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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. Examples of GPCRs in sensory systems/signal transduction: What is the ligand or messenger in each case? ...SIGHT - SMELL - MOOD - FIGHT/FLIGHT etc
Estrogen: steroid; stims LH in luteal surge; causes growth of female sex organs progesterone: prepares/maintains uterus for pregnancy
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
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Most absorption occurs in sm intestine

2. How does duod deal with hi HCl from stom
Normally contracted
Estradiol
Corpus luteum degrades into corpus albicans
Ups bicarbonate secretion by pancreas; raises pH to 6.0

3. Important aspect of crypt of Lieberkuhn - secreted intestinal juice
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
It targets liver conc of prothrombin - fibrinogen etc
Contains lysozyme - which regulates bacteria within intestine; breaks down peptidoglycans (**bact wall); innate immunity
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves

4. What is the function of the loop of Henle
Increases solute conc and osmotic pressure of the ***medulla
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
Pancreas; active at sm intestinal pH; hydrolyzes peptide bonds of (pepsin - digested) peptides
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

5. What do the glomerulus and Bowman's capsule add up to...
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
The renal corpuscle
Processes: axons - dendrites
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle

6. In IBS - What is defective

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7. The path from blood plasma to urine

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8. What does peroxisome do
Two perpendicular semicircular canals involved in balance - equilibrium
Small amounts of hydrolyzed phospholipids and cholesterol: like other fat mols these can diffuse thru enterocyte membrane
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Mostly reabsorbed to liver

9. physiology of gall bladder - liver and pancreatic secretions
Paracrine (local) - endocrine (longer distance)
Testosterone upon stim by LH
Secreted by implanted egg; HCG prevents degeneration of the corpus luteum; HCG in blood/urine is first sign of pregnancy
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

10. signal transduction occurs by 2 paths
Testosterone upon stim by LH
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
1) by integral ion channels 2) transmitted by second messenger system
Mostly reabsorbed to liver

11. Think of spinal cord injury
Adrenocorticotropin; stims adrenal cortex release of glucocorticoids (eg cortisol - a steroid) stress hormones via second messenger system using cAMP
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion
Gonadotropin releasing hormone - GnRH

12. main point of fat transport...
Conjunction of cell body w/axon
ER
Fat is insoluble in blood and requires a carrier like lipoproteins (vLDL...HDL) or albumins; ...vLDL has hi triglycerides - hi cholesterol
Where lipoprotein lipase hydrolyzes TAGs; products diffuse into target tiss (mostly liver - adipose tissue)

13. Thus - central nervous sys is...
Interneurons working to integrate signals received from the peripheral nervous system (sense organs)
Lower blood pH
CARB- Digesting: dextrinase (polysachs produced by hydrolysis of starch) - maltase (glucose - glucose) - sucrase (glucose - fructose) - lactase (galactose - glucose) - Protein- Digesting: peptidases - NUCLEOTIDE- Digesting: nucleosidases
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

14. large intestine E. coli aid absorption of...
Going up - water - impermeable: salt is actively pumped out - filtrate osmolarity goes down as salt leaves
PH 6.0; this accomplished by pancreatic secretion of bicarbonate which ups pH
Vitamin K - b12 - thiamin - riboflavin
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss

15. From that point...
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
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.
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
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

16. almost all cells can store Some glycogen - but...
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
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Beta cells
Only musc and esp ** liver can store large amounts

17. How does glycogen compare to starch
It is the animal counterpart of starch; it is more highly- branched - thus releases more glucose monomers upon repeated hydrolysis than starch
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
Increases blood Calcium
Oxytocin and ADH (aka vasopressin)

18. How does the body mobilize fat stores
Posterior pituitary hormone; acts on uterus - mammary glands; causes uterine contractions - milk ejection
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
***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
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate

19. At post - two weeks ovulation
Corpus luteum degrades into corpus albicans
'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
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
1) by integral ion channels 2) transmitted by second messenger system

20. lysosome main function and derivation
Contains hydrolytic enzymes; thus - digests endocytosed substances; derived from golgi
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
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Mediate complex cell processes thru eg phosphorylation via secondary messenger (G protein) systems = signal transduction pathway - GPCR (G protein coupled receptor)

21. The apical side of the villi...
Only musc and esp ** liver can store large amounts
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons
Faces the lumen
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

