Lecture 18 - Control of Growth and Metabolism Flashcards
What is metabolism and what are the 3 components
It’s the sum of all chemical and physical changes that occur in body tissues
- Basal metabolic rate
- Mobilization and delivery of nutrients to cells
- Anabolism and cell/tissue growth
What is basal metabolic rate (BMR)?
An estimate of the energy intake the entire body requires to produce enough ATP to maintain all its basic functions at rest
Describe the mobilization and delivery of nutrients to cells in the body
Each cell contains a nutrient pool that has nutrients that are immediately available for catabolism by its mitochondria
What is anabolism and cell/tissue growth?
Anabolism is the building of macromolecules from smaller components
Growth in the body involves a combination of anabolism, individual cell growth, cell proliferation (growth and proliferation), and cell survival
How do thyroid hormones regulate BMR and where are thyroid hormone receptors located?
Thyroid hormone signalling can directly regulate BMR by affecting mitochondrial function
Thyroid hormone receptors are located in the mitochondria and upregulate aerobic metabolic activity when activated
How do thyroid hormones affect metabolic processes (ie. regulating nutrient mobilization and uptake, and regulating anabolism and cell/tissue growth)
They indirectly affect these metabolic processes through nuclear receptors
Thyroid hormone receptors located in the nucleus change the expression levels of specific genes in the target cells when activated
How do non-thyroid hormones affect metabolism?
They alter the availability of nutrients in the bloodstream through effects on energy stores
Ex. Epinephrine and glucagon mobilize stored glucose and fatty acids. Glucocorticoids and growth hormones mobilize stored fatty acids and glucose, promote lipid use, and stimulate gluconeogenesis
Describe the “glucose-sparing effect”. What metabolism category does this lie under?
Glucocorticoids and GH show this effect to promote the use of lipids for metabolism by most somatic cells, saving glucose for the CNS. The adipose cells are stimulated to break down stored fat, fuelling growth effects
*The CNS cannot use fatty acids to generate ATP
Mobilization and delivery of nutrients to cells category
How does growth hormone play a primary role in promoting growth? What metabolism cateogry/ies does this fall under?
Growth effects increases uptake of amino acids from the blood and enhances cellular proliferation and reduces apoptosis. They also influence the glucose-sparing effect
Mobilization and delivery of nutrients to cells, anabolism and cell/tissue growth categories
True or false? Only metabolic hormones regulate growth at different life stages
False - metabolic and non-metabolic hormones regulate growth at different life stages
Name 7 symptoms of hyperthyoidism
- Intolerance to heat
- Bulging eyes
- Facial flushing
- Tachycardia
- Increase in systolic blood pressure
- Weight loss
- Muscle wasting
Name 8 symptoms of hypothyroidism
- Intolerance to cold
- Facial and eyelid edema
- Extreme fatigue
- Apathy
- Lethargy
- Anorexia
- Muscle aches and weakness
- Weight gain
What are 6 ways thyroid hormone receptors influence the body?
- Feeding behaviour and activity level - non-endocrine hypothalamic neurons
- Increase cardiovascular output by increasing sensitivity to sympathetic stimulation
- Skeletal muscle growth and repair - directly increase muscle energy expenditure
- Enhance blood production by bone marrow and mineral turnover by bone
- Regulates nutrient homeostasis roles of the liver
- Modulate adipocyte development and regulation
What is the function of the pancreas?
It secretes 2 peptide hormones, glucagon and insulin, that directly regulate blood glucose and glucose use
How does glucagon and insulin work together to maintain blood glucose level?
They use opposing negative feedback loops to help maintain a normal blood glucose level (4-7 mmol/L)
Insulin stimulates glucose uptake by cells
Glucagon stimulates gluconeogenesis and glyconeogenesis in liver and release of glucose to plasma