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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. ligands are the messenger compounds that target secondary messenger systems on effectors
Low because AAs are immediately used in translation
Many modern drugs are ligands for GPCRs
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
75% water/ 25% solid mass: of that solid mass: 10-20% fat = phospholipid bilayer of bacteria - slough - off enterocytes ie stomach lining (must be constantly rebuilt) 10-20% inorganic material 30% roughage = fiber = cellulose (indigestible) 2-3% prot

2. What are the major carbohydrates
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Comes into play in the large intestine - where vitamin b12 is absorbed w/help of E. coli; thus; must travel thru bloodstream to large intestine

3. Embryology
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Fructose is a structural isomer of glucose
Neurons may perform one of three functions....
Zygote (fertilization in fallopian tubes); morula (up to 8 cells - undifferentiated ie totipotent); blastocyst (4+ days - implants into uterus; HCG secretion stims corpus luteum; gradually placenta replaces HCG as estrogen/progest source; cells not t

4. What is feces composed of...
75% water/ 25% solid mass: of that solid mass: 10-20% fat = phospholipid bilayer of bacteria - slough - off enterocytes ie stomach lining (must be constantly rebuilt) 10-20% inorganic material 30% roughage = fiber = cellulose (indigestible) 2-3% prot
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
REABSORPTION: draws off water and ions - increases osmolarity of the medulla while slightly lowering osmolarity of the filtrate -->medulla must have hi osmolarity in order to concentrate urine at collecting duct (final step in nephron)
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors

5. sensory (afferent)/interneurons/motor (efferent)
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Neurons may perform one of three functions....
Epithelial tissue near semniferous tubules

6. Seen in lysosomal storage diseases
Prophase II: no crossing over b/c there are no homologous chromosomes; nuclear envelope dissolves Metaphase II: chromosomes line up at metaphase plate Anaphase II: sister chromatids separate - migrate to opp poles Telophase II: nuclear envelope reap
- enterocytes w/ *microvilli brush border*: membrane - bound digestive enzymes for carbs - fats - nucleic acids - goblet cells: secrete mucous - Deep between villi are the intestinal exocrine glands - the crypts of Lieberkuhn - which secrete pH 7.6 i
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Chyme (by combined activity of exocrine glands)

7. Adrenal cortex hormones (STEROIDS)
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

8. What is a plasmalogen?
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Inner lining of circulatory system
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

9. After meiosis II - Male

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10. When 'coumadin targets liver enzymes to act as anticoagulant'...
AAs enter bloodstream for uptake by all cells (esp liver). If intracellular prot conc is at max AAs can be converted to fats or glucose via gluconeogenesis. Byproduct of gluconeo is ammonia --->urea.
Glucose
It targets liver conc of prothrombin - fibrinogen etc
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch

11. How does blood sugar move into tissues?
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Facilitated diffusion from hi to lo conc
Below hypothalamus
Glucose = aldose fructose = ketose

12. A contracted iris occurs with what kind of stimulation
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Sympathetic: dilates pupil (for night hunting)
90-140 mg/dl

13. Meiosis I Anaphase I
Smooth ER
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
All carbs absorbed at enterocytes are carried to liver by portal vein
Homologous chromosomes separate - migrate towards opposite poles/centrioles

14. 90% digestion - absorption occurs in...
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Has memb - bound organelles - etc...
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Small intestine; duodenum is smallest and does most DIGESTION; jejunum is medium and does most ABSORPTION; ileum is biggest and does most absorption along with jejunum

15. In other words...
vitreous humor - retina - fovea
Food is digested from mouth to stomach (denaturation by gastric acid - digested by pepsin) to duodenum (more digestion); then absorption occurs in jejunum and ileum
Mostly reabsorbed to liver
Signal picked up by sensory cell - goes thru dorsal root ganglion to SC - may continue to interneurons in brain or simple reflex arc in SC - brain integrates info and decides (voluntary) response - travels back down SC to appropriate ventral root gan

16. How does birth control work?
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
- filtration occurs at the fenestrations of the renal corpuscle - most reabsorption and secretion occur in the proximal tubule - medulla is concentrated in the loop of henle - sodium and calcium are reabsorbed in the distal tubule -->collecting tubul
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

