BIO 311D 2nd Edition Lecture 25 Outline of Last Lecture I Diabetes Mellitus II Hypothalamus and pituitary control III Feedback control of thyroid function IV The adrenal glands two part response to stress Outline of Current Lecture I Wrap up hormone examples 3 23 and 3 25 II Principles of transport and exchange in animals III How excretory tubules help with homeostasis Current Lecture I Wrap up hormone examples A Adrenal medulla hormone epinephrine 1 In response to neural stimuli neurosecretory cells in adrenal medulla secrete epinephrine into the blood 2 G proteins can either activate or inhibit pathways In smooth muscle cells around blood vessels a One receptor G protein activates cAMP muscles tighten vessel constricts b Other epinephrine receptor G protein inhibits cAMP production muscle relaxes vessel expands B Two separate feedback systems to control blood glucose around a set level 1 Are the hypothalamus and pituitary directly involved a Adrenal cortex is involved with the hypothalamus b Adrenal medulla is independent from the hypothalamus pituitary pathway The hypothalamus CAN affect the medulla though C How long term stress affects your body 1 Digestive system stomach ache diarrhea weight gain 2 Nervous system sleep disturbance depression 3 Immune system decreased inflammation decreased helper T cell response 4 Other systems increased asthma etc D Module and Discussion Section 1 The functions of the digestive system are ingestion digestion absorption and elimination 2 How is the structure of our digestive system adapted for these functions Specialized regions within the digestive tract making it more efficient 3 How could hormones help control functions 4 Nutrient absorption small intestine blood liver II Principles of transport and exchange in animals A Homeostasis of conditions for cells 1 Oxygen CO2 regulation 2 Glucose regulation 3 pH regulation 4 Temperature regulation 5 Osmoregulation water solute balance 6 Eliminating nitrogenous wastes B In a homeostatic system the blood pH set point is about pH 7 4 If a monitor detected a change towards higher blood pH which of these would be part of an appropriate negative feedback response Application problem Kidney epithelial cells secrete H ions into blood C Nitrogenous wastes cellular waste products from the breakdown of proteins and nitrogenous bases NOT digestive wastes 1 Ammonia most aquatic animals including bony fishes most soluble toxic 2 Urea mammals most amphibians sharks some bony fishes toxic if it gets to high concentration 3 Uric Acid many reptiles including birds insects land snails least soluble not toxic D Osmoregulation 1 Here s the problem a Freshwater solutes 10 mOsm L b Human blood 300 mOsm L c Seawater 1000 mOsm L 2 Transport epithelium is structured to control what gets across or doesn t a Tight junctions controls what can leak through and what cannot leak through b Microvilli increase surface area for absorption 3 By what mechanisms do saltwater and freshwater fish maintain their internal osmolarity Fig 44 4 a Salt water fish excretion of salt ions and small amounts of water in scanty urine from kidneys getting rid of salt and conserve water a bit b Fresh water fish excretion of large amounts of water in dilute urine from kidneys 4 Case study Salmon hatch in freshwater move out to streams then move out to open oceans for the majority of their adult life At sexual maturity they III swim upstream to their native streams and ponds where they spawn and die What osmoregulation changes must occur a In fresh water environment 0 3 solutes how would gill epithelial cells use ATP to maintain osmotic homeostasis Positively charged ions pumped in Cl ions follow through b In seawater environment 3 5 solutes how would gill epithelial cells use ATP to maintain osmotic homeostasis Pump sodium up charge gradient passive transport of Clc Transition period change the membrane proteins Excretory Tubules A General Filtration kidney tubules and other osmoregulation tubules work by filtration of most water and solutes from the blood into the tubule B Selection Reabsorption the tubules change the composition of the filtrate by selective secretion and reabsorption of specific solute molecules C Excretion what s left in the excretory tubules leaves through urine D Excretory tubule demonstrates 1 Structural adaptations 2 Physiological responses short term
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