Chemoreceptors are used to sense taste and smell. Receptors in the nose and the mouth bind to chemicals that enter these regions. Once bound, the receptors send action potentials to the brain in order to stimulate the sensation of smell and taste. Depending on the type of receptor being bound, different sensations can arise.

Vision, hearing, and touch result from photoreceptors and mechanoreceptors. Photoreceptors in the eyes (namely rods and cones) generate electrical signals in response to light. Mechanoreceptors in the cochlea generate action potentials based on the vibrations of sound waves. Mechanoreceptors in the skin respond to pressure and other external stimuli to produce the sensation of touch.

The chorda tympani branch of the facial nerve (cranial nerve VII), which is carried by the lingual branch (of the trigeminal nerve), allow for special sensory taste fibers for the anterior two-thirds of the tongue. The general sensory innervation for the anterior two=thirds of the tongue is provided by the lingual branch of the mandibular nerve from the trigeminal nerve (cranial nerve V).

The glossopharyngeal nerve (cranial nerve IX) provides sensory and taste to the posterior one-third of the tongue. Hypoglossal nerve (cranial nerve XII) provides motor innervation for all the muscles of the tongue (except for palatoglossus which is innervated by the pharyngeal branch of the vagus nerve (cranial nerve X). 

The dermatome responsible for sensation at the level of the nipple is T4.

C2 is responsible for sensation at the posterior half of the skull "cap" and C4 at the level of a low collar shirt. T10 is responsible for sensation at the level of the navel (to remember this think bellybutton...belly buTEN). L4 includes the kneecaps.

Astrocytes provide support and nutrition to neurons within the brain and spinal cord. Myelin sheath insulates the axons of some neurons which allows them to conduct impulses faster. Nerve fibers are single nerve axons that are surrounded by a sheath of connective tissue.  Nerves themselves are cordlike structures that transmit nerve impulses. 

Both A delta and C fibers are associated with the perception of pain. This can be broken down more specifically to A delta fibers that are slightly mylinated and carry "Fast" sharp pain that is immediately felt. While C fibers carry "slow" pain due to being unmyelinated and is associated with chronic pain.

C fibers are associated with chronic pain perception because they transmit "slow pain". This is due to the fibers being unmyelinated. In addition, these fibers send projections to the limbic system and the thalamus which causes the brain to develop chronic pain associations.

Gout is a rheumatic disease that features monosodium urate crystals in tissue as the result of excess levels of uric acid in the blood stream. This can be caused by over or under excretion of uric acid. Gout can be both acute or chronic. Obesity, alcohol consumption, meat-rich diets, and poor kidney function are all risk factors. Ebola is an infectious virus that causes hemorrhagic fever. Asthma is a form of COPD (the other is chronic bronchitis), and is characterized by bronchoconstriction, causing difficulty breathing, especially when exhaling.

Hypernatremia. A pathological heart, is a heart that is not functioning properly. The kidneys rely heavily upon the heart for their perfusion and alteration to their perfusion will cause the activation of the renin-angiotensin-aldosterone system (RAAS). Thus, a pathological heart, which cannot adequately perfuse the kidneys with blood, will lead to the activation of the RAAS, causing hypernatremia (from increased aldosterone levels).

Blood collecting in the left upper quadrant would suggest a splenic laceration.

The spleen is one of the most commonly injured organs with blunt abdominal trauma. It can and will bleed enough to make a patient hemodynamically unstable. Ultrasound performed in the trauma bay looks at four potential spaces of fluid collection: Morrison's pouch (right upper quadrant/liver), splenorenal recess (left upper quadrant/spleen), subxiphoid (heart), and the pouch of Douglas (suprapubic/pelvis). The liver is located in the right upper quadrant of the abdomen and the spleen in the left upper quadrant

This patient's ultrasound showed fluid collection in the perisplenic space as well as extensive bleeding, which would suggest a splenic laceration as the cause of the patient's condition.

The liver is in the right upper quadrant. The right and left iliac arteries are in the right and left lower quadrants, respectively. Bladder laceration would result in fluid collection in the pelvis.

Giardiasis is the disease caused by the Giardia parasite. The parasite is passed through feces and can live up to several weeks outside of a host. Common symptoms of giardiasis is diarrhea, gas, stomach cramps, and dehydration. It is treated via prescription medication. Gastritis is characterized by inflammation of the stomach. In giardiasis, the intestines are affected. Gout is a rheumatoid disease and is not caused by an infectious agent. Geranium is a type of flower.