The tunica externa (New Latin "outer coat"), also known as the tunica adventitia (New Latin "additional coat")(or adventitia for short), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina.
Answer:
By looking for amino acid sequence differences between species, scientists can infer how closely or distantly related two species are in evolutionary time.
Explanation:
have a great day :)
B. smiling when you are happy
This is not an action that is controlled by the process of homeostasis in the body. Homeostasis is the process which is responsible for regulating the the internal environment of the body.
for instance, you go to the bathroom when your kidneys want to eliminate excess water and other substances.
Your lungs need more air when you are exercising so homeostasis is responsible of seeing that you get enough of it.
and sweating when you are hot to remove excess heat from your body via sweat.
These are all involuntary actions controlled by the process of homeostasis.
Smiling is a voluntary action. you do not need to smile. and you can whenever you like and not when you don't.
They're assembled in the endoplasmic reticulum. It's the organelle where lipid components of the cell membrane are assembled, as well as proteins and other materials are exported from the cell.
