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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 15 minutes.
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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. A contracted iris occurs with what kind of stimulation
Collection of cell bodies; cell processes project out from both ends of ganglion; synapses with interneuron in spinal cord on one end and sensory receptor on other
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Sympathetic: dilates pupil (for night hunting)
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

2. After meiosis II...
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
vitreous humor - retina - fovea
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane

3. Contrast PNS- Somatic with PNS- Autonomic
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
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen

4. albumin has What affect on blood osmotic pressure
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Albumin increases osmolarity of blood; increases osmotic pressure
Digestion

5. After meiosis II - Female

6. almost all cells can store Some glycogen - but...
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Needs time for bile - lipase - micelle migration - enterocyte uptake
Only musc and esp ** liver can store large amounts
Cancer; apop can be programmed cell death; mitochon can play important role in apop

7. Failure of apoptosis can result in
Stomach - sm intest - spleen - pancreas from the hepatic portal vein...all blood that passes thru liver go thru flattened spaces called the ***hepatic sinusoids -->hepatic vein --->vena cava
Cancer; apop can be programmed cell death; mitochon can play important role in apop
Has memb - bound organelles - etc...
Faces the lumen

8. How does the body mobilize fat stores
***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
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
Beta cells
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

9. interneurons
***nicotinic is ionotropic; muscarinic is GPCR
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Transfer signals from neuron - neuron; 90% of neurons are interneurons
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

10. pancreatic amylase is much stronger than
Normally contracted
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
Salivary amylase; both hydrolyze glycosidic linkages
Stomach - sm intest - spleen - pancreas from the hepatic portal vein...all blood that passes thru liver go thru flattened spaces called the ***hepatic sinusoids -->hepatic vein --->vena cava

11. What is the path of a sound wave that enters the ear?
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
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
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

12. Meiosis I Metaphase I
Digestion
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
Combined via conjunction of pancreatic duct and common bile duct; common bile duct originates at **cystic duct where gall bladder and liver secretions combine ..cystic duct+common bile duct+pancreatic duct --->into duodenum
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle

13. calcitonin

14. What is an endorphin?
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
An endogenous morphine
Monitors filtrate pressure in the distal tubule; has specialized cells (granular cells) that secrete an enzyme (**renin); renin initiates regulatory cascade that produces angiotensin I - II - III that stim adrenal cortex to secrete aldosterone... ...
- 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

15. fructose enters enterocyte by
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Facilitated diffusion: no symport w/ secondary transport
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

16. Meiosis II: EQUATIONAL DIVISION
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
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
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
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

17. Anterior eye
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
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
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)

18. Epithelium of the sm intestine: enterocytes lined w/brush border (digestion/absorption); goblet cells (mucous); crypts of Lieberkuhn exocrine glands (lysozyme)
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots

19. oxytocin
Most absorption occurs in sm intestine
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
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
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection

20. What is the function of the loop of Henle
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Increases solute conc and osmotic pressure of the ***medulla
via symport - secondary transport (ie by pre - established - ATP- intensive) with Na gradient into enterocyte......with no Na gradient (ie without ATP) carbohydrate monomers could not be transported in
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state

21. inhibin secreted by
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Testosterone and estradiol

22. lining of abdominal cavity=
Uncontracted: parasymp (eg opoid use)
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Smooth ER

23. ligands are the messenger compounds that target secondary messenger systems on effectors
It targets liver conc of prothrombin - fibrinogen etc
Excretes waste products: urea - uric acid - ammonia - phosphate - maintains homeostasis: including body fluid volume (water reabsorption) and solute composition (mineral balance - nutrient reabsorption) - controls *plasma* pH: antiport of Na/K and pr
Sorts - modifies - concentrates proteins from the ER
Many modern drugs are ligands for GPCRs

24. What (typically - ie not pre - ovulation) feeds back to decrease LH - FSH production?
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)
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Testosterone and estradiol
Vitamin K - b12 - thiamin - riboflavin

25. A group of cell bodies in CNS is nucleus - outside CNS is...
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
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Ganglion

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.

