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Example Question #792 : Mcat Biological Sciences
There are a large variety of over-the-counter pregnancy tests, although all of them share a set of common principles.
These home pregnancy tests are immunoassays which detect the presence of the peptide hormone human chorionic gonadotropin (hCG). hCG is produced by the fertilized ovum and released into the mother's bloodstream, preventing the degradation of the corpus luteum and thereby preventing menstruation. By the time of the mother's first missed period, hCG levels in the urine are high enough to detect.
The home pregnancy test generally involves dipping a stick containing immobilized hCG monoclonal antibodies into a urine sample. If hCG is present in the urine, it will bind to the monoclonal antibodies on the dipstick. The dipstick is then placed in a solution containing a second monoclonal antibody which recognizes the bound hCG antibody complex on the surface of the dipstick. This second antibody is conjugated to colloidal gold particles which change color when they are immobilized, indicating a positive test result (i.e., pregnancy).
The same techniques used in the home pregnancy test can be implemented in other clinical tests. Which of the following could not be detected using such techniques?
Reiter's Syndrome caused by a certain strains of bacteria
HIV infection
Strep throat caused by a particular strain of bacteria
Autoimmune diseases such as rheumatoid arthritis
Tryptophan blood levels
Tryptophan blood levels
Answering this question simply requires picking the answer choice that doesn't have anything in common with the others. Conditions in which specific antibodies are produced which might be tested for using the same technique are described in the passage. After all, antibodies are proteins, and monoclonal antibodies can be made to detect them. HIV infection can be detected by assaying for the antibodies against HIV.Arthritis can be detected by looking for antibodies against "self" proteins. Strep throat can be detected by directly assaying for the presence of bacterial proteins. The same technique which was used to detect hCG can be used in these instances. Tryptophan blood levels, however, cannot be determined using the same methodology. For one thing, tryptophan (an amino acid) does not elicit antibody production. Secondly, the actual levels of substances in the blood can't be detected by the type of test described in the passage. This test yields either a "present" or "not-present" result
Example Question #1 : Epithelial Tissue And Integumentary System
Which of the following is not a function of simple squamous epithelium?
Diffusion
Osmosis
Absorption
Filtration
Absorption
Simple squamous epithelium is a single layer of flat cells that is found in areas where passive transfer takes place. This includes the blood vessels (capillaries), the alveoli, and the glomerulus. The capillaries and alveoli are specialized for diffusion and osmosis, while the glomerulus is specialized for filtration.
Absorption is typically associated with simple columnar epithelium (found in the small intestine) and simple cuboidal epithelium (found in the nephrons).
Example Question #2 : Epithelial Tissue And Integumentary System
Which area of the body would not be expected to have stratified squamous epithelium?
Tongue
Skin
Small intestine
Esophagus
Small intestine
Stratified squamous epithelium is primarily associated with protection of the body, and is found in areas that commonly encounter stress. These areas include the skin, the tongue, and the esophagus. The small intestine is associated with absorption, and is lined with simple columnar epithelium.
Example Question #3 : Epithelial Tissue And Integumentary System
The ability to regulate body temperature within a particular range of values, even in varying environmental conditions, is known as __________.
temperature sensitivity
thermal feedback
thermoregulation
thermodynamics
adaptation
thermoregulation
Thermoregulation is a homeostatic mechanism for regulating body temperature in varying conditions. This is accomplished by physiological, structural, and behavioral mechanisms. For example, many mammals will shiver as a result of small muscle contractions to generate heat. Many of the other possible answers sound similar, but are incorrect. Thermoregulation is a type of environmental adaptation, but "adaptation" is too broad of an answer in this case.
Example Question #771 : Biology
Which of the following mechanisms is involved in temperature regulation?
Constriction of blood vessels
Sweating
Shivering
All of these answers
Dilation of blood vessels
All of these answers
All of these mechanisms are used to either increase or decrease body temperature, allowing for proper temperature regulation. When your body becomes cold, shivering (the result of involuntary muscle contractions) helps increase body temperature. Constriction of blood vessels diverts warm blood to the most critical organs and away from extremities. In hot temperatures, blood vessels dilate to allow more blood to the surface of the skin where heat exchange can occur. Sweating allows excess heat to be released through the evaporation of water. Without all of these mechanisms, humans would have difficulty surviving in all the environments we currently inhabit around the world.
