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Questions and Answers
What primarily drives smooth muscle contraction?
What primarily drives smooth muscle contraction?
- Sodium from outside the cell
- Potassium from outside the cell
- Calcium from outside the cell (correct)
- Chloride from outside the cell
Which muscle type undergoes phasic contraction (contracts and relaxes continuously)?
Which muscle type undergoes phasic contraction (contracts and relaxes continuously)?
- Type 2B fast twitch glycolytic fatigable fibers
- Type 1 slow twitch oxidative fibers
- Cardiac muscle
- Smooth muscle (correct)
What type of muscle has a 'Pacemaker Potential'?
What type of muscle has a 'Pacemaker Potential'?
- Smooth muscle
- Type 2A fast twitch oxidative glycolytic fatigue resistant fibers
- Type 2B fast twitch glycolytic fatigable fibers
- Cardiac muscle (correct)
Which muscle type has t-tubules and gap junctions?
Which muscle type has t-tubules and gap junctions?
What is the primary mechanism for activation of cardiac muscle?
What is the primary mechanism for activation of cardiac muscle?
Which muscle type is similar to smooth muscle in being involuntary?
Which muscle type is similar to smooth muscle in being involuntary?
What type of muscle contraction primarily relies on calcium from outside the cell?
What type of muscle contraction primarily relies on calcium from outside the cell?
Which type of muscle has the fastest contracting fibers in skeletal muscle?
Which type of muscle has the fastest contracting fibers in skeletal muscle?
Which type of chemical messengers are secreted by the nervous system?
Which type of chemical messengers are secreted by the nervous system?
What is the approximate time frame for hormones to produce their effects?
What is the approximate time frame for hormones to produce their effects?
How are hormones transported to most body cells?
How are hormones transported to most body cells?
What is the main categorization of hormones based on the location of their target sites?
What is the main categorization of hormones based on the location of their target sites?
How do hormones exert targeted responses?
How do hormones exert targeted responses?
What determines the ability of cells to respond to hormones?
What determines the ability of cells to respond to hormones?
Where are steroid receptors located?
Where are steroid receptors located?
What is the role of the hypothalamus in the neuroendocrine system?
What is the role of the hypothalamus in the neuroendocrine system?
Which stimuli can cause hormone release?
Which stimuli can cause hormone release?
What does the anterior pituitary gland secrete in response to hypothalamic hormones?
What does the anterior pituitary gland secrete in response to hypothalamic hormones?
What hormones are formed in the hypothalamus and released from the posterior pituitary?
What hormones are formed in the hypothalamus and released from the posterior pituitary?
What is the main control mechanism provided by the hypothalamus and pituitary in relation to the adrenal gland?
What is the main control mechanism provided by the hypothalamus and pituitary in relation to the adrenal gland?
What can cause hypocalcemia?
What can cause hypocalcemia?
What is the composition of human bone?
What is the composition of human bone?
Which hormone promotes bone growth in the epiphyseal plate?
Which hormone promotes bone growth in the epiphyseal plate?
What is the primary function of trabecular bone?
What is the primary function of trabecular bone?
What is the role of osteoclasts in bone physiology?
What is the role of osteoclasts in bone physiology?
What can lead to severe hypercalcemia?
What can lead to severe hypercalcemia?
Which substance is responsible for demineralization of bone in severe hypercalcemia?
Which substance is responsible for demineralization of bone in severe hypercalcemia?
What is the primary function of flat bones in the human body?
What is the primary function of flat bones in the human body?
What does the epiphyseal line represent in bone structure?
What does the epiphyseal line represent in bone structure?
What is the primary function of yellow bone marrow?
What is the primary function of yellow bone marrow?
What is the primary cause of osteoporosis?
What is the primary cause of osteoporosis?
Which cells replace chondrocytes and calcify the new bone matrix in bone growth?
Which cells replace chondrocytes and calcify the new bone matrix in bone growth?
What is the role of thyroid hormones T3 and T4?
What is the role of thyroid hormones T3 and T4?
What is the iodine requirement for thyroid hormone synthesis?
What is the iodine requirement for thyroid hormone synthesis?
Which hormones are released during the stress response through the Hypothalamus-Pituitary-Adrenal (HPA) axis?
Which hormones are released during the stress response through the Hypothalamus-Pituitary-Adrenal (HPA) axis?
What are the short-term biological stress responses?
