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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 30 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. What if large intestine isn't working well
In gastric pits; secretions combine into gastric juice
Albumin increases osmolarity of blood; increases osmotic pressure
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
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

2. hypothalamus - AP - ACTH - cortisol release from adrenal cortex
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood 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.
- 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

3. lining of abdominal cavity=
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
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
Primitive streak - which consists of cells of the MESODERM ****

4. pancreatic amylase is much stronger than
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
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
Salivary amylase; both hydrolyze glycosidic linkages
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males

5. Meiosis II: EQUATIONAL DIVISION
Most absorption occurs in sm intestine
Fovea (highest amount of cones)
Digestion
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

6. What is the function of the loop of Henle
Increases solute conc and osmotic pressure of the ***medulla
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
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
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus

7. insulin secreted by
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Beta cells
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
Thru tight junctions by favorable osmotic gradient

8. On what surface of the retina is the eye most sensitive
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
Inner lining of circulatory system
Fovea (highest amount of cones)
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine

9. what happens when glycogen stores are saturated and blood sugar remains high?
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
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
Only musc and esp ** liver can store large amounts

10. 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
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
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

11. How long are peptides when absorbed at brush border
'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
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

12. What surrounds the hydrophilic heads of the new TAGs
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
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions

13. PNS is broken down into
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Somatic nervous sys - autonomic nervous sys

14. Embryology
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
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Below hypothalamus
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

15. is intracellular AA conc hi or low?
Low because AAs are immediately used in translation
Direction of differentiation
Peptides
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

16. what cannot cross the fenestrations of the renal corpuscle
5
Ventrally (picture skeletal vertebrae)
RBCs - large proteins; What does enter is called the filtrate
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

17. main point of fat transport...
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

18. albumin has What affect on blood osmotic pressure
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
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
Albumin increases osmolarity of blood; increases osmotic pressure
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

19. Path of food entering body...
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)

20. Polypeptides are formed with what kind of reaction?
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms

21. Where do pancreatic secretions take effect
Systems (eg digestive system consists of many organs)
Carbohydrates are highly hydrated: one water mol per carbon mol - fats are anhydrous: contain more reduced carbons per unit mass - altogether fats contain 6X energy per unit mass
Lower blood pH
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

22. Sensory neuron cell bodies vs. somatic motor cell bodies
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
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)
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

23. cAMP - cGMP - calmodulin...
Neurons may perform one of three functions....
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)
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Below hypothalamus

24. How does birth control work?
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
All carbs absorbed at enterocytes are carried to liver by portal vein
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

25. interneurons
Increases blood Calcium
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Inner lining of circulatory system

26. Gland: ovaries
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
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

27. What is a plasmalogen?
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
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**
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

28. FLAT PG: LH
- 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
Peptide; responsible for luteal surge (driven in part by LH-->testosterone -->estradiol -->LH positive feedback); results in ovulation (follicle bursting) - releasing egg into fallopian tube/oviduct
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons

29. From that point...
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
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
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.
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

30. Difference between euk and prok flagella
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
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
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
Lysosome

31. gradual increase in FSH typical of primary follicle development;
Form barrier to extracellular fluid
Testosterone upon stim by LH
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP

32. The bolus (chewing) is digested to what in the stomach
Chyme (by combined activity of exocrine glands)
Oxytocin and ADH (aka vasopressin)
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Contain capillary network - lymph vessels (lacteals)

33. After meiosis II...
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Testosterone and estradiol
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
RBCs - large proteins; What does enter is called the filtrate

34. Where does fertilization occur
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
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Fallopian tubes

35. What determines number of chromosomes?
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
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

36. Meiosis I Anaphase I
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Homologous chromosomes separate - migrate towards opposite poles/centrioles
Lysosome
Organs

37. Gastrulation: ectoderm/mesoderm/endoderm
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
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'

38. when thinking of proteins - think
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Nitrogen
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest

39. overview of prot digestion
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
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
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
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

40. Most important nutrients absorbed by large intestine
90-140 mg/dl
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
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.

41. Think of spinal cord injury
Increases blood Calcium
Carbohydrates are highly hydrated: one water mol per carbon mol - fats are anhydrous: contain more reduced carbons per unit mass - altogether fats contain 6X energy per unit mass
Sensory (afferent - dorsal) - motor (efferent - ventral)
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion

42. spermatogonia arise from
Epithelial tissue near semniferous tubules
Lysosome
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
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

43. Interaction of corpus luteum/placenta
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Outermost layer of blood vessel
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

44. FSH - LH - HCG - inhibin are...
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
Mostly reabsorbed to liver
- 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
Peptides

45. How do monoglycerides and ffas get to brush border?
Micelles; micelles (made of bile) go back and forth between brush border and chyme
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
Sympathetic: dilates pupil (for night hunting)
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

46. what happens to bile secretions
Inner lining of blood vessels
Fallopian tubes
Mostly reabsorbed to liver
Low because AAs are immediately used in translation

47. How do nutrients move?
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Gonadotropin releasing hormone - GnRH
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

48. The EYE
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Regulated by gastrointestinal horms
Determined by whether in front of or behind the lens

49. What are the memb - bound enzymes of the brush border?
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Only musc and esp ** liver can store large amounts
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Peptides

50. Anatomy of the villi
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
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
Nitrogen
Contain capillary network - lymph vessels (lacteals)