Metabolism - 5 Flashcards
Definition:
Butterfly shaped gland located inferior to the larynx and anterior to the trachea.
thyroid gland
What 2 cells make up the thyroid gland?
follicular and parafollicular
Definition:
Stimulated by TSH to produce thyroxine (T4) and triiodothyronin (T3) collectively known as thyroid hormones.
Follicular cells
Thyroid hormones function to:
- increase BMR
- help maintain normal body temp
- stimulate protein synthesis
- increase the use of glucose and fatty acids for ATP production
- upregulate beta receptors that attach to catecholamins
- work with hGH and insulin to accelerate body growth
What do parafollicular cells produce?
calcitonin
What does calcitonin do?
helps regulate calcium homeostasis by stimulating osteoblasts and inhibiting osteoclasts which lower the level of calcium in the blood
- also prevent reabsorption of calcium in kidneys
Where are the parathyroid glands found?
Posterior aspect of each lobe of the thyroid gland (a total of 4 pea-sized lobes, 1 superior and 1 superior)
What glands contain cheif/parietal cells responsible for producing PTH?
Parathyrdoid glands
PTH acts to:
- increase the number and activity rate of osteoclasts
- increases rate of calcium and magnesium reabsorption in the kidneys
- promotes formation of calcitrol in the kidneys which acts to increase absorption of calcium and magnesium from GI tract
definition:
Works with calcitonin and calcitriol to regulate calcium homeostasis
PTH
Where are the adrenal glands located? What do they consist of?
On top of each kidney, consist of an outer cortex and inner medulla
What types of hormones are secreteted by the adrenal cortex?
- mineralocorticoids
- glucocorticoids
- androgens
Definition:
Regulates mineral homeostasis
Mineralocorticoids
Glucocorticoids affect what?
glucose homeostasis
Definition:
Hormones with masculinizing effects
androgens
What is the major mineralocorticoid?
Aldosterone
What does aldosterone do?
Help regulate sodium and potassium homeostasis (maintain blood osmolarity)
What controls the secretion of aldosterone?
renin-angiotensin aldosterone (RAA) pathway
Secretion of glucocorticoids (cortisol) is regulated by what?
Reales of corticotropin releasing hormone
Secretion of glucocorticoids (cortisol) functions to help control:
- protein breakdown
- glucose formation
- lipolysis
- resistance to stress
- inflammation
- immune responses
What stimulates the adrenal medulla?
sympathetic nervous system
What does stimulation to the adrenal medulla cause?
The secretion of catecholamines such as epinephrine (adrenaline) and norepinephrin (noradrenaline) both of which are involved in the fight or flight response
T/F: pancreas can be classified as both an exocrine and an endocrine gland
What do the exocrine cells of the pancrease do?
produce digestive enzymes that are delivered to the GI tract through ducts
Definition:
Cluster of endocrine tissues scattered among exocrine cells in the pancrease
pancreatic islets (islets of Langerhans)
Where are alpha and beta cells found in the pancreas?
islets of langerhans
Pancreas
What do alpha cells do?
Secrete glucagon to increase blood glucose levels
Pancreas
What do beta cells do?
secrete insulin to decrease blood glucose levels
Definition:
Pineal Gland
Attached to the roof of the third ventricle of the brain and secretes melatonin
Definition:
Released in a diurnal rythm linked to the dark-light cycle which helps regulate the body’s biological clock
Melatonin
What is seasonal affective disorder (SAD) thought to be due to?
Over-production of melatonin
Definition:
Required for the synthesis of molecules and include growth hormone, insulin-like growth factor, insulin, testosterone and estrogen
Anabolic hormones
Definition:
Catabolic hormones
Stimulate the breakdown of molecules and the production of energy. These include cortisol. glucagon, adranaline/epinepherine, and cytokines.
What are the main hormones that aid in the regulation of metabolism?
Insulin, Glucagon
In a fed state blood glucose leveles are HIGH
Explain how insulin helps regulate metabolism
- increase in insulin secretion
- increases glucose uptake
- increase glucose metabolism
- energy stored as glycogen and fat
- increased use of amino acids
What is the goal of insulin?
To get glucose IN the cells
In a fasting state: Blood glucose levels are LOW
Explain how glucagon regulate metabolism
More glucagon is released
- breakdwon of glycogen
- formation of new glucose
- release of glucose from liver
formation of keytones
What is the goal of glucagon?
When all the blood glucose is gone, think GLUCAGON (ie. more glucose in the blood)
Review glucose and glucagon regulation.
