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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. Human chorionic gonadotropin...
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
Creates one ovum (23 N) and three polar bodies
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)

2. A contracted iris occurs with what kind of stimulation
In mouth - breakdown of starch into polysaccharides
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Abdominal cavity - which is coated in serous fluid
Sympathetic: dilates pupil (for night hunting)

3. 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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4. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
Beta cells
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
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

5. keep in mind that enterocyte is like a regular euk cell
Has memb - bound organelles - etc...
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
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
Liver is the control center for blood glucose; is fed by portal vein from sm intest

6. Meiosis II: EQUATIONAL DIVISION
Prod of steroid hormones in testes - ovaries
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
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
Facilitated diffusion from hi to lo conc

7. important pancreatic enzymes
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Creates one ovum (23 N) and three polar bodies
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Oxytocin and ADH (aka vasopressin)

8. What surrounds the hydrophilic heads of the new TAGs
Lysosome
It targets liver conc of prothrombin - fibrinogen etc
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
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

9. FLAT PG: LH
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
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
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

10. Stomach has no lacteals
Most absorption occurs in sm intestine
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)

11. therefore - How does plasma leave capillary at the renal corpuscle

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12. bile + fat forms
Estradiol
Micelles; micelles transport lipase products to enterocytes for absorption at brush border
Alpha 1-4 and 1-6 (branching) glycosidic linkages
- 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

13. fructose enters enterocyte by
Facilitated diffusion: no symport w/ secondary transport
1) by integral ion channels 2) transmitted by second messenger system
Inner lining of blood vessels
- 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

14. 90% digestion - absorption occurs in...
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
The wall of the body or of a body cavity or hollow structure
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
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy

15. Neuronal cell bodies have extensions ie
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Processes: axons - dendrites
Chylomicrons are much bigger
- 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

16. How does the body mobilize fat stores
Somatic nervous sys - autonomic nervous sys
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
***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

17. What determines number of chromosomes?
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
***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
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome

18. 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
Digestion
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility

19. For focal point that is nearby - what will the lens look like
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
Sympathetic: dilates pupil (for night hunting)
Lens will be rounded; contraction of the lens (ie focusing) is done by ciliary muscle

20. fat digestion is time - intensive
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Needs time for bile - lipase - micelle migration - enterocyte uptake
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Mostly reabsorbed to liver

21. What is secreted into filtrate by cells of the proximal tubule?
About 7.2
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
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)
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics

22. What does lipase attack exactly
Only musc and esp ** liver can store large amounts
Processes: axons - dendrites
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi

23. STOMACH: no absorption
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
In mouth - breakdown of starch into polysaccharides
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
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)

24. Leydig cells produce
- 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
Testosterone upon stim by LH
Regulated by gastrointestinal horms
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons

25. these transport proteins - when concs are high enough...
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
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
Prod of steroid hormones in testes - ovaries
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen

26. overview of prot digestion
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Liver is the control center for blood glucose; is fed by portal vein from sm intest
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
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

27. Chewing does what?
Lower blood pH
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Increases surface area of food ball (bolus)
Glycosaminoglycans - prots - AAs - lipids

28. 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
Faces the lumen
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

29. Think of spinal cord injury
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
Size of fist; two kidneys; have cortex (steroid hormones) and medulla (catecholamines) - receives about 20% of cardiac output - blood travels down arteries - up veins -'urine is created by the kidney and emptied into the renal pelvis - which is empti
Chyme (by combined activity of exocrine glands)
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion

30. euk cell has two principal sides
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Lumen (ie continuous w/body cavity) and cytosol
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

31. thyroid hormones: Not All One Kind of HORM
It targets liver conc of prothrombin - fibrinogen etc
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Eukaryotes
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine

32. So - following blastocyst implantation (4d) - at approx 2 weeks past fertilization
Gastrulation occurs: formation of three primary germ layers = differentiation
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
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

33. Anterior eye
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
Glucose and ketone bodies (not from glycogen stores)
Prod of steroid hormones in testes - ovaries

34. Local vs long - distance mediators
Albumin increases osmolarity of blood; increases osmotic pressure
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
Paracrine (local) - endocrine (longer distance)
All carbs absorbed at enterocytes are carried to liver by portal vein

35. sensory (afferent)/interneurons/motor (efferent)
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
Neurons may perform one of three functions....
Below hypothalamus
Only musc and esp ** liver can store large amounts

36. PNS is broken down into
Somatic nervous sys - autonomic nervous sys
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
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
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)

37. What happens when rod cell is depolarized
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Night vision

38. Difference between euk and prok flagella
Needs time for bile - lipase - micelle migration - enterocyte uptake
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
Homologous chromosomes separate - migrate towards opposite poles/centrioles

39. mitosis creates somatic cells
Below hypothalamus
Meiosis creates germ cells
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
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

40. from thoracic duct - chylomicrons stick to capillary walls...
Direction of differentiation
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)

41. What is a nerve? (PNS)
'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
Digestion
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
Micelles; micelles (made of bile) go back and forth between brush border and chyme

42. What is the net effect of the distal tubule
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
Inner lining of circulatory system
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion

43. Embryology
'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
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
Creates one ovum (23 N) and three polar bodies
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

44. sporic life cycle
Vitamin K - b12 - thiamin - riboflavin
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

45. Morula (...totipotent)
Ammonia; must be converted to urea by liver and excreted in urine by kidney
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage

46. Seen in lysosomal storage diseases
Outermost layer of blood vessel
1) by integral ion channels 2) transmitted by second messenger system
Ganglion
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

47. What is endothelium?
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Inner lining of blood vessels
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
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

48. What does peptic refer to in general
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
Glucose
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)
Digestion

49. from the loop of henle...
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
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
In gastric pits; secretions combine into gastric juice
Epithelial tissue near semniferous tubules

50. After meiosis II - Male

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