Questions and Answers
Define endocrine, paracrine, and autocrine.
Endocrine: Hormones are released into circulation to act on a distant target organ (i.e. TSH, ADH); Paracrine: Hormones act locally on cells close to where they are released (i.e. estrogen and testosterone); Autocrine: Hormones produce a biologic action on the cell that released them (i.e. insulin).
What are the different structural types of hormones?
- Amines and amino acids; 2. Peptides and proteins; 3. Steroids, which are made from cholesterol.
What is the function of the hypothalamus?
The hypothalamus serves as a link between the nervous and endocrine systems. It regulates homeostasis, body temperature, hunger, behavior, emotion, and pain.
What is the role of the pituitary gland?
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Explain the concept of negative feedback and give an example.
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Explain the concept of positive feedback and give an example.
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Explain the ways in which hormones can be over-secreted.
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How does decreased hormone secretion occur?
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Adrenal insufficiency can be caused by what ways?
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With Addison's disease, what hormones and lab values will be altered?
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What can cause Cushing syndrome?
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What are the signs and symptoms of Cushing syndrome?
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What lab values will be altered in primary and secondary hyperthyroidism?
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What are signs and symptoms of hypothyroidism?
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What are the roles of insulin and glucagon?
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Define glycogenesis, glycolysis, gluconeogenesis, and glycogenolysis.
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What is insulin resistance?
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What is metabolic syndrome?
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What are polydipsia, polyphagia, and polyuria?
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What are the primary microvascular complications of diabetes?
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What are the primary macrovascular complications of diabetes?
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Study Notes
Endocrine System Terminology
- Endocrine: Hormones released into circulation to distant target organs (e.g., TSH, ADH).
- Paracrine: Hormones act locally on nearby cells (e.g., estrogen, testosterone).
- Autocrine: Hormones affect the cell that released them (e.g., insulin).
Hormone Structural Types
- Amines and Amino Acids: Simple hormone structure derived from amino acids.
- Peptides and Proteins: Chains of amino acids forming larger hormone molecules.
- Steroids: Hormones derived from cholesterol.
Hypothalamus Functions
- Bridges nervous and endocrine systems.
- Controls functions of other endocrine glands via the pituitary gland.
- Regulates homeostasis, body temperature, hunger, and pain.
- Produces releasing hormones that stimulate pituitary hormone release.
Pituitary Gland Role
- Known as the "master gland" due to its role in stimulating other endocrine glands to release hormones.
Negative Feedback Mechanism
- Maintains homeostasis by monitoring and adjusting hormone levels.
- Prevents over-secretion of hormones.
- Example: ADH release decreases when blood becomes dilute, stopping further secretion.
Positive Feedback Mechanism
- Enhances hormone release in response to stimuli.
- Example: Oxytocin increases uterine contractions, leading to more oxytocin release.
Hormone Over-Secretion Causes
- Pathological over-secretion by target glands.
- Excessive stimulation from the pituitary or hypothalamus.
- Hormones produced by neoplasms (tumors) in other sites.
- Genetic mutations affecting hormone receptors.
Hormone Under-Secretion Causes
- Disorders of the target gland, either congenital or acquired.
- Insufficient stimulating hormone from the pituitary.
- Inadequate releasing hormone from the hypothalamus.
- Defective hormones or unresponsive target organ receptors.
Adrenal Insufficiency Causes
- Primary adrenal insufficiency, such as Addison's disease due to adrenal dysfunction.
- Secondary adrenal insufficiency, from decreased ACTH stimulation.
- Tertiary adrenal insufficiency, from decreased CRH from the hypothalamus.
Addison's Disease Impact
- Insufficient secretion of cortisol and aldosterone results in high ACTH levels.
- Low aldosterone leads to low sodium and high potassium levels, causing hypotension.
Cushing Syndrome Causes
- Latrogenic causes from long-term steroid treatment.
- Over-secretion by adrenal glands due to adenomas or carcinomas.
- ACTH-secreting pituitary tumors (Cushing's disease) or ectopic ACTH tumors.
Cushing Syndrome Symptoms
- Physical features: buffalo hump, abdominal obesity, round face (moon facies).
- Physiological symptoms: muscle weakness, easy bruising, thin skin, osteoporosis.
- Other symptoms include hirsutism, immunosuppression, and psychological changes.
Hyperthyroidism Lab Values
- Primary Hyperthyroidism: Low TSH (thyroid overactivity).
- Secondary Hyperthyroidism: High TSH (pituitary overactivity).
- Elevated T4 and T3 in both types.
Hypothyroidism Symptoms
- Symptoms include weight gain, fatigue, weakness, bradycardia, and cold intolerance.
- Constipation, joint pain, anemia, and possible goiter may occur.
Insulin and Glucagon Functions
- Insulin: Facilitates glucose uptake into cells to lower blood sugar levels.
- Glucagon: Stimulates glucose release into the bloodstream when levels drop.
Metabolic Processes
- Glycogenesis: Insulin-promoted storage of glucose as glycogen.
- Glycolysis: Breakdown of glucose for energy.
- Gluconeogenesis: Formation of glucose from non-carbohydrate sources.
- Glycogenolysis: Breakdown of glycogen to release glucose.
Insulin Resistance
- Condition where insulin fails to stimulate adequate glucose uptake.
- Often associated with obesity and reduced insulin receptor numbers.
Metabolic Syndrome Overview
- A collection of conditions increasing risks for heart disease, stroke, and type 2 diabetes.
- Key features: elevated blood sugar, high cholesterol, hypertension, obesity.
Diabetes Symptoms
- Polydipsia: Increased thirst.
- Polyphagia: Increased appetite.
- Polyuria: Increased urination.
Diabetes Complications
- Microvascular: Retinopathy, nephropathy, neuropathy.
- Macrovascular: Peripheral vascular disease, coronary artery disease, heart attacks, and strokes.
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Description
Test your knowledge on the different types of hormonal actions and their definitions in this Module 9 quiz. Understand the distinctions between endocrine, paracrine, and autocrine signaling as well as the structural types of hormones. Great for students studying human biology or endocrinology.