Hormones Flashcards
Feedback regulation and coordination with the nervous system are common in
endocrine signaling.
What is the endocrine system and what does it regulate?
chemical signaling by hormones- it is one of the two basic systems for communication and regulation in the animal body.
What is a simple endocrine pathway? What is negative feedback?
Endocrine cells respond directly to an internal or environmental stimulus by secreting a particular hormone. Hormone travels in the bloodstream to target cells where it interacts with specific receptors- physiological response.
Negative- response reduces the initial stimulus
What is a simple neuroendocrine pathway? What is positive feedback?
The stimulus is received by a sensory neuron, which stimulates a neurosecretory cell. Then secretes a neurohormone, which diffuses into the bloodstream and travels to target cells.
Positive- reinforces a stimulus, leading to an even greater response
Why are insulin and glucagon considered to be an antagonistic hormone pair?
They are opposing each other. When blood glucose is high insulin is released and when it is low, glucagon is released
What do insulin and glucagon regulate?
Blood glucose level
Insulin and glucagon- What types of pathways are these? What type of feedback is involved in each?
Simple endocrine pathway - negative feedback
How is insulin doing its job of lowering blood glucose levels?
the secretion of insulin triggers the uptake of glucose from the blood into body cells, decreasing the blood glucose concentration
What’s the deal with the liver and glycogen in the presence of insulin?
Rising levels of insulin promote biosynthesis of glycogen from glucose entering the liver in the hepatic portal vein
How is glucagon doing it’s job of raising blood glucose levels?
The secretion of glucagon promotes the release of glucose into the blood from energy stores increasing the blood glucose concentration
What’s the deal with the liver and glycogen in the presence of glucagon?
When blood in the hepatic portal vein has a much lower glucose concentration, glucagon stimulates the liver to break down glycogen, convert amino acids and glycerol to glucose, and release glucose into the blood
What causes diabetes mellitus?
a deficiency of insulin or a decreased response to insulin in target tissues
What happens with regard to glucose?
Blood glucose levels rise, but cells are unable to take up enough glucose to meet metabolic needs - thus fat becomes the main substrate for cellular respiration
What can happen when fat becomes the main substrate for cellular respiration? What happens in the kidneys?
acidic metabolites formed during fat breakdown accumulate in the blood, threatening life by lowering blood pH and depleting sodium and potassium ions from the body;
The level of glucose in the blood may exceed the capacity of the kidneys to reabsorb the nutrient. glucose that remains in the kidney filtrate is excreted
What kind of disease is type 1 diabetes (insulin-dependent diabetes)?
An autoimmune disorder in which the immune system destroys the beta cells of the pancreas- destroying the person’s ability to produce insulin
When does type 1 diabetes usually show up?
During childhood
What is type 2 diabetes (non-insulin-dependent diabetes)?
A failure of target cells to respond normally to insulin
What significantly increases the risk of type 2 diabetes?
excess body weight and lack of exercise
When does type 2 diabetes usually show up?
After age 40
The hypothalamus plays a central role in integrating the
endocrine and nervous systems.
What exactly is the hypothalamus doing?
receives information from nerves throughout the body and, in response, initiates endocrine signaling appropriate to environmental conditions