Homeostasis

glycogensis

• glucose—→ glycogen

• activated by insulin

glycogenolysis

• glycogen—→ glucose

• activated by glucagon

gluconeogensis

• glycerol and amino acids—→ glucose

• activated by glucagon

control of blood glucose

if blood sugar too high

insulin

• insulin secreted from B cells in islets of langerhans

• binds to specific receptors on liver/ muscle cells

• increases permeability to glucose

• more glucose moves in by facilitated diffusion- more channel proteins

• activates an enzyme that converts glucose to glycogen (glycogenesis)

• increased glycolysis

controlling blood glucose

low blood sugar

glucagon

• glucagon secreted from a cells of islets of langerhans

• binds to receptors on liver cells

• activates enzymes that hyrolyse glycogen into glucose (glycogenolysis)

• activates enzymes that convert amino acids and glycerol into glucose (gluconeogensis)

• inhibits glycolysis

second messenger model

adrenaline

• secreted from adrenal glands when blood sugar levels are low

• binds to receptors on liver cells

• activates glycogenolysis

• inhibits glycogenesis

• activates glucagon secretion

• inhibits insulin secretion

• activates adenylate cyclase

• converts ATP into cAMP (second messenger)

• activates enzymes that hydrolyse glycogen into glucose

• cascade reaction

type 1 diabetes

• immune system attacks B cells so they can’t produce insulin anymore

• may be genetic or triggered by infection

• kidneys can’t reabsorb glucose so some urinated out

• treay with insulin injections

type 2 diabetes

• risk factors= obesity

• b cells don’t produce enough insulin or body doesn’t respond to it

• insulin receptors don’t work properly

colorimetry to determine glucose conc

• serial dilution

• benedict’s

• colorimeter

• calibration curve

kidneys

1. ultrafiltration

• happens in bowman’s capsule

• under high pressure

• efferent end is narrower- higher hydrostatic pressure

• forces liquic out of capillary into bowmans capsule

• past three layers

• capillary endothelium

• basement membrane

• epithelium of capsule

• larger molecules e.g proteins too big so stay in blood

kidneys

2. selective reabsorption

• PCT- proximal convoluted tubule

• Na+ pumped out of cell into blood by sodium potassium pump

• conc gradient

• Na+ move from filtrate into cell by cotransporter protein

• bringing amino ancids and glucose along too

• amino acids move out into blood by fac diff

• high w.p

• some water follows by osmosis

adaptattions of PCT

• microvilli- large SA

• many mitochondria- ATP

• many channel/ carrier proteins

loop of Henle

• Na+ and Cl- actively trasnported out of ascending limb into medulla

• lowers w.p in medulla

• water moves out of descending limb by osmosis

• descending has aquaporins, ascending doesn’t

• water reabsorbed into blood by capillary network

• lower w.p at bottom of medulla

• water moves of of DCT and collecting duct by osmosis and reabsorbed into blood

controlling water potential

ADH

• low w.p detected by osmoreceptors in hypothalamus

• increased ADH production by posterior pituitary gland

• ADH in capillary

• binds to complementary receptors

• activates phsophorylase

• vesicles move and fuse with membrane so cell now has aquaporins- more permeable to water

• higher w.p in collecting duct

• water moves into capillary by osmosis through cell and intersitial fluid