Module 3, Lecture 2: Homeostasis: Regulation of Osmolarity, Glucose & Oxygen Flashcards
Osmoregulation
Controls water and salt levels to keep fluid balance stable
Glucose Regulation
Keeps blood sugar in a narrow range using hormones and nerves
Oxygen Regulation
Maintains steady oxygen levels for cells to survive and function
Loop of Henle – Function
- Reabsorbs water and NaCl
- Creates concentrated urine and conserves water.
Countercurrent Flow
Opposite flow in limbs helps concentrate urine and conserve water
Descending Limb
- Water leaves (via aquaporins), salt stays
- Water exists by osmosis
- filtrate becomes more concentrated
Ascending Limb – Thin Segment
- Impermeable to water; NaCl diffuses out
Ascending Limb – Thick Segment
- NaCl actively transported out into interstitial fluid
- Impermeable to water
Osmolarity at Loop Tip
- Highest solute concentration
- Mainly NaCl & urea, due to water loss
Hyposmotic
Water lose
Hyperosmotic
Salt lose
ADH (arginine vasopressin)
Hormone that helps body keep water by letting it be reabsorbed, so you pee out less
Kangaroo Rat
Desert rodent that adapted to dry environments by conserving water through highly efficient kidneys and concentrated urine
How does the kangaroo rat save water during kidney filtration and reabsorption?
- Lots of ADH hormones
- Longer loop of Henle
What happens when glucose is too low?
Secrete glucagon
What happens when glucose is too high?
Secrete insulin
What does the pancreas make?
Makes both insulin and glucagon
Pancreatic Islets
Clusters of endocrine cells in the pancreas
Alpha Cells
Found in islets; produce glucagon
Beta Cells
Found in islets; produce insulin
How do animals keep blood glucose steady when not eating?
Animals use glycogenolysis, gluconeogenesis, and ketosis to make or use energy. Hormones like glucagon, cortisol, and epinephrine keep glucose levels steady.
Glycogenolysis
breaks down stored glycogen
Gluconeogenesis
makes glucose from fats/proteins
Ketosis
Uses fat for energy
How can arctic ground squirrel maintain blood glucose during 7+ month hibernation?
- Bulk up before hibernating
- Become hypothermic and reduce metabolic rate
- Reduce insulin secretion and lower metabolic rate
Bird lungs
Two cycles of inhalation and exhalation are required to pass one breath through the system
Bird lungs - step 1
First inhalation draws oxygen rich air into posterior sacs
Bird lungs - step 2
First exhalation moves fresh air into lungs
Bird lungs - step 3
Secon inhalation moves stale oxygen from lung into anterior air sacs
Bird lungs - step 4
Second exhalation moves air out of anterior air sacs
