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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. Different organs working together
Systems (eg digestive system consists of many organs)
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
Size of fist; two kidneys; have cortex (steroid hormones) and medulla (catecholamines) - receives about 20% of cardiac output - blood travels down arteries - up veins -'urine is created by the kidney and emptied into the renal pelvis - which is empti
Which is why lactase - maltase - dextrinase - sucrase are on brush border

2. Path of urine

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3. what happens to bile secretions
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Inner lining of blood vessels
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Mostly reabsorbed to liver

4. in the dark is rhodopsin active or inactive?
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
***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
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

5. In effect LH - FSH stimulate
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**
Prod of steroid hormones in testes - ovaries

6. 80-90% fat absorbed this way
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
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
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct

7. Sensory - motor neurons are part of which nervous system
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Peripheral nervous sys
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

8. FLAT PG: prolactin
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability

9. Gastrin from G cells stims parietal cells...
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
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)
Salivary amylase; both hydrolyze glycosidic linkages
Lower blood pH

10. A contracted iris occurs with what kind of stimulation
Sympathetic: dilates pupil (for night hunting)
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
- 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
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)

11. gradual increase in FSH typical of primary follicle development;
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
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
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption

12. 90% digestion - absorption occurs in...
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
Epithelial tissue near semniferous tubules
In mouth - breakdown of starch into polysaccharides
Contain capillary network - lymph vessels (lacteals)

13. Bile salts and lipase
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Work together to emulsify fats: bile works as a detergent to increase SA of the fat; increased SA gives more substrate to lipase for digestion
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion

14. thyroid hormones: Not All One Kind of HORM
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
90-140 mg/dl
Sympathetic: dilates pupil (for night hunting)
Peristalsis (esophagus) and segmentation (bi - directional=mixing)

15. Peritoneal refers to...
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.
Abdominal cavity - which is coated in serous fluid
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle

16. trypsin is secreted by
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries

17. 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
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Work together to emulsify fats: bile works as a detergent to increase SA of the fat; increased SA gives more substrate to lipase for digestion
Albumin increases osmolarity of blood; increases osmotic pressure
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

18. chylomicron concentration in blood after meal
Sensory (afferent - dorsal) - motor (efferent - ventral)
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
About 7.2

19. What is the function of the loop of Henle
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
Salivary amylase; both hydrolyze glycosidic linkages
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Increases solute conc and osmotic pressure of the ***medulla

20. Posterior eye
vitreous humor - retina - fovea
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Outermost layer of blood vessel
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state

21. from thoracic duct - chylomicrons stick to capillary walls...
Steroid; target tissue is distal convoluted tubule of nephron and collecting duct; increases blood mineral concentration; potassium - protons secreted (blood pH increases); sodium - chloride reabsorbed (BP increases)
Sorts - modifies - concentrates proteins from the ER
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
Salivary amylase; both hydrolyze glycosidic linkages

22. spermatogonia arise from
Size of fist; two kidneys; have cortex (steroid hormones) and medulla (catecholamines) - receives about 20% of cardiac output - blood travels down arteries - up veins -'urine is created by the kidney and emptied into the renal pelvis - which is empti
Thru tight junctions by favorable osmotic gradient
Epithelial tissue near semniferous tubules
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

23. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
Sympathetic: dilates pupil (for night hunting)
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide

24. smooth ER main function
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Stom= G cells (gastrin) - parietal (oxyntic); chief (peptic); mucous cells (hi ER - Golgi to make sticky glycoprots) - sm intest= enterocytes (w/brush border of maltase - sucrase - lactase - dextrinase; peptidase; lipase; nucleases); goblet cells (mu

25. What is a nerve? (PNS)
Called a tract in the CNS; bundling together of axons/dendrites thru which many diff signals pass; many many neurons are bundled together into a single nerve
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
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
Within the paravertebral ganglion - running parallel to spinal cord

26. 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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27. What is a plasmalogen?
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Ups bicarbonate secretion by pancreas; raises pH to 6.0
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

28. Embryology
Digestion
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Glucose and ketone bodies (not from glycogen stores)

29. The EYE
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)

30. Fructose relates how structurally to glucose
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Pepsin - secreted by chief cells in the stomach epithelial lining and active at low pH - breaks down proteins to polypeptides. Protein hydrolysis is aided by the highly acidic environment (hi gastric acid from parietal cells). Polypeptides are squirt
Fructose is a structural isomer of glucose