17. The bolus (chewing) is digested to what in the stomach
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Chyme (by combined activity of exocrine glands)
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback

18. fructose enters enterocyte by
Facilitated diffusion: no symport w/ secondary transport
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Albumin increases osmolarity of blood; increases osmotic pressure
Increases blood Calcium

19. Creating gradients requires what?
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Lots of energy; eg neurons have hi glucose need for 3Na out 2K in ATPase; stomach epithel tiss needs E for parietal cells to pump protons into lumen and bicarbonate into blood
***nicotinic is ionotropic; muscarinic is GPCR

20. How does water cross the apical membrane
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Oxytocin and ADH (aka vasopressin)
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Thru tight junctions by favorable osmotic gradient

21. Luteal surge
Chylomicrons are much bigger
Outermost layer of blood vessel
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest

22. Kidney physiology...

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23. amylase acts where on carbs
After 4 day+ - morula cells have formed fluid - filled ball (blastocyst); this implants in uterus at day 5-7; blastocyst is made up of EMBRYONIC STEM Cells; once implanted w/blastocyst - female is pregnant
Night vision
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Outermost layer of blood vessel

24. Meiosis I: REDUCTIONAL DIVISION Interphase: G1 (growth; enzymes - structural proteins needed for gametic production are synthesized); S (DNA of homologous chromosomes is duplicated; mother cell goes from 46 2N to 46 2N with sister chromosomes connect
'The hepatic portal vein is not a true vein - because it does not conduct blood directly to the heart. It is a vessel in the abdominal cavity that drains blood from the gastrointestinal tract and spleen to capillary beds in the liver.'
Raises BP; causes collecting ducts at end of nephron (kidney) to become permeable to water - which concentrates urine; coffee - beer block ADH and increase urine volume
Stims release of tyrosine - derived horms T3/T4 (increase basal metabolic rate); TSH increases thyroid cell size - number - rate of T3/T4 synth -----> thus - iodine deficiency causes swollen thyroid due to lack of neg feedback onto TSH in anterior pi
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

25. Alpha - amylase found where
In mouth - breakdown of starch into polysaccharides
All carbs absorbed at enterocytes are carried to liver by portal vein
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)

26. The esophageal sphincter is...
About 7.2
ER
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Normally contracted

27. Inside the kidney: ...JGA (w/granular cells sensitive to hydrostatic pressure able to secrete renin - activate aldosterone - increase BP) is adjacent to distal tubule - monitors filtrate pressure
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Nitrogen
- filtration occurs at the fenestrations of the renal corpuscle - most reabsorption and secretion occur in the proximal tubule - medulla is concentrated in the loop of henle - sodium and calcium are reabsorbed in the distal tubule -->collecting tubul

28. Cell bodies of SYMP postganglionic neurons lie far from effector...
Epithelial tissue near semniferous tubules
Within the paravertebral ganglion - running parallel to spinal cord
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Neurons may perform one of three functions....

29. pancreatic amylase is much stronger than
Salivary amylase; both hydrolyze glycosidic linkages
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Contain rough ER and Golgi to make mucous; mucous is full of **glycoprots (sticky) and electrolytes*; protects epithelial tiss of stomach from low pH and lubricates stomach
Fovea (highest amount of cones)

30. What is endothelium?
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Thru tight junctions by favorable osmotic gradient
Inner lining of blood vessels
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation

31. FSH - LH - HCG - inhibin are...
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Peptides
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Contain rough ER and Golgi to make mucous; mucous is full of **glycoprots (sticky) and electrolytes*; protects epithelial tiss of stomach from low pH and lubricates stomach

32. Most important nutrients absorbed by large intestine
After 4 day+ - morula cells have formed fluid - filled ball (blastocyst); this implants in uterus at day 5-7; blastocyst is made up of EMBRYONIC STEM Cells; once implanted w/blastocyst - female is pregnant
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Meiosis creates germ cells
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

33. How does the body mobilize fat stores
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
***starting with adipose tiss: FFAs are transported in the blood by albumin (major component of blood plasma); one albumin typically carries three fatty acid molecules but can hold up to 30 FAs
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
In mouth - breakdown of starch into polysaccharides

