Cell surface or membrane is made of phospholipid bilayer with embedded proteins and sugars. Cell membrane acts as a barrier between cell and its external environment but it is also responsible for the communication with other cells and transport of molecules inside and outside the cell. It is selectively permeable to ions and molecules (some of them pass through the membrane easily, while others require transport proteins or channels). There are 4 ways of molecule transport:
1. Diffusion – no energy required
2. Facilitated transport – transport proteins included
3. Active and co-transport – energy required
4. Vesicle transport (exocytosis and endocytosis)
Microvilli are extensions of cell membrane that increase its surface for diffusion.
Different types of cell junctions have a different influence on the membrane transport. For example, tight junctions are a barrier and the molecules are unable to pass through.
<em>The answer is: E. it protects the heart and lungs</em>
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<em>Appendicular skeleton covers our upper and lower limb while the heart and lungs are located in the middle. Axial skeleton on the other hand covers all organs from the head all the way down to our waist. This means that heart and lungs are also protected by axial skeleton.</em>
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Answer:
The conditions that will not cause conduction deafness is <em>damage to cochlear hair cells, </em>option B.
Explanation:
Conduction deafness occurs there is an alteration that blocks the transmission of sound from the external and middle ear to the inner ear. It is a mechanical problem in the ear canal or the middle ear.
The outer ear is the external portion that collects sonar waves and directs them to the inner ear. Three structures compose the external ear, these are the auditory pavilion, the ear canal, and the eardrum. Damages in any of these parts might produce conduction deafness.
The middle ear is located between the eardrum and the oval window of the inner ear, to which it transmits sounds. the middle ear is composed of three little bones called ossicles, the oval window, the circular window, and the Eustachian tube. Any damage or alteration in this area will also cause conduction deafness.
There are different causes of deafness, such as earwax plug, <u>damage in the eardrum,</u> otitis, traumatisms or malformations, tumors, outer ear infections, <u>imflamation</u>, fluid accumulation, among others. Any of these might impede the properly sound conduction, thus the sound can not reach the inner ear.
Answer:
1. A natural killer cell identifies unusual cells, combines with them, and discharges perforin and molecules of granzyme that stimulates apoptosis.
2. A basophil comprises huge concentrations of histamine in granules, gets stain with basic dye methylene blue, and helps in inflammation and allergic reactions.
3. A macrophage refers to a huge agranular phagocyte, which is found within the tissues like lungs and brain.
4. An eosinophil comprises histamine and major basic protein in granules gets stain with acidic dye eosin and helps in reactions against the helminths and protozoa.
