What type of epithelium is the "respiratory epithelium"? (Hint: this is NOT the same thing as the "respiratory membrane". The respiratory epithelium is the epithelium that is found in respiratory mucosa.)

The respiratory epithelium is a type of ciliated pseudostratified columnar epithelium.

Explanation:

The epithelium (a type of tissue) lines the blood vessels and inner-outer surfaces of organs. Their function includes protection, secretion, absorption, transport, etc. Based on the shape, they are classified as squamous, columnar, and cuboidal. Also, they can be simple epithelium (a single layer of cells) or stratified (layers of two or more cells).

Respiratory epithelium (airway epithelium) is a type of ciliated pseudostratified columnar epithelium. It is the epithelium that is found in the respiratory mucosa and lines most of the respiratory tract. It protects and moist the airways. It prevents infection by the self-cleaning mechanism of the airways (mucociliary clearance) and thus acts as a barrier to pathogens and foreign particles. It also secretes mucus and prevents tissue injury. The respiratory epithelium contains four types of cells-ciliated, goblet, club and airway basal cells. The arrangement of these multiple cell types as a single layer results in the non- alignment of their nuclei in the same plane. So the epithelium appears as layered or stratified. Hence the name pseudostratified or falsely layered.  

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.

succession returns a disturbed

ecosystem to a more stable state. this is also classified into two (2) types:

primary succession and secondary succession. the primary succession arises when

a new land is transformed and a bare rock has been exposed providing an environment

that can be occupied for the first time. while, secondary succession occurs

when a previously occupied environment was disturbed that kills much of all its

community

explanation: