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Lecture 10 Comp Phys
Lecture 10 Comparative Physiology USD Fall 218 Dr. Kenneth Renner
Question | Answer |
---|---|
What activates phosphodiesterase? | transducin |
What happens when transducin activates phosphodiesterase? | decreases the concentration of cGMP and closes sodium channels |
in a light reaction ___ retinal -> ______ retinal | cis -> trans |
What happens in order for transducin to activate phosphodiesterase? | 1. trans-retinol dissociates from opsin 2. opsin is activated 3. opsin activates transducin (protein) 4.transducin activates phosphodiesterase in the presence of phosphodiesterase, cGMP becomes 5' and isn't recognized by Na channels and they close |
During a light reaction, what does K do? | it leaks out along its concentration gradient through non gated passive channels and hyperpolzarizes the cell |
Where are the non gated passive channels that K leaks out of found? | found on the inner segment |
What does the hyperpolzarization from leaking K do? | hyperpolzarizes the cell from -40mV to -70mV and decreases NT release |
Why does hyperpolzarization of the cell lead to decreased NT release? | Ca channels close and stop docking sequence for exocytosis which decreases NT release |
What happens once light is removed? | transducin becomes in activated |
How does transducin become inactivated when light is removed? | by the hydrolysis of GTP |
What else is deactivated once light is removed? (besides transducin) | rhodopsin |
What shape do most fish have? | fusiform shape with eyes located on the sides of the body |
What do eyes on the side do for fish? | gives them a large visual field |
What is the shape of the cornea for the teleost eye? | flattened |
What is the benefit of the flattened cornea? | it decreases resistance to movement in water |
What role does the cornea play in light refraction in the teleost eye? | It places a small role |
What is the shape of the lens in the teleost eye? | spherical and large |
What is the role of the lens in the teleost eye? | primary source of light refraction |
What is accomodation with the teleost eye? | use of retractor muscle to move lens back and forth |
In the teleost eye, he iris and pupil diameter is ______. | fixed |
Why is the iris and pupil diameter fixed in the teleost eye? | because light intensity changes slowly so there is a decrease in need to alter pupillary apiture |
What do some fish do instead of adjusting pupillary apiture? | change pigment |
True or False: Color vision is common with the teleost eye? | True |
What does water allow the negation of ? | the need for glandular secretions to clear the eye surface |
In aquatic organisms, what reflects light back to the retina? | tapetum lucidum |
What type of eye is used by arthropods? | compound eye |
How are compound eyes organized? | into individual optical units called ommatidia |
What does an ommatidia consist of? | 2 lenses, 8 retinular cells |
What do each retinular cell of the ommatidia consist of? | photosensitive pigments |
What are the retinular cell photosensitve pigments of the ommatidia made of? | microvili called rhabdomeres |
What is a rhabdomere | microvilla that contain photopigments |
What are retinular cells? | photosensitive cells that contain photopigments |
How many major types of compount eyes are there? | 2 |
What are the two types of compound eyes? | apposition eye and superposition eye |
What is an apposition eye? | ommatidium are optically isolated from each otherand receive light from a narrow visual field |
What is the gain from apposition eyes? | increase in visual acuity |
What is the cost of the apposition eye? | limits light gathering ability |
Where are apposition eyes found? | diurinal insects |
What are superposition eyes? | rhabdoms are separated from thelense |
What do rhabdoms receive light from in superposition eyes? | multiple lenses |
What is the gain of superposition eyes? | increase in light gathering ability |
What is the cost of superposition eyes? | lose visual acuity because of multiple lenses |
What are skeletal muscle fibers called? | myofibrils |
What is the plasma membrane of muscle cells called? | sarcolemma |
What is the cytoplasm of muscle cells called? | sarcoplasm |
What is a sarcomere? | repeated contractile units within the subdivisions of the myofibrils |
What is the z-line? | boundary of the sarcomere |
Where is actin found? | in the z-line |
What is the H-zone? | gap between the ends of the actin filaments |
What is the psuedo h zone? | center of the h zone where myocin doesn't have globular heads |
What is the A band? | contains the myocin heads in parallel |
What is the I band? | actin filaments but no myosin |