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Questions and Answers
What is the primary action of growth hormone on tissues?
What is the primary action of growth hormone on tissues?
What can result from decreased secretion of growth hormone before puberty?
What can result from decreased secretion of growth hormone before puberty?
Which hormone is secreted from the thyroid gland in response to TSH?
Which hormone is secreted from the thyroid gland in response to TSH?
What is a consequence of hyperparathyroidism?
What is a consequence of hyperparathyroidism?
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What is the primary function of the parathyroid hormone?
What is the primary function of the parathyroid hormone?
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What disorder is characterized by hypothyroidism in adults?
What disorder is characterized by hypothyroidism in adults?
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Which effect does thyroid hormone have on the body?
Which effect does thyroid hormone have on the body?
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What is the role of the exocrine pancreas?
What is the role of the exocrine pancreas?
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What is the main function of the parathyroid hormone?
What is the main function of the parathyroid hormone?
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What condition results from an increase in growth hormone secretion after puberty?
What condition results from an increase in growth hormone secretion after puberty?
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Which of the following is NOT a function of the thyroid hormone?
Which of the following is NOT a function of the thyroid hormone?
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Which gland serves as the major regulator of calcium concentrations in body fluids?
Which gland serves as the major regulator of calcium concentrations in body fluids?
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What is the effect of hypothyroidism in infants?
What is the effect of hypothyroidism in infants?
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What hormone is secreted from the adrenal glands?
What hormone is secreted from the adrenal glands?
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Which statement about the growth hormone is true?
Which statement about the growth hormone is true?
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What is the consequence of hypoparathyroidism?
What is the consequence of hypoparathyroidism?
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What is the primary mode of secretion for hormones released by endocrine glands?
What is the primary mode of secretion for hormones released by endocrine glands?
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What is the effect of the thyroid hormone on heat production?
What is the effect of the thyroid hormone on heat production?
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Which of the following is a result of hyperparathyroidism?
Which of the following is a result of hyperparathyroidism?
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Which hormone stimulates the release of thyroid hormone from the thyroid gland?
Which hormone stimulates the release of thyroid hormone from the thyroid gland?
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What is a potential outcome of increased growth hormone secretion before puberty?
What is a potential outcome of increased growth hormone secretion before puberty?
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What is a primary function of the parathyroid hormone?
What is a primary function of the parathyroid hormone?
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Which gland secretes hormones that influence stress response?
Which gland secretes hormones that influence stress response?
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What disorder is characterized by low levels of thyroid hormone in adults?
What disorder is characterized by low levels of thyroid hormone in adults?
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What is the main function of the growth hormone?
What is the main function of the growth hormone?
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What causes myxedema in adults?
What causes myxedema in adults?
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How does parathyroid hormone affect plasma calcium concentration?
How does parathyroid hormone affect plasma calcium concentration?
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What disorder is associated with hyperparathyroidism?
What disorder is associated with hyperparathyroidism?
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Which hormone secreted from the thyroid gland helps in growth?
Which hormone secreted from the thyroid gland helps in growth?
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What is a metabolic effect of growth hormone?
What is a metabolic effect of growth hormone?
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What is a consequence of decreased secretion of parathyroid hormone?
What is a consequence of decreased secretion of parathyroid hormone?
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What is the primary role of the endocrine pancreas?
What is the primary role of the endocrine pancreas?
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What condition is associated with an increase in growth hormone secretion before puberty?
What condition is associated with an increase in growth hormone secretion before puberty?
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Which hormone is responsible for stimulating the thyroid gland to release thyroid hormone?
Which hormone is responsible for stimulating the thyroid gland to release thyroid hormone?
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What disorder is linked to hyperthyroidism in adults?
What disorder is linked to hyperthyroidism in adults?
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What is the main mechanism by which parathyroid hormone increases plasma calcium concentration?
What is the main mechanism by which parathyroid hormone increases plasma calcium concentration?
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What effect does thyroid hormone have on the nervous system development?
What effect does thyroid hormone have on the nervous system development?
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What role does the growth hormone play in metabolism?
What role does the growth hormone play in metabolism?
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What is the primary function of the adrenal gland hormones?
What is the primary function of the adrenal gland hormones?
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What is the consequence of hypoparathyroidism?
