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Very extensive, but I saw at the first lecture that some information is missing at the end (this is the only lecture I did look at, so I recognize it). I hope that's not the case with all lectures.
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Homeostasis – nutrients of life 29-10-2018
What does our body take up to survive?
- Oxygen
- Nutrients
o Macronutrients: needed in large quantities (carbohydrates, proteins,
lipids, fibres(can’t be digested but are converted to digest). We need
macronutrients for providing energy.
o Micronutrients: needed in small quantities (trace minerals, vitamins)
o Essential nutrients: micronutrients, certain amino acids, certain fatty acids
- Water (is no nutrient because doesn’t contain calories)
Excretion is removal of metabolic waste or substances from our body.
- Integumentary system: urea
- Respiratory system: CO2
- Digestive system: faeces
Equilibrium: all acting influences are balanced or cancelled by equal opposing forces,
resulting in a stable system.
Total amount of Substance X in the body = existing body load + intake or metabolic
production – excretion or metabolic removal
All chemical reactions in our body are linked to heat production. Heat is a by-product of
metabolism. We can’t stop producing heat. We also use this heat to maintain our body
temperature.
Anabolism: you build more complex structure from smaller molecules
Catabolism: the breakdown of more complex structures
The resting metabolic rate can be measured by determining the heat production.
How does the external environment impact on our life?
- Body can deal with it
o Normal health
o Health challenge
- Body cannot deal with it
o Disease
o Death
Homeostasis refers to the ability of the body to maintain a stable internal environment
despite changes is external conditions.
,Internal environment
- Body water (60%)
o Extracellular (33%)
▪ Plasma (8%)
▪ Intersitital fluid (25%)
o Intracellular (66%)
Extracellular fluid is transported in blood or is surrounding cells. It transports O2, CO2,
nutrients etc. ECF is a transport and mixing system driven by the heart. It constitutes the
internal environment. Homeostasis involves the control of the ECF constituents.
Negative feedback: almost all the mechanisms in our body are negative feedback. This
means that the initial change of the variable always results in the correction of the
variable. This results in a steady state.
Positive feedback: the initial change results in a further change. This is not homeostatic.
A positive feedback loop can only stop when the job of the change is over.
- Injury of blood vessels
- Child birth: cervical stretch leading to uterine contractions
- Lactation: milk till the baby is becoming too big
- Nerve action potential
Homeostatic mechanisms:
- Local control: Initial changes trigger local cellular responses (e.g. blood clotting)
- Reflex control: The sensor and/or integrator of information are far away from the
effector. The response is elicited in another part of the body. This goes by
hormones and by neural signals.
The boundary between the internal and external environment: epithelial tissue
- Many substances go through the epithelial cells to enter the intercellular fluid.
For this you need membrane transporters.
,Autonomic Nervous System I 30-10-2018
You have the heart, lungs, GI system and the kidney.
These organs are connected by the vascular system
and there is a lot of transport between them.
Hormones are added to this system to make a good
communication and to make them work in a proper
way. The nervous system sends signals to all the
organs (efferent communication) and the organs
send information about their function to the central
nervous system (afferent communication).
Nervous system 2 (not controllable)
• Autonomic
• Involuntary
• Vegetative
o Parasympathetic
▪ They arise from the brain stem (number 3, 7, 9 and 10) and go to
your eye, lungs, heart, intestinal organs and to your bladder
▪ For rest and digest, building up and repairing your body (mostly
active during the night)
▪ Acetylcholine (ACH) as transmitter in post-ganglionic neurons (the
nerves split after the ganglions).
o (ortho)sympathetic
▪ The nerves come out of the thoraco-lumbar. There the synapse
connects in ganglia very closely and parallel to the spinal cord.
▪ Action and energy (fight-flight-fright)
▪ Noradrenaline or norepinephrine as transmitter in the post-
ganglionic neurons.
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