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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. when cells hit their limit for prot storage...
AAs can be burned for energy or converted to fat for storage
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
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.
The renal corpuscle

2. How does birth control work?
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Organs
The renal corpuscle
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

3. FLAT PG: LH
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
Pancreatic duct (made of acinar cells?)
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
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

4. ADH
Liposome has phospholipid bilayer
Transfer signals from neuron - neuron; 90% of neurons are interneurons
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
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

5. important pancreatic enzymes
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Increases surface area of food ball (bolus)
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Which is why lactase - maltase - dextrinase - sucrase are on brush border

6. duodenum must have receptors for fat content - protein because
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
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Outermost layer of blood vessel
Thru tight junctions by favorable osmotic gradient

7. fructose enters enterocyte by
Corpus luteum degrades into corpus albicans
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
Facilitated diffusion: no symport w/ secondary transport
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine

8. Embryology
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
- 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
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Zygote - morula (first four days) - blastocyst (4 day+; implants in uterine lining) - gastrula (2 week) - neurula (3 week)...

9. gametic life cycle
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)
(diploid organism) humans are part of gametic life cycle ie produce gametes; diploid germ - line stem cells undergo meiosis to form haploid gametes
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)
Ammonia; must be converted to urea by liver and excreted in urine by kidney

10. signal transduction occurs by 2 paths
Lipoproteins; albumin carries free fatty acids when fat is mobilized from adipose tissue - etc
1) by integral ion channels 2) transmitted by second messenger system
'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.'
Peristalsis (esophagus) and segmentation (bi - directional=mixing)

11. quote on cavities/viscera

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12. axon hillock physiology
Glucose = aldose fructose = ketose
Conjunction of cell body w/axon
Meiosis creates germ cells
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)

13. 'Cell bodies of somatic motor neurons are located in....'
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Below hypothalamus
Vitamin K - b12 - thiamin - riboflavin
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining

14. How does water cross the apical membrane
Testosterone upon stim by LH
Thru tight junctions by favorable osmotic gradient
Oxytocin and ADH (aka vasopressin)
Cancer; apop can be programmed cell death; mitochon can play important role in apop

15. cAMP - cGMP - calmodulin...
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
Only musc and esp ** liver can store large amounts

16. Which fats are not absorbed like this
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
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries

17. what happens to bile secretions
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Mostly reabsorbed to liver
1) by integral ion channels 2) transmitted by second messenger system
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine

18. How does duod deal with hi HCl from stom
The wall of the body or of a body cavity or hollow structure
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Ups bicarbonate secretion by pancreas; raises pH to 6.0
Glucocorticoid (cortisol); mineralocorticoid (aldosterone)

19. Thus - central nervous sys is...
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
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
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
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

20. FLAT PG: TSH aka thyrotropin
Membrane - bound - endocytosed bodies
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
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
'visceral organs develop adjacent to a cavity and invaginate into the bag - like coelom'

21. Three stages of the menstrual cycle
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Night vision
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra

22. Anterior eye vs. posterior eye
Alpha cells; stims gluconeogenesis in liver; acts via cAMP second messenger
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Determined by whether in front of or behind the lens

23. going down the loop of Henle - water - permeable - filtrate osmolarity goes up as water leaves...
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
Oxytocin and ADH (aka vasopressin)
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Inner lining of blood vessels

24. hypothalamus - AP - ACTH - cortisol release from adrenal cortex
Result: stress reaction; increase glycogenolysis - gluconeogenesis; fat/prot breakdown; increase blood glucose
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
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
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

25. parathyroid hormone
Fructose is a structural isomer of glucose
Increases blood Calcium
Membrane - bound - endocytosed bodies
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

26. only monosaccharides are absorbed
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
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Note: enteric= small intestine - double layer of peritoneum that suspends jejunum/ileum from posterior abdominal wall = connective tissue
Glycosaminoglycans - prots - AAs - lipids

27. at lo blood sugar...
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Processes: axons - dendrites
Peripheral nervous sys
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)

28. In effect LH - FSH stimulate
Prod of steroid hormones in testes - ovaries
Peak at 1-2hr after meal; chylomicrons themselves have half - life of about 1hr after formation in enterocytes
Chylomicrons are much bigger
Contain capillary network - lymph vessels (lacteals)

29. bundles of collecting ducts are called
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
Break down TAGs to monoglycerides and free fatty acids
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)

30. How do parietal cells work ** (involves CO2)
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Paracrine (local) - endocrine (longer distance)
Development of placenta begins with implantation; eventually - by end of first trimester - placenta will replace corpus luteum and its estrogen/progest secretions
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach

31. From that point...
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
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.
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

32. Anatomy of the villi
Contain capillary network - lymph vessels (lacteals)
All carbs absorbed at enterocytes are carried to liver by portal vein
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

33. Morula (...totipotent)
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
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
Liver is the control center for blood glucose; is fed by portal vein from sm intest
Fovea (highest amount of cones)

34. What does peptic refer to in general
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
Prophase I: crossing over occurs; nuclear envelope is absorbed into ER; chromosomes condense)
Beta cells
Digestion

35. PNS is broken down into
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
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
Somatic nervous sys - autonomic nervous sys
Glucose = aldose fructose = ketose

36. interneurons
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
Glycosaminoglycans - prots - AAs - lipids
Peptides
Transfer signals from neuron - neuron; 90% of neurons are interneurons

37. golgi body
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
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
TAGS--->FFAs; remember that FFAs are broken down for energy in mito matrix by beta - oxidation
Sorts - modifies - concentrates proteins from the ER

38. mucus cells line the stomach...
Inner lining of circulatory system
Renal pyramids --->renal calyx-->renal pelvis -->ureter -->urethra
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
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability

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

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40. Different tissues working together
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
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
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Organs

41. The path from blood plasma to urine

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42. position of AP...
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
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
Dehydration reaction; broken apart with enzyme - catalyzed hydrolysis
Below hypothalamus

43. What is the path of a sound wave that enters the ear?
5
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
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
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

44. Thus inhibiting parietal cells could do What to blood pH
Lower blood pH
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
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
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

45. Leydig cells produce
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Neurons may perform one of three functions....
Glands w/ducts: Exocrine glands
Testosterone upon stim by LH

46. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
cornea (1.4 refractory index; bends light) - pupil (size of pupil is determined by contraction state of the iris) - aqueous humor
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Facilitated diffusion: no symport w/ secondary transport
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

47. 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)
Formed in kidney (nephron) - sent thru renal pelvis - down ureter to bladder - drained by urethra'
Glucose and ketone bodies (not from glycogen stores)
Can be saturated; conc of a solute is called the transport maximum --->excess goes into urine
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

48. Creating gradients requires what?
Glucose
Corpus luteum degrades into corpus albicans
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
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

49. 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
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Sensory neurons are affector; motor neurons are effector // dorsal afferent (dorsal - Back- side of spinal cord carries sensory signals to brain; ventral effector
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching

50. After meiosis II - Female

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