What is the consequence of hypoparathyroidism?
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What is a potential outcome of increased secretion of parathyroid hormone?
What is a potential outcome of increased secretion of parathyroid hormone?
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What effect does the thyroid hormone have on cardiac function?
What effect does the thyroid hormone have on cardiac function?
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What condition arises from a deficiency of growth hormone before puberty?
What condition arises from a deficiency of growth hormone before puberty?
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What is a primary function of the adrenal hormones?
What is a primary function of the adrenal hormones?
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What hormone triggers the secretion of thyroid hormone from the thyroid gland?
What hormone triggers the secretion of thyroid hormone from the thyroid gland?
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Which of the following is a consequence of hyperthyroidism?
Which of the following is a consequence of hyperthyroidism?
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Which function is associated with the parathyroid hormone?
Which function is associated with the parathyroid hormone?
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What is the result of hypothyroidism in adults?
What is the result of hypothyroidism in adults?
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What is the main role of the growth hormone in the body?
What is the main role of the growth hormone in the body?
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What effect does thyroid hormone have on energy metabolism?
What effect does thyroid hormone have on energy metabolism?
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What is a common symptom of hyperparathyroidism?
What is a common symptom of hyperparathyroidism?
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What is one effect of decreased secretion of thyroid hormone in infants?
What is one effect of decreased secretion of thyroid hormone in infants?
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Which gland primarily regulates calcium concentrations in the body fluids?
Which gland primarily regulates calcium concentrations in the body fluids?
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What condition is often associated with increased secretion of growth hormone before puberty?
What condition is often associated with increased secretion of growth hormone before puberty?
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What disorder results if the parathyroid hormone secretion is decreased?
What disorder results if the parathyroid hormone secretion is decreased?
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What hormone is secreted by endocrine pancreas?
What hormone is secreted by endocrine pancreas?
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What is the primary function of the adrenal hormones?
What is the primary function of the adrenal hormones?
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Which hormonal disorder is associated with the overproduction of thyroid hormone?
Which hormonal disorder is associated with the overproduction of thyroid hormone?
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What effect does an increase in parathyroid hormone have on the kidneys?
What effect does an increase in parathyroid hormone have on the kidneys?
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What is the main effect of thyroid hormone on heat production?
What is the main effect of thyroid hormone on heat production?
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What is a consequence of increased growth hormone secretion prior to puberty?
What is a consequence of increased growth hormone secretion prior to puberty?
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Which hormone is responsible for stimulating the release of parathyroid hormone?
Which hormone is responsible for stimulating the release of parathyroid hormone?
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What disorder results from a lack of sufficient thyroid hormone in infants?
What disorder results from a lack of sufficient thyroid hormone in infants?
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How does the parathyroid hormone primarily regulate calcium levels in blood?
How does the parathyroid hormone primarily regulate calcium levels in blood?
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Study Notes
Endocrine System
- Endocrine glands are ductless glands that secrete hormones directly into the bloodstream.
- Hormones travel through the bloodstream and exert their actions on target cells and organs.
Pituitary Gland
- Located in the brain.
- Connected to the hypothalamus, a brain region that controls many bodily functions.
Growth Hormone
- Released from the pituitary gland.
- Promotes growth of almost all tissues including skeletal muscles, bones, and viscera.
- Increases protein synthesis, elevates blood glucose levels, and breaks down fat (lipolysis).
- Gigantism: Excessive growth hormone before puberty.
- Acromegaly: Excessive growth hormone after puberty.
- Dwarfism: Deficient growth hormone before puberty.
Thyroid Gland
- Located in the neck.
- Secretes thyroid hormone, which is stimulated by thyroid-stimulating hormone (TSH) from the pituitary gland.
- Functions of thyroid hormone:
- Increases heat production (calorigenic effect).
- Enhances myocardial contractility.
- Crucial for nervous system development.
- Facilitates growth.
- Breaks down protein (catabolism).
- Increases carbohydrate absorption from the gastrointestinal tract.
- Lowers blood cholesterol.
-
Hypothyroidism: Deficiency in thyroid hormone.
- Myxedema: Hypothyroidism in adults.
- Cretinism: Hypothyroidism in infants.
-
Hyperthyroidism: Excess thyroid hormone.
- Graves' disease: An example of hyperthyroidism.
