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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. In general - parietal=
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
The wall of the body or of a body cavity or hollow structure
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
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

2. chylomicron concentration in blood after meal
Facilitated diffusion from hi to lo conc
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
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

3. calcitonin

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4. sensory (afferent) neurons
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
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
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded

5. microvilli: increase SA of enterocyte; have hi conc of digestive enzymes

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6. Both divisions (somatic - autonomic) of PNS consist of...
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Sensory (afferent - dorsal) - motor (efferent - ventral)
Lysosome
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)

7. Aldosterone (sodium uptake - potassium secretion)
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
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)
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Chyme (by combined activity of exocrine glands)

8. Embryology
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
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
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
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

9. The esophageal sphincter is...
AAs can be burned for energy or converted to fat for storage
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Normally contracted
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

10. cAMP - cGMP - calmodulin...
Vitamin K - b12 - thiamin - riboflavin
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
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
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

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

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12. Determination is different than differentiation
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
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
Conjunction of cell body w/axon
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

13. What is a dorsal root ganglion?
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
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
Normally contracted
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

14. How do parietal cells work ** (involves CO2)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Fallopian tubes

15. What determines number of chromosomes?
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

16. What do villli do
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
- 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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera

17. golgi body
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
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
Sorts - modifies - concentrates proteins from the ER
Meiosis creates germ cells

18. cholinergic receptors: NICTONIC and MUSCARINIC Nicotinic: neuromuscular effectors (ionotropic) Muscarinic: PARA effectors (GPCRs) Adrenergic: SYMP effectors (GPCRs)
Glycosaminoglycans - prots - AAs - lipids
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
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis

19. smooth ER main function
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
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
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
Glucose

20. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Lumen (ie continuous w/body cavity) and cytosol
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Chylomicrons are much bigger
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation

21. So - following blastocyst implantation (4d) - at approx 2 weeks past fertilization
Gastrulation occurs: formation of three primary germ layers = differentiation
RBCs - large proteins; What does enter is called the filtrate
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5

22. ligands are the messenger compounds that target secondary messenger systems on effectors
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Many modern drugs are ligands for GPCRs
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Somatic nervous sys - autonomic nervous sys

23. FLAT PG: LH
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Beta cells
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
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

24. fructose enters enterocyte by
Facilitated diffusion: no symport w/ secondary transport
Beta cells
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)

25. Some epithelial cells are... others...
- 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
Gastrulation occurs: formation of three primary germ layers = differentiation
- 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
5

26. interneurons
- 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
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)
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Lumen (ie continuous w/body cavity) and cytosol

27. How is the follicle developed during oogenesis
'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
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
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
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

28. Sensory neuron cell bodies vs. somatic motor cell bodies
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Glucose and ketone bodies (not from glycogen stores)
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
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

29. Adrenal medulla hormones (TYR- DERIVED)
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Micelles; micelles (made of bile) go back and forth between brush border and chyme
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

30. In other words...
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Transfer signals from neuron - neuron; 90% of neurons are interneurons
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
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

31. large intestine E. coli aid absorption of...
Systems (eg digestive system consists of many organs)
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Vitamin K - b12 - thiamin - riboflavin
Fallopian tubes

32. these transport proteins - when concs are high enough...
Needs time for bile - lipase - micelle migration - enterocyte uptake
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
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
Systems (eg digestive system consists of many organs)

33. Seen in lysosomal storage diseases
Buildup of macromolecules in lysosome due to deficient lysosome enzymes
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)
Estradiol
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose

34. How is glucose absorbed in sm intest
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Facilitated diffusion: no symport w/ secondary transport
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid 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

35. What is a nerve? (PNS)
Facilitated diffusion: no symport w/ secondary transport
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Faces the lumen
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

36. Meiosis I Anaphase I
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
5
Homologous chromosomes separate - migrate towards opposite poles/centrioles

37. What is the net effect of the loop of Henle
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
Water flows from the tubule - concentrating the filtrate - raising BP
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
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)

38. testosterone can be aromatized to...
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
In mouth - breakdown of starch into polysaccharides
Estradiol

39. keep in mind that enterocyte is like a regular euk cell
Has memb - bound organelles - etc...
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

40. Path of food entering body...
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
'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
Processes: axons - dendrites

41. what happens to bile secretions
Mostly reabsorbed to liver
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Liver is the control center for blood glucose; is fed by portal vein from sm intest

42. pancreatic amylase is much stronger than
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Salivary amylase; both hydrolyze glycosidic linkages
Increases surface area of food ball (bolus)
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal

43. PNS review: SAME DAVE
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
It targets liver conc of prothrombin - fibrinogen etc
Abdominal cavity - which is coated in serous fluid
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector

44. What does lipase attack exactly
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
It targets liver conc of prothrombin - fibrinogen etc

45. main point of fat transport...
Somatic nervous sys - autonomic nervous sys
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
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
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

46. gametic life cycle
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Sympathetic: dilates pupil (for night hunting)
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Oxytocin and ADH (aka vasopressin)

47. What is the pH at the entrance to the duodenum
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
90-140 mg/dl
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

48. sporic life cycle
Corpus luteum degrades into corpus albicans
Via secondary active transport proteins (COSTS E TO FILTER BLOOD - ESTABLISH FLUID/ION BALANCE)
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
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

49. Three stages of the menstrual cycle
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Meiosis creates germ cells
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

50. Contrast PNS- Somatic with PNS- Autonomic
Zygotes are diploid
Two perpendicular semicircular canals involved in balance - equilibrium
Within the paravertebral ganglion - running parallel to spinal cord
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons