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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. Mucus - digestive enzymes released thru
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
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Glands w/ducts: Exocrine glands
Inner lining of circulatory system

2. What is the path of a sound wave that enters the ear?
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
Lower blood pH
Contain capillary network - lymph vessels (lacteals)
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

3. small intestine=
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Duodenum (wraps around pancreas; most digestion occurs here) - jejunum (pH 7-9; 2m) - ileum
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

4. STOMACH: no absorption
Chyme (by combined activity of exocrine glands)
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons

5. The EYE
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Normally contracted

6. How do nutrients move?
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
Glucose and ketone bodies (not from glycogen stores)

7. sensory (afferent)/interneurons/motor (efferent)
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Neurons may perform one of three functions....
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Beta cells

8. these transport proteins - when concs are high enough...
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
75% water/ 25% solid mass: of that solid mass: 10-20% fat = phospholipid bilayer of bacteria - slough - off enterocytes ie stomach lining (must be constantly rebuilt) 10-20% inorganic material 30% roughage = fiber = cellulose (indigestible) 2-3% prot
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes

9. A contracted iris occurs with what kind of stimulation
Membrane - bound - endocytosed bodies
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
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.
Sympathetic: dilates pupil (for night hunting)

10. Sensory - motor neurons are part of which nervous system
Peripheral nervous sys
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
HCl; secreted by parietal cells under stim by gastrin
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

11. PNS is broken down into
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
Somatic nervous sys - autonomic nervous sys
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

12. week three: neurulation; mesoderm induces ectoderm; thus - NEURULATION INVOLVES SC Development - at week three
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Eukaryotes

13. Most important nutrients absorbed by large intestine
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Organs

14. Alpha - amylase found where
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
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)
In mouth - breakdown of starch into polysaccharides
Creates one ovum (23 N) and three polar bodies

15. 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.
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
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
Beta cells

16. when thinking of proteins - think
Regulated by gastrointestinal horms
Chyme (by combined activity of exocrine glands)
Normally contracted
Nitrogen

17. SYMP neurons originate in= PARA neurons originate in=
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)
Testosterone upon stim by LH
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection

18. fructose enters enterocyte by
Primitive streak - which consists of cells of the MESODERM ****
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Facilitated diffusion: no symport w/ secondary transport

19. What is the net effect of the distal tubule
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
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
Sorts - modifies - concentrates proteins from the ER
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

20. What is a nerve? (PNS)
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule
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
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges
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

21. FLAT PG: FSH
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

22. Meiosis I Telophase I
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

23. In effect LH - FSH stimulate
Processes: axons - dendrites
Chyme (by combined activity of exocrine glands)
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

24. What do lipases do
Break down TAGs to monoglycerides and free fatty acids
Digestion
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor

25. glucagon secreted by
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
Travels vas deferens - urethra; mixes with prostate fluids - seminal vesicles - couper's gland - etc
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions

26. What does lipase attack exactly
Lysosome
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

27. Thus inhibiting parietal cells could do What to blood pH
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
Glucose
Lower blood pH

28. Where would materials slated for digestion go?
Homologous chromosomes line up w/ attachment of spindle fibers/microtubule polymers to centromeres via kinetochores; identical in appearance under light microscope to metaphase of mitosis
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right
Lysosome
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

29. lysosome pH
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
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)
5
***nicotinic is ionotropic; muscarinic is GPCR

30. What is the mesentery?
Lower blood pH
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

31. Luteal surge
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
- 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

32. What is the function of the loop of Henle
Two perpendicular semicircular canals involved in balance - equilibrium
Increases solute conc and osmotic pressure of the ***medulla
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
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)

33. Four tissues
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
Epithelial tissue near semniferous tubules
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

34. Sensory neuron cell bodies vs. somatic motor cell bodies
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue

35. pancreatic amylase is much stronger than
Salivary amylase; both hydrolyze glycosidic linkages
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
At the first capillary bed of the nephron called the glomerulus which is encased by ***Bowman's capsule

36. little by little chyme is squirted out thru pyloric sphincter
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
Regulated by gastrointestinal horms
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

37. Cell determination begins At what stage of development
Low because AAs are immediately used in translation
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
23 N; 23 chromosomes and haploid (no homologous chromosomes); each chromosome has two sister chromatids Male: primary spermatocyte -->REDUCTIONAL DIVISION (first stim'd at puberty by GnRH - LH-->secondary spermatocyte Female: primary oocyte (arreste

38. protein absorption at enterocyte
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
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
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Testosterone and estradiol

39. pancreas secretes enzymes via
Form barrier to extracellular fluid
Pancreatic duct (made of acinar cells?)
Somatic nervous sys - autonomic nervous sys
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

40. signal transduction occurs by 2 paths
1) by integral ion channels 2) transmitted by second messenger system
'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
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Normally contracted

41. interneurons
Transfer signals from neuron - neuron; 90% of neurons are interneurons
RBCs - large proteins; What does enter is called the filtrate
Thru tight junctions by favorable osmotic gradient
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch

42. PNS review: SAME DAVE
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Peripheral nervous sys
Digestion
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

43. Kidney physiology...

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44. cytosol pH
- 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
Eukaryotes
About 7.2
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

45. liver receives blood from...
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
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
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
HCl; secreted by parietal cells under stim by gastrin

46. What determines number of chromosomes?
Zygotes are diploid
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.
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase

47. How does water cross the apical membrane
Thru tight junctions by favorable osmotic gradient
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
ER
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

48. After meiosis I - daughter cells are...

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49. large intestine E. coli aid absorption of...
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Vitamin K - b12 - thiamin - riboflavin
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
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

50. What is a dorsal root ganglion?
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
Increases solute conc and osmotic pressure of the ***medulla
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'
Facilitated diffusion from hi to lo conc