What are the short-term biological stress responses?
How are T3 and T4 stored in the thyroid gland?
How are T3 and T4 stored in the thyroid gland?
What is the main function of T3 in cells?
What is the main function of T3 in cells?
What are the effects of hyperthyroidism?
What are the effects of hyperthyroidism?
How do thyroid hormones maintain their effects in plasma?
How do thyroid hormones maintain their effects in plasma?
Which hormone is formed from skin cholesterol and dietary vitamin D, and plays a vital role in calcium absorption and bone formation?
Which hormone is formed from skin cholesterol and dietary vitamin D, and plays a vital role in calcium absorption and bone formation?
What can lack of T3 & T4 due to dietary iodine deficiency cause in children?
What can lack of T3 & T4 due to dietary iodine deficiency cause in children?
What did Walter Cannon coin the term for in 1915?
What did Walter Cannon coin the term for in 1915?
Which hormone regulates net dietary calcium absorption, and is formed from skin cholesterol and dietary vitamin D?
Which hormone regulates net dietary calcium absorption, and is formed from skin cholesterol and dietary vitamin D?
What is the main role of the thyroid gland?
What is the main role of the thyroid gland?
What is the role of T3 in gene expression?
What is the role of T3 in gene expression?
What can low blood calcium levels, or hypocalcaemia, potentially cause?
What can low blood calcium levels, or hypocalcaemia, potentially cause?
Which hormone is involved in regulating blood calcium levels and plays a role in bone formation and growth?
Which hormone is involved in regulating blood calcium levels and plays a role in bone formation and growth?
What is the consequence of hypothyroidism?
What is the consequence of hypothyroidism?
What can hypercalcaemia, or high blood calcium, lead to?
What can hypercalcaemia, or high blood calcium, lead to?
Which hormone is involved in regulating blood calcium levels and promotes calcium reabsorption from the kidneys and calcium release from the bones?
Which hormone is involved in regulating blood calcium levels and promotes calcium reabsorption from the kidneys and calcium release from the bones?
What is the daily calcium requirement for adults?
What is the daily calcium requirement for adults?
What can hypocalcaemia combined with vitamin D deficiency cause in adults?
What can hypocalcaemia combined with vitamin D deficiency cause in adults?
Which hormone is released by the thyroid gland, requires iodine for production, and increases metabolic rate?
Which hormone is released by the thyroid gland, requires iodine for production, and increases metabolic rate?
What can lack of T3 & T4 due to dietary iodine deficiency cause in adults?
What can lack of T3 & T4 due to dietary iodine deficiency cause in adults?
Which hormone is involved in regulating blood calcium levels and inhibits calcium release from the bones?
Which hormone is involved in regulating blood calcium levels and inhibits calcium release from the bones?
What is the primary difference in the initiation of muscle contraction between smooth muscle and skeletal muscle?
What is the primary difference in the initiation of muscle contraction between smooth muscle and skeletal muscle?
Which type of muscle has the 'Pacemaker Potential'?
Which type of muscle has the 'Pacemaker Potential'?
What is the main mechanism for activation of cardiac muscle?
What is the main mechanism for activation of cardiac muscle?
What is the primary similarity between cardiac muscle and smooth muscle?
What is the primary similarity between cardiac muscle and smooth muscle?
Which type of muscle contraction primarily relies on calcium from outside the cell?
Which type of muscle contraction primarily relies on calcium from outside the cell?
What is the primary function of yellow bone marrow?
What is the primary function of yellow bone marrow?
What is the approximate time frame for hormones to produce their effects?
What is the approximate time frame for hormones to produce their effects?
What does the epiphyseal line represent in bone structure?
What does the epiphyseal line represent in bone structure?
Which type of receptors do lipid-soluble hormones primarily bind to?
Which type of receptors do lipid-soluble hormones primarily bind to?
Which of the following is a mechanism of hormone distribution to target cells?
Which of the following is a mechanism of hormone distribution to target cells?
What is the primary role of the hypothalamus in the neuroendocrine system?
What is the primary role of the hypothalamus in the neuroendocrine system?
Which of the following hormones is released from the posterior pituitary gland?
Which of the following hormones is released from the posterior pituitary gland?
What is the primary mechanism for activation of cardiac muscle?
What is the primary mechanism for activation of cardiac muscle?
Which of the following hormones is involved in the sympathetic output to the adrenal medulla?
