CEP Flashcards
How can hormones travel in the blood?
- In free form
- Bound to a protein (typically lipid hormones)
What are the three types of hormones?
- Amino acid derivative
- Peptide hormone
- lipid derivative (steroids and thyroid hormones)
How do protein and amino acid derived hormones bind to cells to initiate a response?
Bind to cell receptors on the plasma membrane.
How do steroid and thyroid hormones bind to cells to initiate a response?
Pass through the plasma membrane as they are lipid derived and bind to cell receptors in the cytoplasm.
What is the hypothalamus responsible for producing?
Antidiuretic Hormone and oxytocin
Regulatory hormones
What is secreted by the posterior lobe of the pituitary?
ADH and oxytocin.
They are produced in the hypothalamus but released by the pituitary.
What is secreted from the anterior lobe of the pituitary?
ACTH-(Adrenocorticotropic hormone) TSH-(Thyroid stimulating hormone) GH-(growth hormone) PRL-(prolactin) FSH-(follicle stimulating hormone) LH-(lutenising hormone)
What regulates secretion of hormones from the anterior pituitary?
Regulatory hormones produced by the hypothalamus
What does the pineal glad secrete?
Melatonin-internal body clock
pineal gland located in brain
What is secreted by the thyroid gland?
Throxine (T4) (increase metabolic rate)
triiodothyronine (T3) (increase metabolic rate)
Calcitonin
What is secreted by the parathyroid gland?
PTH-(parathyroid hormone)
What is secreted by the adrenal cortex?
Mineralcorticoids-Aldosterone
Glucocorticoids-Cortisol
Androgens-testosterone
What is secreted by the adrenal medulla?
Adrenaline and noradrenaline
What saliva is produced by the parotid gland?
watery serous saliva
What saliva is produced by the submandibular glands?
Mixed serous and mucous saliva
What saliva as produced by the sublingual glands?
Mixed saliva that is thicker
Which salivary gland produces the majority of the saliva?
The submandibular gland produces 60%
Which nerve supplies the parotid gland?
parasympathetic motor component of the glossopharngeal nerve
What nerve supplies the submandibular gland?
supplied by the secretomotor fibres of the chorda tympani branch of facial nerve
What nerve supplies the sublingual gland?
Supplied by the chorda tympani branch of the facial nerve
Because of their relationship to the cavernous sinus which cranial nerves are susceptible to compression or injury from infections?
CN III, CN IV, CN V, CN VI
How does an integral ion channel work?
2 agonists bind to receptor
Breaks down hydrophobic interactions opening the pore
Allows specific ion movement
How does an integral tyrosine kinase work?
Agonist binds
tyrosine kinase phosphorylates receptor
causes a change in conformation
How does a steroid receptor work?
Steroid can move through membrane as it is lipid soluble
binds to receptor on nucleus
has effect by promoting or suppressing gene expression
How does a G protein coupled receptor work?
Agonist binds to g protein coupled receptor
this interacts with the g protein
this interacts with the effector protein
this starts the signal transduction pathway by producing a second messenger
What molecule is bound to the alpha sub-unit of a non activated G-protein?
GDP
What happens to a G-protein when a ligand binds to a g-protein coupled receptor?
Causes a conformational change that activates the G-protein
This causes the alpha sub unit to lose its GDP and pick up GTP
What happens to the G-protein when GTP binds to the alpha sub-unit?
It breaks off from the beta and gamma complex and moves to the effector
here it will either activate or inhibit it
What happens after an alpha subunit of a G protein has activated or inhibited its effector?
It hydrolyses the GTP back to GDP
The alpha subunit reattaches to the beta gamma complex
What are the three types of GPCRs?
Gs Protein- Stimulates Adenylyl cyclase
Gi Protein- Inhibits Adenylyl cyclase
Gq/G11 protein- activate phospholipase C
What is the effector protein in the cell membrane for the Gq/G11 protein?
Phopholipase C
What happens when the alpha sub unit attaches to phospholipase C?
It hydrolyses the membrane protein PIP2 to DAG and IP3
What do DAG and IP3 do in the cell signalling pathway?
DAG recruits protein kinase C
IP3 increases intracellular calcium that is essential for DAGs function
How does cAMP work as a second messenger?
Activates protein kinase A which phosphorylates specific target proteins
What happens in the G1 phase of the cell cycle?
Cell growth
this prepares the cell for DNA replication
What happens in the S phase of the cell cycle?
DNA replication occurs
Forms two sets of genes that can then be seperated
What happens in the G2 phase of the cell cycle?
Organelle replication occurs
increase in the amount of cytoplasm also occurs
What are the stages of mitosis?
Prophase- chromosomes condense
Metaphase- Chromosomes line up on the metaphase plate
Anaphase- chromosomes pulled apart by spindle fibres
Telophase- chromosomes are at poles ready for cell division
What is checked at the G1 checkpoint in the cell cycle?
Checks the cell has sufficient nutrients to divide into two daughter cells
What is checked at the G1/S checkpoint?
That there is no damage to the dna before it undergoes division
What is checked at the G2 checkpoint?
Checks that DNA replication the the S phase has been completed correctly
How does regulation at the G1 checkpoint occur?
If the G1 cyclin is present from growth factors then this will activate G1-CDK
This CDK phosphorylates pRB (retinoblastoma protein)
This causes it to release its binding of transcription factor regulators
These activate the genes for cell proliferation.
How does regulation at the G1/S checkpoint occur?
DNA damage increases the concentration of p53
This activates the transcription of p21 which is an inhibitor of G1/S CDK
If this CDK is not present prevents continuation into S phase
How does a growth factor signalling pathway work?
When a growth factor binds to the receptor it activates a RAS protein
This causes a kinase cascade which affects gene regulatory proteins
these cause cell proliferation
What is the Arterial supply to the thyroid gland?
Superior thyroid artery is branch off external carotid artery
supplies superior and anterior aspects
Inferior thyroid arteries branch from the thyrocervical trunk that is a branch of the subclavian artery
supplies the inferio-posterior aspects
What is the venous drainage of the Thyroid Gland?
The middle and superior thyroid veins drain into the internal jugular vein
The inferior thyroid vein drains into the brachiocephalic vein
What is the arrangement histologically of the thyroid tissue?
circular lobules of follicle cells that produce the thyroid hormones
Blood vessels run between adjacent lobules
What is the process by which thyroid hormone is released?
TRH (thyrotropin releasing hormone is released by the hypothalamus)
This stimulates release of TSH from the anterior pituitary
This binds to a GPCR on the thyroid cells which cause an increase in cAMP
This stimulates secretion of T3 and T4
How do thyroid follicular cells produce thyroid hormones?
Thyroglobulin precursor is made by the smooth ER which is the packaged by the golgi apparatus and transported into the lumen of the lobule containing the fluid coloid
Iodide ions symported into follicular cells with Na+ then antiported with cl- into lumen
Here Iodide is converted to iodine and combines with thyroglobulin to form T3 and T4 chains
These chains are pinocytosed into follicular cells where lysosomes break them down into individual hormones which are secreted into the blood
How do T3 and T4 travel in the bloodstream?
Bound to Thyroid binding proteins because they are lipid soluble