Other General Biology - NCLEX-PN

Patients who are taking potassium sparing diuretics must be counseled to eat a diet low in potassium. This is due to the fact that consumption of potassium-rich foods, such as orange juice, can lead to dangerously high potassium levels. Excess potassium levels can cause heart arrhythmia and sudden cardiac death.

The kidney is the main route of potassium excretion in the body. During kidney failure, the kidneys are unable to remove excess potassium from the blood. This can lead to hyperkalemia, which can cause nausea, weakness, numbness, arrhythmia, and cardiac arrest.

The brain stem consists of the medulla, the pons, and the midbrain. The cerebellum is an outgrowth posterior to the pons. The corpus callosum is the broad bundle of neural fibers that attaches the left hemisphere of the brain to the right hemisphere.

Olfaction is form of chemoreception, or a translation of a chemical signal into an action potential. Smells are triggered by molecules of volatile chemicals that trigger chemoreceptors in the epithelium of the olfactory cleft.

Mitochondria are often called "the powerhouse of the cell" because they produce ATP, the body's most basic unit of energy. The nucleus houses the cell's DNA, the rough endoplasmic reticulum is the site of cellular protein manufacturing, and the Golgi apparatus packages protein manufactured in the cell for release and transport to the rest of the body.

While the nucleus houses the DNA and plays an integral role in the transcription of genetic code in order to produce specific proteins, actual protein synthesis is carried out by the ribosomes. These organelles consist of two subunits and are either independent in the cytoplasm of the cell or housed in the rough endoplasmic reticulum. Note that ribosomes can be in the cytoplasm or on the endoplasmic reticulum, hence making it rough.

A hypotonic solution is one that contains solutes at a lower concentration than the cell. A cell, such as a red blood cell, will swell when exposed to a hypotonic solution as water moves into the cell to balance the osmotic gradient.

Intrinsic factor, a molecule necessary for the absorption of dietary B12, is produced by the parietal cells of the stomach. Its release stimulated by the same factors that stimulate release of hydrochloric acid: histamine, gastrin, and acetylcholine.

Gastric chief cells secrete pepsinogen and chymosin, while beta islet cells of the pancreas secrete insulin. Brunner's glands secrete a mucus that protects th lining of the intestine.

Vitamin K deficiency can cause a variety of issues related to inability to form blood clots such as petechiae, excessive bleeding, bruising, heavy menses. This vitamin is also an important part of bone and cartilage formation, with deficiency resulting in malformation of developing bones and cartilage, or deposition of calcium into cartilage or arterial walls.

An intake of 1-6 grams of cinnamon has been shown in studies to lower blood sugar in patients with type 2 diabetes by as much as 25%, possibly due to its ability to improve insulin sensitivity.

The mot common cause of osteomalacia (known as rickets in children) in the United States is vitamin D deficiency. This is due to vitamin D's vital role in calcium absorption, homeostasis, and metabolism. Osteomalacia is categorized by the softening of the bones.

Vitamin C chelates non-heme iron in food while exposed to the acidic pH of the stomach. This chelated iron then becomes more soluble in the alkaline pH of the duodenum, resulting in increased intestinal absorption of iron.

Serotonin, melatonin, and niacin are all synthesized from L-tryptophan, an amino acid prevalent in many foods including chocolate, oats, dates, milk, sesame seeds, eggs, meat, and cheese. L-tyrosine is involved in the synthesis of dopamine. Acetylcholine is the neurotransmitter released at the neuromuscular junction, which stimulates contraction of skeletal muscle. Taurine has many biological functions in the cardiovascular, muscular, and nervous systems, as well as others.

Methylene tetrahydrofolate reductase (MTHFR) is an enzyme with multiple important metabolic roles, including the methylation of folate, vitamin B12, and homocysteine. MTHFR deletions can result in folate and B12 related anemias and high homocysteine due to interruption of homocysteine recycling into methionine.

Biotin, or vitamin B7, plays an important role in the health of the hair, nails, and skin. Deficiency generally manifests as alopecia, loss of hair color, brittle nails, and dermatitis.

The olfactory nerves travel through the cribiform plate of the ethmoid bone. The grooves of the cribiform plate support the olfactory bulb, and the bone is perforated by many tiny foramen for transmission of the olfactory nerves from the epithelium of the nasal cavity to the olfactory bulb.

The other structures listed are all bony features of the ethmoid bone, but they do not allow the passage of olfactory nerves.

Olfactory receptor neurons require 7-8 molecules of a volatile odorant to trigger an action potential, and approximately 40 action potentials must be triggered in an olfactory receptor neuron in order for a smell to be detected.

There are three types of cells embedded in the olfactory epithelium: basal cells, supporting cells, and olfactory sensory neurons. All three of these cells play a significant role in the sense of smell, though the olfactory sensory neurons are the only cell type that actually respond to chemical stimuli.

The olfactory perception is managed by several parts of the brain, the primary areas being the piriform cortex, the insula, and the orbitofrontal cortex. Other lesser involved areas of the brain include the anterior olfactory nucleus, the amygdala, the entorhinal cortex, and the olfactory tubercle.

The arcuate nucleus is an area of the hypothalamus that is involved in regulation of hunger and satiety.

The olfactory epithelium is located at the roof of the nasal cavity in a relatively large area that includes the superior turbinate and the superior portion of the nasal septum. There are no specialized olfactory cells on the inferior turbinates, and no olfactory receptors in either the sphenoid sinus of the eustachian tube.