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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.
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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. FLAT PG: LH
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Digestion
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

2. 80-90% fat absorbed this way
Thru tight junctions by favorable osmotic gradient
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
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
It targets liver conc of prothrombin - fibrinogen etc

3. What do lipases do
Fallopian tubes
Neurons may perform one of three functions....
Nuclear envelope reassembled in daughter cells; cytokinesis occurs; nucleoli reappear (site of rRNA synthesis)
Break down TAGs to monoglycerides and free fatty acids

4. How is the follicle developed during oogenesis
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
On the chyme exiting the stomach and entering duodenum thru the pyloric sphincter
Sympathetic: dilates pupil (for night hunting)
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males

5. Morula (...totipotent)
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Zygote (morula) composed of eight or more cells; All cells at this stage are TOTipOTENT STEM Cells: do not grow - form by cleavage
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
An endogenous morphine

6. Epithelium of the sm intestine: enterocytes lined w/brush border (digestion/absorption); goblet cells (mucous); crypts of Lieberkuhn exocrine glands (lysozyme)
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
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

7. oxytocin
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
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
The crypts of Lieberkuhn: sm intestine pH is not right; brush border enzs won't work right

8. During meiosis I and II in females - rather than creating four chromosomally- equivalent gametes...
Creates one ovum (23 N) and three polar bodies
Glucose and ketone bodies (not from glycogen stores)
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
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)

9. bile + fat forms
RBCs - large proteins; What does enter is called the filtrate
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
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
Micelles; micelles transport lipase products to enterocytes for absorption at brush border

10. Path of urine

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11. Different tissues working together
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
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
Gonadotropin releasing hormone - GnRH
Organs

12. After meiosis II...
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
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
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
Sorts - modifies - concentrates proteins from the ER

13. What is somatostatin
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Zygotes are diploid
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

14. 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.
Gonadotropin releasing hormone - GnRH
ER
Follicular phase: primary - secondary - ovulation (1 week) luteal phase: ovulation - thickening of uterine lining w/corpus luteum secretion - corpus luteum degrades (2 weeks) flow: shedding of uterine lining (4 days)

15. in mammals - gastrulation involves formation of the
The wall of the body or of a body cavity or hollow structure
Primitive streak - which consists of cells of the MESODERM ****
'tones the bone'; decreases free Calcium conc; acts opposite to parathyroid hormone; thyroid polypeptide
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5

16. 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
Outermost layer of blood vessel
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
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH

17. Stomach has no lacteals
Most absorption occurs in sm intestine
To the organelle w/ lumen: smooth ER; they are resynthesized into TAGs
Synthesizes lipids (including steroids); detoxifies drugs; is continuous with lumen
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)

18. Bile salts and lipase
90-140 mg/dl
Inner lining of blood vessels
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
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

19. Sensory neuron cell bodies vs. somatic motor cell bodies
Glucose = aldose fructose = ketose
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)

20. FLAT PG: hGH aka somatotropin
(haploid organism) many fungi and protozoa; individuals are typically haploid; fertilization may occur with immediate meiosis back to haploid state
Within the paravertebral ganglion - running parallel to spinal cord
Sensory (afferent - dorsal) - motor (efferent - ventral)
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)

21. How does the body mobilize fat stores
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Peptides
***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
Facilitated diffusion from hi to lo conc

22. 'Cell bodies of somatic motor neurons are located in....'
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
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)
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

23. What is the path of a sound wave that enters the ear?
Digestion
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
Nitrogen
Membrane - bound - endocytosed bodies

24. at lo blood sugar...
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
Secondary follicle: Theca cells differentiate from interstitial tissue - surround follicle - secrete testosterone when stimd by LH (compare to Leydig cells)
Liver breaks down glycogen (glycogenolysis); at hi blood sugar it builds up glycogen (glycogenesis)
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids

25. Where else does ADH act
Processes: axons - dendrites
At the collecting duct: becomes more permeable to water which passively diffuses *into the medulla* concentrating the urine
Increases blood Calcium
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback

26. duodenum must have receptors for fat content - protein because
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
About 7.2
Mostly reabsorbed to liver
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

27. exocrine types
Membrane - bound - endocytosed bodies
Paracrine (local) - endocrine (longer distance)
Sudiferous (sweat) - sebaceous - digestive (bile - pancreatic enzs) - mucosal
Contain capillary network - lymph vessels (lacteals)