27. How does water cross the apical membrane
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Peptides
Thru tight junctions by favorable osmotic gradient
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

28. In other words...
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
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
Sorts - modifies - concentrates proteins from the ER

29. Luteal surge
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver

30. Anatomy of the villi
Needs time for bile - lipase - micelle migration - enterocyte uptake
Conjunction of cell body w/axon
Corpus luteum degrades into corpus albicans
Contain capillary network - lymph vessels (lacteals)

31. FLAT PG: TSH aka thyrotropin
In gastric pits; secretions combine into gastric juice
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
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Peptide; stims growth of nearly all cell of body; all other anterior pituitary horms have specific targets; upregulates anabolic pathways; use of fat for energy goes up (fat - burning); increases AA transport across cell membrane (nutrient uptake)

32. Stomach has no lacteals
Most absorption occurs in sm intestine
'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.'
Albumin increases osmolarity of blood; increases osmotic pressure
Combined via conjunction of pancreatic duct and common bile duct; common bile duct originates at **cystic duct where gall bladder and liver secretions combine ..cystic duct+common bile duct+pancreatic duct --->into duodenum

33. What are phagosomes
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.
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Membrane - bound - endocytosed bodies

34. Where does fertilization occur
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Fallopian tubes
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)

35. Sensory - motor neurons are part of which nervous system
About 7.2
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Zygotes are diploid
Peripheral nervous sys

36. spermatogonia arise from
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
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
Gastrulation occurs: formation of three primary germ layers = differentiation
Epithelial tissue near semniferous tubules

37. Bile salts and lipase
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)
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Lumen (ie continuous w/body cavity) and cytosol
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

38. Most important nutrients absorbed by large intestine
- 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
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Testosterone upon stim by LH
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)

39. How do parietal cells work ** (involves CO2)
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Form barrier to extracellular fluid

40. Some PNS nerves are found in brain - spinal cord
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
An endogenous morphine
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

41. What do lipases do
Meiosis creates germ cells
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Break down TAGs to monoglycerides and free fatty acids
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate

42. hypothalamus - AP - ACTH - cortisol release from adrenal cortex
Secondary oocyte (stim'd by LH stimulation of theca cells causing release of testosterone - converted to estradiol; eventually brings about luteal surge -->EQUATIONAL DIVISION-->ovum released during ovulation into fallopian tube; burst follicle becom
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Cancer; apop can be programmed cell death; mitochon can play important role in apop
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

43. golgi body
Regulated by gastrointestinal horms
Sorts - modifies - concentrates proteins from the ER
HCl; secreted by parietal cells under stim by gastrin
Thru tight junctions by favorable osmotic gradient

44. Where do absorbed fats go in the enterocyte
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Lysosome
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes

45. Interaction of corpus luteum/placenta
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Vitamin K - b12 - thiamin - riboflavin
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra

46. What else do parietals do?
Combined via conjunction of pancreatic duct and common bile duct; common bile duct originates at **cystic duct where gall bladder and liver secretions combine ..cystic duct+common bile duct+pancreatic duct --->into duodenum
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
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
Beta cells

47. Think of spinal cord injury
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
90-140 mg/dl
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

48. cholinergic receptors: NICTONIC and MUSCARINIC Nicotinic: neuromuscular effectors (ionotropic) Muscarinic: PARA effectors (GPCRs) Adrenergic: SYMP effectors (GPCRs)
Collection of cell bodies; cell processes project out from both ends of ganglion; synapses with interneuron in spinal cord on one end and sensory receptor on other
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors

49. Gastrin from G cells stims parietal cells...
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Glands w/ducts: Exocrine glands
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons

50. only monosaccharides are absorbed
Nitrogen
Amino acid monomers - di - tri absorbed by symport at enterocyte; each AA has slightly diff mechanism; from entero - AAs enter bloodstream where they are taken up by all cells of the body - esp the liver by active or facilitated transport (NEVER PASS
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol