Exam 1 Flashcards
Physiology
Study of how living organisms work
Functions, processes, and integrations within living things
Knut Schmidt Nielson
Alternative physiology definition
Study of how organisms work requiring heuristic metric of when organisms are and are not working well
George Bartholomew
Every level of biological organization finds its mechanism at lower levels and its significance at higher levels of the organization
What are the 3 General categories of chemical messengers?
- Hormones- released into blood stream for delivery
- Neurotransmitters- released directly to target cell
- Paracrine- triggers response in cells around it
Autocrine- releases and comes back to trigger something on the same cell
What are the major body compartments and their percentages of they hold?
Plasma- 7%
Interstitial Fluid- 28%
Intracellular Fluid- 67%
Aristotle
Shaped the way we go about doing science with morality, aesthetics, logic and systematic
Galen
Deduced a pattern of blood flow through the body, first to document this, was wrong
William Harvey
First to correctly document the circulation of blood pumped through the body
Claude Bernard
Father of modern Physiology
Milieu Interieur
Constancy of the internal environment is the condition for a free and independent life
Walter Cannon
Coined the term Homeostasis
Mechanisms that detect and respond to deviations in physiological variables form their set point values by initiating effector responses that restore the variables to the optimal physiological range
What are the components of homeostatic systems?
Sensors (receptors)- monitor detect variables
Integration center- place that processes the information (brain)
Effector- responds to bring back to set point
What mechanism primarily maintains homeostasis in the body?
Negative feedback, detects and corrects
Afferent pathway
carry signals towards integrating center
Stimulus -> receptor -> integrating center
Efferent Pathways
integrating center -> Effector -> Response
Carry signals away from integrating center towards effector
Dynamic Constancy
Levels shifting throughout the day, high to low to normal
Body Temp regulation:
Mechanism?
Steps (components):
Negative feedback
Stimulus- deviation cold or hot
Receptors- signaling rate increases in temperature sensitive nerve endings
Integrating center- nerve cells in brain alters their rates of firing
Result- Heat loss- constriction of the smooth muscles in skin blood vessels (white hands)
Heat production- skeletal muscle contraction leading to shivering
Where are the hormones of the pancreas secreted from?
What are two of the cell types?
Pancreatic Islets
Beta cells-insulin
Alpha cells- Glucagon
Insulin
Decreases blood glucose levels
Stimulates transport of glucose into liver, skeletal muscles and adipose (fat) tissue where it is stored
Glucagon
Increases glucose in the blood by converting glycogen to glucose in the liver
Diabetes mellitus
metabolic disorders characterized by an abnormally high level of glucose in the blood
Excess urine (sweet urine), increased thirst, increased appetite
Excess urine production
polyuria
increased thirst
polydipsia
increased appetite
polyphagia
Diabetes mellitus
Mechanism?
What happens?
Steps:
Negative Feedback
Blood is supposed to absorb the glucose and water but this does not occur causing the individual to lose water and sugar in urination
Low glucose: Pancreas secretes glucagon -> Liver breaks down glycogen to glucose -> blood glucose increases
High glucose: pancreas secretes insulin -> muscle cells take up glucose OR adipose tissue uses glucose to form fat OR liver stops breakdown of glycogen to glucose
Positive feedback
and pathway
response reinforces the stimulus sending the parameter farther form the setpoint
Continues until outside factor is present to turn it off
Factor -> sensor -> integrating center -> effector
Labor and delivery
Mechanism?
Steps:
Positive Feedback
1. Baby’s head triggers stretch receptors in the cervix
2. Firing of receptors change sending message to the brain
3. Hypothalamus releases oxytocin into bloodstream
4. Oxytocin triggers contractions
5. Contractions casue baby’s head to push harder on the cervix
6. Steps 1-5 are repeated
7. Baby is born -> no more stretch -> process stops
Fluid-Mosaic Model
Used to describe our cell membranes.
Not ridged, dynamic in constant motion made up of different parts and pieces
Describe the Structure of a phospholipid
Polar, hydrophilic head and a nonpolar, hydrophobic tail
Amphipathic
Has both polar and nonpolar components
In our cells it creates the bilayer, affecting the passage of material in and out of the membrane
Saturated vs unsaturated fats
Saturated are tightly packed, viscous with single bonds
Unsaturated can’t be packed as tightly allowing more motion (fluid) and has one or more double bonds
Membrane Fluidity
Measure of the ease with which phospholipids can move within the membrane
Indicated by the amount of saturated vs. Unsaturated fats
Homeoviscous Adaptation
Maintenance of a relatively constant membrane fluidity
Changing the phospholipids
Higher temp= increase fluidity
Lower temp+ more ridged
Peripheral vs Integral proteins
Peripheral- On one side of the layer or the other, bonded to integral proteins or lipids
Integral- embedded in the bilayer
What is the role of Cholesterol in the bilayer?
Regulates membrane fluidity
The more cholesterol the more ridged the structure
How are solutes transported across the cell membrane?
