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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.
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1. What hormones affect the stomach?
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
HCl; secreted by parietal cells under stim by gastrin
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
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

2. Anatomy of the villi
Determined by whether in front of or behind the lens
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
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

3. STOMACH: no absorption
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Fallopian tubes
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)

4. What is secreted into filtrate by cells of the proximal tubule?
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
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
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate

5. Determination is different than differentiation
Excretes waste products: urea - uric acid - ammonia - phosphate - maintains homeostasis: including body fluid volume (water reabsorption) and solute composition (mineral balance - nutrient reabsorption) - controls *plasma* pH: antiport of Na/K and pr
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
- 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
Paracrine (local) - endocrine (longer distance)

6. 80-90% fat absorbed this way
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
Collection of cell bodies; cell processes project out from both ends of ganglion; synapses with interneuron in spinal cord on one end and sensory receptor on other
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
Prod of steroid hormones in testes - ovaries

7. hypothalamus controls anterior pit - posterior pit release with inhibitory/releasing hormones of its own; these should have fairly self - explanatory names
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
Water flows from the tubule - concentrating the filtrate - raising BP
ER
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate

8. From that point...
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.
Increases surface area of food ball (bolus)
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Paracrine (local) - endocrine (longer distance)

9. 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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10. Cell determination begins At what stage of development
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Micelles; micelles (made of bile) go back and forth between brush border and chyme
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on

11. What is a plasmalogen?
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
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
Needs time for bile - lipase - micelle migration - enterocyte uptake
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

12. gradual increase in FSH typical of primary follicle development;
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Needs time for bile - lipase - micelle migration - enterocyte uptake
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

13. examples of different cavities... (compartments for viscera)
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
AAs can be burned for energy or converted to fat for storage
Peristalsis (esophagus) and segmentation (bi - directional=mixing)

14. sporic life cycle
Creates one ovum (23 N) and three polar bodies
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
Regulated by gastrointestinal horms
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

15. 90% digestion - absorption occurs in...
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Uncontracted: parasymp (eg opoid use)
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
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)

16. Interaction of corpus luteum/placenta
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
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
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

17. What does lipase attack exactly
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Pancreatic duct (made of acinar cells?)
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation

18. FLAT PG: hGH aka somatotropin
Many modern drugs are ligands for GPCRs
Testosterone upon stim by LH
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)
Form barrier to extracellular fluid

19. Where else does ADH act
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Beta cells

20. What is the adventitia?
Low because AAs are immediately used in translation
Outermost layer of blood vessel
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded

21. spermatogonia arise from
Gonadotropin releasing hormone - GnRH
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Epithelial tissue near semniferous tubules
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen

22. Path of food entering body...
Facilitated diffusion: no symport w/ secondary transport
Lumen (ie continuous w/body cavity) and cytosol
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus

23. fructose enters enterocyte by
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
- 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
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Facilitated diffusion: no symport w/ secondary transport

24. what else is located in the inner ear (not directly related to auditory)
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Two perpendicular semicircular canals involved in balance - equilibrium
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions

25. How does the body mobilize fat stores
***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
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
It targets liver conc of prothrombin - fibrinogen etc

26. FLAT PG: TSH aka thyrotropin
AAs can be burned for energy or converted to fat for storage
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Night vision
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

27. important because in meiosis germ - line cells begin as 46 2N w/ 23 pairs of homologous chromosomes which are replicated in S phase of interphase to 23 pairs of sister chromatids = still 46 2N
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
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
Thru tight junctions by favorable osmotic gradient

28. What is main difference is signal transmission in nicotinic vs muscarinic?
***nicotinic is ionotropic; muscarinic is GPCR
Somatic nervous sys - autonomic nervous sys
Many modern drugs are ligands for GPCRs
Zygotes are diploid

29. what happens when glycogen stores are saturated and blood sugar remains high?
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

30. At post - two weeks ovulation
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Corpus luteum degrades into corpus albicans
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

31. mucus cells line the stomach...
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
Processes: axons - dendrites
Oxytocin and ADH (aka vasopressin)
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

32. these transport proteins - when concs are high enough...
Inner lining of blood vessels
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
About 7.2
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine

33. How does blood sugar move into tissues?
Facilitated diffusion from hi to lo conc
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Eukaryotes

34. parathyroid hormones
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
'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.'
Facilitated diffusion from hi to lo conc
Beta cells

35. The bolus (chewing) is digested to what in the stomach
Chyme (by combined activity of exocrine glands)
Somatic nervous sys - autonomic nervous sys
Below hypothalamus
Liver is the control center for blood glucose; is fed by portal vein from sm intest

36. light detection via GPCRs
Oxytocin and ADH (aka vasopressin)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
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
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

37. zygotic life cycle
Micelles; micelles (made of bile) go back and forth between brush border and chyme
Night vision
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state

38. what cannot cross the fenestrations of the renal corpuscle
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
RBCs - large proteins; What does enter is called the filtrate
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Increases surface area of food ball (bolus)

39. lysosome main function and derivation
Moves down thru esophageal sphincter
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue

40. What are phagosomes
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
Digestion
Membrane - bound - endocytosed bodies
'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.'

41. How is the follicle developed during oogenesis
vitreous humor - retina - fovea
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
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
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle

42. Peritoneal refers to...
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Abdominal cavity - which is coated in serous fluid
Lumen (ie continuous w/body cavity) and cytosol
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)

43. After meiosis II - Female

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44. Alpha - amylase found where
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
In mouth - breakdown of starch into polysaccharides
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.
Chylomicrons are much bigger

45. gametic life cycle
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Smooth ER
Meiosis creates germ cells

46. Anterior eye vs. posterior eye
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Determined by whether in front of or behind the lens
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

47. Some epithelial cells are... others...
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
- 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
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
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

48. overall - fatty - prot - rich food in duod causes
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Somatic nervous sys - autonomic nervous sys
Creates one ovum (23 N) and three polar bodies
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production

49. trypsin is secreted by
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
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
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
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides

50. In effect LH - FSH stimulate
Facilitated diffusion: no symport w/ secondary transport
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
Prod of steroid hormones in testes - ovaries
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