MCAT Bio

Question 1

Digestive Pathway

Answer 1

Oral Cavity
Pharynx
Esophagus
Stomach
Small Intestine (duodenum to jejunum to ileum)
Large Intestine Rectum

Question 2

Stomach

Answer 2

An acidic (pH = 2) environment. Four parts: fundus, body, antrum
and pylorus. The enzyme pepsin chemically breaks down proteins.

Question 3

Secretory cells that line the stomach

Answer 3

Mucous Cells: Produce bicarbonate-rich mucus to protect
stomach wall from acid.

Chief Cells: Secrete pepsinogen, a protease activated by the
acidic environment.

Parietal Cells: Secrete HCl and intrinsic factor, which is needed for
vitamin B12 absorption.

G-Cells: Secrete gastrin, a peptide hormone that increase ­HCl
secretion & gastric motility.

Question 4

antibodies

Answer 4

Y shaped proteins that bind antigens (foreign substances) allowing for better recognition + destruction of anitgens by immune cells

epitopes are variable regions that bind specific antigen regions. Can bind only ONE type of antigen

Question 5

Excretory (urine) Pathway

Answer 5

Bowman’s space
proximal convoluted tubule descending limb of the loop of Henle
ascending limb of the loop of Henle distal convoluted tubule
collecting duct
renal
pelvis
ureter
bladder
urethra

Question 6

pancreas endocrine hormones

Answer 6

beta cells produce insulin (decreases glucose), which inhibits neighboring alpha cell function (paracrine)

alpha cells produce glucagon (increase glucose and hunger), also paracrine and can inhibit beta cell functioning in certain settings

delta cells produce somatostatin, a hormone that has an inhibitory effect on digestive function and can suppress insulin + glucagon release

Question 7

peptide hormones

Answer 7

water-soluble (hydrophilic)

• can dissolve in blood stream but cannot cross the hydrophobic plasma membrane without a receptor

Question 8

steroid hormones

Answer 8

fat-soluble hydrophobic lipid hormones so must be bound to carrier protein in bloodstream. But can diffuse across plasma membrane

Question 9

glucagon effects

Answer 9

exchange of GTP for GDP
adenylate cyclase activity
conversion of ATP to cAMP
protein Kinase A activity

Question 10

leptin v ghrelin

Answer 10

leptin secreted by adipocytes to trigger appetite suppression via hypothalamus

ghrelin released by stomach gastric cells to trigger hunger