Download - Homeostasis DL_2015 FNL
The “milieu interieur” The “sea within us”
“The living body, though it has need of the surrounding environment, is nevertheless relatively independent of it. This independence which the organism has of its external environment, derives from the fact that in the living being, the tissues are in fact withdrawn from direct external influences and are protected by a veritable internal environment which is constituted, in particular, by the fluids circulating in the body Claude Bernard
Leçons sur les Phénomènes de la Vie Communs aux Animaux et aux Végétaux (1878)
Extracellular Intracellular
Na+ (mM) 140
15
K+ (mM) 4 120
Cl- (mM) 110 20
HCO3- (mM) 24 15
Ca2+ (mM) 1 10-7
pH 7.4 7.2
Osmolarity (mOsm/l) 300
300
Composition of Body Fluids
Similar values are found in fresh and salt-water fish, amphibia, reptiles, birds and other mammals.
Body Fluid Compartments
Plasma
3L or 5% Interstitial
12 L or 15% Intracellular
25 L or 40% Total
40 L or 60% BW
Remedies for disruptions of homeostasis
Induce/activate ion channels
Proton transport
Induce catalases, SODs
Water transport, solute synthesis
DNA damage responses
Induction of the heat shock response
Changes in extracellular ion concentrations:
Changes in extracellular pH:
Presence of oxidative stresses:
Changes in osmolarity:
Exposure to UV/Radiation:
Changes in temperature:
Besides muscles, there is an extensive conduction pathway in the heart. These are modified cardiomyocytes, not nerve cells
Action Potential in non-cardiac cell (a neuron)
Depolarization:Na+ rushing INTO cell
Repolarization:K+ rushing OUT of cell
Arterial Side:10% blood volumehigh resistance vesselscontrols blood pressure
Venous Side:70% blood volumelow resistance, low pressure
Flow arterial side=Flow venous side
VASCULAR SYSTEM
Cardiac Output = the amount of blood pumped from 1 ventriclein 1 minute
In a healthy female it is about 5 L/min, in a male about 6 L/min
How would you calculate cardiac output?
CO = SV x HR
It is probably the most important index in cardiac medicine and is impaired in myocardial infarction, hypertension, valvular heart disease, congenital heart disease, cardiomyopathy, pulmonary disease, arrhythmias, drug effects, fluid overload, decreased fluid volume, and electrolyte imbalance.
(SV= stroke volume, the amount of blood (mls) ejected from the left ventricle per beat)
HR = heart rate in beats/min)
How local flow is alteredin exercise
Homeostasis: Exercise – an increase in demand for O2 and glucose
Essentially a nervous system response
Essentially endocrine responses:
RAAS – renin angiotensin activating system(kidney)
Catecholamine release – adrenal medullaVasopressin release - pituitary