Which of these is a neurotransmitter?

A) GABA-ergic:
GABA-ergic neurons use gamma-aminobutyric acid (GABA) as their neurotransmitter, not acetylcholine (ACh). GABA is the main inhibitory neurotransmitter in the brain, playing a crucial role in reducing neuronal excitability.

B) Dopaminergic:
Dopaminergic neurons release dopamine as their neurotransmitter. Dopamine is involved in several critical functions, including movement, reward, and regulation of mood. Since acetylcholine is not involved in dopaminergic transmission, this is not the correct answer.

C) Cholinergic:
Cholinergic neurons use acetylcholine (ACh) as their neurotransmitter. These neurons are involved in many functions, including muscle activation (in the somatic nervous system), as well as modulating parasympathetic responses in the autonomic nervous system.

D) Serotonergic:
Serotonergic neurons release serotonin (5-HT), which is a neurotransmitter involved in regulating mood, appetite, sleep, and other functions. Acetylcholine is not involved in serotonergic transmission

A) The blood cells will migrate to the bone marrow:
While the bone marrow is responsible for producing red blood cells, dehydration and hypertonicity of the blood would not cause the red blood cells to migrate to the bone marrow. Migration of blood cells typically refers to white blood cells moving toward sites of infection or inflammation, not a response to dehydration.

B) The red cells will precipitate out of circulation:
Red blood cells do not precipitate out of circulation due to dehydration or hypertonic conditions. Instead, dehydration causes a shift in water balance that leads to changes in the shape and function of the red blood cells. Precipitation of cells is not a physiological response in this context.

C) They will swell and eventually rupture:
In conditions of hypertonicity, where the concentration of solutes (such as sodium) in the blood is higher than normal, red blood cells actually shrink, not swell. When blood is hypertonic, water moves out of the red blood cells into the extracellular space to balance the osmotic pressure, leading to cell shrinkage. Cells only swell in hypotonic conditions, when water moves into the cell.

D) The cells will shrink and shrivel, decreasing their oxygen-carrying ability:
When the body becomes dehydrated, the blood becomes hypertonic (more concentrated), leading to a shift of water out of the red blood cells to try to balance the osmotic gradient. As a result, the red blood cells shrink and shrivel. This shrinkage can impair their ability to carry oxygen effectively, as the cells may become more rigid and less flexible, making it difficult for them to navigate through small blood vessels and perform gas exchange in the lungs and tissues.