Bio 9-10 Flashcards Preview

MCAT > Bio 9-10 > Flashcards

Flashcards in Bio 9-10 Deck (56):
1

Intracellular digestion vs extracellular

Intracellular: (apart of metabolism) involves oxidation of glucose and fatty acids for energy

Extracellular: where nutrients are obtained from food and occurs within the lumen of the alimentary canal

2

What is absorption in relation to the digestive system

The transport of products of digestion from the digestive tract into the circulatory system for distribution to tissues

3

Enteric nervous system

One hundred million neurons that govern the function of the GI system

Can function independently of the brain and spinal cord

4

What are all glands of the body innervated by?

Parasympathetic nervous system

(Except for sweat glands)

5

Peristalsis

Rhythmic contractions of the gut tube

6

What affect does the parasympathetic and sympathetic NS have on the digestive system

PNS increases secretions from all of the glands of the digestive system

SNS slows peristalsis

7

ADH and aldosterone with digestive system

Both trigger sensation of thirst

8

Glucagon and ghrelin with digestive system

Glucagon: secreted by pancreas

Ghrelin: secreted by stomach and pancreas

Both stimulate feelings of hunger

9

Leptin and CCK with digestive system

Both stimulate feelings of being full (satiety)

10

Emesis

Vomiting (reversal of peristalsis)

11

Where is swallowing initiated

In the muscles of the oropharynx

Constitutes the upper esophageal sphincter

12

Rugae

Lining of the stomach that is thrown into folds

13

What do gastric glands respond to signals from

The vagus nerve (Parasympathetic NS)

Activated in response to sight, taste and smell of food

14

Mucous cells

In gastric glands

Produce bicarbonate rich mucus that protects muscular wall from acidic env of the stomach

15

Gastric juice

Combination of secretions from chief cells and parietal cells of the gastric gland

16

Pepsinogen

Inactive zymogen form of pepsin

Secreted by chief cells

17

What does HCl do

Cleaves pepsinogen to pepsin

secreted by parietal cells

18

What does pepsin do

Digests proteins by cleaving peptide bonds near aromatic AA

Most active at low pH

19

What is intrinsic factor

Secreted by parietal cells; a glycoprotein involves in the proper absorption of vitamin B12

20

What are the 6 things that the stomach secretes

HCl, pepsinogen, mucus, bicarbonate, water, intrinsic factor

21

What does gastrin do

Secreted by G cells in pyloric glands

Induces the parietal cells in stomach to secrete more HCl and signals stomach to contract to mix its contents

22

Where does most absorption in the small intestine take place

Jejunum and ileum

Duodenum is responsible for majority of chemical digestion

23

Brush border enzymes

Present of luminal surface of cells lining duodenum and break down dimers/trimers into monomers.

Ex: maltase, isomaltase, lactase, sucrase

24

Enteropeptidase

Secreted by duodenum

Activates trypsinogen to trypsin

Activates procarboxypeptidases A and B to their active forms

25

Maltase, isomaltase, lactase, sucrase

Digests: maltose, isomaltose, lactose and sucrose

26

Secretin

Peptide hormone that causes pancreatic enzymes to be released into duodenum

Regulates pH of digestive tracy by reducing HCl and increasing bicarbonate

Allows slow motility (an enterogastrone)

27

CCK

Cholecystokinin

Secreted in response to entry of chyme into duodenum

Stimulates release of bile and pancreatic juices

28

Bile salts

Derived from cholesterol; serve as a bridge btw aqueous and lipid env (because they have a hydrophobic and hydrophilic region)

Emulsify fats and cholesterol in small intestine into micelles

29

Pancreatic juices

Bicarbonate rich alkaline solution that neutralizes acidic chyme

Provides ideal working env for each of the digestive enzymes

30

Functions of the liver

Processing of nutrients, production of urea, detoxification of chemicals, production of bile, synthesis of albumin and clotting factors

31

What are the main components of bile

Bile salts, pigments (bilirubin), and cholesterol

32

What is the small intestine lined with

Villi (lined with microvilli); increases surface area available for absorption

Villi contain a capillary bed and a lacteal

33

Large intestine does what?

Absorbs water and salts forming semisolid feces

34

What pancreatic enzymes digest carbohydrates?

Pancreatic amylase

35

What pancreatic enzymes digest proteins?

Trypsin, chymotrypsin, carboxypeptidases A and B

36

What pancreatic enzymes digest fats?

Pancreatic lipase

37

What are the 4 fat soluble vitamins

A, D, E and K

38

Which intestine absorbs more water

Small intestine

Therefore any disease causing diarrhea most likely infects the small intestine

39

What is the pathway of urine

Bowman’s space -> PCT -> descending LOH -> ascending LOH -> DCT ->collecting duct -> renal pelvis -> ureter -> bladder -> urethra

40

Cortex vs medulla of the kidney

Cortex: outermost layer

Medulla: sits within the cortex

41

What do the renal artery, renal vein and ureter enter and exit through?

Renal hilium

42

Explain the renal portal system

Renal artery branches out, passes through medulla and enters cortex as afferent arterioles; capillary tufts coming from these are called glomeruli

After blood passes through glomeruli, the efferent arterioles form a second capillary bed (vasa recta)

43

Internal urethral sphincter

Smooth muscle

Involuntary control

44

External urethral sphincter

Skeletal muscle

Voluntary control

45

List the 3 key concepts of osmoregulation of kidneys

1. Filtration: movement of solutes from blood to filtrate at Bowman’s capsule

2. Secretion: movement of solutes from blood to filtrate anywhere besides Bowman’s capsule

3. Reabsorption: movement of solutes from filtrate to blood

46

What is the mnemonic for major waste products excreted in the urine

Dump the HUNK

H+
Urea
NH3
K+

47

Explain the descending loop of henle (LOH)

It’s permeable to water but not salt so as the filtrate moves into the more osmotically concentrated medulla, water is reabsorbed.

The vasa recta and nephron flow in opp directions creating a countercurrent multiplier system that allows maximum reabsorption of water

48

Explain the ascending LOH

It’s permeable to salt but not water, so salt is reabsorbed.

The diluting segment is in the outer medulla and it’s the last part of the ascending LOH; this is when water concentration is greater than solutes in the filtrate (because salt is reabsorbed)

49

Diff btw osmotic and oncotic pressure

Osmotic: “sucking” pressure that draws water into the vasculature caused by dissolved particles

Oncotic: osmotic pressure that’s attributable to dissolved proteins specifically

50

Explain acid-base balance with the kidney

Kidneys selectively increase or decrease secretion of H+ and bicarbonate

When blood pH is low = kidneys reabsorb bicarbonate (and excrete H+)

When blood pH is high = kidneys reabsorb H+ (and excrete bicarbonate)

51

List the vessels in the renal pathway in order

Renal artery -> afferent arteriole -> glomerulus -> efferent arteriole -> vasa recta -> renal vein

52

Bowman’s capsule

Site of filtration; water, AA, ions, vitamins and glucose pass .

53

What are the layers of the skin

(Deepest to outer)

Hypodermis -> dermis -> epidermis

54

What is the mnemonic for the layers (strata) of the epidermis

(Superficial to deep): Come Let’s Get Sun Burned

Stratum Corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum Basale

55

What originates in the dermis

Sweat glands, blood vessels and hair follicles

56

What are Merkel cells, meissner’s corpuscles, ruffini endings, and pacinian corpuscles? Where are they found

Merkel: sensory receptors at the epidermal-dermal junction

Meissner: light touch nerve endings

Ruffini: respond to stretch

Pacinian: respond to deep pressure and vibration

All are found in the dermis