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MCAT - Bio/Biochem > Misc. > Flashcards

Flashcards in Misc. Deck (52):
1

Are steroid hormones stored in the cell?

No, they are synthesized as needed

2

What is the difference between endocrine and exocrine.

Exocrine = ducts. Final location is external to the body or within a body cavity (e.g. lumen of gut).

Endocrine = ductless. Location is the bloodstream.

3

How would you describe the speed of peptide hormones?

Act very fast, but effects don't last very long.

4

How do peptide hormones work?

They bind to cell surface receptors and activate 2nd messenger systems

5

How do steroid hormones work?

Bind intracellularly to bind DNA and modify transcription

6

How would you describe the speed of steroid hormones?

Act more slowly than peptide hormones, but the effects are longer-lasting.

7

What are the hormones of the anterior pituitary?

FLAT PiG

FSH, LH, ACTH, TSH, Prolactin, Growth hormone

8

What are the hormones of the posterior pituitary?

Oxytocin and ADH

9

What type of tissue is the anterior pituitary?

Adenohypophysis

Made from gland tissue, controlled hormonally by the hypothalamus.

MAKES and secretes 6 hormones

10

What type of tissue is the posterior pituitary?

Neurohypophysis

Made from nervous tissue.

STORES and secretes 2 hormones

11

What are lymph nodes?

Collections of WBCs that drain lymph checking it for signs of infection.

12

What are the heart sounds?

First sound = beginning of systole = closure of AV valves

Second sound = end of systole = closure of semilunar valves

13

What are the differences between cardiac muscle AP and typical neuronal AP?

After the cell depolarizes and sodium channels start to close, in cardiac muscles voltage-gated Ca channels open, causing Ca to move into the cell. This leads to a "plateau phase" before repolarization.

14

What is tetany?

The ability to keep our skeletal muscles contracted for a period of time (e.g. arm muscle while carrying something). It is achieved by the short refractory periods in skeletal muscle compared to cardiac. This allows frequent APs in skeletal muscle.

15

How does the SA node act as the pacemaker?

SA is most likely to reach threshold and fire an AP which then gets sent throughout the heart directly via gap junctions.

16

Describe the pathway of the cardiac conduction system.

SA node -> AV node -> bundle branch -> purkinje fibers -> ventricles

17

What is the function of the AV node delay?

Gives the atria time to finish contracting before the ventricles contract.

18

Are O2 and CO2 hydrophobic or hydrophilic? What does this mean for their blood transport

Hydrophobic.

Must travel in bloodstream attached to protein (O2 to hgb) or as an ion (Bicarb for CO2)

19

How do B cells generate such high diversity to be specific to so many things?

They rearrange their DNA!

20

MHC I is found on _________

All cells.

21

MHC II is found on _________ and ________.

B Cells and Macrophages

22

What is the difference between the primary and secondary immune responses?

Primary = first exposure to antigen--response takes 7 to 10 days

Secondary = second exposure to antigen,

23

Where are self-recognizing B cells matured and weeded out?

Bone marrow

24

Where are self-recognizing T cells matured and weeded out?

Thymus

25

What four things does PTH do?

1. Promote bone resorption
2. Favor osteoclast rather than osteoblast activity
3. Increase Ca absorption in the kidney
4. Increase phosphate excretion in kidneys

26

How does aldosterone work?

Acts on the distal tubule and CD to increase sodium reabsorption (and thus water retention).

27

What is thyroid hormone derived from and where does it bind in/on the cell? Is this curious?

Yes! Derived from an AA (tyrosine) yet binds intracellularly (like a steroid)

28

What kind of substances does the liver excrete?

Hydrophobic things
Either by conjugating them to hydrophilic things (like glucuronic acid) or wrapping them in bile salts and sending to the colon.

The waste is absorbed in the bloodstream to reach the liver, but is never dissolved in the plasma.

29

What kind of substances does the kidney excrete?

Wastes that are absorbed in the bloodstream AND dissolved in the plasma.

30

What are the main functions of the kidney?

1. ion balance
2. water balance
3. blood pressure
4. secretion of EPO
5. Activation of Vitamin D

31

What is an approximate GFR for a healthy person?

125 mL/min

32

ADH works on _______ channels in the ___________.

Water channels
Collecting duct

33

Describe the R-A-A pathway

Renin (from JG cells) coverts angiotensinogen (made by liver) to angiotensin I. Then ACE in the lungs converts angiotensin I to angiotensin II. Angiotensin II (1) causes systemic vasoconstriction (2) stimulates aldosterone release and directly acts on kidneys to increase water reabsorption via increased sodium reabsorption.

All this leads to increased blood pressure!!

34

What kind of monitoring goes on in the distal convoluted tubule?

Chemoreceptors that monitor plasma osmolarity. If found to be too concentrated, it will directly dilate the afferent arteriole and in activate the renin system.

35

What is ANP?

Atrial Naturetic Peptide

Found as a stretch receptor in the atria and recognizes increases in BP. To lower BP it INHIBITS aldosterone release, preventing reabsorption of sodium (and thus water).

36

What does bile do?

Emulsify fat for easier digestion.

37

What are the endocrine and exocrine functions of the pancreas?

Endocrine: insulin and glucagon (plus somatostatin but thats not as impt)

Exocrine: main source of digestive enzymes (proteases, lipases, nucleases, amylases) + bicarb to counteract stomach acid and return gut pH to normal.

38

Where does starch digestion begin and with what enzyme?

The mouth - amylase

39

What two enzymes are in the saliva and what do they digest?

Amylase - starch
Lysozyme - kills bacteria

40

What is and what is the role of the cardiac sphincter?

Sphincter between the esophagus and stomach that prevents stomach acid from coming up into the esophagus.

41

What is and what is the role of the pyloric sphincter?

Sphincter between the stomach and the small intestine. REGULATES entry.

42

Where are parietal cells located and what do they secrete?

Located in the stomach
Secreate HCl

43

Where are chief cells located and what do they secrete?

Located in the stomach. Secrete pepsinogen and proteases.

44

Where are G cells located, what do they secrete and what does the product do?

Located in stomach
Secrete gastrin
Activate gastric glands (chief cells and parietal cells)

low pH will negatively feedback inhibit gastrin

45

What does enterokinase do?

Activate trypsin in the small intestine.

Trypsin then activates all (most) of the other zymogens

46

What does enterogastrone do?

Reduce stomach motility and emptying

47

What does CCK do?

Increase bile from liver/gall bladder
Triggered by fats and proteins

48

What does secretin do?

Increase bicarb release from pancreas
Triggered by low intestinal pH

49

In Lineweaver-Burke plots, how do you find Km and Vmax on the graph?

Slope = Km/Vmax
1/Vmax = y intercept
-1/Km = x intercept

50

How many electrons does cytochrome C carry in oxidative phosphorylation?

1

51

What makes a good primer transcription?

GC-rich especially Gs/Cs on the 5' and 3' ends

52

Curiously, the mouth is derived from which germ layer?

Ectoderm