Homeostasis And Physiological Control Flashcards
What is physiology?
The study of how organisms function and how function is controlled and maintained in order to keep us alive and healthy
Physiological variable
Measure of a bodily function or bodily condition
Homeostasis
Dynamic maintenance of physiological variables within a predictable range
Negative feedback
The most common mechanism for the maintenance of physiological variables
Set point
Normal value for a physiological variable
Hypertension
High blood pressure
Hypoxemia
Low oxygen levels in the blood
Hyperglycemia
High blood glucose levels
Osmolality
Salt/water balance
Efferent pathway
Carries signals from integrating centre to effectors
Afferent pathway
Carries signals from sensors to integrating centre
Integrating centre
Compares inputs from sensors against physiological set point and elicit a response
Three main types of negative feedback
Neuronal
Endocrine
Paracrine
Negative feedback loop
Stimulus - change from normal set point
Sensors detect the change
Afférent pathway to integrating centre
Efferent pathway
Effectors to produce response
Neuronal integrating centres
Mostly in midbrain or brain stem
Hypothalamus
Pons
Medulla
What do neuronal integrating centres control?
Temperature
Osmolality
Blood pressure/flow control
Blood gas/breathing control
Sympathetic vs parasympathetic nervous system
Sympathetic - noradrenaline
Parasympathetic - acetylcholine
Human endocrine organs
Hypothalamus
Posterior pituitary
Anterior pituitary
Thyroid gland
Adrenal gland
Kidney
Pancreas
Testes
Ovaries
Tyrosine derivative hormones
Thyroxine
Adrenaline
Where is adrenaline produced?
In the adrenal medulla
Classes of hormones
Protein hormones
Steroid hormones
Amine hormones
Peptide hormone examples + where are they produced?
ADH
Oxytocin
Posterior pituitary
Polypeptide examples + where are they produced?
Insulin (pancreas)
Growth hormone (anterior pituitary)
Glycopeptides
Luteinising hormone
Follicle stimulating hormone
Thyroid stimulating hormone
Anterior pituitary gland
Eg of steroid hormones
Estradiol
Cholesterol
Testosterone
Aldosterone
Cortisol
What hormones are produced by the adrenal cortex?
Cortisol and aldosterone
Paracrine homeostatic control
Negative feedback loop operates locally
Sensory, integrating centres and effectors are all located in the same tissue
Feed forward
Anticipation of a change brings about the response to that change before the change can be detected by negative feedback sensors
Positive feedback
A change in a variable triggers a response that causes further change in that variable
Amplification of a change
