Samenvatting
Summary physiology
- Vak
- Physiology
- Instelling
- Rijksuniversiteit Groningen (RuG)
This summary contains all the information from the lectures, I had a 6,5 last year.
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Lecture 1 Scheurink -> Chapter 1/6/7 P. 37-54/201-203 and 215-227/232-233Physiology studies the functioning of the body:
molecular (intracellular) level
organ level
interactions between organisms and the environment
Special focus:
integration of function across many levels of organisation (bring elements together to create
a whole).
physiological mechanisms follow survival of the individual by staying alive and growth.
includes integumentary (skin), musculoskeletal, respiratory (pulmonary, longen), digestive
(gastrointestinal), urinary (renal, nier), reproductive, circulatory (cardiovascular, hart en
bloedvaten), nervous and endocrine and immune systems.
Fight-flight response:
activation of brain area that releases energy substrate and stimulates the cardiovascular system.
Release (afgifte) of adrenalin
activation of sympathetic system: glucose is released and FFAs are used by active muscle
heart rate and blood pressure rises
reduced immune response after stress
Communication between the brain and the body is done by chemical messengers: neurotransmitters
and hormones.
no fight / flight : pathological condition -> wat samenhangt met en te verklaren is vanuit een
bepaalde ziekte. Diseases can be internal or external caused. storage of fat in the endothelium and
chronic blood pressure too high by stress.
The function of a physiological system or event is the ‘why’ of the system or event, it is the
teleological approach: why red blood cells transport oxygen? Because cells need oxyfen and red
blood cells bring it to them. This answer explains why red blood cells transport oxygen not how.
In contrast you have the mechanistic approach: the how of a system, so you say how red blood cells
transport oxygen and nothing about the importance.
There are 5 major themes in physiology:
structure and function across all levels of organization. Subdivides into: molecular
interactions and compartmentation: verdeling van ruimte zodat functies kunnen
specialiseren.
Energy transfer, storage and use.
Information flow coordinates body functions, of DNA from generation to generation to
communication within the body.
Homeostasis maintains (behoudt) internal stability, feedback mechanisms.
Evolution
Claude Bernard: wrote about the internal environment which the body itself keeps in balance. First
from external environment but now on itself.
the internal environment of the body is the extracellular fluid ECF which is a transition
(overgang) between external environment and intracellular fluid (vloeistof) inside cells. ECF is
a buffer zone between cells and the outside world, but it has to be in a normal state.
Walter Cannon: concept of homeostasis, failure of homeostasis: Pathology.
A example of homeostasis is on slides 20-25.
1
,Negative feedback: turns response loop off, aid the system in maintaining homeostasis.
Control systems: have an input signal, controller (integrating centre, integrates incoming information
and initiates a response) and output signal that creates a response.
Stimulus: is een afwijking van het setpoint (optimale waarde). Slide 30
Some sensors are more sensitive than others, for example the sensors that
trigger reflexes to conserve water activate when blood concentration
increase only 3% above normal but sensors for low oxygen in the
blood will not respond until oxygen has decreased by 40%.
Clearance: the rate at which a substance disappears from the blood
- kidneys and liver are main organs that secrete substances.
- Hepatocytes (liver cells) metabolize different kinds of
molecules (drugs, alcohol etc) and secrete them into blood
of intestines (darmen), but saliva, sweat, breast milk and hair also contain cleared
substances.
Steady state: composition of both body compartments (ECF and ICF) is relatively stable
- no net movement of materials between the compartments
- Equilibrium (evenwicht): composition of body compartments is identical. This is not the case
in your body
- the ECF and ICF are in a relatively stable disequilibrium -> goal is to maintain dynamic steady
states of compartments, not make them exactly the same.
Positive feedback: is not homeostasis. Response reinforces the stimulus rather than decreasing it,
sending it further from the setpoint. This is eg in hormonal control of uterine contraction during
childbirth -> More stretching = more oxytocin release = more contractions (weeën) = more stretching
etc. stimulus stimulates response which stimulates stimulus etc. Slide 36.
Circadian rhythmicity: daily biological rhythm. They result from changes in a setpoint like oral body
temp rises during the day and falls during the night and the plasma cortisol peeks at 9 am and drops
really low at night.
Chapter 6 Communication is needed for integration of bodily functions. Communication is done
through the nervous system, blood, lymph, air and water. It’s done by neurotransmitters, hormones,
pheromones etc.
human body consists of 75 trillion cells which have to rapidly and good communicate.
Autocrine: one cell gives the signal to itself, hormone gives effect on the gland (klier) that him
released.
Paracrine: from a cell to neighbor cell. Hormone gives effect on his neighbor gland.
Endocrine: released from cell to blood and brought to another cell via blood transport.
Neuroendocrine molecule: chemical released from neuron.
Neurotransmission: neuron communication.
4 basis methods of cell to cell communication of which local (LC) and long-distance communication:
(LC) Gap junctions: form direct cytoplasmic connections between adjacent cells -> ions and
small molecules as ATP, amino acids and cAMP diffuse through them.
(LC) Contact-dependent signals: require interaction between membrane molecules on 2 cells
-> Cell adhesion molecules CAMs are receptors in cell-to-cell signaling, they transfer in both
directions.