Parathyroid Glands
- Four small glands located on the back of the thyroid gland.
- Secrete parathyroid hormone (PTH).
- Calcium homeostasis: PTH is crucial for calcium regulation in the body.
- PTH actions:
- Increases calcium mobilization from bones.
- Enhances calcium absorption from the intestines.
- Increases calcium reabsorption in the kidneys.
- Hypoparathyroidism: Deficient PTH, leading to low blood calcium (hypocalcemia).
- Hyperparathyroidism: Excess PTH, leading to high blood calcium (hypercalcemia).
Adrenal Glands
- Two glands located on top of the kidneys.
- Divided into two sections:
- Adrenal cortex: Outer layer, secretes corticosteroids (e.g., cortisol, aldosterone).
- Adrenal medulla: Inner layer, secretes catecholamines (e.g., epinephrine, norepinephrine).
Pancreas
- An organ involved in both digestion and hormone secretion.
- Exocrine pancreas: Secretes digestive enzymes.
-
Endocrine pancreas: Releases hormones:
- Insulin: Secreted by beta cells, lowers blood glucose levels.
- Glucagon: Secreted by alpha cells, raises blood glucose levels.
Diabetes Mellitus
- A metabolic disorder characterized by high blood sugar levels.
- Primarily due to either insufficient insulin production (type 1 diabetes) or insulin resistance (type 2 diabetes).
Let’s think together solutions:
- Role of the parathyroid gland in calcium homeostasis: The parathyroid gland releases parathyroid hormone (PTH), which is essential for maintaining calcium balance within the body fluids. PTH increases calcium levels by promoting bone resorption (release of calcium from bones), enhancing intestinal absorption of calcium, and increasing kidney reabsorption of calcium.
- Posterior pituitary: The posterior pituitary gland secretes oxytocin and antidiuretic hormone (ADH).
- Thyroid hormone effects: Thyroid hormone increases metabolic rate, promotes growth, increases protein anabolism, and lowers cholesterol levels.
Endocrine Glands
- Endocrine glands are ductless glands that secrete hormones directly into the bloodstream.
Pituitary Gland
- Located in the brain, it is connected to the hypothalamus.
- Secretes growth hormone.
Growth Hormone
- Promotes growth of tissues including skeletal muscles, bones, and viscera.
- Increases blood glucose level and causes lipolysis.
Growth Hormone Disorders
- Increased secretion before puberty causes gigantism.
- Increased secretion after puberty causes acromegaly.
- Decreased secretion before puberty causes dwarfism.
Thyroid Gland
- Secretes thyroid hormone after stimulation by thyroid stimulating hormone (TSH) from the pituitary gland.
Thyroid Hormone Functions
- Increases heat production.
- Increases myocardial contractility.
- Essential for nervous system development.
- Contributes to growth.
- Promotes protein catabolism.
- Increases carbohydrate absorption from the gut.
- Lowers blood cholesterol.
Thyroid Gland Disorders
- Hypothyroidism in adults causes myxedema.
- Hypothyroidism in infants causes cretinism.
- Hyperthyroidism, such as Graves' disease.
Parathyroid Glands
- There are four parathyroid glands located on the back of the thyroid gland.
- They secrete parathyroid hormone.
Parathyroid Hormone
- The major regulator of calcium concentration in body fluids.
- Increases plasma calcium concentration by:
- Mobilizing calcium from bones.
- Increasing calcium absorption from the intestines.
- Increasing calcium reabsorption in the kidneys.
Parathyroid Gland Disorders
- Hypoparathyroidism causes hypocalcemia.
- Hyperparathyroidism causes hypercalcemia.
Adrenal Glands
- Located on top of the kidneys.
- Composed of the adrenal cortex and adrenal medulla.
Adrenal Gland Hormones
- Adrenal cortex:
- Glucocorticoids (cortisol)
- Mineralocorticoids (aldosterone)
- Androgens
- Adrenal medulla:
- Epinephrine
- Norepinephrine
Adrenal Hormone Functions
- Glucocorticoids:
- Regulate blood glucose levels.
- Suppress inflammation.
- Promote protein breakdown.
- Mineralocorticoids:
- Regulate electrolyte balance.
- Increase sodium reabsorption in the kidneys.
