Lecture 19: Calcium Regulation & Metabolic Regulation

Why We Need to Eat

• Food is a source of energy for the body, necessary for various activities such as movement, muscle contractions, and active transport.
• Food provides building blocks for the body, including minerals, vitamins, and raw materials for making proteins, carbohydrates, nucleic acids, and other molecules.

Vitamins and Minerals

• Vitamins are small organic molecules needed by the body in smaller quantities, classified as micronutrients.
• Minerals are inorganic molecules needed by the body, also classified as micronutrients.
• Vitamins can be either fat-soluble (e.g., A, D, E, K) or water-soluble (e.g., B vitamins, folic acid, vitamin C).
• Fat-soluble vitamins are hydrophobic and can be retained in the body's fat tissue.
• Water-soluble vitamins are hydrophilic and dissolve in fluids, but tend not to be stored in the body and are cleared through the kidneys.

Functions of Vitamins

• Vitamin A is essential for vision, as it's a precursor molecule for the photopigment in the eye.
• Vitamin D is important for calcium regulation and has other roles.
• Vitamin E has various functions in the body.
• Vitamin K is necessary for blood cell formation.
• B vitamins, folic acid, and vitamin C have various functions in the body, including acting as coenzymes and being important for immune function.

Vitamin Deficiencies

• Scurvy is a vitamin C deficiency that can cause problems such as bleeding gums and bruising easily due to the importance of vitamin C in connective tissue production and immune function.
• Rickets is a vitamin D deficiency that can lead to deformed bones in children due to the importance of vitamin D in calcium absorption and bone growth.

Minerals

• Major minerals include potassium, sodium, calcium, phosphorus, magnesium, and chloride.
• Trace minerals, needed in very small quantities, include iron, zinc, copper, and others.
• Minerals have various functions, such as acting as cofactors for enzymes, maintaining osmotic balance, and being involved in membrane potential and oxygen transport.
• Iron is essential for oxygen transport.

Why We Need to Eat

• Food serves as a source of energy for the body, enabling various activities such as movement, muscle contractions, and active transport.
• It provides building blocks for the body, including minerals, vitamins, and raw materials for producing proteins, carbohydrates, nucleic acids, and other molecules.

Vitamins and Minerals

• Vitamins are small organic molecules required by the body in small quantities, classified as micronutrients.
• Minerals are inorganic molecules needed by the body, also classified as micronutrients.
• Vitamins can be classified into two categories: fat-soluble (e.g., A, D, E, K) and water-soluble (e.g., B vitamins, folic acid, vitamin C).
• Fat-soluble vitamins are hydrophobic and can be stored in the body's fat tissue.
• Water-soluble vitamins are hydrophilic, dissolve in fluids, and tend not to be stored in the body, being cleared through the kidneys instead.

Functions of Vitamins

• Vitamin A is essential for vision, serving as a precursor molecule for the photopigment in the eye.
• Vitamin D plays a crucial role in calcium regulation and has other functions.
• Vitamin E has various functions in the body.
• Vitamin K is necessary for blood cell formation.
• B vitamins, folic acid, and vitamin C have various functions, including acting as coenzymes and being important for immune function.

Vitamin Deficiencies

• Scurvy is a vitamin C deficiency, leading to issues such as bleeding gums and bruising easily due to the importance of vitamin C in connective tissue production and immune function.
• Rickets is a vitamin D deficiency, resulting in deformed bones in children due to the importance of vitamin D in calcium absorption and bone growth.

Minerals

• Major minerals include potassium, sodium, calcium, phosphorus, magnesium, and chloride.
• Trace minerals, needed in very small quantities, include iron, zinc, copper, and others.
• Minerals have various functions, such as acting as cofactors for enzymes, maintaining osmotic balance, and being involved in membrane potential and oxygen transport.
• Iron is essential for oxygen transport.

Why We Need to Eat

• Food serves as a source of energy for the body, enabling various activities such as movement, muscle contractions, and active transport.
• It provides building blocks for the body, including minerals, vitamins, and raw materials for producing proteins, carbohydrates, nucleic acids, and other molecules.

Vitamins and Minerals

• Vitamins are small organic molecules required by the body in small quantities, classified as micronutrients.
• Minerals are inorganic molecules needed by the body, also classified as micronutrients.
• Vitamins can be classified into two categories: fat-soluble (e.g., A, D, E, K) and water-soluble (e.g., B vitamins, folic acid, vitamin C).
• Fat-soluble vitamins are hydrophobic and can be stored in the body's fat tissue.
• Water-soluble vitamins are hydrophilic, dissolve in fluids, and tend not to be stored in the body, being cleared through the kidneys instead.

