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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. Adrenal cortex hormones (STEROIDS)
Normally contracted
Fructose is a structural isomer of glucose
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

2. Ovum development is halted At what stage until fertilization...
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

3. 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
- 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
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum

4. from thoracic duct - chylomicrons stick to capillary walls...
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

5. Where else does ADH act
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

6. FLAT PG: prolactin
Two perpendicular semicircular canals involved in balance - equilibrium
Needs time for bile - lipase - micelle migration - enterocyte uptake
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Determined by whether in front of or behind the lens

7. What happens when rod cell is depolarized
Night vision
Glucose = aldose fructose = ketose
Needs time for bile - lipase - micelle migration - enterocyte uptake
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

8. Exocrine GlandS: stomach
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Digestion
- 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
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)

9. Spinal cord horns (thick knobs) point
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Ventrally (picture skeletal vertebrae)
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Neurons may perform one of three functions....

10. What is the path of a sound wave that enters the ear?
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
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Water flows from the tubule - concentrating the filtrate - raising BP
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

11. 3 phases of menstrual cycle
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
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
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)
Lower blood pH

12. sporic life cycle
Somatic nervous sys - autonomic nervous sys
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
vitreous humor - retina - fovea

13. What are phagosomes
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Membrane - bound - endocytosed bodies
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes

14. What force is acting upon chyme to move it forward down sm intestine
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
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
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Peristalsis (esophagus) and segmentation (bi - directional=mixing)

15. After meiosis II - Female

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16. Peritoneal refers to...
Abdominal cavity - which is coated in serous fluid
AAs can be burned for energy or converted to fat for storage
Vitamin K - b12 - thiamin - riboflavin
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on

17. Where are these exocrine glands located
In gastric pits; secretions combine into gastric juice
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
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

18. medium for paracrine hormones
Interstitial fluid (eg prostaglandins - cytokines)
Zygotes are diploid
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Water flows from the tubule - concentrating the filtrate - raising BP

19. What does lipase attack exactly
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
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

20. review: parietals secrete intrinsic factor...
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
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
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
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

21. Aldosterone (sodium uptake - potassium secretion)
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)
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
Digestion
visual (rhodopsin is receptor - derived from Vit A; conformation change occurs with photon to hyperpolarize rod cells; cone cells use photopsin for receptor) - olfactory - mood (NTs targeted by antidepressants - antipsychotics - etc; GABA is inhibit

22. at lo blood sugar...
Determined by whether in front of or behind the lens
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
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
***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

23. Meiosis I Metaphase I
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**
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
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
Below hypothalamus

24. FSH - LH - HCG - inhibin are...
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
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Somatic nervous sys - autonomic nervous sys
Peptides

25. 80-90% fat absorbed this way
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
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
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

26. overview of prot digestion
Micelles; micelles (made of bile) go back and forth between brush border and chyme
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
Lower blood pH
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

27. from the loop of henle...
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins

28. bundles of collecting ducts are called
- 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
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
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

29. little by little chyme is squirted out thru pyloric sphincter
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Moves down thru esophageal sphincter
Lysosome
Regulated by gastrointestinal horms

30. FLAT PG: TSH aka thyrotropin
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
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
1) by integral ion channels 2) transmitted by second messenger system
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)

31. When 'coumadin targets liver enzymes to act as anticoagulant'...
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
It targets liver conc of prothrombin - fibrinogen etc
Facilitated diffusion from hi to lo conc
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

32. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Oxytocin and ADH (aka vasopressin)
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Chylomicrons are much bigger
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

33. lining of abdominal cavity=
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)
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
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
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

34. components of interstitial fluid
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
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)
Glycosaminoglycans - prots - AAs - lipids
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)

35. Embryology
Glands w/ducts: Exocrine glands
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
HCl; secreted by parietal cells under stim by gastrin
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

36. Glycogenolysis/gluconeogenesis
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
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
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
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases

37. lysosome main function and derivation
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Facilitated diffusion from hi to lo conc
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

38. almost all exocytosed proteins pass through this
'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
Smooth ER
Zygotes are diploid
Fovea (highest amount of cones)

39. What (typically - ie not pre - ovulation) feeds back to decrease LH - FSH production?
Testosterone and estradiol
Prod of steroid hormones in testes - ovaries
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
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

40. interneurons
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Creates one ovum (23 N) and three polar bodies
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
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

41. Tight junctions
Form barrier to extracellular fluid
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
- 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
90-140 mg/dl

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

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43. portal vein physiology...

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44. gametes are haploid
Adrenal gland -- AC: steroids (cortisol - aldosterone); AM: catecholamines (epi - norepi); Islets of langerhans: peptides (insulin/glucagon) ANTAGONISTS: calcitonin (thyroid - peptide lowers Ca in blood); parathyroid hormone - peptide - vitamin D pat
In mouth - breakdown of starch into polysaccharides
Zygotes are diploid
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

45. Three stages of the menstrual cycle
Regulated by gastrointestinal horms
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Peptides
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

46. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Thru tight junctions by favorable osmotic gradient
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Needs time for bile - lipase - micelle migration - enterocyte uptake

47. Four tissues
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
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
Peripheral nervous sys
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

48. glucagon secreted by
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger

49. extracellular matrix formed mainly of...
Low because AAs are immediately used in translation
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Only musc and esp ** liver can store large amounts
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability

50. The EYE
'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.'
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
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
Sympathetic: dilates pupil (for night hunting)