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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. What do villli do
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

2. What controls release of LH - FSH from anterior pituitary
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Chyme (by combined activity of exocrine glands)
Gonadotropin releasing hormone - GnRH
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

3. E storage per unit mass
Systems (eg digestive system consists of many organs)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Peptides
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

4. What are the major carbohydrates
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
Testosterone and estradiol
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Called a tract in the CNS; bundling together of axons/dendrites thru which many diff signals pass; many many neurons are bundled together into a single nerve

5. 90% digestion - absorption occurs in...
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Contain capillary network - lymph vessels (lacteals)
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
Zygotes are diploid

6. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Only musc and esp ** liver can store large amounts
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

7. 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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8. Leydig cells produce
Testosterone upon stim by LH
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**
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
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. PNS nerve signal
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
ER
In mouth - breakdown of starch into polysaccharides
The renal corpuscle

10. How long are peptides when absorbed at brush border
Facilitated diffusion from hi to lo conc
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Primitive streak - which consists of cells of the MESODERM ****
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

11. SYMP neurons originate in= PARA neurons originate in=
Organs
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
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Facilitated diffusion from hi to lo conc

12. The apical side of the villi...
Faces the lumen
Sorts - modifies - concentrates proteins from the ER
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
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

13. Sensory neuron cell bodies vs. somatic motor cell bodies
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
***nicotinic is ionotropic; muscarinic is GPCR
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

14. portal vein physiology...

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15. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
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
Carry signals to musc OR Gland
Homologous chromosomes separate - migrate towards opposite poles/centrioles
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

16. Seen in lysosomal storage diseases
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
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... ...
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

17. What is a toxic byproduct of gluconeogenesis from proteins
Outermost layer of blood vessel
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
Ammonia; must be converted to urea by liver and excreted in urine by kidney
AAs can be burned for energy or converted to fat for storage

18. Interaction of corpus luteum/placenta
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
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Break down TAGs to monoglycerides and free fatty acids

19. The esophageal sphincter is...
Normally contracted
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

20. sensory (afferent)/interneurons/motor (efferent)
Neurons may perform one of three functions....
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
In mouth - breakdown of starch into polysaccharides
Inner lining of circulatory system

21. Path of urine

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22. little by little chyme is squirted out thru pyloric sphincter
'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
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Regulated by gastrointestinal horms
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

23. Determination is different than differentiation
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Only musc and esp ** liver can store large amounts
Abdominal cavity - which is coated in serous fluid

24. what happens when glycogen stores are saturated and blood sugar remains high?
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Two perpendicular semicircular canals involved in balance - equilibrium

25. 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
Glycosaminoglycans - prots - AAs - lipids
Glucose
Liposome has phospholipid bilayer

26. remaining secondary follicle becomes
Within the paravertebral ganglion - running parallel to spinal cord
Regulated by gastrointestinal horms
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
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

27. Posterior eye
Gonadotropin releasing hormone - GnRH
vitreous humor - retina - fovea
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
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)

28. large intestine E. coli aid absorption of...
'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
Fallopian tubes
Vitamin K - b12 - thiamin - riboflavin
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

29. almost all exocytosed proteins pass through this
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
Smooth ER
- 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
Liposome has phospholipid bilayer

30. Thus - central nervous sys is...
Outermost layer of blood vessel
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Ammonia; must be converted to urea by liver and excreted in urine by kidney

31. Polypeptides are formed with what kind of reaction?
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
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
The wall of the body or of a body cavity or hollow structure
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes

32. peroxisome is derived from this
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
Lumen (ie continuous w/body cavity) and cytosol
ER
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)

33. Thus inhibiting parietal cells could do What to blood pH
Lower blood pH
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

34. in fat and liver cells monoglycerides and ffas are once again
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Within the paravertebral ganglion - running parallel to spinal cord
Somatic nervous sys - autonomic nervous sys
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

35. Glucose is a .... sugar; fructose is a .... sugar
Organs
***nicotinic is ionotropic; muscarinic is GPCR
Glucose = aldose fructose = ketose
Below hypothalamus

36. Meiosis I Metaphase I
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
Prod of steroid hormones in testes - ovaries
Night vision
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver

37. Exocrine GlandS: stomach
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
Ammonia; must be converted to urea by liver and excreted in urine by kidney
- 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
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity

38. Chewing does what?
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
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Increases surface area of food ball (bolus)
Low because AAs are immediately used in translation

39. in mammals - gastrulation involves formation of the
Primitive streak - which consists of cells of the MESODERM ****
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Carry signals to musc OR Gland
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

40. Gastrin from G cells stims parietal cells...
Outermost layer of blood vessel
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
Contain capillary network - lymph vessels (lacteals)

41. keep in mind that enterocyte is like a regular euk cell
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
The renal corpuscle
Has memb - bound organelles - etc...

42. 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
Homologous chromosomes separate - migrate towards opposite poles/centrioles
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
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

43. How do parietal cells work ** (involves CO2)
Growth 1 (G1) phase: STRUCTURAL ProteinS - ENZYMES; This is a very active period - where the cell synthesizes its vast array of proteins - including the enzymes and structural proteins it will need for growth. In G1 stage each of the chromosomes cons
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

44. from the loop of henle...
Prod of steroid hormones in testes - ovaries
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
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
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins

45. What force is acting upon chyme to move it forward down sm intestine
Fructose is a structural isomer of glucose
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)
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Smooth ER

46. is intracellular AA conc hi or low?
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
Low because AAs are immediately used in translation
Liposome has phospholipid bilayer
Contain capillary network - lymph vessels (lacteals)

47. ADH
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
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
- 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

48. only monosaccharides are absorbed
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Vitamin K - b12 - thiamin - riboflavin
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose

49. How do monoglycerides and ffas get to brush border?
Eukaryotes
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Micelles; micelles (made of bile) go back and forth between brush border and chyme
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

50. euk cell has two principal sides
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Lumen (ie continuous w/body cavity) and cytosol
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
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