Functions of Vitamins

• Vitamin A is essential for vision, serving as a precursor molecule for the photopigment in the eye.
• Vitamin D plays a crucial role in calcium regulation and has other functions.
• Vitamin E has various functions in the body.
• Vitamin K is necessary for blood cell formation.
• B vitamins, folic acid, and vitamin C have various functions, including acting as coenzymes and being important for immune function.

Vitamin Deficiencies

• Scurvy is a vitamin C deficiency, leading to issues such as bleeding gums and bruising easily due to the importance of vitamin C in connective tissue production and immune function.
• Rickets is a vitamin D deficiency, resulting in deformed bones in children due to the importance of vitamin D in calcium absorption and bone growth.

Minerals

• Major minerals include potassium, sodium, calcium, phosphorus, magnesium, and chloride.
• Trace minerals, needed in very small quantities, include iron, zinc, copper, and others.
• Minerals have various functions, such as acting as cofactors for enzymes, maintaining osmotic balance, and being involved in membrane potential and oxygen transport.
• Iron is essential for oxygen transport.

Calcium in the Body

• Calcium plays crucial roles in maintaining bone health, signaling, muscle contraction, and blood clotting.
• It functions as a second messenger in signal transduction pathways, signaling the release of neurotransmitters from neurons.
• Calcium is necessary for muscle contraction, as its release into the cytoplasm allows muscles to contract.

Calcium Regulation

• Calcium levels in the blood are influenced by bone deposition, bone resorption, intestinal absorption, and kidney reabsorption and secretion.
• Bone deposition reduces calcium levels in the blood by storing calcium in bones.
• Bone resorption releases calcium into the blood, increasing calcium levels.

Bones and Calcium

• Bones provide structure, attachment points for muscles, and store calcium and phosphate.
• The bone matrix is composed of calcium, phosphate, and collagen, providing hardness and strength to the bone.
• Bone is dynamic, constantly changing and being remodeled by osteoblasts and osteoclasts.

Hormonal Regulation

• Calcium levels are regulated by parathyroid hormone (PTH), vitamin D, and calcitonin.
• PTH is released in response to low calcium levels, stimulating osteoclast activity, promoting calcium reabsorption, and helping synthesize vitamin D.
• Vitamin D is essential for calcium absorption, produced in the skin upon UV light exposure, and in the kidney.
• Vitamin D stimulates calcium absorption, increasing calcium levels in the blood.
• Calcitonin is released in response to high calcium levels, decreasing calcium and phosphate levels by stimulating bone deposition and inhibiting calcium and phosphate reabsorption.

Hormonal Interaction

• Estrogen is important for maintaining bone health, stimulating bone deposition, bone growth, and sealing growth plates during puberty.
• A decline in estrogen levels can lead to osteoporosis.

Osteoporosis

• Osteoporosis is characterized by a loss of mineral and organic matrix, leading to reduced bone density and an increased risk of fractures.
• It is common in older adults, particularly post-menopausal women, due to declining estrogen levels.

Calcium in the Body

• Calcium plays crucial roles in maintaining bone health, signaling, muscle contraction, and blood clotting.
• It functions as a second messenger in signal transduction pathways, signaling the release of neurotransmitters from neurons.
• Calcium is necessary for muscle contraction, as its release into the cytoplasm allows muscles to contract.

Calcium Regulation

• Calcium levels in the blood are influenced by bone deposition, bone resorption, intestinal absorption, and kidney reabsorption and secretion.
• Bone deposition reduces calcium levels in the blood by storing calcium in bones.
• Bone resorption releases calcium into the blood, increasing calcium levels.

Bones and Calcium

• Bones provide structure, attachment points for muscles, and store calcium and phosphate.
• The bone matrix is composed of calcium, phosphate, and collagen, providing hardness and strength to the bone.
• Bone is dynamic, constantly changing and being remodeled by osteoblasts and osteoclasts.

Hormonal Regulation

• Calcium levels are regulated by parathyroid hormone (PTH), vitamin D, and calcitonin.
• PTH is released in response to low calcium levels, stimulating osteoclast activity, promoting calcium reabsorption, and helping synthesize vitamin D.
• Vitamin D is essential for calcium absorption, produced in the skin upon UV light exposure, and in the kidney.
• Vitamin D stimulates calcium absorption, increasing calcium levels in the blood.
• Calcitonin is released in response to high calcium levels, decreasing calcium and phosphate levels by stimulating bone deposition and inhibiting calcium and phosphate reabsorption.

Hormonal Interaction

• Estrogen is important for maintaining bone health, stimulating bone deposition, bone growth, and sealing growth plates during puberty.
• A decline in estrogen levels can lead to osteoporosis.