22. cholinergic receptors: NICTONIC and MUSCARINIC Nicotinic: neuromuscular effectors (ionotropic) Muscarinic: PARA effectors (GPCRs) Adrenergic: SYMP effectors (GPCRs)
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord
Spinal cord ventral horns; somatic motor neurons use acetylcholine for NTs (voluntary)
Liver is the control center for blood glucose; is fed by portal vein from sm intest
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors

23. lysosome pH
5
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Gastric inhibitory pep; increase of pancreatic - enz activating enzymes (which cleaves zymogens like trypsinogen); increased gall bladder contraction; decreases stomach mobility
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

24. What force is acting upon chyme to move it forward down sm intestine
Sorts - modifies - concentrates proteins from the ER
Peristalsis (esophagus) and segmentation (bi - directional=mixing)
Four 23 N daughter cells are formed from one 46 2N mother (germ - line) cell; four haploid gametes
Nervous - muscle - epithelial (defines inner/outer) - connective (extensive matrices)

25. Which fats are not absorbed like this
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
Glucose and ketone bodies (not from glycogen stores)
Smaller - more water soluble short - chain FAs go directly to bloodstream at villi capillaries
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

26. Sensory neuron cell bodies vs. somatic motor cell bodies
Systems (eg digestive system consists of many organs)
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
sucrose (gluc+fruc) - lactose (gluc+galactose) - starch (gluc+gluc)
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord

27. Anterior eye vs. posterior eye
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest
After morula - with blastocyst (+8 cell count)--->totipotent to embryonic stem cell and so on
Determined by whether in front of or behind the lens
Membrane - bound - endocytosed bodies

28. in the presence of ADH what happens to movement of water across nephron membr
Lower blood pH
Below hypothalamus
Water flows from the tubule - concentrating the filtrate - raising BP
Interstitial fluid (eg prostaglandins - cytokines)

29. Blastocyst
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
'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
Ganglion
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

30. What kind of cells make up epithel tiss of stom - then sm intest?
Receive signals from receptor cell w/ ability to interact with its environment; 99% sensory input is discarded
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
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Spike in estrogen - LH levels; secondary follicle bursts - releases into body cavity - swept along by fimbriae

31. alpha - amylase in the mouth digests what kind of bond
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Secreted by delta cells of Islets of langerhans; inhibits insulin and glucagon; slows digestion
Ketone bodies; thus excessive reliance on fat for energy (eg low carb diets) results in ketosis; blood acidity increases
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid

32. Determination is different than differentiation
Hydrostatic pressure forces some plasma thru *fenestrations of the glomerular endothelium* and into Bowman's capsule; B.C. is continuous with lumen of nephron
Determination is a pre - programmed fate - differentiation is the actual materialization of that fate
Follicular (proliferative)= 8d - Luteal (post - ovulation; corpus luteum secretions)= 13d - Menstruation (shed uterine lining if no implantation)= 5
Sorts - modifies - concentrates proteins from the ER

33. only monosaccharides are absorbed
An ether phospholipid; hi conc in myelin; thus - hi conc in heart tiss - nervous tiss
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Prod of steroid hormones in testes - ovaries
Neurons may perform one of three functions....

34. Some PNS nerves are found in brain - spinal cord
Moves thru lymph sys; emptied into large veins (thus into bloodstream) of the neck at Thoracic duct
Eg spinal nerve - cranial nerve; Not All Nervous Tissue In Brain - SC Is CNS Tissue
Prod of steroid hormones in testes - ovaries
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

35. Path of food entering body...
Mouth - esophagus - stomach - duodenum - jejunum - ileum - ascending colon - transverse colon - descending colon - sigmoid colon - rectum - anus
Oxidizes macromolecules; breaks down very long - chain FAs by beta - oxidation; products (acetyl - CoA) are shuttled to mitochondrion for citric acid cycle
Regulated by gastrointestinal horms
Injury that does not sever SC (causes deep lesion from back - front) might cause loss of feeling without full loss of motion

36. Meiosis II: EQUATIONAL DIVISION
= catecholamines; fight/flight; vasoconstrictors of internal organs - skin; vasodilators of skel musc; also considered stress hormones; epinephrine - norepinephrine
Increase surface area of sm intestine; this improves digestion (enzymes adsorbed to villi) and absorption
Arrested at primary oocyte; hypothalamus GnRH->FSH released at puberty stims granulosa cell development; granulosa secrete zona pellucida = primary follicle
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

