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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. when cells hit their limit for prot storage...
AAs can be burned for energy or converted to fat for storage
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
Paracrine (local) - endocrine (longer distance)
Neurons may perform one of three functions....

2. inhibin secreted by
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
AAs can be burned for energy or converted to fat for storage
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production

3. Where else does ADH act
Lumen (ie continuous w/body cavity) and cytosol
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
'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.'

4. Adrenal cortex hormones (STEROIDS)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
Glands w/ducts: Exocrine glands

5. What is the net effect of the loop of Henle
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
'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
Which is why lactase - maltase - dextrinase - sucrase are on brush border
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)

6. Anterior eye vs. posterior eye
Determined by whether in front of or behind the lens
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
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
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)

7. Aldosterone (sodium uptake - potassium secretion)
Peptides
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)
Increases blood Calcium
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

8. Embryology
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
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
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

9. What if large intestine isn't working well
Digestion
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
Within the paravertebral ganglion - running parallel to spinal cord
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

10. Where does blood to be filtered by kidney enter the nephron?

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11. lysosome pH
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
5
Outermost layer of blood vessel
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

12. what happens to bile secretions
Mostly reabsorbed to liver
Lumen (ie continuous w/body cavity) and cytosol
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
An endogenous morphine

13. From that point...
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
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.

14. How is glucose absorbed in sm intest
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
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
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Liposome has phospholipid bilayer

15. After meiosis II - Male

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16. What is the endothelium?
Inner lining of circulatory system
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
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

17. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Which is why lactase - maltase - dextrinase - sucrase are on brush border
5
Chylomicrons are much bigger
Primitive streak - which consists of cells of the MESODERM ****

18. Both divisions (somatic - autonomic) of PNS consist of...
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
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**
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
Sensory (afferent - dorsal) - motor (efferent - ventral)

19. Important aspect of crypt of Lieberkuhn - secreted intestinal juice
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Peptides
Needs time for bile - lipase - micelle migration - enterocyte uptake
Carry signals to musc OR Gland

20. from thoracic duct - chylomicrons stick to capillary walls...
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
HCl; secreted by parietal cells under stim by gastrin
Lumen (ie continuous w/body cavity) and cytosol

21. Where do absorbed fats go in the enterocyte
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Faces the lumen
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs

22. these transport proteins - when concs are high enough...
Facilitated diffusion: no symport w/ secondary transport
Paracrine (local) - endocrine (longer distance)
Meiosis creates germ cells
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine

23. zygotic life cycle
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
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
Smooth ER

24. Morula (...totipotent)
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
1) by integral ion channels 2) transmitted by second messenger system
'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.'
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

25. energy source of neurons
Homologous chromosomes separate - migrate towards opposite poles/centrioles
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
- 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
Glucose and ketone bodies (not from glycogen stores)

26. Four tissues
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)
Only musc and esp ** liver can store large amounts
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
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

27. medium for paracrine hormones
Interstitial fluid (eg prostaglandins - cytokines)
After 4 day+ - morula cells have formed fluid - filled ball (blastocyst); this implants in uterus at day 5-7; blastocyst is made up of EMBRYONIC STEM Cells; once implanted w/blastocyst - female is pregnant
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases

28. Where does fertilization occur
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Fallopian tubes
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

29. What is the function of the loop of Henle
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
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
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
Increases solute conc and osmotic pressure of the ***medulla

30. Cell determination begins At what stage of development
Interneurons working to integrate signals received from the peripheral nervous system (sense 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
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Regulated by gastrointestinal horms

31. Gastrulation: ectoderm/mesoderm/endoderm
Paracrine (local) - endocrine (longer distance)
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
- 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
Smooth ER

32. Most important nutrients absorbed by large intestine
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
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
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

33. Adrenal medulla hormones (TYR- DERIVED)
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.
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Within the paravertebral ganglion - running parallel to spinal cord

34. Ovum development is halted At what stage until fertilization...
Testosterone upon stim by LH
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
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)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

35. Path of food entering body...
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
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
Low because AAs are immediately used in translation
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

36. When 'coumadin targets liver enzymes to act as anticoagulant'...
Neurons may perform one of three functions....
Low because AAs are immediately used in translation
It targets liver conc of prothrombin - fibrinogen etc
Normally contracted

37. After meiosis I - daughter cells are...

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38. Gastrin from G cells stims parietal cells...
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Vitamin K - b12 - thiamin - riboflavin
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Lysosome

39. What is the mesentery?
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
***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

40. micelles also pick up
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
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

41. albumin has What affect on blood osmotic pressure
ER
Gonadotropin releasing hormone - GnRH
Moves down thru esophageal sphincter
Albumin increases osmolarity of blood; increases osmotic pressure

42. What are the memb - bound enzymes of the brush border?
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
The renal corpuscle

43. At post - two weeks ovulation
'Microvilli function as the **primary surface of nutrient absorption in the gastrointestinal tract**. Because of this vital function - the microvillar membrane is packed with enzymes that aid in the breakdown of complex nutrients into simpler compoun
Corpus luteum degrades into corpus albicans
Regulated by gastrointestinal horms
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.

44. What does portal vein do
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
All carbs absorbed at enterocytes are carried to liver by portal vein
'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.'

45. 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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46. Peritoneal refers to...
Low because AAs are immediately used in translation
Abdominal cavity - which is coated in serous fluid
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

47. The EYE
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
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
Normally contracted

48. euk cell has two principal sides
Lumen (ie continuous w/body cavity) and cytosol
5
Ventrally (picture skeletal vertebrae)
- 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

49. testosterone can be aromatized to...
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
AAs can be burned for energy or converted to fat for storage
Estradiol
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

50. How long are peptides when absorbed at brush border
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
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
vitreous humor - retina - fovea