Biochemistry Flashcards
What hormones are released by the anterior and posterior pituitary glands?
Anterior
- LH + FSH
- GH
- ACTH
- Prolactin
- TSH
Posterior
- Oxytocin
- ADH
How many times does a G-protein coupled receptor cross the cell membrane?
7 times
What is the largest kind of hormone receptor?
G-protein coupled receptor
What is the largest type of hormone?
What are the two other smaller types?
Largest = protein/polypeptide
Steroid
AA derived
Where are steroid hormone receptors found?
Typically intracellular - within cytoplasm/nucleus
Why is dynamic testing important?
The production of hormones varies throughout the day
When is cortisol at its highest level?
In the morning and then drops throughout the day
What is the only hormone produced by the anterior pituitary gland that secretes based on gaps in negative feedback loop as opposed to secretion by hormone trigged from hypothalamus?
Prolactin
What is the purpose of prolactin?
Relatively unknown
Acts on breast tissue to induce lactation
What kind of receptor does insulin bind to?
Compare the length of activation time of this kind of receptor compared to G-protein receptors
RTK - receptor tyrosine kinase
These receptors can cause longer activation than G-protein coupled receptors
Describe how ligand-gated ion channels work.
What is their purpose?
They cause de/repolarisation of the cell membrane
Hormone (type of ligand) binds to receptor causing it to open and ions to flood through
Ligand-gated ion channels and G-protein coupled receptors are both membrane bound receptors that only need a few on the cell membrane to make a big response.
Why do they only need a few?
Both cause very quick reactions
G-protein coupled receptors can all be v. similar, what part of the receptor indicates the response that it will cause?
G-alpha subunit (this is the part that activates/inhibits the enzyme)
For steroid, amine derived and protein/polypeptide hormones comment on each of the following factors:
- How are they transported in the blood?
- Are they stored?
- How do they enter the cell?
Steroid
- bound to carrier proteins
- not stored
- enter cell and bind to receptor inside
Protein
- travel freely
- stored
- bind to receptors on cell membrane
Amine derived
- travel freely (apart from thyroid hormones)
- can be stored
- bind to receptors on cell membrane
What carrier protein is responsible for transporting the following hormones:
- sex-steroid
- T4
- cortisol (+ sometimes aldosterone)
SSBG (sex-steroid binding globulin)
TBG (thyroxine binding globulin)
CBG (cortisol binding globulin)
What inhibits GH from being produced?
Inhibits GH-releasing hormone
Too much GH
Somatomedins (small hormones produced by liver, bones and muscles)
Together trigger hypothalamus to produce somatostatin -> inhibits GH-releasing hormones
How does the majority of cortisol travel in the body?
Bound to CBG (cortisol-binding globulin)
How is the anterior pituitary connected to the hypothalamus?
Hypophyseal portal system (only other portal system in body apart from liver)
Where is oxytocin and ADH produced?
Hypothalamus and released from posterior
What hormone stimulates ACTH production?
CRH
What type of receptor does growth hormone bind to?
Cytokine receptor
What must cholesterol be converted to at the start of all all steroid hormone (cortisol, testosterone and aldosterone) synthesis?
Pregnenolone
What effect can be observed on insulin and thyroxine production post-operatively?
Decreased production
What effect can steroids have on blood sugar levels?
HYPERglycaemia
