Biochem - Pharmacology and Patient Safety Flashcards
What are hormones
Chemical messengers that control and regulate biological functions
What do hormones bind to in order to act
Spp receptors, either on the cell surface or within the target cell
Interaction w/ receptor triggers and coordinates the biological effect
Types of hormone transport
Autocrine
Paracrine
Endocrine
Autocrine transport
Local cell-cell diffusion
Act on neighbouring cells of the same type
Paracrine transport
Local cell-tissue diffusion
Act of diff cells in the same tissue
Endocrine transport
Distributed by blood
Act on distant target cells
Types of hormones
Peptide Amino-acid derived hormones Steroid and sterol Lipid Gaseous
Examples of peptide hormones
Adrenocorticotropic hormone (ACTH) Antidiuretic hormone (ADH) Calcitonin Human chorionic gonadotrophin (hCG) Thyroid-stimulating Hormones (TSH) Thyrotropin-releasing hormone (TRH)
Examples of Amino-acid hormones
Adrenaline
Dopamine
Melatonin
Serotonin
Examples of steroid and sterol hormones
Aldosterone
Cortisol
Progesterone
Testosterone
Examples of lipid hormone
Leukotrienes
Prostacyclin
Prostaglandins
Examples of gaseous hormones
Nitric oxide
Membrane bound receptors - ion channels
Hormone bind to receptor (ion channel), and this causes a conformational change
Allowing ions to move from extracellular site of cell to intracellular —> membrane depolarisation
Membrane bound receptors - G protein coupled receptors
Conformational change when hormone binds and GDP is swapped for GTP on the alpha subunit of G protein
Alpha subunit dissociates and binds to another effector protein
After action of protein, the GTP then gets hydrolysed back into GDP, leading to the dissociation of the alpha subunit from the effector protein
The alpha subunit reassociates to the beta and gamma subunits of the G protein
Examples of effector proteins for G protein
Ca channel open and allows Ca+ move into the cell leading to increase in intracellular mediators
What else can the alpha-subunit of the G protein do after dissociation
Associate with adenylyl cyclase to activate the catalysation of ATP into cAMP
Associate w/ guanylyl cyclase for GTP for cGMP
Both activates protein kinases
Associate w/ phospholipase C
What does phospholipase C do
Catalyse the conversion of PIP2 to IP3 and DAG, which regulate enzyme activity
Membrane bound receptors - kinases
Binding of the hormone activates kinase to phosphorylate proteins using ATP
Intracellular receptors
Hormones move into the cell and either binds to receptor and hormone-receptor complex moves into nucleus or
Hormone goes alone to bind receptor in nucleus to affect DNA transcription
Endocrine glands
Hypothalamus Thymus Pancreas Ovaries Testicles Adrenal Parathyroids Pituitary
Lipids
Collective name for all fats and fat-like substances
Classes of lipids
Fatty acids Triglycerols (fats and oils) Glycerophospholipids (membrane lipids) Sphingolipids (membrane lipids) Cholesterol
Features of fatty acids
Long chain -COOH
Can be saturated or unsaturated
Most unsaturated fatty acids have cis configuration
Unbranched
What are fatty acids precursors for
Infl mediators:
Prostaglandins, thromboxanes and leukotrienes
What do leukotrienes cause
Constriction of bronchioles and smooth muscle in intestine and increases permeability of capillaries
What do lipoproteins do
Transport triacylglycerols
Where are triacylglycerols stored
Adipocytes
Metabolism of triacylglycerols
Triacylglycerols are too big so are broken down into fatty acids by lipoprotein-lipase
Fatty acids are taken up by adipocytes and converted to acyl-CoA
Glucose enters and metabolised into glycerol-3-P, this joins to acyl-CoA to re-form a triacylglycerol
What happens when triacylglycerol is needed
Hormone-sensitive lipase breaks it down into glycerol and fatty acids, the fatty acids travel in the blood as a fatty acid-albumin complex
Structure of glycerophospholipids
Amphiphilic
Hydrophobic fatty acid chains (2)
Polar head group (phosphate and alcohol)
Glycerol molecule in between
Cleavage of glycerophospholipases
Cleaved by phospholipases of the pancreas
Features of sphingolipids
Amphiphilic
Structure of sphingomyelin
Hydrophobic fatty acid chain
Sphingosine molecule
Polar head group - phosphate and choline
Structure of glycolipids
Hydrophobic fatty acid chain
Sphingosine molecule
Polar head group - sugar
Structure of cholesterol
Weakly amphiilic
Polar OH group
Hydrophobic steroid ring system
Metabolism of sphingolipids
Ceramides
This can react w/ palmitate to form fatty acids
Structure of cholesterol
Hydrophobic steroid ring system
Site of cholesterol synthesis
All cells
Liver and intestines major sites
