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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. STOMACH: no absorption
Most absorption occurs in sm intestine
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Liposome has phospholipid bilayer
RBCs - large proteins; What does enter is called the filtrate

2. Contrast PNS- Somatic with PNS- Autonomic
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Contain capillary network - lymph vessels (lacteals)
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron

3. fat digestion is time - intensive
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
Needs time for bile - lipase - micelle migration - enterocyte uptake
Ventrally (picture skeletal vertebrae)
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP

4. Sensory - motor neurons are part of which nervous system
Uncontracted: parasymp (eg opoid use)
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Peripheral nervous sys

5. At post - two weeks ovulation
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Prod of steroid hormones in testes - ovaries
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Corpus luteum degrades into corpus albicans

6. protein absorption at enterocyte
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
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
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
All carbs absorbed at enterocytes are carried to liver by portal vein

7. During meiosis I and II in females - rather than creating four chromosomally- equivalent gametes...
Creates one ovum (23 N) and three polar bodies
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)
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
Increases blood Calcium

8. Interaction of corpus luteum/placenta
Prod of steroid hormones in testes - ovaries
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
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**

9. small intestine=
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
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
- 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
Outermost layer of blood vessel

10. energy source of 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
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
Glucose and ketone bodies (not from glycogen stores)
All carbs absorbed at enterocytes are carried to liver by portal vein

11. liver receives blood from...
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
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

12. Spinal cord horns (thick knobs) point
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
'Increased absorptive area is useful because digested nutrients (including sugars and amino acids) pass into the villi through diffusion - which is effective only at short distances. In other words - **increased surface area (in contact with the flui
Ventrally (picture skeletal vertebrae)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue

13. these transport proteins - when concs are high enough...
In mouth - breakdown of starch into polysaccharides
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Ammonia; must be converted to urea by liver and excreted in urine by kidney

14. Fructose relates how structurally to glucose
Liposome has phospholipid bilayer
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)
Membrane - bound - endocytosed bodies
Fructose is a structural isomer of glucose

15. Liver Functions
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
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

16. What does portal vein do
All carbs absorbed at enterocytes are carried to liver by portal vein
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
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Epithelial tissue near semniferous tubules

17. is intracellular AA conc hi or low?
Glucose and ketone bodies (not from glycogen stores)
Regulated by gastrointestinal horms
Thru tight junctions by favorable osmotic gradient
Low because AAs are immediately used in translation

18. How does glycogen compare to starch
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
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
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
It targets liver conc of prothrombin - fibrinogen etc

19. Cell bodies of SYMP postganglionic neurons lie far from effector...
Membrane - bound - endocytosed bodies
Within the paravertebral ganglion - running parallel to spinal cord
Facilitated diffusion from hi to lo conc
Gastrulation occurs: formation of three primary germ layers = differentiation

20. FLAT PG: FSH
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Lumen (ie continuous w/body cavity) and cytosol
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
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

21. Human chorionic gonadotropin...
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Paracrine (local) - endocrine (longer distance)
Mostly reabsorbed to liver

22. A group of cell bodies in CNS is nucleus - outside CNS is...
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
Ganglion
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Oxytocin and ADH (aka vasopressin)

23. FLAT PG: hGH aka somatotropin
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
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)
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

24. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Sympathetic: dilates pupil (for night hunting)
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane

25. How do monoglycerides and ffas get to brush border?
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Micelles; micelles (made of bile) go back and forth between brush border and chyme
***nicotinic is ionotropic; muscarinic is GPCR
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

26. Stomach has no lacteals
Gonadotropin releasing hormone - GnRH
Most absorption occurs in sm intestine
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
RBCs - large proteins; What does enter is called the filtrate

27. Thus - central nervous sys is...
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production

28. What is the pH at the entrance to the duodenum
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
vitreous humor - retina - fovea
Only musc and esp ** liver can store large amounts
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)

29. lysosome pH
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
5

30. What (typically - ie not pre - ovulation) feeds back to decrease LH - FSH production?
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Liver Functions pt. 2 - Carb metabolism: blood is sent straight to liver from sm intest thru portal vein; liver is control center for blood glucose; _______________ - fat metabolism: oxidizes fat for energy by beta - oxidation - forms most lipoprotei
Testosterone and estradiol
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity

31. Kidney physiology...

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32. Where does the juxtaglomerular apparatus come into play...renin --->inc angiotensins -->inc aldosterone - ups BP
Fructose is a structural isomer of glucose
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... ...
Smooth ER
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

33. gametes are haploid
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Zygotes are diploid
Testosterone upon stim by LH
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

34. Local vs long - distance mediators
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
Paracrine (local) - endocrine (longer distance)
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
23 N; 23 chromosomes and haploid (no homologous chromosomes); each chromosome has two sister chromatids Male: primary spermatocyte -->REDUCTIONAL DIVISION (first stim'd at puberty by GnRH - LH-->secondary spermatocyte Female: primary oocyte (arreste

35. week three: neurulation; mesoderm induces ectoderm; thus - NEURULATION INVOLVES SC Development - at week three
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord

36. interneurons
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Transfer signals from neuron - neuron; 90% of neurons are interneurons
1) by integral ion channels 2) transmitted by second messenger system
Interstitial fluid (eg prostaglandins - cytokines)

37. How long are peptides when absorbed at brush border
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Cancer; apop can be programmed cell death; mitochon can play important role in apop
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
The renal corpuscle

38. Different organs working together
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Oxytocin and ADH (aka vasopressin)
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Systems (eg digestive system consists of many organs)

39. Ovum development is halted At what stage until fertilization...
Pancreatic duct (made of acinar cells?)
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Beta cells

40. signal transduction occurs by 2 paths
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
Albumin increases osmolarity of blood; increases osmotic pressure
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
1) by integral ion channels 2) transmitted by second messenger system

41. only monosaccharides are absorbed
Glands w/ducts: Exocrine glands
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Inner lining of circulatory system
Cancer; apop can be programmed cell death; mitochon can play important role in apop

42. Adrenal cortex hormones (STEROIDS)
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Glands w/ducts: Exocrine glands

43. 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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44. Posterior eye
vitreous humor - retina - fovea
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
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

45. Some epithelial cells are... others...
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
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
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)
- 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

46. Exocrine GlandS: stomach
Beta cells
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
- 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
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

47. mitosis creates somatic cells
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
The wall of the body or of a body cavity or hollow structure
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Meiosis creates germ cells

48. What happens when rod cell is depolarized
Chylomicrons are much bigger
Within the paravertebral ganglion - running parallel to spinal cord
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Night vision

49. Beta - oxidation in liver produces...
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
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**
Glands w/ducts: Exocrine glands
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases

50. The esophageal sphincter is...
Normally contracted
Nitrogen
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
AAs can be burned for energy or converted to fat for storage