37. parathyroid hormones
Pancreatic duct (made of acinar cells?)
Many modern drugs are ligands for GPCRs
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)
Parathyroid hormone (peptide; increases blood Ca); thus - might increase osteoclast/decrease osteoblast activity

38. So - following blastocyst implantation (4d) - at approx 2 weeks past fertilization
Know that 90% digestion - absorption occurs in sm intestine --> fine breakdown of carbs - fat - prots
Outermost layer of blood vessel
Gastrulation occurs: formation of three primary germ layers = differentiation
**NO*** lipase digests fat; no bonds broken by bile; only opens up more SA for lipase

39. parathyroid hormone
FAT=9 cal per gram Carbs=4.5 cal per gram - Prot=4 cal per gram - these seem to be for anhydrous forms
Increases blood Calcium
Serous membrane (slick - reducing friction) that forms lining of the coelom --> secretes lubricating fluid
Secrete intrinsic factor; important for absorbing vitamin B12 in sm intest

40. albumin has What affect on blood osmotic pressure
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
Digestion
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)
Albumin increases osmolarity of blood; increases osmotic pressure

41. FLAT PG: FSH
Nourishes follicle growth; stimulates granulosa cell growth around primary oocyte at puberty = primary follicle; also - stimulates Sertoli cells in males
Increases blood Calcium
**only para effectors have muscarinic receptors; symp effectors are adrenergic (epi - norepi); **neuromuscular junction uses nicotinic receptors
Changes: volume of filtrate does not change: osmolarity of filtrate --->reabsorbed ions like sodium carry water across membrane

42. STOMACH: no absorption
Salivary amylase (weak); sm intest amylase (breaks down large polysaccharides)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins
Drugs - toxins - bile pigments (color the urine) - uric acid - antibiotics
Protein digestion begins in stomach; low pH denatures proteins - kills bacteria; mixes - stores food and destroys it to chyme (BOLUS-->CHYME)

43. Leydig cells produce
Testosterone upon stim by LH
Which is why lactase - maltase - dextrinase - sucrase are on brush border
Contain capillary network - lymph vessels (lacteals)
At metaphase II of meiosis II (halted during reductional division); if fertilized - process continues toward haploid gamete

44. What is endothelium?
Focuses light thru the vitreous humor onto retina; acts as a converging lens (image is real - inverted)
In mouth - breakdown of starch into polysaccharides
Inner lining of blood vessels
Organs

45. components of interstitial fluid
Eukaryotes
Glycosaminoglycans - prots - AAs - lipids
Moves down thru esophageal sphincter
Somatic sensory = dorsal root ganglia (outside spinal cord); somatic effector = ventral horns of spinal cord

46. remaining secondary follicle becomes
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
Inactive: rhodopsin is activated by photons; activated rhodopsin hyperpolarizes rod cells - causes photobleaching
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Corpus luteum; secretes estradiol - progesterone throughout pregnancy OR if no pregnancy - for about 2 weeks (till menstruation = shedding of uterine lining)

47. What is the endothelium?
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
pericardial cavity - pleural cavity (contains lungs) - peritoneal cavity (abdominal)
Alpha 1-4 and 1-6 (branching) glycosidic linkages
Inner lining of circulatory system

48. A group of cell bodies in CNS is nucleus - outside CNS is...
Ganglion
Ventrally (picture skeletal vertebrae)
Sensory (afferent - dorsal) - motor (efferent - ventral)
PNS- Somatic - afferent (dorsal root ganglion) + efferent (ventral horns) PNS- ANS- afferent (sensors on viscera) + SYMP - PARA pre - post - ganglionic neurons

49. gametes are haploid
Zygotes are diploid
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
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
Water flows from the tubule - concentrating the filtrate - raising BP

50. from the loop of henle...
Ectoderm: outer coverings - nervous system Mesoderm: between covering ie musc - bone - etc - endoderm: digestive tract - viscera
Glucose
Systems (eg digestive system consists of many organs)
On to the distal tubule where sodium - calcium are reabsorbed - protons - bicarbonate - potassium are secreted via membrane transport proteins