Endocrine System Flashcards
What is homeostasis?
A state of overall internal chemical and physical stability that is required for the survival of cells and the body
What do homeostatic mechanisms do?
Maintain a constant internal environment despite a variable external environment
What does deviation from homeostasis indicate?
Disease
What is a set point?
The physiological value around which the normal range fluctuates
What is a negative feedback loop?
A feedback loop where the the effect opposes the original stimulus
What are the elements of a feedback loop?
Stimulus, receptor, integrator, effector, response
What is positive feedback?
Where the response increases the original stimulus
What are the two types of hormones?
Lipid hormones
Non lipid hormones, peptides
Pathway of steroids hormones
- lipid soluble - diffuse directly through the cell membrane
- enter the cytoplasm
- enter the nucleus
- form a hormone receptor complex (transcription factor)
- binds to promoter regions of genes
- stimulates or inhibits the transcription of those genes
Pathway of peptide hormones
- binds to a receptor on the cell membrane
- activates a Secondary messenger
Paracrine
Hormone stimulates a nearby cell, travels through extra cellular material
Autocrine
The hormone secretion acts on the cell itself or cell type
Which hormones does the anterior pituitary secrete?
ACTH, TSG, FSH, LH, GH, prolactin
Which hormones does the posterior pituitary produce?
ADH, oxytocin
What does the adrenal cortex secrete?
Cortisol, aldosterone, sex hormones
What does the adrenal medulla secrete?
Adrenaline and noradrenaline
What do the ovaries and testes secrete?
Sex hormones
What does the pineal gland secrete?
Melatonin
What does the thyroid secrete?
Thyroid hormone
Calcitonin
What does thyroid hormone do?
Regulates metabolism
What does calcitonin do?
Lowers blood Ca2+
What do the parathyroid glands secrete?
Parathyroid hormone
What does parathyroid hormone do?
Regulates blood calcium levels
What are normal blood glucose levels?
Fasting: 4.0 - 5.4mmol/L
After a meal: <7.8mmol/L
What is the exocrine function of the pancreas?
Secretion of digestive enzymes
Hypothalamus-pituitary-thyroid axis
- hypothalamus releases thyrotropin releasing hormone
- anterior pituitary releases thyroid stimulating hormone
- thyroid releases thyroid hormone
- thyroid hormones have negative feedback on the hypothalamus and anterior pituitary
What is hypothyroidism?
Low levels of thyroid stimulating hormone
What is hyperthyroidism?
High levels of thyroid hormone
What are symptoms of hypothyroidism?
Fatigue
Weight gain
Intolerance to cold temperatures
Dry skin
What are the symptoms of hyperthyroidism?
High heart rate High blood pressure Heavy sweating Heat intolerance Weight loss
What is pituitary dwarfism?
Underproduction of GH or insensitivity of receptors to GH during childhood
What happens to effective circulating blood volume and blood pressure when someone is bleeding internally?
They both drop
What causes and increase in blood pressure in the bleeding internally case?
Sympathetic nervous system - adrenaline
Effect of adrenaline on sweat glands and blood vessels of the skin
- blood vessels constrict
- sweat glands stimulated to secrete
What is hypovolemic shock?
An emergency condition in which severe fluid or blood loss makes the heart unable to pump enough blood to the body
What are some symptoms of hypovolemic shock?
- rapid heartbeat
- low blood pressure
- nauseous
- thirsty
- rapid shallow breathing
- weakness
Internal bleeding case: what type of cellular respiration will the casualties non essential organs be using?
Anaerobic - results in a build up in lactic acid which decreases neural function
Internal bleeding case: why is the casualty nauseous?
Lack of blood flow to the gut
What happens to cells if there is insufficient insulin in a diabetic?
Cells are starved of energy since they cannot use the glucose in the blood
What is a byproduct of the breakdown of fat?
Ketones - volatile, blown off at the lungs
What happens when ketones build up in the blood?
Ketoacidosis