Example Question #1 : Epithelial Tissue And Integumentary System
In order to maintain homeostasis of body temperature, humans must utilize regulatory mechanisms to respond to an increase in temperature. Which of the following would NOT represent such a mechanism?
Decrease in skeletal muscle activity
Behavioral preference for a cooler environment
Dilation of arteriole sphincters leading to skin capillary beds
Activation of sweat gland excretion
Pilorection of hairs on the skin
Pilorection of hairs on the skin
This question is asking for a thermoregulatory mechanism that is NOT active in response to an increase in temperature. Preference for a cooler environment would be an apt response to increased temperature. Activation of sweat gland excretion would secrete liquid onto the skin's surface—the evaporation of this liquid carries heat away from the skin. Dilation of arteriole sphincters would increase overall blood flow, which carries heat, to the skin; this heat can dissipate to the environment. Decrease in skeletal muscle activity would lead to less metabolic activity and subsequent heat production.
The pilorection of hairs on the skin surface would not be an appropriate response to a temperature increase. This is because when erect, hairs would reduce the flow of air over the skin and retain body heat. Goosebumps are formed in pilorection, and this is typically seen in a response to cold temperatures.
Example Question #2 : Epithelial Tissue And Integumentary System
Other than acting as a barrier for the body from the environment, the integumentary system is also responsible for thermoregulation. Which of the following occurs when body temperature drops below a certain threshold?
Erector muscles contract and causes hair to lay flat against the skin
The skin opens vital pores, which allow more water exchange
The skin secretes sodium, and water passively follows through the process of osmosis
Erector muscles contract and causes hair to stand up
Mechanoreceptors in the skin are primed for easier activation of action potentials
Erector muscles contract and causes hair to stand up
Beneath the surface of the skin, erector muscles are attached to hairs. When it is cold these muscles contract, causing hair to stand up. When hair stands it creates a collective mass of air that maintains temperature by lowering drafts. The erect hairs essentially dull the effects of convection heat transfer by trapping warm air against the skin.
Example Question #2 : Epithelial Tissue And Integumentary System
The skin is able to contribute to thermoregulation in which of the following ways?
Increase in blood flow to skin helps raise body temperature
Sweat and its evaporation lower body temperature
Release of chemicals helps to warm the environment
Constriction of blood vessels keeps body temperature warmer
Constriction of blood flow helps lower body temperature
Sweat and its evaporation lower body temperature
The skin is part of the integumentary system, and is also partly responsible for thermoregulation.
In warm climates, the skin helps lower body temperature by sweating and promoting vasodilation. It is able to open up pores to secrete sodium, which is followed by chloride and water. When water evaporates on the skin, it lowers the temperature of the skin because the water requires an input of thermal energy to transition to the gaseous state. Vasodilation in hot climates allows blood to exchange heat with the environment by flowing close to the skin.
In cold climates, the skin helps raise body temperature by promoting vasoconstriction and goose bumps (cutis anserina). Vasoconstriction helps prevent heat loss to the environment by reducing blood flow to regions of high surface area. Goose bumps raise the hairs in the skin to prevent convection from transferring heat away from the skin.
Example Question #8 : Epithelial Tissue And Integumentary System
Which of the following is found in sweat?
Chloride ions
Sodium and chloride ions
Chloride and potassium ions
Sodium ions
Sodium and potassium ions
Sodium and chloride ions
Sweat is produced in response to increased body temperature, which triggers a response from the hypothalamus that increases sweat secretion. Sweat is composed of water, sodium, and chloride ions. The evaporation of the water requires an input of energy (it is an endothermic process). This energy comes from the heat of the body, and is dissipated when the water transitions to the gaseous state. The byproduct is sodium chloride salt.
Example Question #9 : Epithelial Tissue And Integumentary System
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Which of the following is most likely true of the endothelial cells depicted in the passage?
Endothelial cells are specialized to prevent clotting
Endothelial cells have extensive smooth muscle to allow capillaries to change size
Endothelial cells are specialized with surface proteins to promote clotting, preventing uncontrolled bleeding
Endothelial cells always have fenestrations to permit gas and nutrient exchange with tissues
Endothelial cells are biologically inert, and serve mainly as a barrier to the extravascular space
Endothelial cells are specialized to prevent clotting
Endothelial cells are specialized to prevent clotting in their intact form. When disrupted, the endothelium retracts to expose the basement membrane. Proteins in this region will activate the clotting cascade.
Arterioles are the main type of vessel that regulates vessel size and pressure, and exchange over endothlieum can occur with or without fenestrations.
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