Which of the following hormones is involved in the sympathetic output to the adrenal medulla?
What drives smooth muscle contraction?
What drives smooth muscle contraction?
Which type of muscle undergoes phasic contraction?
Which type of muscle undergoes phasic contraction?
What is the approximate time frame for hormones to produce their effects?
What is the approximate time frame for hormones to produce their effects?
What is the consequence of hypothyroidism?
What is the consequence of hypothyroidism?
Which of the following is a category of organic chemical messengers?
Which of the following is a category of organic chemical messengers?
What is the primary mechanism of control provided by the hypothalamus and pituitary in relation to the adrenal gland?
What is the primary mechanism of control provided by the hypothalamus and pituitary in relation to the adrenal gland?
What is the iodine requirement for thyroid hormone synthesis?
What is the iodine requirement for thyroid hormone synthesis?
Where are T3 and T4 stored?
Where are T3 and T4 stored?
What is the main role of T3 in cells?
What is the main role of T3 in cells?
What is the consequence of hypothyroidism?
What is the consequence of hypothyroidism?
How do T3 and T4 circulate in the blood?
How do T3 and T4 circulate in the blood?
What is the primary role of the thyroid gland?
What is the primary role of the thyroid gland?
What is the primary function of T4 and T3 in cells?
What is the primary function of T4 and T3 in cells?
What are the effects of hyperthyroidism?
What are the effects of hyperthyroidism?
What is the role of T3 in gene expression?
What is the role of T3 in gene expression?
What primarily drives smooth muscle contraction?
What primarily drives smooth muscle contraction?
What is the consequence of hypothyroidism on heart rate?
What is the consequence of hypothyroidism on heart rate?
What is the main source of iodine for thyroid hormone production?
What is the main source of iodine for thyroid hormone production?
Which hormone is primarily responsible for regulating blood calcium levels and promoting calcium reabsorption from the kidneys and calcium release from the bones?
Which hormone is primarily responsible for regulating blood calcium levels and promoting calcium reabsorption from the kidneys and calcium release from the bones?
What is the primary source of 1,25-dihydroxyvitamin D3, which plays a vital role in calcium absorption and bone formation?
What is the primary source of 1,25-dihydroxyvitamin D3, which plays a vital role in calcium absorption and bone formation?
What can low blood calcium levels, or hypocalcaemia, potentially cause?
What can low blood calcium levels, or hypocalcaemia, potentially cause?
What can hypercalcaemia, or high blood calcium, potentially lead to?
What can hypercalcaemia, or high blood calcium, potentially lead to?
What is the primary function of calcitonin in relation to blood calcium levels?
What is the primary function of calcitonin in relation to blood calcium levels?
What can lack of T3 & T4 due to dietary iodine deficiency cause in children?
What can lack of T3 & T4 due to dietary iodine deficiency cause in children?
What is the approximate daily calcium requirement for adults?
What is the approximate daily calcium requirement for adults?
What is the main role of the thyroid hormones T3 and T4?
What is the main role of the thyroid hormones T3 and T4?
What can hypocalcaemia combined with vitamin D deficiency cause in adults?
What can hypocalcaemia combined with vitamin D deficiency cause in adults?
What is the primary cause of rickets in children?
What is the primary cause of rickets in children?
What are the potential consequences of myxoedema (postnatal hypothyroidism) in adults?
What are the potential consequences of myxoedema (postnatal hypothyroidism) in adults?
What is the primary function of 1,25-dihydroxyvitamin D3 in the body?
What is the primary function of 1,25-dihydroxyvitamin D3 in the body?
Which of the following can lead to severe hypercalcemia?
Which of the following can lead to severe hypercalcemia?
What is the primary cause of hypocalcemia?
What is the primary cause of hypocalcemia?
Which hormone plays a role in regulating blood calcium levels and inhibits calcium release from the bones?
Which hormone plays a role in regulating blood calcium levels and inhibits calcium release from the bones?
What is the primary composition of bone?
What is the primary composition of bone?
What is the primary function of bone marrow?
What is the primary function of bone marrow?
What type of bones include vertebrae and ribs?
What type of bones include vertebrae and ribs?
Which cells replace chondrocytes and calcify the new bone matrix in bone growth?
Which cells replace chondrocytes and calcify the new bone matrix in bone growth?
What primarily drives smooth muscle contraction?
What primarily drives smooth muscle contraction?
