8/29/24, 5:10 Human Phy Week 2 - Lecture notes Week 2 of
PM lecture
Osmosis in action
- Hypertonic= more solute compared to another solution
- Isotonic= same amount of solutes
- Hypotonic= less solutes compared to another solution
Endocytosis and Exocytosis
- Endocytosis= bulk movement of molecules into cell
- Exocytosis= bulk movement of molecules out of cell
Endocytosis
- Phagocyte= “eating”, engulfing a large molecule
- Pinocytosis= “drinking”, small molecules
- Receptor-mediated endocytosis= will bind with receptors, when enough bind the
engulfment will occur
o Most of the time there will be proteins on inner that will alert what is inside
Exocytosis
- Vesicles will fuse to the cell membrane and releases its contents
Chemical messengers
- Examples: neurotransmitters, hormones
- Detection
o Transduction= release neurotransmitter and will build to protein then transduction
will occur
Chemical messengers bind to a target protein
- Initiates a sequence of events in the cell leading to a response
o Response is called signal transduction
Review of receptors
- Ligand will bind to protein receptors
- Protein receptor= specific to what can bind to. Found everywhere ttcell membrane,
cytoplasm, nucleus)
- If cell doesn’t have the receptor it will not be effected
Other receptor terms
- Affinity
- Saturation= how many can bind to protein
- Competition= opposite effects, blocking
Antagonistic vs Agonistic
- Beta blocker ttantagonistic) and antihistamine ttantagonistic)
- Decongestant ttagonistic)
about:bl 1
, 8/29/24, 5:10 Human Phy Week 2 - Lecture notes Week 2 of
PM lecture
How are receptors regulated?
- Can make more if want to be more sensitive
- Can make less= down regulation
o Due to a prolonged, high concentration of a messenger
o Target cell receptors decrease
o Cells are desensitized
- Up-regulation= increase number of receptors
o Cells exposed to low concentrations of a messenger may produce addition
receptors= super sensitivity
Signal Transduction Pathways
- Sequence of events by which the binding of a chemical messenger to a receptor causes the
cell to respond
- Ex. EKG electrocardiogram
Initial Step
- Receptor activation
o Messenger binds to the receptor
o Change in 3D shape
Signal Transduction
Causes changes in
1. Permeability, transport properties, or electrical state of the cell’s plasma membrane
2. Cells metabolism
3. Cell’s secretory activities
ffi. Cell’s rate of proliferation and differentiation
5. Cell’s contractile activity
Lipid Soluble Messengers vs Water soluble Messenger
- Lipid soluble messengers = non
polar
o Can go through lipid bilayer
o Bind with receptor inside cell
o Steroid hormones, thyroid hormones
o Bind to receptor
▪ Often in nucleus
o “Transcription Factor”
- Water soluble messenger= polar
o Cannot enter cell
o Hormones. Neurotransmitters, paracrine/autocrine compounds
o Bind to extracellular receptor proteins
about:bl 2
PM lecture
Osmosis in action
- Hypertonic= more solute compared to another solution
- Isotonic= same amount of solutes
- Hypotonic= less solutes compared to another solution
Endocytosis and Exocytosis
- Endocytosis= bulk movement of molecules into cell
- Exocytosis= bulk movement of molecules out of cell
Endocytosis
- Phagocyte= “eating”, engulfing a large molecule
- Pinocytosis= “drinking”, small molecules
- Receptor-mediated endocytosis= will bind with receptors, when enough bind the
engulfment will occur
o Most of the time there will be proteins on inner that will alert what is inside
Exocytosis
- Vesicles will fuse to the cell membrane and releases its contents
Chemical messengers
- Examples: neurotransmitters, hormones
- Detection
o Transduction= release neurotransmitter and will build to protein then transduction
will occur
Chemical messengers bind to a target protein
- Initiates a sequence of events in the cell leading to a response
o Response is called signal transduction
Review of receptors
- Ligand will bind to protein receptors
- Protein receptor= specific to what can bind to. Found everywhere ttcell membrane,
cytoplasm, nucleus)
- If cell doesn’t have the receptor it will not be effected
Other receptor terms
- Affinity
- Saturation= how many can bind to protein
- Competition= opposite effects, blocking
Antagonistic vs Agonistic
- Beta blocker ttantagonistic) and antihistamine ttantagonistic)
- Decongestant ttagonistic)
about:bl 1
, 8/29/24, 5:10 Human Phy Week 2 - Lecture notes Week 2 of
PM lecture
How are receptors regulated?
- Can make more if want to be more sensitive
- Can make less= down regulation
o Due to a prolonged, high concentration of a messenger
o Target cell receptors decrease
o Cells are desensitized
- Up-regulation= increase number of receptors
o Cells exposed to low concentrations of a messenger may produce addition
receptors= super sensitivity
Signal Transduction Pathways
- Sequence of events by which the binding of a chemical messenger to a receptor causes the
cell to respond
- Ex. EKG electrocardiogram
Initial Step
- Receptor activation
o Messenger binds to the receptor
o Change in 3D shape
Signal Transduction
Causes changes in
1. Permeability, transport properties, or electrical state of the cell’s plasma membrane
2. Cells metabolism
3. Cell’s secretory activities
ffi. Cell’s rate of proliferation and differentiation
5. Cell’s contractile activity
Lipid Soluble Messengers vs Water soluble Messenger
- Lipid soluble messengers = non
polar
o Can go through lipid bilayer
o Bind with receptor inside cell
o Steroid hormones, thyroid hormones
o Bind to receptor
▪ Often in nucleus
o “Transcription Factor”
- Water soluble messenger= polar
o Cannot enter cell
o Hormones. Neurotransmitters, paracrine/autocrine compounds
o Bind to extracellular receptor proteins
about:bl 2