- Androgens:
- Contribute to sexual development.
- Epinephrine & Norepinephrine:
- "Fight-or-flight" response.
- Increased heart rate and blood pressure.
Pancreas
- Contains:
- Exocrine pancreas: secretes digestive juices.
- Endocrine pancreas: releases hormones.
Pancreatic Hormones
- Insulin:
- Lowers blood glucose levels.
- Promotes glucose uptake by cells.
- Glucagon:
- Raises blood glucose levels.
- Stimulates glycogen breakdown in the liver.
Diabetes Mellitus
- A condition characterized by hyperglycemia due to:
- Insulin deficiency.
- Insulin resistance.
Parathyroid Gland and Calcium Homeostasis
- The parathyroid gland plays a crucial role in maintaining calcium balance by secreting parathyroid hormone, which increases plasma calcium levels.
Posterior Pituitary Gland
- Secretes oxytocin.
Thyroid Hormone
- Increases metabolic levels, growth, and protein anabolism.
- Decreases blood cholesterol.
The Endocrine System
- The endocrine system comprises ductless glands that secrete hormones directly into the bloodstream.
- Hormones reach their target sites and exert their actions through the bloodstream.
Pituitary Gland
- The pituitary gland, located in the brain, is connected to the hypothalamus.
- The hypothalamus controls the pituitary gland's activity.
Growth Hormone
- Growth hormone (GH) is secreted by the pituitary gland.
- It induces growth in various tissues like skeletal muscles, bones, and viscera.
- GH increases protein synthesis (anabolic effect), raises blood glucose levels, and promotes lipolysis.
Growth Hormone Disorders
- Excessive GH secretion before puberty leads to gigantism.
- Increased GH secretion after puberty causes acromegaly.
- Deficient GH secretion before puberty results in dwarfism.
Thyroid Gland
- The thyroid gland secretes thyroid hormone after stimulation by thyroid-stimulating hormone (TSH) from the pituitary gland.
Thyroid Hormone Functions
- Thyroid hormone increases heat production (calorigenic effect).
- It enhances myocardial contractility.
- It plays a crucial role in nervous system development.
- It supports growth and protein catabolism.
- It facilitates carbohydrate absorption from the gastrointestinal tract.
- It lowers blood cholesterol levels.
Thyroid Gland Disorders
- Hypothyroidism in adults causes myxedema.
- Hypothyroidism in infants leads to cretinism.
- Hyperthyroidism, such as Graves' disease, is another disorder.
Parathyroid Glands
- Four parathyroid glands are located on the back of the thyroid gland.
- They secrete parathyroid hormone.
Parathyroid Hormone Function
- Parathyroid hormone is the primary regulator of calcium levels in body fluids.
- It increases plasma calcium concentration through:
- Mobilization of calcium from bones
- Enhanced calcium absorption from the intestine
- Increased calcium reabsorption in the kidneys
Parathyroid Gland Disorders
- Hypoparathyroidism causes hypocalcemia.
- Hyperparathyroidism leads to hypercalcemia.
Adrenal Gland
- The adrenal glands are located above the kidneys.
- They consist of two parts:
- Cortex: Secretes corticosteroids
- Medulla: Secretes catecholamines (epinephrine and norepinephrine)
Adrenal Gland Hormones
- Cortisol (stress hormone): regulates blood sugar and inflammation.
- Aldosterone (mineralocorticoid): regulates electrolyte balance.
- Epinephrine and norepinephrine (catecholamines): influence heart rate and blood pressure.
Pancreas
- The pancreas is composed of two types of secretory glands:
- Exocrine pancreas: secretes digestive juices.
- Endocrine pancreas: releases hormones like insulin and glucagon.
Pancreatic Hormones
- Insulin (secreted by beta cells): Lowers blood glucose levels
- Glucagon (secreted by alpha cells): Raises blood glucose levels
Diabetes Mellitus
- Diabetes is a metabolic disorder characterized by hyperglycemia (high blood sugar).
- It occurs due to either insulin deficiency or resistance to its effects.
Let's Think Together
- The parathyroid gland plays a crucial role in calcium homeostasis by regulating its levels in body fluids.
- The posterior pituitary gland secretes oxytocin.
- Thyroid hormone increases metabolic levels and supports growth.
