Specialized Tissues, Stem Cells And Tissue Renewal II

Question 1

The sensory epithelia is derived from?

Answer 1

Ectoderm

Question 2

What does the sensory epithelia contain?

Answer 2

Elaborate devices that collect signals from the external environment and deliver them to the CNS

Question 3

Function of sensory cells in the sensory epithelia?

Answer 3

Act as transducers, converting signals from the environment into an electrical form that can be interpreted by the CNS - well conserved

Question 4

What are the 3 sensory cells ?

Answer 4

Olfactory sensory neurons; auditory hair cells; photoreceptors

Question 5

The apical end of sensory cells contains?

Answer 5

A specialized structure that detects the external stimulus and converts it into a a change in membrane potential

Question 6

The basal end of epithelial cells contains what?

Answer 6

Where it makes synapse w/ neurons that relay the sensory info to. Specific sites in the brain

Question 7

Describe an olfactory neuron

Answer 7

Bipolar neurons w/ a dendrite facing the extracellular environment (interior spcce of the nasal cavity) and an axon that travels along the olfactory nerve to the olfactory bulb in the brain

Question 8

What protrudes from the dendrite of olfactory neurons?

Answer 8

Many tiny hair-like cilia

Question 9

What types of cells are present between the olfactory neurons and what is their funtion?

Answer 9

Supporting cells - hold nuerons in place and separate them from one another

Question 10

What do the free surfaces of cilia contain?

Answer 10

Odor and receptor proteins (olfactory receptors)

Question 11

What type of receptor is the olfactory receptor?

Answer 11

GPCR

Question 12

Why can the cell only response to 1 class of odorant?

Answer 12

Because each neuron only expresses one odor receptor gene

Question 13

What does the receptor recognize from the odorant?

Answer 13

The odorants structural features

Question 14

What is the result of an activated olfactory receptor?

Answer 14

It activates intracellular G protein which activates adenylate cyclase which produces cyclic AMP. Opening of ion channels in the pm results in an influx of NA and Ca in to the cells which causes the neuron to depolarize generating an action potential.

Question 15

When an action potential is relayed via the axon to the brain, what are the relay stations in the brain called?

Answer 15

Glomeruli

Question 16

Where are glomeruli located?

Answer 16

In olfactory bulbs - one on each side of the brain

Question 17

How many glomeruli/bulb in the mouse brain?

Answer 17

1800

Question 18

Olfactory neurons expressing the same odorant receptor can be located in different places on the olfactory epithelium - so where do their axons converge?

Answer 18

On the same glomerulus

Question 19

How long to individual olfactory neurons survive?

Answer 19

One month

Question 20

What generates replacements for lost olfactory neurons?

Answer 20

Neural stem cells residing in the olfactory epithelium

Question 21

What is the function of the odorant receptor proteins in the regeneration of olfactory neurons?

Answer 21

They help in axonal guidance and allow the growth cone to migrate to and establish connection w/ the correct glomerulus in the olfactory bulb.

Question 22

What is one of the few instances of adult neruogenesis in the CNS?

Answer 22

Recreation of olfactory receptor cells

Question 23

What is the relationship b/w olfaction and age and neurodegenerative disease?

Answer 23

Reduced olfaction has been observed in aged individuals and in people w/ age-dependent neurodegenerative disorders

Question 24

What is the trend seen with smell and idiopathic Parkinson’s disease?

Answer 24

Reduced sense of smell precedes clinical symptoms of the disease by almost 10 years

Question 25

In Alzheimer’s disease, its severity correlates with what?

Answer 25

The degree of loss of olfaction but mechanism isn’t understood

Question 26

What system is the most difficult to contruct in adult life?

Answer 26

CNS

Question 27

Adult brain and spinal cord have ________ ___________ to self-repair or regenerate.

Answer 27

Little capacity

Question 28

It was recently discovered that the brain has stem cells - they can make what 2 cells?

Answer 28

Neurons and glial cells

Question 29

Regeneration of cells in the brain only happens in what 2 parts?

Answer 29

Ventricles of the forebrain - cells from this region migrate to the olfactory bulb. And Hippocampus - region involved in learning and memory.

Question 30

What are neuro spheres?

Answer 30

Clusters of neural stem cells; can be propagated through several generations and can differentiate to produce both neurons and glial cells

Question 31

A transformation is common in non-mammalian species which are able to regenerate lost tissues and organs - what is an example of this?

Answer 31

Regeneration of a newt limb following amputation.

Question 32

Describe the process of regeneration of a newt limb

Answer 32

Differentiated muscle cells in the stump renter the cell cycle, de-differentiate and become embryonic cells and proliferate to form a limb bud similar to the embryo. Regenerates the missing limb.

Question 33

Sensory epithelia

Answer 33

Specialized epithelium that covers certain parts of the body (sensory tissue of the nose, ears and eyes)