Endocrine system Flashcards
Define sensitivity
Sensitivity is the ability of living organisms to respond or react to a stimulus
What are some secondary effects of adrenaline secretion
- Hair erector muscles contract, producing goosebumps
- Increase rate of blood coagulation
Name examples of endocrine glands
- Hypothalamus
- Pituitary gland
- Adrenal gland
- Pancreas
What is the endocrine system
The endocrine system is a collection of endocrine glands that secrete hormones directly into the bloodstream to be carried towards target cells or organs
Define a gland
A gland is a group of cells that produce and secrete chemicals for release, such as enzymes or hormones
Define a hormone
A hormone is a chemical substance produced by an endocrine gland and carried by the blood to alter the activity of specific target organs and is then destroyed by the liver
What are the characteristics of hormones
- Small, soluble molecules
- Effective in low concentrations
- Produced by 1 organ
- Secreted into and carried throughout body by the blood
- Target site is different from synthesised site
- Specific in action
What stimuli can result in adrenaline secretion
- Stress
- Fear
- Anxiety
- Anger
What are the main effects of adrenaline secretion
- Liver and muscles speed up breakdown of glycogen to glucose so blood glucose levels increase
- Liver increases metabolic rate so more energy is released in respiration
- Heart rate increases so oxygen and nutrients are carried to muscles faster
- Lungs increase rate and depth of ventilation to take in more oxygen
- Skin arterioles vasoconstrict so more blood can be channelled to muscles
- Pupils dilate to enhance vision
What happens when blood glucose concentration increases beyond the norm
- Pancreas detects increase in blood glucose concentration and secretes more insulin into blood
- Blood transports insulin to body cells, liver and muscles
- Insulin promotes the uptake of glucose by almost all body cells and stimulates liver and muscles to convert excess glucose to glycogen
- Negative feedback sent to pancreas to prevent further corrective action once blood glucose concentration decreases to norm
What happens when blood glucose concentration decreases below the norm
- Pancreas detects decrease in blood glucose concentration and secretes more glucagon into blood
- Blood transports glucagon to body cells, liver and muscles
- Glucagon stimulates liver and muscles to convert glycogen to glucose and increases the release of glucose from liver into blood
- Negative feedback sent to pancreas to prevent further corrective action once blood glucose concentration increases back to norm
What endocrine disorder is marked by high blood glucose concentration
Diabetes mellitus
What is type 2 diabetes
- Known as late-onset diabetes
- Caused by a decreased response to insulin in target tissues
What is type 1 diabetes
- Known as early-onset diabetes
- Caused by islets of Langerhans in pancreas not producing enough insulin
What are some signs of diabetes mellitus
- Persistently high blood glucose concentration
- Wounds difficult to heal
- Presence of glucose in urine
