MCAT Exam Questions and Answers
Which division of the nervous system can exert control over the digestive system - Answer-Autonomic nervous system:
1. parasympathetic division: involved in stimulation; "rest and digest"
2. sympathetic division: involved in inhibition; "flight or fight"
What t...
MCAT Exam Questions and Answers Which division of the nervous system can exert control over the digestive system - Answer -Autonomic nervous system: 1. parasympat hetic division: involved in stimulation; "rest and digest" 2. sympathetic division: involved in inhibition; "flight or fight" What transport is associated with absorption of simple sugars and amino acids, into the gut? - Answer -active transport and facili tated diffusion into the epithelial lining of the gut - then, they move across the epithelial cells into the intestinal capillaries What is a ganglion - Answer -a group of nerve cell bodies outside of the CNS (in the PNS) what is a flexor - Answer -a muscle which BENDs at a joint what is an extensor - Answer -a muscle with EXTENDS at a joint what is an aBDuctor - Answer -a muscle which moves a body part AWAY from the midline of the body what is an ADDuctor - Answer -a muscle which moves a body part TOWARDS t he midline of the body the unit of a muscle fiber is called - Answer -myofibril name for the cell membrane in a muscle cell - Answer -sarcolemma (and cytoplasm called sarcoplasm) myofibrils consist of what 2 major filaments - Answer -actin thin filaments and myosin thick filaments twitch - Answer -response produced when muscle is sufficiently stimulated; proportional to the strength of the voltage when the strength and stimulation to muscle tissue is FASTER and stronger, the muscle tissue does not recover sufficiently between stimulations, however, the twitches accumulate. This response produce summations due to - Answer -incomplete tetanus complete tetanus - Answer -when contraction is smooth, sustained and normal to muscle tissue _________ is the neurotransmitter in muscle that produces contraction - Answer -
acetylcholine actin filaments consist of what two proteins in muscle fiber - Answer -troponin and tropomyosin as soon as cont raction occurs, the sarcolemma secretes - Answer -an enzyme (acetylcholinesterase) that degrades acetylcholine so that recovery from stimulus can happen and prepare for next contraction When the body harvests ATP energy in excess (energy in phosphate bones ), some energy is temporarily stored as? - Answer -creatine phosphate (CP) - When ATP energy is reduced (ADP), a phosphate bond is broken and phosphate energy is released to ADP to form ATP enterocytes - Answer -intestinal absorptive cells what mechanism of transport do glucose and amino acid molecules use - Answer -
facilitated transport (type of passive transport) and can also use active transport in the GI tract via Na+/K+ pumps what is the difference between micelles and chylomicrons, in regards to fat di gestion and absorption - Answer -1. micelles: the products of fat digestion are incorporated into these small, water -soluble micelles, with the help of phospholipids and bile salts; this is the form in which digested fats are absorbed INTO the intestinal ce lls (enterocytes) 2. chylomicrons: the products of fat digestion are used for synthesizing new fats, which are released by the intestinal cells into the LYMPH, in the form of droplets/lipoprotein called chylomicrons; this is the form in which the synthesi zed fats (triglycerides and esterified cholesterol) are liberated from the intestinal cells (enterocytes) monoglyceride - Answer -1 glycerol attached to 1 fatty acid fat composed of what structure - Answer -1 glycerol molecule + 3 fatty acids what are detergents - Answer -detergents are polar molecules, that when placed in an aqueous solution, naturally form MICELLES about how many nephrons per kidney - Answer -about 1 million what is beta oxidation - Answer -beta oxidation is the process by whi ch FATTY ACIDS are broken down in the MITOCHONDRIA (matrix) to produce ACETYL -COA, which enters the CITRIC ACID CYCLE, and NADH and FADH2, which are used by the ELECTRON TRANSPORT CHAIN . what does ACE stand for? and what do they do? - Answer -angiotensin -converting enzyme; catalyzes a reactions that converts a PEPTIDE called ANGIOTENSIN I to ANGIOTENSIN II. The ANGIOTENSIN II peptide then stimulates the activity of the hormone ALDOSTERONE, which activates the kidneys to REABSORB more water into the blood ve ssels, thereby INCREASING BLOOD PRESSURE. **stop the blood pressure -increasing pathway early by inhibiting ACE, and blood pressure will decrease ! ADH (vasopressin) does what ? - Answer -its two primary functions: 1. retain water in the body 2. constrict blood vessels -regulates the body's retention of water by acting to increase H2O re -absorption in the collecting duct of the kidney nephron (makes the collecting duct "leaky") enzyme -catalyzed reactions tend to DOUBLE in rate for every _________ degrees celsius increase in temperature, until the optimum temperature is reached - Answer -10C **for the human body, this is 37degC; after this, activity falls of sharply, as the enzyme will denature at higher temperatures what factors affect enzyme reactivity - Answer -temperature and pH pancreatic enzymes, working in the small intestine, work best around what pH? - Answer -8.5 stomach enzymes work best at what pH? - Answer -2 what is an allosteric enzyme - Answer -multiple binding sites feedback inihibition - Answer -in feedback inhibition, the product may bind to an enzyme or enzymes that acted earlier in its biosynthetic pathway, thereby making the enzyme unavailable for other substrates to use **How many of the HORMONES in our body are regulated aspirin scientific name - Answer -acetylsalicyclic acid prostaglandins - Answer -group of lipid compounds that are enzymatically derived from fatty acids; they are locally acting messenger molecules, unlike hormones, which are distant acting mes senger molecules.
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