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MCAT Prep - 2

Subjects : mcat, science

Instructions:

Answer 50 questions in 15 minutes.
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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. FLAT PG: TSH aka thyrotropin
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
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
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Night vision

2. from the loop of henle...
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Interstitial fluid (eg prostaglandins - cytokines)

3. Most important nutrients absorbed by large intestine
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Carry signals to musc OR Gland
Ganglion

4. serous membranes have a viscera - facing layer and a body wall - facing layer
The renal corpuscle
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
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity
Liposome has phospholipid bilayer

5. smooth ER main function
Meiosis creates germ cells
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Processes: axons - dendrites
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)

6. What is a plasmalogen?
AAs can be burned for energy or converted to fat for storage
1) by integral ion channels 2) transmitted by second messenger system
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)

7. almost all exocytosed proteins pass through this
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Smooth ER
Inner lining of blood vessels

8. what else is located in the inner ear (not directly related to auditory)
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
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.
Two perpendicular semicircular canals involved in balance - equilibrium
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

9. lining of abdominal cavity=
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Sympathetic: dilates pupil (for night hunting)
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right

10. gametes are haploid
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Zygotes are diploid

11. What is secreted into filtrate by cells of the proximal tubule?
In gastric pits; secretions combine into gastric juice
Lysosome
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae

12. Embryology
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
Many modern drugs are ligands for GPCRs
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
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

13. What hormones affect the stomach?
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
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
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)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue

14. Anatomy of the villi
Glucose = aldose fructose = ketose
Beta 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
Contain capillary network - lymph vessels (lacteals)

15. What do villli do
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
HCl; secreted by parietal cells under stim by gastrin
Facilitated diffusion from hi to lo conc
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption

16. quote on cavities/viscera

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17. in the presence of ADH what happens to movement of water across nephron membr
Water flows from the tubule - concentrating the filtrate - raising BP
Faces the lumen
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

18. What is somatostatin
Facilitated diffusion: no symport w/ secondary transport
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
Within the paravertebral ganglion - running parallel to spinal cord
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion

19. What if large intestine isn't working well
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... ...
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals
5
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

20. Where does fertilization occur
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
Testosterone upon stim by LH
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
Fallopian tubes

21. Where else does ADH act
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Organs
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

22. Aldosterone (sodium uptake - potassium secretion)
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Alpha 1-4 and 1-6 (branching) glycosidic linkages
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)

23. Exocrine GlandS: stomach
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
- 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

24. In other words...
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
Fovea (highest amount of cones)
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
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

25. liver receives blood from...
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
Zygotes are diploid
Glucose
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

26. What is the pH at the entrance to the duodenum
Form barrier to extracellular fluid
Uncontracted: parasymp (eg opoid use)
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

27. Stomach has no lacteals
Most absorption occurs in sm intestine
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

28. position of AP...
RBCs - large proteins; What does enter is called the filtrate
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Below hypothalamus
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger

29. E storage per unit mass
Lower blood pH
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
Contain capillary network - lymph vessels (lacteals)
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

30. A pinpoint iris is contracted or uncontracted
5
Uncontracted: parasymp (eg opoid use)
Chylomicrons are much bigger
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

31. cytosol pH
About 7.2
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
Lumen (ie continuous w/body cavity) and cytosol

32. What is the endothelium?
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Meiosis creates germ cells
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
Inner lining of circulatory system

33. albumin has What affect on blood osmotic pressure
Below hypothalamus
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Albumin increases osmolarity of blood; increases osmotic pressure
Mostly reabsorbed to liver

34. fat digestion is time - intensive
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)
Organs
Needs time for bile - lipase - micelle migration - enterocyte uptake
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

35. Which fats are not absorbed like this
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
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
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes

36. mitosis creates somatic cells
Ganglion
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Increases surface area of food ball (bolus)
Meiosis creates germ cells

37. Epithelium of the sm intestine: enterocytes lined w/brush border (digestion/absorption); goblet cells (mucous); crypts of Lieberkuhn exocrine glands (lysozyme)
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots

38. The apical side of the villi...
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Faces the lumen
Organs

39. ADH
Water flows from the tubule - concentrating the filtrate - raising BP
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
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
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

40. What surrounds the hydrophilic heads of the new TAGs
Albumin increases osmolarity of blood; increases osmotic pressure
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

41. Ovum development is halted At what stage until fertilization...
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
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

42. main point of fat transport...
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Membrane - bound - endocytosed bodies
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

43. micelles also pick up
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons

44. sensory (afferent) neurons
Digestion
- 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
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded

45. What does peptic refer to in general
The wall of the body or of a body cavity or hollow structure
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Digestion
1) by integral ion channels 2) transmitted by second messenger system

46. pancreatic amylase is much stronger than
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Sorts - modifies - concentrates proteins from the ER
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Salivary amylase; both hydrolyze glycosidic linkages

47. STOMACH: no absorption
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Diarrhea: excess water loss in feces; poor absorption of vitamins - minerals

48. What is main difference is signal transmission in nicotinic vs muscarinic?
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
***nicotinic is ionotropic; muscarinic is GPCR
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
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

49. motor (efferent) neurons --> VENTRAL
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Carry signals to musc OR Gland
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

50. FLAT PG: ACTH
Thru tight junctions by favorable osmotic gradient
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
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP