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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. liver and blood glucose...
Facilitated diffusion: no symport w/ secondary transport
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
Inner lining of blood vessels
Liver is the control center for blood glucose; is fed by portal vein from sm intest

2. examples of different cavities... (compartments for viscera)
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
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)
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)
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)

3. How do nutrients move?
Which is why lactase - maltase - dextrinase - sucrase are on brush border
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
Secondary spermatocyte (stim'd by FSH from Sertoli cells -->EQUATIONAL DIVISION-->spermatid - which matures further into spermatozoa; released into semeniferous tubule; transported to epididymis
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue

4. What is the net effect of the distal tubule
Inner lining of blood vessels
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
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen

5. What is an endorphin?
Normally contracted
An endogenous morphine
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine

6. size of chylomicrons (fat + apoproteins) vs lipoproteins ('cholesterol')
Chylomicrons are much bigger
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
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males

7. FLAT PG: LH
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
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

8. at lo blood sugar...
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
'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
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct

9. Four tissues
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Facilitated diffusion from hi to lo conc

10. inhibin secreted by
- 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
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
Most absorption occurs in sm intestine
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on

11. Blastocyst
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
Night vision
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility

12. Think of spinal cord injury
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Lots of water - minerals (electrolyte balance) - vitamins (aided by gut bacteria)
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right

13. Difference between euk and prok flagella
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Carry signals to musc OR Gland
Outermost layer of blood vessel
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

14. golgi body
Number of centromeres - Not number of chromatids eg - two sister chromatids connected by one centromere = one chromosome
Sorts - modifies - concentrates proteins from the ER
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
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

15. Alpha - amylase found where
Glucose
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)
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
In mouth - breakdown of starch into polysaccharides

16. Adrenal cortex hormones (STEROIDS)
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
Paracrine (local) - endocrine (longer distance)
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc

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

18. Energy from fat - prot - gluc
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Most absorption occurs in sm intestine
Conjunction of cell body w/axon
Cancer; apop can be programmed cell death; mitochon can play important role in apop

19. What kind of cells make up epithel tiss of stom - then sm intest?
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
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
Normally contracted
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

20. AP- peptides (FSH - LH - ACTH - TSH - prolactin - hGH); PP- peptides (ADH - oxytocin); thyroid - peptide *and* tyr - derived (T3/T4 - calcitonin); parathyroid - peptide (PTH; raise blood Ca via pathway involving vitamin D)
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
***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
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
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)

21. zygotic life cycle
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.
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
Membrane - bound - endocytosed bodies

22. Gastrin from G cells stims parietal cells...
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Tight regulation of parietal cells needed b/c gastric acid secretion is E- intensive; parietal cells are hi in mitochons
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
90-140 mg/dl

23. Adrenal medulla hormones (TYR- DERIVED)
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Fructose is a structural isomer of glucose
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides

24. Seen in lysosomal storage diseases
RBCs - large proteins; What does enter is called the filtrate
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Buildup of macromolecules in lysosome due to deficient lysosome enzymes

25. pancreatic amylase is much stronger than
Form barrier to extracellular fluid
Salivary amylase; both hydrolyze glycosidic linkages
Gonadotropin releasing hormone - GnRH
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

26. What is a toxic byproduct of gluconeogenesis from proteins
Ammonia; must be converted to urea by liver and excreted in urine by kidney
Hypothalamus --->AP--->target tissues eg TSH - thyroid - T3/T4 release - increase basal metabolic rate
The wall of the body or of a body cavity or hollow structure
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries

27. Ovum development is halted At what stage until fertilization...
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Primitive streak - which consists of cells of the MESODERM ****
1) by integral ion channels 2) transmitted by second messenger system

28. Tight junctions
Form barrier to extracellular fluid
Needs time for bile - lipase - micelle migration - enterocyte uptake
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Alpha 1-4 and 1-6 (branching) glycosidic linkages

29. Different tissues working together
Glands w/ducts: Exocrine glands
Within the paravertebral ganglion - running parallel to spinal cord
Organs
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

30. Some epithelial cells are... others...
Organs
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
- 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
Carry signals to musc OR Gland

31. in mammals - gastrulation involves formation of the
Primitive streak - which consists of cells of the MESODERM ****
In mouth - breakdown of starch into polysaccharides
Moves down thru esophageal sphincter
vitreous humor - retina - fovea

32. What is a plasmalogen?
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

33. thyroid hormones: Not All One Kind of HORM
Vitamin K - b12 - thiamin - riboflavin
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Calcitonin (peptide; lowers blood Ca); T3/T4 (tyrosine - derived; increase basal metabolic rate); T4= thyroxine
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

34. How do parietal cells work ** (involves CO2)
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
Contain capillary network - lymph vessels (lacteals)
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach

35. 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
Notochord (mesoderm) induces ectoderm to thicken into neural plate --->neural tube --->spinal cord
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5

36. Human chorionic gonadotropin...
An endogenous morphine
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)
***nicotinic is ionotropic; muscarinic is GPCR

37. sensory (afferent) neurons
Night vision
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
HCl; secreted by parietal cells under stim by gastrin
Bacterial flagellin: hollow filament (not microtub); euk: 9+2 microtubule w/dynein bridges

38. Kidney physiology...

39. FLAT PG: prolactin
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
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
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
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector

40. What is somatostatin
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine

41. A contracted iris occurs with what kind of stimulation
Inner lining of blood vessels
Sympathetic: dilates pupil (for night hunting)
Sorts - modifies - concentrates proteins from the ER
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

42. Anterior eye
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Lumen (ie continuous w/body cavity) and cytosol
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
Photon (hv)- rhodopsin - conformation change - GPCR- Na less permeable - hyperpolarized rod cells - generates AP= photobleaching at visible light wavelengths (390-700nm)

43. A pinpoint iris is contracted or uncontracted
Uncontracted: parasymp (eg opoid use)
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Estradiol
Facilitated diffusion: no symport w/ secondary transport

44. What Changes - Doesn't Change as a result of movement of molecules across membranes in the proximal tubule
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'

45. What does portal vein do
Oxytocin and ADH (aka vasopressin)
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
About 7.2
All carbs absorbed at enterocytes are carried to liver by portal vein

46. 'Cell bodies of somatic motor neurons are located in....'
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Below hypothalamus
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct

47. Path of urine

48. Where do pancreatic secretions take effect
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter

49. What is the endothelium?
About 7.2
Gall bladder - pancreatic secretions increase - arrive via ampulla of vater (duct glands); insulin secretion increases (fed state; ductless glands)
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
Inner lining of circulatory system

50. From that point...
Chylomicrons are much bigger
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
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
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.