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Questions and Answers
What is the primary role of calcitonin released by the thyroid gland?
What triggers the secretion of parathyroid hormone (PTH)?
What is the normal range for blood calcium levels?
Graves' disease is characterized by which of the following?
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Which physiological processes depend on adequate levels of calcium?
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What is the primary effect of Addison Disease on hormone production?
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Which gland is primarily responsible for the production of melatonin?
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What important role does thymosin play in the body?
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Where is the thyroid gland located in the human body?
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Which statement is true regarding the thymus gland?
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What is a symptom associated with hypercalcemia?
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Which best describes tetany?
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What role do insulin and glucagon play in the body?
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What can occur if blood glucose levels fall too low?
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Where is the pancreas located in the body?
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What is the principal function of aldosterone?
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What role does cortisol play in the body?
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Which symptom is not typically associated with Cushing syndrome?
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How does excess cortisol affect carbohydrate metabolism?
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What additional condition is often associated with hypersecretion of adrenal androgens in Cushing syndrome?
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Which statement regarding glucocorticoids is true?
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What effect does aldosterone have on water balance?
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What triggers the secretion of insulin by the pancreas?
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What happens to glucose levels after insulin triggers cellular uptake?
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Which hormone is released when blood glucose levels fall below a certain point?
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What is the primary role of glucagon in blood glucose regulation?
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What is a possible health implication of diabetes affecting the nervous system?
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Which type of diabetes is an autoimmune disease?
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What is a common outcome for women who experience gestational diabetes?
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What is the primary function of insulin in the body?
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Study Notes
Thyroid Tissue
- Secretes T3 and T4
- Calcitonin decreases blood calcium levels by moving it into the bone
- Calcitonin helps regulate calcium levels in the blood
Parathyroid Glands
- Located on the posterior side of the thyroid gland
- Produce parathyroid hormone (PTH)
- PTH increases blood calcium levels by moving it from the bone into the blood
Key Facts
- Most people have four parathyroid glands, but the number and location can vary
- Blood calcium levels are tightly regulated, with a 1% decrease triggering a doubling of PTH secretion
- Adequate calcium levels are crucial for normal nerve and muscle function, blood clotting, and certain enzyme activities
Thyroid Disorders
- Graves' disease is characterized by hypersecretion of thyroid hormone (TH), leading to increased metabolism
- Iodine is essential for TH synthesis
- Hypocalcemia refers to low blood calcium levels
- Hypercalcemia refers to high blood calcium levels
Normal Blood Calcium Level
- 8.4 – 10.4 mg/dL
Addison Disease
- Also known as adrenal cortical insufficiency
- Characterized by hyposecretion of mineralocorticoids and glucocorticoids
- Life-threatening without treatment
Pineal Gland
- Produces melatonin, a hormone that increases at night and decreases during the day
- High melatonin levels promote sleepiness, playing a key role in the sleep-wake cycle
- Located in the center of the brain
- Excessive melatonin can increase the risk of blood clots and seizures
Thymus
- Secretes thymosin and thymopoietin, hormones involved in immune system development
- Located in the mediastinum, beneath the sternum
- Large in children, but shrinks during puberty and becomes mostly fat and fibrous tissue in old age
Thyroid Gland
- The largest endocrine gland, consisting of two lobes connected by the isthmus
- Located in the neck, below the trachea, wrapping around its anterior and lateral portions
- Normal blood calcium level: 8.4-10.4 mg/dL
Hypercalcemia Symptoms
- Muscle tremors
- Spasms
- Tetany
- Laryngeal spasms (severe cases)
Symptoms of Low Blood Glucose
- Muscle weakness
- Sluggish reflexes
- Cardiac arrest (severe cases)
Tetany
- Sustained muscle contraction
Pancreas
- Functions as both an exocrine and endocrine gland
