Endocrine System Flashcards
Growth Hormone
Release by pituitary gland
Targets the liver
Causes release of IGF1
Anabolic agent
IGF1
“Insulin-like Growth Factor-1”
Causes growth - increased muscle mass, bone growth, increases metabolism and uptake of nutrients like fat/amino acids
Doping with GH
Can cause over-development in young horses, and lead to orthopedic issues as they grow older
Anabolic agent
Positive responses, such as tissue building and energy storage
Catabolic agent
Negative responses, such as tissue breakdown and energy release
Insulin
Released due to increase blood-glucose levels
Targets pancreas
Anabolic agent
Positive Effects of Insulin: GO
- glucose uptake
- glycolysis (breakdown of glucose, form ATP)
- glycogen synthesis (storage form of glucose)
- protein synthesis
- uptake of ions
Effects of Insulin: STOP
- gluconeogenesis (generates glucose from non-carb sources)
- glycogenolysis (breakdown of glucose)
- lypolysis (breakdown of fats/lipids)
- ketogenesis (breakdown of fatty acids)
- proteolysis (breakdown of proteins)
Insulin Resitance
The maximum effect insulin has on removing glucose from the blood stream
- Normal has a balance of glucose in the blood stream and in the tissues
- Resistant cannot clear glucose from the blood stream; it builds up there and is not passed into the tissues
Measuring Glucose Tolerance
FSIGT - Frequently sampled intravenous glucose tolerance test
A large amount of glucose is given to the horse, then blood is drawn every 15 minutes for ~3 hours to measure the level of glucose and insulin
Exercise and Insulin
As exercise increases, demand for glucose increases. Insulin concentration will decrease so that glycogenolysis and gluconeogenesis can draw energy from storage
- GLUT4 transporters - increase the amount of glucose brought into tissues
Post-Exercise Glucose
After exercise, glucose (in starch/sugar form) should be fed to the horse to replenish glucose lost in muscles
- Important for high-energy work - racing, eventing. etc
Testosterone
Steroid
Anabolic
Lipophylic - can easily cross cell membrane without a transporter
- Within cell - androgen receptor, and initiates gene expression, RNA translation, and protein production
Males - increases muscle mass and leaner build
Females have less - lower muscle mass, extra padding
Cortisol
Steroid
Catabolic
Released from hypothalamus pituitary adrenal gland
Caused by stress, such as exercise, and ATCH
Stimulates glycogenolysis and inhibits gluconeogensis
Adrenaline/Epinephrine
Steroid
Catabolic
Caused by exercise
Increase HR, cause beta receptors to release fatty acids to use as energy
- too much can cause nervous/jittery horse