- Thyroid hormone causes a decrease in blood cholesterol.
Endocrine Glands
- Endocrine glands are ductless glands that release hormones directly into the bloodstream.
- Hormones travel through the bloodstream to target cells and tissues where they exert their effects.
- Examples of endocrine glands include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, and pancreas.
Pituitary Gland
- The pituitary gland is located in the brain.
- The pituitary gland is connected to the hypothalamus, which controls its activity.
Growth Hormone
- The pituitary gland secretes growth hormone.
- Growth hormone promotes growth in nearly all tissues, including skeletal muscles, bones, and organs.
- Growth hormone stimulates protein synthesis and increases blood glucose levels.
- Growth hormone also breaks down fat (lipolysis).
Growth Hormone Disorders
- Excess growth hormone production before puberty leads to gigantism.
- Excess growth hormone production after puberty results in acromegaly.
- Insufficient growth hormone production before puberty causes dwarfism.
Thyroid Gland
- The thyroid gland is located in the neck.
- The thyroid gland secretes thyroid hormone in response to stimulation by thyroid-stimulating hormone (TSH) from the pituitary gland.
Thyroid Hormone Functions
- Thyroid hormone increases metabolic rate and heat production.
- It strengthens heart muscle contractions.
- It is crucial for nervous system development.
- It contributes to growth.
- It breaks down protein (protein catabolism).
- It enhances carbohydrate absorption from the digestive tract.
- It lowers blood cholesterol levels.
Thyroid Disorders
- In adults, hypothyroidism (low thyroid hormone) causes myxedema.
- In infants, hypothyroidism leads to cretinism.
- Hyperthyroidism (high thyroid hormone), such as Graves' disease, is another thyroid disorder.
Parathyroid Glands
- There are four parathyroid glands located behind the thyroid gland.
- The parathyroid glands secrete parathyroid hormone.
Parathyroid Hormone Function
- Parathyroid hormone is essential for regulating calcium levels in body fluids.
- Its primary function is to elevate plasma calcium levels.
Parathyroid Hormone Mechanisms
- Parathyroid hormone stimulates calcium release from bones.
- It enhances calcium absorption in the intestines.
- It increases calcium reabsorption in the kidneys.
Parathyroid Disorders
- Hypoparathyroidism (low parathyroid hormone) causes hypocalcemia (low blood calcium).
- Hyperparathyroidism (high parathyroid hormone) causes hypercalcemia (high blood calcium).
Adrenal Glands
- The adrenal glands are located above the kidneys.
- The adrenal glands produce various hormones.
Adrenal Gland Hormones
- The adrenal cortex (outer layer) secretes:
- Cortisol (stress hormone)
- Aldosterone (regulates blood pressure)
- Androgens (sex hormones)
- The adrenal medulla (inner layer) secretes:
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline)
Adrenal Hormone Functions
- Cortisol helps regulate metabolism, blood sugar levels, and inflammation.
- Aldosterone controls blood pressure by regulating sodium and potassium levels.
- Androgens contribute to sexual development and function.
- Epinephrine and norepinephrine play essential roles in the "fight-or-flight" response, increasing heart rate, blood pressure, and glucose levels.
Pancreas
- The pancreas is both an exocrine and endocrine gland.
- The exocrine pancreas secretes digestive enzymes into the small intestine.
- The endocrine pancreas contains clusters of cells called islets of Langerhans, which release hormones.
Pancreatic Hormones
- The islets of Langerhans produce:
- Insulin: lowers blood glucose levels
- Glucagon: raises blood glucose levels
Diabetes Mellitus
- Diabetes mellitus occurs when the pancreas does not produce enough insulin or the body cannot use insulin properly.
- This leads to high blood sugar levels, which can damage various organs.
Thinking Together
-
Parathyroid gland role in calcium homeostasis: The parathyroid gland plays a critical role in maintaining calcium balance in the body by releasing parathyroid hormone, which increases calcium levels in the blood.
-
Posterior pituitary gland secretions: The posterior pituitary gland does not produce hormones but stores and releases hormones produced by the hypothalamus. These hormones are:
- Oxytocin: involved in social bonding, labor, and milk release.
- Antidiuretic hormone (ADH): regulates water balance in the body.