Simple diffusion, facilitated diffusion, active transport, endo and exocytosis
Simple Diffusion, and example
Passive process (no ATP), moves down concentration gradient (high to low), freely passing through lipid bilayer until equilibrium is reached (equal movement)
Must be small and lipid soluble
Ex: blood gases (oxygen), and steroids
Rate Factors
Define
List
Factors that influence diffusion
Lipid solubility (faster), Molecular size (smaller=faster)
Cell membrane thickness (thicker=slower), Concentration gradient (higher difference= faster), Membrane surface area, Composition of lipid layer
Ion Channels and examples
Used in diffusion meaning it is passive and moves down gradient
For ions that are not lipid soluble, and are water soluble
Ex: Na, K, Cl, Ca, and H2O (aquaporin) channels
Ligand-gated channels and examples
Binding of messenger causes a change of ion channel, either opening or closing it
Ligand is not the same molecule going through
Ex; neurotransmitter acetylcholine opens Na channels in neurons
Agonist vs Antagonist
Agonist- mimics something in you body triggering something to happen
Antagonist- blocks a response
What sources of transport are under Carrier-mediated transport? What does it mean?
Facilitated Diffusion, Active Transport
Binds to the protein, changes the shape and releases it on the other side
Compare the reflux rate of diffusion vs mediated transport
Diffusion can keep going and the concentration increased but mediated will eventually plateau when it becomes saturated
Facilitated Diffusion and example
Movement from high to low concentration with the aid of membrane proteins by a physical binding, passive transport
Ex: Glucose, it binds, changes the shape, and it is let through
Active transport and example
form low to high concentration with the help of membrane proteins and ATP
ex: Na, K, H transporters
Primary Active transport with example
Directly consumes and uses ATP against the gradient. Thing binding is going through the channel
Ex Sodium potassium pump
Describe the Sodium Potassium Pump
Sodium Potassium ATPase Pump
3 sodium’s from low to high concentration (in to out) bring in 2 potassium’s
Both are going against gradient
The most energetic process in the body, uses the most ATP in the body when the body is at rest
Electrogenic pump with example
imbalance of charge across cell, inside of cell is slightly more negative
Sodium potassium pump
Secondary Active transport and example
Does not directly consume ATP going from low to high concentration. Done by utilizing an established gradient of another molecule. Molecules entering/existing one with and the other against its gradient.
Na moving back in
What are the two types of Secondary active transport and describe?
Cotransport (symport)- ion and the second solute cross the membrane in the same direction
Counter transport (antiport)- ion and the second solute move in opposite directions
Sodium Ion: Extra and Intra
140, 12 mM
Potassium ion: Extra and Intra
5, 150 mM
Calcium ion: Extra and Intra
1, 0.0001 mM
Chloride Ion: Extra and Intra
100, 7 mM
HCO3- : Extra and Intra
24, 10 mM
Pi (inorganic Phosphate): Extra and Intra
2, 40 mM
Glucose: Extra and Intra
5.6, 1 mM
Osmolarity (osmotic concentration)
The total concentration of solutes (ions, sugars, protein) in a solution/cell
What is the typical osmolarity of Humans?
300 mOsm
Define:
Isosmotic
Hypoosmotic
Hyperosmotic
Same concentration as our cells
less than the solute concentration of our cells <300
More than the solute concentration of our cells >300
Tonicity
describes the effect of a solution on cell volume, need more information about the molecules to determine like if they are penetrating or non penetrating
Define:
Hypertonic
Isotonic
Hypotonic
Hypertonic- cell shrinks, water moves from inside to outside
Isotonic- no change in volume
Hypotonic- cells swell, water moves from outside to inside
What is the relationship between water and solute?
Inversely related
Penetrating solute
Solutes that can move in or out of the cell freely followed by water
It will cause cell burst when moving into the cell (hypotonic)
It will cause cell shriveling when moving out of the cell (hypertonic)
What is the name of the gene that causes cystic fibrosis?
Cystic Fibrosis transmembrane conductance regulator
Non-penetrating solute
Will not effect tonicity
hyperosmotic solution is also hypertonic, isomotic is isotonic, and hyposmotic is hypertonic
What are the 3 categories of CF mutations? How many genetic mutations are out there that can casue CF?
Blocked CFTR- gating issue (4%)
Truncated CFTR- stop codon before necessary (10%)
Misfolded CFTR- 86%
>1600
Describe cystic fibrous including symptoms and effects
Genetic disorder that causes a mutation in the CFTP protein which is responsible for a chloride ion channel. It causes think mucus build up in a variety of organs especially the lungs causing a diminished gradient for water, prevents gas exchange, and a breeding ground for bacteria leading to chronic lung infections. It also causes issues with the pancreas and the secretion of enzymes in the stomach leading to malnourishment.
What was the first drug made to target the pathology of CF and describe its function? What was the next one and describe its function.
VX-770 (Kalydeco)- treats the blocked CFTR, improves gating of the CFTR
Trikafta- for misfolded CFTR, promotes the proper folding of the CFTR so it can be inserted into the membrane
Clathrin
Protein that causes the membrane to round off and pinch during endocytosis.
