Control of Growth and Metabolism Flashcards
What is metabolism?
Sum of all chemical and physical changes that occur in the body tissue
What are the three main components of metabolism?
- Basal metabolic rate
- Mobilization and delivery of nutrients to cells
- Anabolism and cell/tissue growth
What is basal metabolic rate?
Think CALORIES
Generation of ATP
- measure of energy
- how many nutrients are available
- how much ATP can be generated (some waste will be produced)
- how much ATP do we need to make to maintain basic processes/functions
- typically measured in CALORIES
- the number of calories your body needs to accomplish its most basic (basal) life-sustaining functions.
- an estimate of the energy intake the entire body requires to produce enough ATP to maintain all its basic functions at rest
What is mobilization and delivery of nutrients to cells?
- movement of nutrients and delivery of them to cell so that they can use that ATP for other processes
- hormones affect the ability to move nutrients
- mobilizing and distributing the nutrient pool to cells throughout the body
- nutrients are obtained through the digestive tract
What is anabolism and cell/tissue growth?
- small molecules building up larger molecules (building of macromolecules from smaller components)
- synthesis of complex molecules (from fatty acids, glucose, smaller molecules, etc.)
- requires use of ATP
- smaller components build up for cell growth/tissue growth
- involves cell division, growth and proliferation
Heat is a byproduct of using ATP: Explain its uses
- waste is produced as a result of using ATP
- heat is one of those waste products
- heat contributes to maintaining general body temperature
What is a nutrient pool of a cell?
All the nutrients that are immediately available for catabolism by its mitochondria
- may find stores of nutrients in cells
- will be available for certain cell types to generate ATP at any time
Briefly summarize what each effect is and an example of a hormone that regulates this aspect of metabolism:
Direct regulation of BMR
BMR - how much ATP is needed to maintain basic functions (calories)
Direct effect of THYROID hormones
Briefly summarize what each effect is and an example of a hormone that regulates this aspect of metabolism:
Regulating nutrient mobilization and uptake
Movement/delivery of nutrients to different cells (availability to produce ATP at a given time)
Thyroid hormones, epinephrine, cortisol, growth hormone, glucagon, insulin
Briefly summarize what each effect is and an example of a hormone that regulates this aspect of metabolism:
Regulating anabolism and cell/tissue growth
Building up of larger molecules from small molecules
Thyroid hormones, growth hormone, somatomedins, sex steroids, calcitriol
Recall: What are class 1 hormones?
Amino-acid derivatives
- hydrophobic
- epinephrine and thyroid hormones
- produced and stored in vesicles
- released as needed or when calcium levels rise
What are class 2 hormones?
Peptide hormones
- hydrophilic
- stored in large vesicles and released when calcium levels rise
What are class 3 hormones?
Lipid-derivative hormones
- hydrophobic
- travel through blood with a carrier protein because they are lipid-soluble and cannot travel through the fluid by themselves
- bind to intra-cellular receptors
How do thyroid hormones directly regulate BMR?
Regulate BMR by affecting mitochondrial function
- thyroid hormones are hydrophobic hormones that act through intracellular receptors
- bind to protein receptors on mitochondria and within nucleus
- directly changes the rate in which ATP is generated
- directly affects MBR because the hormone binds to receptor on mitochondria
- can increase ATP production in mitochondria = more waste = more heat (thermal regulation)
What does is mean for thyroid hormones to be hydrophobic?
They are class 1 - amino-acid derivative hormones
- they are hydrophobic
- have the ability to pass through the membrane on its own but cannot travel through the bloodstream by itself
- must bind to carrier proteins to reach target cells
- acts on intracellular proteins because they do not interact with the membrane
How do thyroid hormones indirectly affect metabolic processes?
Thyroid hormones indirectly affect metabolic processes by changing gene expression through nuclear receptors
- can affect nutrient mobilization and uptake
- can regulate anabolism and cell/tissue growth
Instead of acting on the mitochondria (direct effect), thyroid hormones act on intracellular receptors located in the nucleus to change the expression levels of specific genes in the target cells when activated
How do non-thyroid hormones affect metabolism? Which non-thyroid hormones do this?
Non-thyroid hormones that affect metabolism alter the availability of nutrients in the bloodstream through effects on energy stores
- affect the mobilization and delivery of nutrients to cells
HORMONES: epinephrine, glucagon, growth hormone, glucocorticoids
Non-thyroid hormones: Epinephrine and glucagon
How do they affect metabolism in the liver and adipose tissue?
ACTS ON LIVER AND ADIPOSE TISSUES
- Epinephrine
- Glucagon
- release fatty acids (mobilize stored glucose and fatty acids)
- release fatty acids and mobilized stored glucose (increase blood glucose when it is low)
What is the glucose sparing effect and which non-thyroid hormone controls this?
The effects of glucocorticoids/GH include the stimulation of triglyceride breakdown (breakdown of lipids) and release into the blood by adipocytes
This results in a switch by most tissues from utilizing glucose as an energy source to utilizing fatty acids
This process is called a glucose-sparing effect
Allows for the body to reserve glucose for the brain and use fatty acids for the rest of the body to supply energy for basic functions
- tells other parts of the body to use fatty acids instead of glucose as energy
Non-thyroid hormones: Glucocorticoids and growth hormone
How do they affect metabolism in the liver and adipose tissue?
ACTS ON LIVER AND ADIPOSE TISSUES
- Glucocorticoids
- Growth hormone
- stores glucose and can synthesize glucose and fatty acids (glucose sparing effect)
- mobilize stored fatty acids and glucose AND promote lipid use AND stimulate gluconeogenesis
How do glucocorticoids and GH have the glucose sparing effect?
- liver
- muscle fibres
- adipose tissue
- brain/CNS
They promote the use of lipids for metabolism by most somatic cells to save glucose for the CNS/brain
- tells the liver to make glucose but tells the rest of the body to use fatty acids instead of glucose (stores glucose and can synthesize glucose, fatty acids, and ketones)
- if glucose stores run out, there are amino acid stores in muscle fibres that can be used if glucose levels become dangerously low
- both hormones release fatty acids but streamline glucose to the CNS to maintain the function of the brain
- hoards all the good stuff for the brain
- the rest of the tissues use fatty acids
Why do we need the glucose sparing effect?
To save up glucose for the CNS to use because the CNS cannot use fatty acids to generate ATP
- tells other tissue types to use fatty acids instead of glucose
- release stored glucose in the liver for the brain
What are the effects of synthesizing ketones for metabolism?
Production of ketone leads to the production of many toxins
- long-term: very harmful
- short-term: maintains brain
How does the pituitary growth hormone play a primary role in promoting growth?
- mobilization and delivery of nutrients to cells
- anabolism and cell/tissue growth
Release of GH causes:
- glucose-sparing effect
- growth effects
- increases uptake of amino acids from the blood
- enhances cellular proliferation and reduces apoptosis
- indirectly (somatomedins) acts on liver and stimulates liver to release hormones/release glucose/produce more glucose
- diabetogenic effect
- stimulates liver to break down glycogen into glucose, fueling growth effects
- can have a negative feedback effect on the inhibition of GH from the anterior pituitary