Answer:
Tendon sheaths <u>act as friction-reducing structures.</u>
Explanation:
Tendon sheaths are fibrous tissue that is around tendons to protect and make the movements of these smoother. For example, they reduce the friction of the flexors and extensors tendons of the hand. These are tendons that we constantly use to open and close our hands when we want to grab objects. Without the sheath, the tendons will not move easily, and due to the excessive use, there can be inflammation.
The sheats have two layers, one internal, which is a synovial one that produces synovial fluid to lubricate the tendon, and the external, which is a fibrous layer.
endomembrane system does not include the membranes of either mitochondria or chloroplasts.
<span>Types of Nucleic Acids. The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA is the genetic material found in all living organisms, ranging from single-celled bacteria to multicellular mammals.
https://www.boundless.com/biology/textbooks/boundless-biology-textbook/biological-macromolecules-3/n...
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The immune system is spread throughout the body and involves many types of cells, organs, proteins, and tissues. Crucially, it can distinguish our tissue from foreign tissue — self from non-self. Dead and faulty cells are also recognized and cleared away by the immune system.
If the immune system encounters a pathogen, for instance, a bacterium, virus, or parasite, it mounts a so-called immune response. Later, we will explain how this works, but first, we will introduce some of the main characters in the immune system.
