this is coupled to the degradation
of energy compouds (like ATP). Each chemical reaction will produce some free
energy as heat.
Distribution
Distribution of substances within our body
• Nutrients, water, oxygen must be transported to
each of our body cells.
• Cellular metabolism produces heat and wastes,
which must be transported away from cells.
• Cells are surrounded by fluids that exchanges
material with the fluid in the bloodstream.
• This is how nutrients reach our cells and how the waste produced from the
cells are expelled (going back to our blood and the excreted).
• There are different barriers that need to be passed through for the nutrients to
arrive to their destination.
• The waste needs also to be returned to the blood vessels
• Transport mechanisms that drive the distribution of substances in our body:
• By diffusion nutrients/O2 are reaching each cell and cellular wastes diffuse
back into the blood stream.
• Osmosis and filtration facilitate fluid exchange at the level of the capillary
• Cellular transport mechanisms ensure exchange of nutrients and wastes at
the level of capillaries and orchestrate cellular uptake and waste removal
Nutrients of life
Components of food
What does our body take up to survive?
• We need a lot of water (it has no calories)
• Fibers are important (becteria in
intestines can degrade them → what is
produced from their metabolism ends up
in our body). Makes up important stuff
• Some minerals (Na, Ca, K) we need in
larger mounts
• Trace minerals like cugald, manganese ->
also requeired for us to function
• We can't generate carbohydrates, water or
proteins. We synthesis lipids ourselves.
Calories
How much energy does our body require to survive?
• Daily energy requirement (example):
• 70% resting daily energy expenditure ( ≈ proportional to lean body mass)
• 20% physical activity (e.g. standing, walking, and sports)
• 10% digestion
• Contributions of exercise can be much higher! Maintaining body temperature in
cold environment has a large influence
Dynamic equilibrium
Excretion
• What does our body excrete?
• Carbon dioxide (not saliva or gastric juice)
• Saliva is produced by glands in mouth. It helps with digestion, we swallow it
and it remains in our body (secretion of glands). (Same for gastric juice)
• Carbon dioxide is the only one that leaves our body.
• Excretion is removal of metabolic waste (or substances) from our body.
• Which organ system produces excretions?
• Excretory/ urinative system- itself it does
not make stuff
leave the body,
it's the kidney
that makes it
work and forms
the excretion
• Respiratory- CO2
• Integumentary (skin)- e.g. urea
Absorption
• Metabolism transforms nutrients/substances:
body load
Input vs output
• In between there is metabolism: convert a substance (X) into another (Y)
Total amount of Substance X in the body = Existing body load of X + Intake or
Metabolic production of X –Excretion or Metabolic removal of X
• This is relatively stable thanks to homeostasis
, Mass balance: Daily intake and output of
water (some of it is produced by metabolism)
We can’t know if our body is in equilibrium
with the environment
Metabolism and heat
Physiology is the dynamic study of life
• The equilibrium in our body requires a lot of effort (= dynamic equilibrium). It’s
a steady state equilibrium- we need to burn energy to mantain it.
• We have mass balance (taking in substances and through metabolism running
producing waste).
→ Humans are open systems. Our bodies exchange material and heat with our
environment. So we can't be in equilbrium with the environment (only when
we're dead)
Why does our body produce heat?
• We cannot stop producing heat. It's part of life
• We need to mantain our body temperature.
• Our brian produces heat.
• Physical activity causes heat production.
Heat is a byproduct of metabolism and work
• Resting metabolic rate can be measured by determining
heat production.
• Some biosynthesis reactions create substances that keep
higher level of energy; this is coupled to the degradation
of energy compouds (like ATP). Each chemical reaction will produce some free
energy as heat.
Distribution
Distribution of substances within our body
• Nutrients, water, oxygen must be transported to
each of our body cells.
• Cellular metabolism produces heat and wastes,
which must be transported away from cells.
• Cells are surrounded by fluids that exchanges
material with the fluid in the bloodstream.
• This is how nutrients reach our cells and how the waste produced from the
cells are expelled (going back to our blood and the excreted).
• There are different barriers that need to be passed through for the nutrients to
arrive to their destination.
• The waste needs also to be returned to the blood vessels
• Transport mechanisms that drive the distribution of substances in our body:
• By diffusion nutrients/O2 are reaching each cell and cellular wastes diffuse
back into the blood stream.
• Osmosis and filtration facilitate fluid exchange at the level of the capillary
• Cellular transport mechanisms ensure exchange of nutrients and wastes at
the level of capillaries and orchestrate cellular uptake and waste removal