What is the primary function of yellow bone marrow?
What is the primary function of yellow bone marrow?
Which hormone promotes bone growth in the epiphyseal plate?
Which hormone promotes bone growth in the epiphyseal plate?
What does osteoporosis involve?
What does osteoporosis involve?
What are the symptoms of severe hypercalcemia?
What are the symptoms of severe hypercalcemia?
Study Notes
Thyroid Hormones and Calcium Regulation
- Thyroid gland releases T3 and T4 hormones, requiring iodine for production, which increases metabolic rate and has various other effects on growth and development.
- Lack of T3 & T4 due to dietary iodine deficiency can cause irreversible brain damage in children and impaired brain function in adults.
- Myxoedema (postnatal hypothyroidism) and Grave’s disease (hyperthyroidism) are thyroid hormone disorders with distinct symptoms and causes.
- Thyroid hormone deficiency can lead to impaired brain development, hearing loss, muscle rigidity, and mood changes in children.
- Daily calcium requirements are about 1g per day, but net dietary calcium absorption is only about 150 mg/day, regulated by three hormones: 1,25-dIhydroxyvitamin D3, parathyroid hormone (PTH), and calcitonin.
- 1,25-dihydroxyvitamin D3 is formed from skin cholesterol and dietary vitamin D, and plays a vital role in calcium absorption and bone formation.
- Vitamin D is mainly formed in the skin during U-V light exposure and is crucial for calcium absorption in the body.
- Low blood calcium levels, or hypocalcaemia, can be caused by dietary calcium and vitamin D deficiency, low UV-light exposure, or hypoparathyroidism, resulting in potential severe effects like convulsions and numbness.
- Hypocalcaemia combined with vitamin D deficiency can cause rickets in children and osteomalacia in adults.
- Hypercalcaemia, or high blood calcium, can be caused by excessive absorption of dietary calcium, and can lead to symptoms like kidney stones and abnormal heart rhythms.
- The regulation of blood calcium levels is crucial for many cellular functions, including neurotransmitter and hormone secretion, and muscle contraction.
- Calcium plays a vital role in bone formation and growth, with its concentration in the blood being regulated by vitamin D, PTH, and calcitonin.
Human Skeletal System and Bone Structure
- Hypercalcemia (calcium > 2.6 mmol/L) can be caused by parathyroid tumors, malignancy, large doses of Vitamin D, and extra-renal synthesis of 1,25-dihydroxyvitamin D3.
- Severe hypercalcemia can lead to abdominal pain, nausea, vomiting, demineralization of bone, calcification of soft tissues and blood vessels, kidney stones, increased blood pressure, anxiety, confusion, weakness, and coma.
- Treatment of hypercalcemia depends on its cause and involves regulating blood concentration of calcium through Vitamin D, PTH, and Calcitonin.
- Hypocalcemia is usually due to Vitamin D deficiency and can lead to convulsions, arrhythmia, tetany, and numbness, and poor bone formation.
- The human skeleton contains 10-12 kg of bone, 1-2 kg of calcium, and 0.5-0.75 kg of phosphorus, with 70% of bone being hydroxyapatite and 30% being osteoid.
- Bone serves as mineral storage, support, protection, movement, and blood cell formation.
- Different types of bones include long, short, flat, irregular, and sesamoid bones.
- Bones consist of cartilage, epiphysis/metaphysis, epiphyseal line, trabecular and cortical bone, and bone marrow producing red and white blood cells.
- Bone cell types include osteogenic, osteoblasts, osteocytes, and osteoclasts.
- Bone growth in the epiphyseal plate is promoted by growth hormone and sex steroids, with osteoblasts replacing chondrocytes and calcifying the new bone matrix.
- Osteoporosis involves faster reabsorption of bone than its reformation, leading to bone thinning and greater fracture risks, especially in trabecular bone.
- Bone marrow contains stem cells, produces osteoprogenitors, and red bone marrow produces red and white blood cells, while yellow bone marrow contains fat cells.
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Description
Test your knowledge of thyroid hormones and calcium regulation with this quiz. Explore the effects of T3 and T4 hormones on growth and development, as well as their role in conditions like myxoedema and Grave’s disease. Delve into the importance of calcium in the body, its absorption regulation by hormones like 1,25-dIhydroxyvitamin D3 and PTH, and the potential consequences of calcium deficiency or excess.
