Notes
Hormones
- Endocrine glands release hormones into the blood. Only target cells with receptors respond. Steroid hormones enter cells; peptide hormones bind surface receptors.
- Release is triggered by hormonal, humoral or neural stimuli, and is mostly controlled by negative feedback.
Major glands
- Hypothalamus and pituitary: ADH and oxytocin (posterior); GH, TSH, ACTH, PRL, FSH and LH (anterior).
- Thyroid sets metabolic rate (iodine needed). Parathyroid PTH raises calcium. Adrenal cortex (aldosterone, cortisol) and medulla (epinephrine).
- Pancreas: insulin (lowers glucose) and glucagon (raises glucose). Others: pineal (melatonin), thymus, gonads, kidneys (EPO).
Diabetes
- Type 1: autoimmune loss of beta cells, so little insulin. Type 2: insulin resistance. Signs: polyuria, polydipsia, polyphagia.
Topics in this unit
Each topic has its own short notes and practice.
Practice
Insulin is released by beta cells when glucose is high and lowers blood glucose.
Aldosterone from the adrenal cortex promotes sodium reabsorption, which draws water along.
The pituitary is responding appropriately; the thyroid is not producing enough hormone.
Absent insulin due to beta cell destruction is type 1 diabetes.
The anterior pituitary makes tropic hormones such as TSH, ACTH, FSH and LH.
Cortisol raises blood glucose and suppresses inflammation and immune responses.
Free response
Write your answer first, then open the scoring guide.
Free-response question
Maria has type 1 diabetes. One morning she skips breakfast and exercises intensely. Later she eats a large pasta meal.
(a) Explain what normally happens to insulin and glucagon in a person without diabetes during the long fast and exercise.
Show the answer and scoring guide
Blood glucose falls, so alpha cells release more glucagon and beta cells release less insulin. The liver breaks down glycogen and releases glucose to raise blood glucose.
Check off the points you earned:
(b) After the pasta meal, explain why Maria's blood glucose will rise much higher than a person without diabetes.
Show the answer and scoring guide
Her beta cells were destroyed by an autoimmune attack, so she cannot release enough insulin. Without insulin, cells cannot take up glucose efficiently, and glucose stays in the blood.
Check off the points you earned:
(c) Name two symptoms of persistently high blood glucose and explain one.
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Frequent urination, excessive thirst, and hunger. Glucose in the urine pulls water out with it, so urine volume rises and the person becomes dehydrated and thirsty.
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