- Located behind the stomach, within the curve of the duodenum, with its tail reaching the spleen
- Plays a crucial role in regulating blood glucose levels
Regulation of Blood Glucose
- Insulin and glucagon are two major pancreatic hormones with opposite effects on blood glucose levels
- After eating, blood glucose levels rise, stimulating insulin secretion from beta cells
- Insulin promotes glucose uptake by cells and storage as glycogen in the liver, lowering blood glucose levels
- When blood glucose drops below a certain level, alpha cells release glucagon
- Glucagon stimulates the liver to break down glycogen and release glucose into the bloodstream, raising blood glucose levels
Health Implications
- Nerve damage (neuropathy)
- Hypoglycemia (low blood sugar)
- Type 1 diabetes (autoimmune disease)
- Gestational diabetes (diabetes during pregnancy, usually resolves after birth)
- Women with gestational diabetes are at increased risk of developing type 2 diabetes later
- Diabetes damages the cardiovascular and nervous systems
- Gonads (testes and ovaries) are primary sex organs
Adrenal Disorders
- Hormones
- Mineralocorticoids
- Aldosterone is the main mineralocorticoid
- Promotes sodium retention and potassium excretion in the kidneys
- Causes water retention
- Glucocorticoids
- Cortisol is the main glucocorticoid
- Helps the body adapt to stress and repair damaged tissue by:
- Stimulating breakdown of fat and protein into glucose
- Releasing fatty acids and glucose into the blood
- Having an anti-inflammatory effect
- Suppressing the immune system
- Maintaining blood pressure
- Sex steroids
- Mineralocorticoids
Life Lesson: Adrenal Disorders
Cushing Syndrome
- Results from hypersecretion of cortisol from the adrenal gland
- Classic Symptoms:
- Moon face and buffalo bump
- Hyperglycemia, muscle weakness, and edema due to disruptions in carbohydrate and protein metabolism
- Muscle wasting and bone loss due to protein breakdown
- Hypertension due to sodium and water retention
- Hypersecretion of adrenal androgens can lead to premature puberty in children and masculine characteristics in women
CH 13 ENDCRINE SYSTEM
- The endocrine system is composed of various glands and specialized cells that secrete hormones
- Hormones are chemical messengers that travel throughout the body via the bloodstream
How Target Cells Work
- Target cells possess receptors for specific hormones
- Hormones bind to their corresponding receptors on target cells to elicit specific responses
Difference between Endocrine and Exocrine
- Exocrine glands release secretions through ducts to an external environment
- Endocrine glands secrete hormones directly into the bloodstream
Hormones
- Hormones can be classified as steroid or nonsteroid:
- Steroid hormones: synthesized from cholesterol, including sex hormones and aldosterone
- Nonsteroid hormones: protein-based and synthesized from amino acids
The Pituitary Gland and Hypothalamus
- The pituitary gland is a tiny gland that sits beneath the hypothalamus, exerting a strong influence on various bodily processes
- Pituitary hyposecretion (lack of growth hormone) can lead to pituitary dwarfism
Pituitary Dwarfism
- Condition resulting from hyposecretion of growth hormone while a child is still growing
Posterior Pituitary
- Made of neural tissue and stores hormones synthesized by the hypothalamus
- Two hormones:
- Antidiuretic hormone (ADH): regulates urine volume and prevents dehydration
- Oxytocin: stimulates uterine contractions during childbirth and milk release during lactation
Control of Pituitary Secretions
- Pituitary hormone release is not continuous but occurs in phases, influenced by different factors such as time of day or menstrual cycle
Adrenal Glands
- Located atop each kidney, consisting of two parts:
- Adrenal medulla: inner portion, composed of modified neurons, forming part of the sympathetic nervous system
- Adrenal cortex: outer portion, glandular tissue secreting steroid hormones (corticosteroids)
Classes of Hormones Secreted by Adrenal Cortex
- Corticosteroids: include hormones involved in sodium, water regulation, and response to stress
The Pituitary Gland
- Consists of two distinct parts: anterior pituitary and posterior pituitary
- Anterior pituitary is larger and glandular, synthesizing and secreting various hormones under the influence of the hypothalamus
6 Hormones Produced and Secreted by Anterior Pituitary
- Thyroid-stimulating hormone (TSH) or thyrotropin: stimulates thyroid hormone release from the thyroid
- Prolactin: stimulates milk production in females
- Adrenocorticotropic hormone (ACTH): stimulates cortisol secretion from the adrenal cortex
- Growth hormone (GH) or somatotropin: promotes protein synthesis throughout the body
- Luteinizing hormone (LH): stimulates ovulation and estrogen production
- Follicle-stimulating hormone (FSH): stimulates egg and sperm production
Life Lesson:
- Hypersecretion (too much growth hormone) can lead to gigantism (excessive skeletal growth) or acromegaly (enlargement of hands, feet, face, and jaw) if epiphyseal plates are fused
- Hyposecretion (lack of growth hormone) leads to pituitary dwarfism
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Description
Test your knowledge on the anatomy and functions of the thyroid and parathyroid glands. This quiz covers key topics such as hormone secretion, calcium regulation, and common disorders. Perfect for learners interested in human biology and endocrine system functions.