28. remaining secondary follicle becomes
Inner lining of circulatory system
Albumin increases osmolarity of blood; increases osmotic pressure
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

29. What does peptic refer to in general
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
Glucose = aldose fructose = ketose
Digestion
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles

30. protein absorption at enterocyte
Fat synthesis; carbs stored as free fatty acids - esterified to TAGs (requires small amount of E)
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
All carbs absorbed at enterocytes are carried to liver by portal vein
Normally contracted

31. 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
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
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
Creates one ovum (23 N) and three polar bodies

32. What does peroxisome do
Ganglion
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Result is proton secreted into lumen - bicarbonate into interstitial fluid (diffuses into blood); result is also increased blood pH and decreased pH stomach
5

33. Think of spinal cord injury
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Reconstituted into TAGs at smooth ER; first stop for most digested fat is liver
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
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms

34. Adrenal medulla hormones (TYR- DERIVED)
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Polysaccharides w/proteoglycans attached = glycosaminoglycans; often give pliability

35. What is endothelium?
- 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
Abdominal cavity - which is coated in serous fluid
Inner lining of blood vessels
Lysosome

36. How long are peptides when absorbed at brush border
The renal corpuscle
Di - tri - peptides; inside enterocytes are hydrolyzed to amino acids
Increases solute conc and osmotic pressure of the ***medulla
Water flows from the tubule - concentrating the filtrate - raising BP

37. signal transduction occurs by 2 paths
1) by integral ion channels 2) transmitted by second messenger system
In gastric pits; secretions combine into gastric juice
Corpus luteum degrades into corpus albicans
Epithelial tissue near semniferous tubules

38. What testosterone released by secondary follicle by LH stim is converted to...
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
Thru tight junctions by favorable osmotic gradient
Estradiol (estrogen - steroid horm); prepares uterine wall for pregnancy; just before ovulation - release of estradiol stims LH in pos feedback
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)

39. Thus inhibiting parietal cells could do What to blood pH
About 7.2
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
Lower blood pH
RBCs - large proteins; What does enter is called the filtrate

40. Creating gradients requires what?
Peptide; prolactin promotes milk production; prolactin release is stimulated by act of suckling - which in turn inhibits menstrual cycle
Trypsinogen is activated by enterokinase in the brush border; in turn - it activates other enzymes
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
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

41. How do nutrients move?
Testes>Semeniferous tubules>Sertoli cells; feedback on AP FSH production
From lumenal (apical) to enterocyte to basolateral side of epithelial tissue
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
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

42. Both divisions (somatic - autonomic) of PNS consist of...
Gastrulation occurs: formation of three primary germ layers = differentiation
Paracrine (local) - endocrine (longer distance)
Somatic nervous sys - autonomic nervous sys
Sensory (afferent - dorsal) - motor (efferent - ventral)

43. A contracted iris occurs with what kind of stimulation
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
Sympathetic: dilates pupil (for night hunting)
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
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

44. fat digestion is time - intensive
Maintains hi estrogen levels; body does not recognize luteal surge - ovulation does not occur; hi progesterone can lessen shedding by thickening the uterine lining
All carbs absorbed at enterocytes are carried to liver by portal vein
Needs time for bile - lipase - micelle migration - enterocyte uptake
'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.'

45. main point of fat transport...
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
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
Inner lining of blood vessels
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol

46. What is the pH at the entrance to the duodenum
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Trypsin(- ogen; activates other panc enzymes after it is activated by enterokinase of sm intest); chymotrypsin - amylase - lipase
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Homologous chromosomes separate - migrate towards opposite poles/centrioles

47. Beta - oxidation in liver produces...
Paracrine (local) - endocrine (longer distance)
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
Visceral layer= parietal layer; serous membrane is the container of the coelom/peritoneal cavity

48. Sensory - motor neurons are part of which nervous system
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
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase
Peripheral nervous sys

49. Some PNS nerves are found in brain - spinal cord
(diploid and haploid individuals = ALTERNATION of GENERATIONS) a fusion of gametic and zygotic life cycles
Oxytocin and ADH (aka vasopressin)
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
'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

50. Contrast PNS- Somatic with PNS- Autonomic
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)
Pancreatic duct (made of acinar cells?)
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity