Materials are able to enter the CSF from the blood supply because
A) the capillaries of the choroid plexus are highly permeable, allowing free exchange.
B) there is always a lower concentration gradient in the CSF of all needed molecules.
C) specialized ependymal cells use both active and passive transport to secrete CSF.
D) All of the answers are correct.
E) None of the answers are correct.
C) specialized ependymal cells use both active and passive transport to secrete CSF.
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What is occurring when a muscle experiences an involuntary quick movement?
a. Twitch contraction. b. Tetanic contraction. c. Isotonic contraction. d. Isometric contraction.
If the genotype of an individual contains alleles for a particular trait that differ in their expression, the individual is said to be ________ for that trait
A) homozygous B) heterozygous C) recessive
Polar R groups of closely positioned amino acids often enter into ________ with each other, which helps give a protein its three-dimensional shape.
A. van der Waals repulsions B. ionic bonds C. sulfur-carbon bonds D. hydrophobic interactions E. hydrogen bonds
List the four types of general sensory receptors based on function, and identify the type of stimulus that excites each type
A) nociceptors (temperature), thermoreceptors (pain), mechanoreceptors (physical distortion), and chemoreceptors (chemicals dissolved in body fluids) B) nociceptors (chemicals dissolved in body fluids), thermoreceptors (physical distortion), mechanoreceptors (pain), and chemoreceptors (temperature) C) nociceptors (physical distortion), thermoreceptors (chemicals dissolved in body fluids), mechanoreceptors (pain), and chemoreceptors (temperature) D) nociceptors (temperature), thermoreceptors (physical distortion), mechanoreceptors (temperature), and chemoreceptors (pain) E) nociceptors (pain), thermoreceptors (temperature), mechanoreceptors (physical distortion), and chemoreceptors (chemicals dissolved in body fluids)