34. Gland: ovaries
Water flows from the tubule - concentrating the filtrate - raising BP
Hormones --->stimulate exocrine glands - acetylcholine (increases all secretion of gastric pits) - gastrin (from G cells) - histamine (increases HCl secretion of parietals) ...Ach increases all secretions; gastrin increases gastric acid (parietal cel
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
- enterocytes w/ *microvilli brush border*: membrane - bound digestive enzymes for carbs - fats - nucleic acids - goblet cells: secrete mucous - Deep between villi are the intestinal exocrine glands - the crypts of Lieberkuhn - which secrete pH 7.6 i

35. alpha - amylase in the mouth digests what kind of bond
Low because AAs are immediately used in translation
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Mostly reabsorbed to liver
Alpha 1-4 and 1-6 (branching) glycosidic linkages

36. What do villli do
Apoproteins attach to outside of globules; these move to Golgi and are released into interstitial fluid via exocytosis as chylomicrons --->most go to lacteal system
Raises BP; causes collecting ducts at end of nephron (kidney) to become permeable to water - which concentrates urine; coffee - beer block ADH and increase urine volume
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption

37. Important aspect of crypt of Lieberkuhn - secreted intestinal juice
REABSORPTION: draws off water and ions - increases osmolarity of the medulla while slightly lowering osmolarity of the filtrate -->medulla must have hi osmolarity in order to concentrate urine at collecting duct (final step in nephron)
Growth 1 (G1) phase: STRUCTURAL ProteinS - ENZYMES; This is a very active period - where the cell synthesizes its vast array of proteins - including the enzymes and structural proteins it will need for growth. In G1 stage each of the chromosomes cons
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Processes: axons - dendrites

38. Where do pancreatic secretions take effect
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Gastrulation occurs: formation of three primary germ layers = differentiation
Glucose = aldose fructose = ketose
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

39. in mammals - gastrulation involves formation of the
Primitive streak - which consists of cells of the MESODERM ****
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males

40. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
Needs time for bile - lipase - micelle migration - enterocyte uptake
AAs can be burned for energy or converted to fat for storage
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes

41. Liver Functions
Moves down thru esophageal sphincter
Prod of steroid hormones in testes - ovaries
Stores blood: when expanded liver serves as blood reservoir for body - filters blood: Kupfer cells phagocytize bacteria picked up from intestines - destroys bad RBCs: also done by Kupfer cells - detoxifies blood: detoxified chemicals are excreted eit
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

42. In effect LH - FSH stimulate
Facilitated diffusion from hi to lo conc
Prod of steroid hormones in testes - ovaries
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

43. signal transduction occurs only in
REABSORPTION: draws off water and ions - increases osmolarity of the medulla while slightly lowering osmolarity of the filtrate -->medulla must have hi osmolarity in order to concentrate urine at collecting duct (final step in nephron)
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Eukaryotes
Abdominal cavity - which is coated in serous fluid

44. cytosol pH
Carry signals to musc OR Gland
About 7.2
Primitive streak - which consists of cells of the MESODERM ****
vitreous humor - retina - fovea

45. Exocrine GlandS: stomach
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
- parietal cells (**oxyntic= hi oxygen consumption - hi E??): have hi conc mito; need lots of energy to create proton gradient; thus - responsible for extremely harsh pH conditions in stom; denaturing conditions - chief cells (peptic): synthesize pep
- filtration occurs at the fenestrations of the renal corpuscle - most reabsorption and secretion occur in the proximal tubule - medulla is concentrated in the loop of henle - sodium and calcium are reabsorbed in the distal tubule -->collecting tubul
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum

46. Important of villi (='shaggy hair') More fluid makes contact with the epithelial tissue: thus nutrients in solution have less distance to travel to diffuse into villi.

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47. What force is acting upon chyme to move it forward down sm intestine
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Follicular phase: primary - secondary - ovulation (1 week) luteal phase: ovulation - thickening of uterine lining w/corpus luteum secretion - corpus luteum degrades (2 weeks) flow: shedding of uterine lining (4 days)
Glucose = aldose fructose = ketose

48. Four tissues
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Chylomicrons are much bigger
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

49. thyroid hormones: Not All One Kind of HORM
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Ventrally (picture skeletal vertebrae)
Break down TAGs to monoglycerides and free fatty acids

50. calcitonin

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