lecture 11 - an introduction to hormonal regulation of energy metabolism Flashcards
what is a hormone?
chemical messengers released from glands and organs which can be transported around the body to regulate numerous processes e.g. growth, reproduction and metabolism
how do hormones communicate?
endocrine system acts via the bloodstream to communicate to distant cells.
what does the endocrine system signal to?
distant cells via the bloodstream which allows for whole-body comm between tissues e.g. insulin, cortisol and testosterone
what does the paracrine system signal to?
nearby cells via extracellular/interstitial fluid which is often short lived signals for transient signals e.g. growth factors and nitric oxide
what does the autocrine system signal to?
itself via extracellular/interstitial fluid which allows for self-regulation of cells
what is a peptide hormone?
protein hormone, made up of diff amino acids e.g. insulin
what is a steroid hormone?
made from cholesterol, can be affective at switching genes on and off e.g. cortisol, oestrogen, testosterone
what is an amino-acid derived hormone?
from single AA e.g. adrenaline, thyroid hormones
what is a lipid derived hormone?
derived from fatty acids and is exclusive to the paracrine system
how do glands know when to secrete hormones?
Endocrine cascade – starts with a stimulus, hormone release, transport to the targe tissue where it is recognised and it has an effect on the target tissue.
what is the most common pathway for the release of hormones?
hypothalamus- pituitary target organ axis
what is the hypothalamus- pituitary target organ axis pathway?
1) Stimulus from the environment
2) CNS activity – something happens in the brain when you see, hear something
3) Hypothalamus releases neuro-hormones
4) Stimulates hormone release from pituitary gland
5) Hormones act on target tissue
what detects changes in blood glucose concentration levels?
alpha and beta cells - this triggers the release of glucagon and insulin
what does insulin promote?
storage
- it wants to make (anabolic)
- it signals that energy is available
what does glucagon promote?
release
- it wants to break (catabolic)
- it signals that energy is needed
why do insulin and glucagon act in a contrasting manner?
to regulate blood glucose homeostasis
what is an example of a storage/ anabolic process?
glycogenesis
what is an example of a liberating/ catabolic process?
glycogenolysis
how do insulin and glucagon act upon target tissue?
1) Hormone
2) Receptor – needs to be detected on the membrane by a receptor
3) Signal transduction – so that it can have some sort of action on the process of a cell
4) Action
what is glycogenolysis regulated by?
glycogen phosphorylase
what is glycogenesis regulated by?
glycogen synthase
what pathway does glucagon trigger?
GPCR
- this is the signal transduction
does glucagon activate or inhibit glycogenolysis?
activate
what does PKA activate?
glycogenolysis
what switches glycogenolysis on so that glucose can be released into the liver and into circulation?
PKA
what kind of reaction is adrenaline?
catabolic - it wants to breakdown to liberate fuels (to fight or flee)
what is the skeletal muscle transporter?
GLUT4