Ligand binds to receptor, initiating clathrin to come to the surface to assist in the pinching of the cell membrane
Endocytosis and example
Requires ATP, membrane folds in, forming small pocket that pinch off to produce intracellular, membrane-bound vesicle. Transports Large or bulk quantities in or out of the cell.
Receptor Mediated (proteins and cholesterol)
Exocytosis and example
Requires ATP, Intracellular vesicles fuse with membrane, releasing contents into extracellular space
Release of Neurotransmitter at the terminal neuron
Action potential cause vesicles to move towards membrane to release contents outside
What is the difference between lipid soluble and water soluble messengers?
Lipid soluble molecules- can pass through the membrane and are typically transcription factors that regulate gene expression, need carrier molecule while in plasma
water soluble- most common, have a hard time passing through the membrane so receptors are on the surface
First messenger vs second messenger
first- extracellular, water soluble triggers second messenger
Second messenger- intracellular, membrane to eventually trigger a response
Protein kinase vs Protein phosphatase
Kinase- enzyme that transfers a phosphate to another molecule, phosphorylates activating a molecule.
Phosphatase- removes phosphates form a molecule turning it off
How are GPCR pathways named?
After the effector protein
GPCR
Pathways that use a g protein
Describe the general steps of the lignad gated channel and give and example
- Binding of first messenger (ligand)
- Conformqtional cange of ion channel
- opens (or closes) the channel
Neurotransmitter acetylcholine opening Na channel
G-proteins and its subunits
Membrane proteins that couple membrane recenters to ion channels or membrane enzymes, the receptor does nothing but bind
subunits- alpha, beta and gamma
Beta and gamma are anchors for alpha and alpha activates effector protein
Basic pathway for GPCR
- Binding of first messenger increases affinity for GTP (another form of cellular energy)
- Alpha subunit dissociates, link with membrane protein.
- Alpha activates effector protein
- Cleaves GTP and again combines with beta and gamma
cAMP’s functions in the body
Glycogen breakdown, Cytoskeleton, Regulate gene expression, protein synthesis/Ca transport, ion channels and transport
Adenyl cyclase-cAMP pathway
- First messenger binds to GPCR activating G protein
- G protein turns on adenylyl cyclase
- Adenylyl cyclase converts ATP to cyclic AMP
- cAMP activates protein kinase A (cAMP- dependent protein kinase)
- Protein kinase A phosphorylates other proteins eventually leading to a response
What is the most common second messenger and the one in Adenyl cyclase-cAMP pathway
cAMP
Describe the amplification
Start out with one small signal or stimulus and get a big response with a high degree of efficiency
Phosphodiesterase
Family of enzymes that ends the cAMP pathway by degrading it, turns cAMP to AMP
Cholera and its mechanism of action
Flu like, diarrhea symptoms cause by a bacteria ingested through contaminated drinking water.
The acid in the stomach causes the bacteria to release a toxin that activates adenyl cyclase. Leads to an overactivation of the CFTR causing a flux of chloride ions and therefore water and sodium as well
Steps to the Phospholipase C system
- First messenger binds activating receptor and G protein
- G protein activates phospholipase C, amplifier enzyme
- PL-C converts membrane phospholipids into two second messengers: diacylglycerol (remain in membrane) and IP3 which goes into cytoplasm
- DAG activates protein kinase C which phosphorates proteins.
- IP3 causes a release of Ca form organelles creating a Ca signal
What is one of the most important signaling molecules and where can it be found?
Calcium
Intracellular- The endoplasmic reticulum
Extracellular- voltage gated channel (change in voltage), allowing the calcium in from ouside the cell
Describe the quantity and what happens when calcium enters the cell and why
Very little amounts (0.0001 mM) and it is quickly bound up by proteins to form a complex. This is done because it is a cytotoxin and can cause cell death (apoptosis)
Nitric oxide (NO)
Where does it come from, what does it do (mechanism)
Endothelial cells (in every blood vessel in the body, single layer)
Acts as neurotransmitter and causes vasodilation of arterioles (regulates blood flow)
Endothelial Cells monitor chemical composition of the blood and release NO into the local environment, it stimulates Guanylyl cyclase and leads to the production of cGMP (second messenger) in smooth muscle, leads to dilation when smooth muscle relaxes
What terminates the cGMP pathway?
Phosphodiesterase
PDE-5 in Viagra
What produces lipid messengers (precursor) and where are they made from?
Arachidonic acid and membrane phospholipids
What are the Eicosanoids? What enzyme produces them? what are their functions?
Prostaglandins and Thromboxane (cycloxygenase)- sleep, inflammation, pain, fever, vascular actions
Leukotriene (Lipoxygenase)- mediate allergic response
What are some examples of NSAIDs? what does it do and what are its risks?
Aspirin, ibuprofen
Block cycloxygenase 1 and 2, inhibit production of prostaglandins and thromboxanes
Reduce inflammation, pain, fever, inhibit platelets from clotting
GI bleeding
What are some examples of Paracetomols? What does it do and what are the risks?
Acetaminophen and Tylenol
Selectively block COX-2
Tend to have weaker anti-inflammatory effects
Liver damage
