Ocular: Gen Rev Physiology Flashcards
About how many cells make up the human body?
About 100 trillion
About how many cells types are there in the human body?
about 200 different types of
What are the four basic tissue types?
- Epithelial
- Connective *most widely spread
- Muscle
- Nervous
Which types of the four basic tissue types are associated with the eye?
ALL OF THEM SILLY
What percentage of body weight is water?
60%
Bodily fluid is compartmentalized by what two major compartments?
Intercellular and extracellular fluid
How are the two major compartments of bodily fluid separated?
The plasma membrane causing them to have very different chemical components
How is chemical composition maintained and what important effects does it have on the cell?
The chemical composition is maintained by the cell.
- cell membrane potential, cell excitability, cellular metabolism, and transport of substance into and out of the cell
What are the differences between ECF and ICF?
ECF: aka internal environment
-high [Na+]
-low[K+]
split into two compartments:
-interstitial fluid-fluid between body cells
-plasma- fluid portion of blood
ICF:
Fluid within the cells
-low [Na+]
-high [K+]
Ocular examples of epithelial tissue:
Corneal and conjunctival epithelium
Ocular examples of nervous tissue:
-retina
-optic nerve
Ocular examples of connective tissue:
-corneal stroma
-sclera
Why is the compositions of the internal environment important?
The internal environment determines whether cells can obtain from it what they need to produce proteins and other molecules essential to their existence
Why is protein conformation important?
Its shape allows it to carry out its specific function
Why are enzymes important?
-Formed by proteins
They are biological catalysts for biological metabolic processes
Why are membrane lipids important?
-form the foundation of the bilayer,
Why are membrane proteins important ?
primarily responsible for membrane function
What membrane functions are membrane protein responsible for?
-transport for ions and polar molecules
- binding of hormones
-signal transduction across membrane
structural stabilization of bilayer
What are the molecular components of the lipid bilayer?
Bilayer of phospholipid molecules
Hydrophilic portion:
-head of phospholipid
-towards outside
Hydrophobic potion:
-tail of phospholipid
-towards inside
the lipid barrier clusters together forming a barrier to the…
passage of water-soluble particles
What type of barrier is the plasma membrane?
Selective barrier- regulates molecular movement into and outs of the cell
Gradients are responsible for:
the diffusion of ions and molecules in solution
What is the difference between passive transport and active transport?
Passive transport does not require energy
-moves with concentration gradient
Active transport does require energy
-moves against concentration gradient
-primary and secondary
What type of particles can pass through the lipid bilayer via diffusion?
Small charged particles can pass through bilayer such as O2, CO2, and N2, as a well as small uncharged molecules such as ethanol, glycerol, and urea)
What is facilitated diffusion?
Uses transmembrane integral protein that act as carriers of channels to enable passage of substances
What are some factors of facilitated diffusion
-high rate of solute diffusion
-saturable process- transport rate is limited
-highly specific process
-can be blocked by competitive inhibitors
What are aquaporins?
-can use osmosis
small water-soluble transmembrane proteins that rapidly move water across hydrophobic lipid bilayer
-present in brain, eye, lung, and kidney
What are the factors specific to ion channels?
-High velocity
-doesn’t expend energy
-specific to ion charge and size
All channels are formed by what type of protein?
Transmembrane proteins
What is the function for channel gating?
-ion flow depends on number of channels open
-specific for ion size and charge
What are the five types of gating mechanisms?
- Voltage gated
- Ligand gated
- 2nd messenger gated
- Mechanically gated
- Gap junctions
What is an electrochemical gradient?
the combined influence of concentration gradient and electrical gradient on ion movement
What is the resting embrace potential and why is it important ?
-about 70 mV
-results in positively charged solutes to move across plasma membrane into the cell, while opposing entry of negatively charged solutes
Leakage of what ion is the major contributor to the resting membrane potential?
K+
Why is the Na-K ATPase pump important for RMP?
- pumping out 3NA+ and 2K+ in
-maintains large K+ gradient so small flux can occur and generates the RMP
What is the difference between primary and secondary active transport?
primary- direct coupling to energy yield -ATP
secondary- driven by energy stored in electrochemical gradient for another solute
ATP hydrolysis results in movement of what ions in and out of the cell and how many?
3 Na+ out/ 2 K+ in
What drives secondary active transport?
energy stored in electromagnetic gradient for another solute
Why is sodium important for secondary active transport?
the movement of solutes is coupled with Na+
What is the difference between symport and antiport ?
symport follows Na+ movement
antiport goes opposite of Na+ movement
What are action potentials and why are they important?
-information conveyed over long distances in a nerve or muscle cell
-fleeting, self-renewing, wave a membrane depolarization that propagates without decrement
What is the difference between electrical and chemical synapse?
electrical- e.g gap junctions
- direct connections between cells which allows ions to flow between
chemical- e.g retinal synapses
- driven by chemicals
What is a syncytium?
-seen in electrical synaspes
-a bunch of cells acting like one cell
What are EPSPs?
-synaptic potential that makes postsynaptic neuron more likely to fire an AP
-glutamate
Why is depolarization important?
it sparks the AP by making the cell environment less negatively charged
Why is glutamate important?
it is the main excitatory neurotransmitter in the nervous system
What are IPSPs?
- synaptic potential that makes a postsynaptic neuron less likely to fire an AP
Why is hyper polarization important?
-regulates the refractory period
Name two inhibitory neurotransmitters?
GABA and glycine
Ionotropic and metabotropic are neurotransmitter receptors. What are their functions?
ionotropic- receptor is an ion channel
metabotropic- receptor is coupled to an intracellular protein
-most are GPRCs
What is Uhthoff’s phenomena and what disease is it associated with?
-multiple sclerosis demyelinating disease
-MRI of patient with optic neuritis shows multiple hyperintense foci in the white matter
What are the three cardinal principles of the ANS?
-two chains (pre and post ganglionic)
-innervates smooth muscle, cardiac muscle, glands
-excitatory and inhibitory
Hat neurotransmitters are used for pre and postganglionic nerves in SNS vs PNS?
Sympathetic pathway:
pre-ACh
post-Norepinephrine
Parasympathetic pathway:
pre- Ach
post-Ach
What division of the ANS is compromised in Horner’s syndrome?
sympathetic
What are four clinical manifestations of Horner’s syndrome?
ptosis
miotic pupil
hemi-facial anhydrosis
hemi-facial flush
