Zaidi tissues 2

Question 1

Describe sensory epithelia

Answer 1

• specialized epithelium that covers certain part of the body
• derived from the ectoderm
• collects signals and deliver to the CNS via an electrical form

Question 2

Describe the sensory cells that are present in the eyes, ears, and nose

Answer 2

eyes- photoreceptors
ears- auditory hair cells
nose- olfactory sensory neurons

apical end detects the external stimulus and converts into membrane potential

basal end synapses with the neurons to relay sensory info

Question 3

Describe olfactory neurons

Answer 3

bipolar neurons with dendrites with cilia facing the extracellular env and an axon along the olfactory nerve

have supporting cells to hold everything in place and has basal cells in contact with the basal lamina

moist and protected by fluid

Question 4

Describe the olfactory receptors

Answer 4

-odorant receptor proteins
-GPCR
- an olfactory receptor can bind to a single class of odorant molecules and activated Golf (intracell G protein)
which activates adenylate cyclase that produces cyclic AMP

THIS opens ion channels for the influx of sodium and calcium which causes an action potential that goes to the brain glomeruli in the olfactory bulbs

Question 5

Describe the regenerative of the olfactory neurons

Answer 5

• life san 1 month
• stem cells in basal find replacements and divide and differentiate
• axonal guidance and connect with the glomerulus
• regenerate olfactory receptor

Question 6

Where are the stem cells in the brain located?

Answer 6

ventricles of the forebrain ( migrate into olfactory stem cells) and the hippocampus (learning and memory formation)

Question 7

Describe a Planaria

Answer 7

Fresh-water flatworm, has an epidermis, gut, brain, eyes, peripheral nervous system, musculature, excretory, and reproductive system; has capacity to regenerate; small tissue sample can form a complete animal; when starved, gets smaller by reducing its cell numbers while maintaining body proportions, but when fed goes back to normal size; cycles of de-growth and growth repeated indefinitely without impairing survival or fertility

If not emphasized in class, this can be deleted

Question 8

Stem Cells

Answer 8

Along with differentiated cells are undifferentiated cells called neoblasts; 20% of cells in body are neoblasts and are widely distributed; neoblasts are stem cells that continually differentiate into body cells which are dying via apoptosis; corpses are phagocytosed and digested by neighboring cells in a process called “cell cannibalsim”; cell birth, death, and cannibalism well coordinated; upon X-ray radiation, animal loses ability to undergo cell division and dies; injection of a single neoblast rescues this and helps develop the full organism with all its body parts

If not emphasized in class, this can be deleted

Question 9

Regeneration in Non-Mammalian Organisms

Answer 9

Transformation common in non-mammalian species which are able to regenerate lost tissues and organs (such as regeneration of a newt limb following amputation); differentiated muscle cells in the stump reenter the cell cycle, de-differentiate and become embryonic cells and proliferate to form a limb bud similar to the embryo; regenerate the missing limb

If not emphasized in class, this can be deleted