-
Thyroid hormone effects: Thyroid hormone has numerous effects on the body, including:
- Increased metabolic rate
- Enhanced growth
- Increased protein synthesis
- Lowered blood cholesterol
- It does not cause hypercholesterolemia (high cholesterol).
Endocrine System
- Endocrine glands are ductless glands that release hormones directly into the bloodstream.
- Hormones act on target organs and tissues to regulate various bodily functions.
Pituitary Gland
- Location: Located at the base of the brain.
- Connection with Hypothalamus: The pituitary gland is connected to the hypothalamus through a stalk called the infundibulum. The hypothalamus controls the release of hormones from the pituitary gland.
Growth Hormone
- Function: Promotes growth in most tissues, including skeletal muscles, bones, and internal organs.
- Metabolic Effects: Increases protein synthesis, raises blood glucose levels, and promotes fat breakdown (lipolysis).
-
Disturbances:
- Gigantism: Excessive growth hormone secretion before puberty.
- Acromegaly: Excessive growth hormone secretion after puberty.
- Dwarfism: Deficiency in growth hormone secretion before puberty.
Thyroid Gland
- Location: Located in the neck, below the larynx.
- Thyroid Hormone Production: The thyroid gland secretes thyroid hormone in response to thyroid-stimulating hormone (TSH) from the pituitary gland.
-
Functions of Thyroid Hormone:
- Calorigenic Effect: Increases heat production.
- Increases Myocardial Contractility: Enhances heart muscle contraction.
- Brain Development: Essential for proper brain development.
- Growth Promotion: Contributes to growth.
- Protein Catabolism: Breaks down proteins.
- Carbohydrate Absorption: Increases carbohydrate absorption from the digestive system.
- Lowers Blood Cholesterol: Reduces cholesterol levels in the blood.
-
Disorders:
-
Hypothyroidism: Deficiency in thyroid hormone production.
- Myxedema: Hypothyroidism in adults.
- Cretinism: Hypothyroidism in infants, leading to mental and physical retardation.
-
Hyperthyroidism: Excessive thyroid hormone production.
- Graves’ disease: A common form of hyperthyroidism.
-
Hypothyroidism: Deficiency in thyroid hormone production.
Parathyroid Glands
- Location: Four small glands located on the back of the thyroid gland.
- Parathyroid Hormone (PTH): The main hormone secreted by the parathyroid glands.
-
Function of PTH: Regulates calcium levels in the body fluids.
- Increases Calcium Mobilization from Bones: PTH releases calcium from bones into the bloodstream.
- Increases Calcium Absorption from the Gut: PTH enhances calcium absorption from the small intestine.
- Increases Calcium Reabsorption in the Kidneys: PTH promotes calcium reabsorption from the kidneys, preventing its excretion in urine.
-
Disorders:
- Hypoparathyroidism: Deficiency in PTH, leading to low calcium levels (hypocalcemia).
- Hyperparathyroidism: Excessive PTH production, leading to high calcium levels (hypercalcemia).
Adrenal Glands
- Location: Located on top of each kidney.
-
Adrenal Gland Hormones:
-
Cortex (Outer Layer):
- Cortisol: Regulates stress response, blood sugar levels, and inflammation.
- Aldosterone: Regulates blood pressure and electrolyte balance.
- Androgens: Male sex hormones synthesized in small amounts.
-
Medulla (Inner Layer):
- Epinephrine (Adrenaline): Fight-or-flight response hormone.
- Norepinephrine: Contributes to the stress response.
-
Cortex (Outer Layer):
Pancreas
- Location: Located in the abdomen, behind the stomach.
-
Two Types of Secretory Glands:
- Exocrine Pancreas: Produces digestive enzymes.
-
Endocrine Pancreas: Produces hormones:
- Insulin: Secreted by beta cells, lowers blood glucose levels by promoting glucose uptake and storage.
- Glucagon: Secreted by alpha cells, raises blood glucose levels by stimulating the release of glucose from stores.
Diabetes Mellitus
- Cause: A metabolic disorder characterized by either a deficiency in insulin production or an inability of the body's cells to respond properly to insulin.
- Consequences: High blood sugar levels, leading to damage in various organs, including the eyes, kidneys, nerves, and blood vessels.
