Homeostasis and hormones Flashcards
Define homeostasis
The presence of a stable internal environment
What is a set point
A set point that some ones levels will oscillate around. This creates the individuals normal range
What is a reference range
This is often a populations reference range. It is wider than individuals and includes the breadth of a populations range.
What is the relationship between an individuals normal range and a populations reference range
An individual can be within the populations reference range but outside of their own normal range. But most will be within.
Describe a synaptic system
Neural pathway - Neurotransmitter released at synapse. Good for quick and brief responses
Describe Endocrine system
Hormonal - Released into the blood. Receptors used on specific cells. Slow. Good for widespread sustained responses
What does the endocrine system consist of
Endocrine glands secretes hormones
Blood stream carries to the target cell
Describe the job of the hypothalamus
Links the nervous system to the endocrine system. Controls secretion of many endocrine glands
Name 4 physiological variables
Blood sugar concentrations
Growth and repair
Basal metabolic rate
Blood calcium concentration
What are hormones
True hormones are chemical messengers.
They are produced in one location and transported to another through the bloodstream.
Describe receptors
Cells have specific receptors (proteins) that allow them to respond to specific hormones
Describe water-soluble hormones
Mostly peptides. Made and stored until required Travel dissolved in the blood stream Cannot cross cell membrane Receptors therefore in cell membranes 2nd messengers
What is an example of a water-soluble hormone
Adrenaline and noradrenaline
Describe lipid(fat)- soluble hormones
Steroids.
Made as required.
Travel in blood bound to a carrier protein
Can diffuse across membrane
Receptor located in cytoplasm or nucleus.
Alters gene transcription
What is an example of a lipid-soluble hormone and how it varies
Thyroid hormones - they can be stored until required unlike other lipid soluble hormones