What is the mechanical and chemical breakdown of food called?
Digestion
Ingestion
Compaction
Absorption
Extraction
The Correct Answer is A
A. Digestion: This physiological process involves both mechanical mastication and chemical hydrolysis to convert complex food into absorbable molecules. It begins in the oral cavity and continues through the stomach and small intestine. It is the specific term for the multi-modal breakdown of nutritional matter.
B. Ingestion: This term refers specifically to the act of taking food or liquid into the body via the oral cavity. It is the entry phase of the nutritional process rather than the breakdown mechanism itself. Digestion follows ingestion but represents a distinct set of biochemical and physical actions.
C. Compaction: This process occurs primarily in the large intestine where water is absorbed from indigestible residue. It converts liquid chyme into consolidated feces for eventual excretion. It involves the dehydration of waste products rather than the constructive breakdown of food for nutrient extraction.
D. Absorption: This stage involves the movement of digested nutrients from the lumen of the gastrointestinal tract into the blood or lymph. It occurs after the mechanical and chemical breakdown of food is largely complete. It describes the uptake of molecules, not the process of breaking them down.
E. Extraction: In a biological context, this word is often used generally for the removal of specific substances from a mixture. It is not the standard clinical term used to describe the integrated digestive functions of the alimentary canal. It lacks the specificity required to describe human gastrointestinal physiology.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
A. 6: Hemoglobin lacks the structural capacity to bind 6 oxygen molecules simultaneously. The protein is a tetramer, meaning it consists of only 4 polypeptide subunits. Each subunit is limited to the binding of a single heme group and its associated iron ion.
B. 2: This number represents only half of the potential carrying capacity of a fully saturated hemoglobin molecule. In the high partial pressure of oxygen found in pulmonary capillaries, hemoglobin typically binds more than two molecules. This would reflect a low oxygen saturation level of 50%.
C. 3: Binding 3 molecules would result in 75% oxygen saturation, which occurs as blood unloads oxygen to resting tissues. However, it does not represent the maximum theoretical or physiological limit of the transport protein. The molecular structure allows for one additional binding site to be filled.
D. 4: Each hemoglobin molecule is a tetramer composed of 4 globin chains, each containing a central heme group with a ferrous iron atom. Each iron atom can reversibly bind 1 molecule of O2. Therefore, a single hemoglobin molecule can carry a maximum of 4 oxygen molecules.
E. 5: Human hemoglobin does not possess a fifth binding site or heme group to accommodate an extra oxygen molecule. The quaternary structure is strictly limited to 4 subunits. Any value above 4 is biologically and chemically impossible for a standard adult hemoglobin A molecule.
Correct Answer is B
Explanation
A. Hormone at E - Growth Hormone (GH): The diagram indicates that hormone E is released from the anterior pituitary and targets the liver and skeletal muscles. In the liver, it stimulates the production of insulin-like growth factors (IGFs) to promote systemic growth. Its action on skeletal muscle facilitates protein synthesis and tissue hypertrophy.
B. Hormone A - Prolactin (PRL): The diagram depicts hormone A traveling from the adenohypophysis to the mammary glands. This protein hormone is essential for initiating and maintaining milk production following parturition. Its secretion is regulated by hypothalamic dopamine, which serves as a primary prolactin-inhibiting factor.
C. Hormone B - Thyroid-stimulating Hormone (TSH): The pathway labeled B shows a tropic hormone targeting the thyroid gland. TSH stimulates the follicular cells of the thyroid to synthesize and release thyroxine and triiodothyronine. This hormone is a critical regulator of systemic basal metabolic rate and cellular heat production.
D. Hormone C - Gonadotropins (FSH and LH): Label C represents the gonadotropins, specifically follicle-stimulating hormone and luteinizing hormone, which target the testes and ovaries. These hormones regulate gametogenesis and the secretion of sex steroids like testosterone and estrogen. They are essential for the maintenance of reproductive cycles and secondary sexual characteristics.
E. Hormone at D - Adrenocorticotropic Hormone (ACTH): The diagram shows hormone D being secreted from the anterior pituitary and traveling specifically to the adrenal gland. More specifically, it targets the adrenal cortex to regulate the production of steroid hormones. It is a critical component of the hypothalamic-pituitary-adrenal (HPA) axis.
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