Let's Think Together
- Parathyroid Gland Role in Calcium Homeostasis: The parathyroid gland plays a crucial role in maintaining calcium balance by releasing PTH, which increases calcium levels in the blood.
- Posterior Pituitary Hormone: The posterior pituitary gland secretes oxytocin, which is responsible for uterine contractions during childbirth and milk ejection during breastfeeding.
- Thyroid Hormone Effects: Thyroid hormone increases metabolic levels, promotes growth, and increases protein anabolism (protein building). Thyroid hormone does not cause hypercholesterolemia (high cholesterol levels).
Endocrine System
- Endocrine glands are ductless glands that secrete hormones directly into the bloodstream.
- Hormones are transported through the bloodstream to target tissues, where they exert their effects.
Pituitary Gland
- Located in the brain, connected to the hypothalamus.
-
Growth hormone:
- Stimulates growth of various tissues, including skeletal muscles, bones, and viscera.
- Has metabolic effects: increases protein synthesis, raises blood glucose levels, and promotes lipolysis (fat breakdown).
-
Growth hormone disorders:
- Gigantism: excessive growth hormone secretion before puberty.
- Acromegaly: excessive growth hormone secretion after puberty.
- Dwarfism: inadequate growth hormone secretion before puberty.
Thyroid Gland
- Secretes thyroid hormone after stimulation by thyroid-stimulating hormone (TSH) from the pituitary gland.
-
Functions of thyroid hormone:
- Calorigenic effect: increases heat production.
- Myocardial contractility: increases the force of heart muscle contractions.
- Nervous system development: crucial for the development of the brain and nervous system.
- Growth: supports overall growth.
- Protein catabolism: breaks down proteins.
- Carbohydrate absorption: increases the absorption of carbohydrates from the gastrointestinal tract.
- Lowers blood cholesterol: reduces cholesterol levels in the blood.
-
Thyroid disorders:
-
Hypothyroidism: deficiency of thyroid hormone.
- Myxedema: in adults.
- Cretinism: in infants.
-
Hyperthyroidism: excess of thyroid hormone.
- Graves' disease is an example.
-
Hypothyroidism: deficiency of thyroid hormone.
Parathyroid Glands
- Four small glands located on the back of the thyroid gland.
- Secrete parathyroid hormone (PTH).
-
Functions of PTH:
- Calcium homeostasis: primary regulator of calcium levels in body fluids.
-
Increase plasma calcium:
- Mobilizes calcium from bones.
- Increases calcium absorption from the intestine.
- Increases calcium reabsorption in the kidneys.
-
Parathyroid disorders:
- Hypoparathyroidism: low PTH levels, causing hypocalcemia (low calcium levels).
- Hyperparathyroidism: high PTH levels, causing hypercalcemia (high calcium levels).
Adrenal Glands
- Located on top of the kidneys.
- Produce various hormones, including:
- Cortisol: stress hormone, regulates blood sugar, suppresses immune responses.
- Aldosterone: regulates blood pressure by controlling electrolyte balance.
- Adrenaline (epinephrine): "fight or flight" hormone, increases heart rate and blood pressure.
Pancreas
- Contains both exocrine and endocrine components.
- Exocrine pancreas: secretes digestive juices.
-
Endocrine pancreas: secretes hormones, including:
- Insulin: regulates blood glucose levels by promoting glucose uptake by cells.
- Glucagon: raises blood glucose levels by stimulating glycogen breakdown in the liver.
- Diabetes mellitus: a disorder characterized by hyperglycemia, resulting from insulin deficiency or resistance.
Calcium Homeostasis and the Parathyroid Gland
- The parathyroid gland plays a crucial role in maintaining calcium levels in the blood.
- PTH acts to increase calcium levels by promoting calcium absorption from the gut, release from bone, and reabsorption in the kidneys.
Posterior Pituitary Gland
- Secretes oxytocin and antidiuretic hormone (ADH).
Thyroid Hormone Effects
- Thyroid hormone increases metabolic rate, promotes growth, and increases protein anabolism (protein synthesis).
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Description
Explore the key components and functions of the endocrine system, including the pituitary and thyroid glands. Understand the role of hormones and the effects of growth hormone, along with conditions such as gigantism and dwarfism. This quiz covers important concepts on how hormones influence growth and bodily functions.
