Metabolism S7 - Endocrinology Flashcards
Define tropic hormones
A hormone that has another endocrine gland as their target
Define trophic hormones
a hormone that stimulates growth in a target tissue
Define hormones
Chemical signals produced in endocrine glands or tissue, which travel in the bloodstream causing an effect on other tissues
List the classes of hormones
1) Polypeptide hormones (largest group)
2) Glycoprotein hormones
3) Amino acid derivatives
4) Steroids
Where is thyrotropin released from?
Hypothalamus
What does thyrotrophin stimulate?
Release of thyroid stimulating hormone
Where is thyroid stimulating hormone released from?
The anterior pituitary
Where is corticotrophin released from?
Hypothalamus
What does corticotrophin stimulate?
The release of adrenocorticotrophic hormone
Where is adrenocorticotrophic hormone released from?
Anterior pituitary
What does somatotrophin stimulate?
Growth hormone
Where is growth hormone released from?
Anterior pituitary
Where is somatotrophin released from?
Hypothalamus
How are steroid hormones inactivated?
Relatively small changes in their chemical structure increases their water solubility. This allows them to be easily excreted from the body in the urine or via the bile
How are protein hormones inactivated?
undergo extensive chemical changes and are degraded into amino acids that are then reused
What major action does insulin have on carbohydrates, lipids and amino acid metabolism?
- Increased glycogenesis
- Increased glycolysis in liver/adipose tissue
- Increased lipoprotein lipase activity in capillary bed of tissues such as adipose tissue
- Increase amino acid uptake and protein synthesis in liver, muscle and adipose tissue
- Decreased proteolysis in liver, skeletal muscle and adipose tissue
- Decreased glycogenolysis in liver/muscle
- Decreased gluconeogenesis in liver
- Decreased lipolysis in adipose tissue
- Decreased ketogenesis in liver
What major action doe glucagon have?
- Increased glycogenolysis
- Increased gluconeogenesis in the liver
- Increased ketogenesis in the liver
- Increased lipolysis in adipose tissue
- Decreased glycogenesis in liver
What do β-cells in the islets of Langerhaans produce?
Insulin
What do α-cells in the islets of Langerhaans produce?
Glucagon
What are the main, general features of control systems in the body?
Communication - Hormones, action potentials
Control centre - Determines set point, analyse input, determines response
Receptor - Signal afferent pathway
Effector - Efferent pathway
Give two examples of biological rhythms?
Circadian rhythm - controlled by the suprachiasmatic nucleus in the hypothalamus
Menstrual cycle
Describe two methods of hormone transport?
Lipophilic - bound to transport proteins
hydrophilic - free in plasma
What type of hormone would bind to cell surface receptors?
polypeptide and glycoprotein hormones
What type of hormone binds to intracellular receptors, cytoplasmic or nucleus?
Steroid
Where is the control centre for appetite?
Arcuate nucleus in the hypothalamus
What hormone stimulates the primary excitatory centre?
Ghrelin - released from empty stomach
What is released from primary excitatory centre?
Neuropeptide Y
Agouti-related peptide
What hormones stimulate the primary inhibitory centres?
Leptin - released from adipose
PYY - Released from small intestine
Insulin and amylin - released from the pancreas
What is released from the primary inhibitory centre?
POMC - a pro-hormone that is cleaved to give:
- α-MSH which act on melanocortin 4 receptors which suppresses appetite
- ACTH
- β-endorphins - reward system, euphoria and tiredness
List the features of metabolic syndrome?
Hypertension, impaired glucose tolerance, insulin resistance, dyslipidaemia
What is metabolic syndrome?
A common pattern of symptoms that arise in obese patients
What is the Developmental Origins of Health and Disease?
Study that the incidence of certain adult disease are related to low birth weight. This suggests that the experience of the foetus in utero during development somehow determines the future health of the individual
What is metabolic acidosis?
Metabolic acidosis is a condition that occurs when the body produces excessive quantities of acid or when the kidneys are not removing enough acid from the body
Describe results you would see for a glucose tolerance test if glucose utilisation was abnormally slow?
Glucose levels rise but stay abnormally high for a long time and take a while to drop down to normal levels
What enzyme is rate limiting in glycogenolysis?
Glycogen phosphorylase
Give one example of negative feedback in the body?
- Insulin release in response to hyperglycaemia
Give one example of positive feedback in the body?
Blood clotting
Ovulation
Explain why epigenetic is different to genetic mutation?
Genetic mutation involves changes in the nucleotide sequence (changes in DNA sequence)
Epigenetics involves methylation of DNA and changes in histone structure that affect gene transcription