Osteoporosis

• Osteoporosis is characterized by a loss of mineral and organic matrix, leading to reduced bone density and an increased risk of fractures.
• It is common in older adults, particularly post-menopausal women, due to declining estrogen levels.

Energy from Food

• Calories on a nutrition label represent the total energy in a food, regardless of its macronutrient source (fats, carbohydrates, proteins, etc.)
• Percent daily values on nutrition labels are based on a 2000 calorie diet, but individual daily calorie requirements vary depending on metabolic rate

Metabolic Rate

• Metabolic rate is the rate at which the body expends energy per unit of time
• It's measured by oxygen consumption and carbon dioxide production
• Basal metabolic rate (BMR) is the metabolic rate under specific conditions: awake, comfortable temperature, 12-14 hours since eating, and relaxed
• BMR varies depending on age, sex, body surface area, and thyroid hormone secretion
• Physical activity, eating, and surrounding temperature are factors that influence metabolic rate

Energy Balance and Weight

• When energy input (caloric intake) exceeds energy expenditure, weight gain occurs
• When energy input is less than energy expenditure, weight loss occurs
• The body normally maintains a normal body weight range, with a set point, making it difficult to gain or lose weight
• When trying to lose weight, a plateau may be reached due to the body's response to reduce appetite and increase metabolism

Extreme Dieting and Weight Loss

• A study on The Biggest Loser contestants found that 13 out of 14 regained weight, and 4 now weighed more than before the show
• Extreme dieting may lower metabolic rate in the long term, making it harder to keep the weight off

Eating Behavior Regulation

• The hypothalamus is a key control center in the brain that regulates eating behavior
• Hormones from various tissues (stomach, pancreas, small intestine, adipose tissue) influence the hypothalamus to regulate hunger and satiety
• Hormones involved in eating behavior regulation include ghrelin, insulin, CCK, and leptin

Hormones and Eating Behavior

• Ghrelin stimulates hunger when released by the stomach when it's empty
• Insulin suppresses hunger and promotes feelings of satiety when released by the pancreas after eating
• CCK suppresses hunger and promotes feelings of satiety when released by the small intestine after a high-calorie meal
• Leptin suppresses hunger and promotes feelings of satiety, and also influences metabolic rate, when released by adipose tissue

Obesity and Hormones

• A study on mice found that knocking out the leptin receptor or leptin gene led to constant hunger and weight gain due to overeating and slower metabolism
• Leptin has implications for understanding obesity and its role in regulating metabolic rate and hunger

Energy from Food

• Calories on a nutrition label represent the total energy in a food, regardless of its macronutrient source (fats, carbohydrates, proteins, etc.)
• Percent daily values on nutrition labels are based on a 2000 calorie diet, but individual daily calorie requirements vary depending on metabolic rate

Metabolic Rate

• Metabolic rate is the rate at which the body expends energy per unit of time
• It's measured by oxygen consumption and carbon dioxide production
• Basal metabolic rate (BMR) is the metabolic rate under specific conditions: awake, comfortable temperature, 12-14 hours since eating, and relaxed
• BMR varies depending on age, sex, body surface area, and thyroid hormone secretion
• Physical activity, eating, and surrounding temperature are factors that influence metabolic rate

Energy Balance and Weight

• When energy input (caloric intake) exceeds energy expenditure, weight gain occurs
• When energy input is less than energy expenditure, weight loss occurs
• The body normally maintains a normal body weight range, with a set point, making it difficult to gain or lose weight
• When trying to lose weight, a plateau may be reached due to the body's response to reduce appetite and increase metabolism

Extreme Dieting and Weight Loss

• A study on The Biggest Loser contestants found that 13 out of 14 regained weight, and 4 now weighed more than before the show
• Extreme dieting may lower metabolic rate in the long term, making it harder to keep the weight off

Eating Behavior Regulation

• The hypothalamus is a key control center in the brain that regulates eating behavior
• Hormones from various tissues (stomach, pancreas, small intestine, adipose tissue) influence the hypothalamus to regulate hunger and satiety
• Hormones involved in eating behavior regulation include ghrelin, insulin, CCK, and leptin

Hormones and Eating Behavior

• Ghrelin stimulates hunger when released by the stomach when it's empty
• Insulin suppresses hunger and promotes feelings of satiety when released by the pancreas after eating
• CCK suppresses hunger and promotes feelings of satiety when released by the small intestine after a high-calorie meal
• Leptin suppresses hunger and promotes feelings of satiety, and also influences metabolic rate, when released by adipose tissue

Obesity and Hormones

• A study on mice found that knocking out the leptin receptor or leptin gene led to constant hunger and weight gain due to overeating and slower metabolism
• Leptin has implications for understanding obesity and its role in regulating metabolic rate and hunger