HOMEOSTASIS

• The body maintains a constant internal environment • All internal organs interact to maintain homeostasis

• We will focus on liver, and kidneys

LIVER STRUCTURE

• Two lobes• Right is larger

• Divided into lobules• Contain hepatic cells

• Hepatic vein: transport O2 poor blood out

• Hepatic artery: transports O2 rich blood in

• Hepatic portal vein: transport blood with nutrients from intestines to liver

• Bile duct: transports bile to gallbladder

LIVER AND HOMEOSTASIS

• Regulates blood composition• Stores glucose as glycogen• Creates the nitrogenous waste urea

• With high blood glucose levels, pancreas secretes insulin• Liver takes up glucose and stores as glycogen

• With low blood glucose levels, hormone glucagon breaks down glycogen releasing glucose

EXPERIMENT

• We will test three different blood vessels involved in digestion/storage for glucose: • – Hepatic vein• – Hepatic portal vein,• Mesenteric artery (leads to the intestine).

• We will test each before and after eating• Form a hypothesis: Which blood vessel would we expect

to have high glucose levels before eating? After?

BENEDICT’S TEST

• Needs to be heated for 5 minutes• Wear goggles.

• Benedict’s turns from blue to a red color in the presence of glucose• Blue → green → yellow → orange → red

KIDNEYS

• Filtering organ of our body• Produce urine (nitrogenous waste)• Get rid of excess water and salts (osmoregulation)• Maintain pH

NEPHRON: FUNCTIONING UNIT

• Filters water and salts and sugars from the blood

• Does not remove blood cells or proteins

KIDNEY FUNCTION: 4 PROCESSES

• Filtration: Bowman’s capsule: molecules move out of glomergulus into capsule

• Reabsorption: in proximal tubule • Glucose and amino acids get reabsorbed

• Secretion: Certain substances, like histamines, H + and ammonia get secreted into nephron tube from peritubular capillaries

• Water reabsorption: Loop of Henle and collecting duct

KIDNEY FUNCTION: OSMOREGULATION

• Salt and water balance• Hormone: ADH from

pituitary gland • Changes permeability of the

collecting duct • Can absorb more of less

water as a result

KIDNEY FUNCTION: PH

• Can remove excess acids (H+) or bases (bicarbonate) through urine production

H+ + HCO3– ↔ H2CO3 ↔ CO2 + H2O