(LC) Autocrine signals: act on same cell that released them paracrine signals: act on adjacent
(aangrenzende) cell from which released them.
Long-distance communication: 2 ways to coordinate function and maintain homeostasis:
2
, - Electrical signals passing along neurons, change in membrane potential.
Nervous system (use combination of chemical signals and electrical signals to communicate
over long distances) first electrical along a neuron until it reaches the end of the cell where it
translated into a chemical signal.
neurotransmitters: chemicals secreted by neurons that diffuse across a small gap to a target
cell.
neurohormones: chemicals released (gemaakt) by neurons in the blood for action at distant
targets.
- Chemical signals that travel through blood.
Endocrine system that release hormones from the pituitary (hypofyse) and hypothalamus.
hormones: secreted by endocrine glands or cells into the blood. Only target cells will respond
to the signal. Pagina 202.
Cytokines: communication molecules / regulatory peptides.
control immune responses, cell development and cell differentiation.
Pheromones: signal molecules that transfer messages between individuals of the same species,
woman can be attractive for men. Slide 49
Long-distance reflex pathways are involved in endocrine and
nervous system. They have 3 major compartments: input,
integration and output.
Input: with stimulus which is monitored by sensor
which sends input (aanvoerend) signal to integrating centre.
Integrating centre: compares input signal with setpoint
and if it’s too different it initiates an output signal.
Output: output signal travels to the target (effector)
which carries out a response to return to the setpoint.
Reflex steps:
1. Sensors are receptors: sensory receptors. They can be central or peripheral (buiten hersenen en
ruggenmerg) and all have a threshold: the minimum stimulus needed to set up a reflex response. 2.
Input signal 3.Integrating centre: lies in endocrine cell, in endocrine reflexes and lies in central
nervous system CNS with neural reflexes 4.Output signal 5.Target 6.Response: can be cellular,
tissue or organ or systemic response.
Control systems vary in their:
- Specifity: to which target cell a neuron sends it’s message.
- Nature of signal: neural: signals pass through neurons and neurotransmitters. Endocrine:
secreted in blood for distribution through the body.
- Speed: neural: very rapid. Endocrine: much slower.
- Duration of action: neural: very short, responses are mediated by neuromodulators.
Endocrine: last longer.
- Coding for stimulus intensity: neural: each signal is identical in strength, the higher the
frequency the higher the intensity. Endocrine: the more hormone secreted the higher the
intensity. Neuraal is netwerk van neuronen (zenuwcellen), Endocrien is hormoonstelsel.
Lecture 2 Scheurink -> Chapter 8/11/21 P. 260-262/392-404/700-701
3
, Brain and spinal chord (in the spine,ruggenmerg) are control centre of central nervous system (CNS).
linked to it are neurons or nerve cells, they carry electrical signals rapidly. They often release
neurotransmitters to communicate with neighboring cells.
Peripheral nervous system (PNS), located outside of skull and spine and takes information in and out
of CNS.
> Peripheral Nervous System
• Somatic nervous system -> part of peripheral nervous system with control of body movement.
§ Afferent nerves (sensory) -> waarnemingsorganen ogen, oren, neus, huid enz.
§ Efferent nerves (motor) -> spieren.
• Autonomic nervous system -> It innervates the systems that can’t be controlled by the conscious
brain such as heart, smooth muscle, blood vessels, visceral organs (liver, pancreas) and endocrine
organs
§ Sympathetic (actie) and parasympathetic (rust) nerves.
§ Both afferent (aankomen) and efferent (verlaten) nerves. Slide 4, 12 and 23
Signal -> sensory receptors -> sensory neurons -> CNS -> efferent neurons -> somatic motor neurons
-> skeletal muscles -> autonomic neurons -> sympathetic and parasympathetic control of muscles,
cells and tissues.
CNS can also initiate signals without a signal, for example when thinking or dreaming.
Sympathetic (ortho=opstaan): activation of the body,
mediated through the hypothalamus -> fight or flight.
- increase in heart rate and blood pressure, blood vessels
dilate and liver produces glucose for energy of muscles. Blood
from digestion goes to skeletal muscles
short preganglionic and long postganglionic nerves
preganglionic neurotransmitter Ach (acetylcholine).
postganglionic neurotransmitter noradrenalin by
noradrenergic receptors.
Parasympathetic: activated when body is in rest -> rest and
digest (verteren)
- Reduction (verlaging) in heart rate, vasodilation (verwijding
bloedvaten), storage of energy (anabolic)
Long preganglionic nerves and extremely short
postganglionic nerves
Most important nerve: vagus nerve, the longest of the cranial nerves.
Preganglionic neurotransmitter ACh
Postganglionic neurotransmitter : ACh, activates muscarinic receptors Figuur 11.7
Homeostasis is a dynamic balance between the autonomic branches.
Hypothalamus also contains receptors, eg for osmolarity, temperature control and water balance.
Spinal reflexes take place without input from the brain.
Para- and sympathetic pathways are antagonistic of the autonomic nervous system:
exceptions are sweat glands and smooth muscle in blood vessels, these are only controlled
by the sympathetic pathway.
they sometimes work together, eg with an erection
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