31. these transport proteins - when concs are high enough...
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Ventrally (picture skeletal vertebrae)
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach

32. going down the loop of Henle - water - permeable - filtrate osmolarity goes up as water leaves...
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Somatic nervous sys - autonomic nervous sys
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

33. What is somatostatin
Presence of fat - prot in duodenum causes release of **gastric inhibitory peptide**; result is slower stomach contraction; slower emptying into duod thru pyloric sphincter (slower chyme secretion); more time to properly digest - absorb nutrients
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
In liver (RBC recycling of heme); stored in gall bladder; released via cystic duct to common bile duct (shared w/liver); common bile duct joins up with panc duct...everything feeds into the sm intest at the ampulla of vater**
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons

34. Morula (...totipotent)
Increases solute conc and osmotic pressure of the ***medulla
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Chyme (by combined activity of exocrine glands)
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

35. In general - parietal=
The wall of the body or of a body cavity or hollow structure
Organs
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Peristalsis (esophagus) and segmentation (bi - directional=mixing)

36. Polypeptides are formed with what kind of reaction?
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord

37. SYMP neurons originate in= PARA neurons originate in=
- 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
SYMP: spinal cord --->paravetebral ganglion PARA: spinal cord - brain; cell processes --->ganglion near effector organ (preganglionic neurons) extend outside of spinal cord to synapse at ganglia - go on along postganglionic neurons
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Has memb - bound organelles - etc...

38. What is the path of a sound wave that enters the ear?
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Outer ear= pinna (auricle)- external auditory canal - eardrum (tympanic membrane) inner ear= malleus - incus - stapes - ...oval window - cochlea - where sound is transduced into neural signal...enters cochlea at scala vestibuli - where pressure chang
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane

39. food in duod stims release of gastrointestinal hormones
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Lowers osmolarity of the filtrate (IONS - Water Are Taken Back Up By The Kidney)--->at the end of the distal tubule (the collecting tubule) is where aldosterone acts - along with the JGA
Digestion

40. What do villli do
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Somatic nervous sys - autonomic nervous sys

41. The apical side of the villi...
Faces the lumen
Homologous chromosomes separate - migrate towards opposite poles/centrioles
Testosterone upon stim by LH
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback

42. only monosaccharides are absorbed
Homologous chromosomes line up w/ attachment of spindle fibers/microtubule polymers to centromeres via kinetochores; identical in appearance under light microscope to metaphase of mitosis
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Increases surface area of food ball (bolus)
Which is why lactase - maltase - dextrinase - sucrase are on brush border

43. How does glycogen compare to starch
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
The wall of the body or of a body cavity or hollow structure

44. pancreas secretes enzymes via
Pancreatic duct (made of acinar cells?)
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
AAs can be burned for energy or converted to fat for storage
Increases solute conc and osmotic pressure of the ***medulla

45. cholinergic receptors: NICTONIC and MUSCARINIC Nicotinic: neuromuscular effectors (ionotropic) Muscarinic: PARA effectors (GPCRs) Adrenergic: SYMP effectors (GPCRs)
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
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
It targets liver conc of prothrombin - fibrinogen etc
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

46. Thus - central nervous sys is...
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Fructose is a structural isomer of glucose
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.

47. almost all cells can store Some glycogen - but...
Stom= G cells (gastrin) - parietal (oxyntic); chief (peptic); mucous cells (hi ER - Golgi to make sticky glycoprots) - sm intest= enterocytes (w/brush border of maltase - sucrase - lactase - dextrinase; peptidase; lipase; nucleases); goblet cells (mu
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Only musc and esp ** liver can store large amounts

48. microvilli: increase SA of enterocyte; have hi conc of digestive enzymes

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49. pancreatic amylase is much stronger than
Membrane - bound - endocytosed bodies
Salivary amylase; both hydrolyze glycosidic linkages
Urine enters kidneys via artery - to arteriole - capillary bed - glomerulus - Bowman's capsule - proximal tubule - loop of henle (concentrates medulla) - distal tubule - collecting tubule - collecting duct (renal pyramids) - renal calyx - renal pelvi
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule

50. The esophageal sphincter is...
Sympathetic: dilates pupil (for night hunting)
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Normally contracted
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes