Lecture 20, 06 Nov 2003Chapter 13, Respiration, Gas Exchange, Acid-Base Balance

Chapter 14, Osmoregulation and Kidney Function

Vertebrate PhysiologyECOL 437

University of ArizonaFall 2003

instr: Kevin Boninet.a.: Bret Pasch

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Vertebrate Physiology 437

1. Blood-Gas Chemistry (CH13)

2. Osmoregulation Kidney Function (CH14)

3. Announcements…-No lecture Tues?-mini-lecture Wed.?-Eldon Braun Thurs.

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Osmoregulation by Birds

Eldon J. BraunDepartment of PhysiologyUniversity of Arizona

Name that student:

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Alana_Kurosakipopulation genetics

Amber_Blytheformerly with cast

Ben_Abtdentist-to-be

Research/Laboratory Aide - Job number 27067 (http://www.hr.arizona.edu/27067xrsxptxoutx.htm)

5 positions available, 40 hours per week, $9.02 per hour

Position Summary: This position assists in collecting small mammal and invertebrate data at Fort Huachuca Military Reservation in southeastern

Arizona. The research project involves investigating fire-based restoration of biodiversity in grassland ecosystems. Study plots are located at approximately 4,400-4,900 feet elevation.

Duties and Responsibilities: Traps small mammals and invertebrates on established study plots at Fort Huachuca.

Collects and records data accurately on captured small mammals, including species identification, body measurements, sex determination, etc.

Processes captured invertebrate specimens and accurately records data. Helps maintain field supplies.

Assists with some computer data entry and/or proofing.

To apply:Please submit an official University of Arizona job specific application (found at: http://www.hr.arizona.edu/01_rec/forms/empapplication.pdf) by mail or fax to:

The University of Arizona - Human Resources 888 N. Euclid Avenue, #114

P.O. Box 210158Tucson, Arizona 85721-0158

Fax: (520) 621-9098Customer Service: (520) 621-3660

Please reference job number 27067 and Research/Laboratory Aide as the job title on your application materials. Review of materials will begin 12/1/03 and will continue until positions are filled.

NOTE: Human Resources currently is unable to accept application materials via e-mail or the internet.

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CO transport in blood2

CO2 + H2O H2CO3 H+ + HCO-3

Proportions of CO2 , HCO-3 depend on pH, T, ionic strength of

blood

At normal pH, Temp:

80% of CO2 in form of bicarbonate ion HCO-3

5-10% dissolved in blood

10% in form of carbamino groups

(bound to amino groups of hemoglobin)

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HCO-3 H+

+ CO2-3

CO2 + OH- HCO-3

bicarbonate

carbonate

carbonic acid

CO2 transfer at tissue• enters/leaves blood as CO2 (more rapid diffusion)

• passes thru RBCs

• CO2 produced = O2 released no change in pH

only in RBC, not plasma

maintain charge balance

oxygenation of hemo: acidify

interior (release H+ )

deox of hemo: increase pH (bind H+)

Band III protein

-Chloride Shift-Carbonic Anhydrase

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(13-10)

Jacob-Stewart Cycle7

(13-17)

Move acid in or out of RBC

(e.g., help buffer CO2 rise in plasma)

(13-23)

Lung Ventilation

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Knut Schmidt_Nielsen 1972

Panting Dogs?9

Shakes 2002

Mammalian Ventilation

-lungs are elastic bags

-suspended in pleural cavity within thoracic cage (ribs and diaphragm define, fluid lining)-low volume pleural “space” between lung and thoracic wall

-negative pressure to inflate lungs (increase volume)

-pneumothorax

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Mammalian Ventilation (13-28)

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Mammalian Ventilation

(13-30)

-expiration usually passive

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Knut Schmidt_Nielsen 1997

MammalianLung

Alveoli and Capillaries

RBC (not to scale)

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Pulmonary Surfactants

-Reduce liquid surface tension in alveoli

-Lipoproteins

-keep alveoli from getting stuck closed

Atelectasis = collapsed lung

-premature babies may need artificial surfactant

-Allows for compliance and low-cost expansion of lung

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Frog Ventilation

(13-33)

-Positive pressure ventilation

1. Into mouth (buccal cavity)

2. Close nares, open glottis and force air into lungs by raising buccal floor

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Knut Schmidt_Nielsen 1972

Bird LungParabronchi

Mammal LungAlveoli

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Bird Ventilation

(13-32)

-lung volume changes very little, air sacs instead

(13-32)

Unidirectional

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Knut Schmidt_Nielsen 1997

Bird Lung Ventilation

Unidirectional!!

~ Continuous ventilation

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Knut Schmidt_Nielsen 1997

Relative Gill Surface Area in Fishes

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Knut Schmidt_Nielsen 1997

Fish Gill

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Knut Schmidt_Nielsen 1997(see your figure 13-40)

Fish Gill

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-breathing in water

-need much higher ventilation rate-unidirectional

-pump water across gills (or ram ventilation)

Knut Schmidt_Nielsen 1997

Lake Titicaca Frog

(Bolivian Navy; Peru-Bolivia border)

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Rate and Depth Regulation

-Primarily via CO2 changes (central)

-O2 controls respiration in aquatic vertebrates

(13-46)

-Innervate Medullary Respiratory Center(phrenic nerve to diaphragm and intercostals)

-Peripheral Chemoreceptors PO2, PCO2, pH

-Emotions, sleep, light, temperature, speech, volition, etc.

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Rate and Depth Regulation

(13-48)

-Central Chemoreceptors

Long term

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(13-45)

To Diaphragm

alveolar

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Hering-Breuer reflex

-Stimulation of stretch receptors inhibits medullary inspiratory center

-Prevent overinflation

-Ectotherms often breathe intermittently

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(13-45)

1

1

2

2

To Diaphragm

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Extreme Conditions

- Hypoxia, non-aquatic responses (e.g., altitude) I:

-Drop in blood PO2 stimulates chemoreceptors increased lung ventilation

-But this increases CO2 elimination and pH increases, leading to reduced ventilation

-Over time (a week), bicarbonate released to bring pH back down even with increased ventilation

-Chemoreceptors reset to higher pH/lower CO2

-Hb with increased affinity for O2

-DPG levels increased to maintain Hb ability to unload O2 at tissues (reduced Hb O2 affinity)

Student

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Extreme Conditions

- Hypoxia, non-aquatic responses (e.g., altitude) II:

-Systemic vasodilation and increased cardiac output (short-term)

-Blood volume increases by 1/3 (chronic hypoxia)

-Pulmonary vasoconstriction leads to: 1. increased pulmonary BP2. hypertrophied right ventricle3. large lung to body ratio

-Increase number of RBCs via erythropoietin (produced in liver in kidney in response to low blood PO2) action on bone marrow

-Vascular endothelial growth factors increase capillary density

Student

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Knut Schmidt_Nielsen 1997

Oxygen dissociation curvesand altitude

Student

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Osmoregulation-Ionic and Osmotic

Balance

-Kidney Function

Chapter 1431

Osmoregulation

-life arose in salty sea

-extracellular fluids ~ similar

-terrestrial organisms (and their descendents) regulate internal environment (homeostasis)

-salt and water regulation (waste excretion)

-dist’n limited by temperature and osmotic pressure

(dehydration, ionic composition)

-kidneys, salt glands, gills

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Obligatory Osmotic Exchanges

2-Surface-to-Volume Ratio-Small animals dehydrate or hydrate more

rapidly-Skin, and Respiratory surface (higher metabolism with higher per/gram respiratory surface)

3-Integument Permeability-Transcellular or Paracellular

-Aquaporins = water channel proteins

1-Gradients-Frog in freshwater-Fish in ocean

-Frogs vs. Lizards, Pelvic Patch etc.

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Obligatory Osmotic Exchanges

4-Feeding, Metabolism, Excretion-metabolic waste products

ammonia, urea, etc.-metabolic water (desert!)-ingestion of salts-kidneys, salt glands, gills (more later)

5-Respiration

-internalize respiratory surface-temporal countercurrent system (dry and cool IN, becomes moist and warm; recover) (countercurrent blood flow also)-temperature regulation vs. water conservation-ectotherm vs. endotherm (in deserts)

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Osmoregulation

-Water Breathing

1. Fresh

Blood osmolarity 200-300 mosm/LWater ~ 50 mosm/L

- hyperosmotic animals, danger of swelling, losing salts- get their water across skin- dilute urine- active uptake of salts across epithelium- fish gills, frog skin, etc.

Ambystoma tigrinum

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Osmoregulation

-Water Breathing

2. Salt

Most marine vertebrates hypo-osmotic

(e.g., teleost or bony fishes)

- danger of losing water, gaining too many salts- drink saltwater- excess salts actively secreted (gills, kidneys)- chloride cells for salt secretion (Pelis et al. paper)

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(~1,000 mosm/L)

Osmoregulation

-Air Breathing

Have to lose water to allow gas exchange

- Marine reptiles and marine birds can drink seawater and secrete salts in high [ ]- SALT GLANDS

- Mammals rely on kidney

(14-8)

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Osmoregulation

-Air Breathing Desert Mammals

Behavior and Physiology

Kangaroo Rat-Reduce Activity-Remain in Cool Burrow-Highly concentrated urine-Very dry feces (rectal absorption)-Metabolic water

(14-9)

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Excretion of Nitrogeneous waste

-When amino acids catabolized, amino group (-NH2) is released (deamination)-If not reused, need to excrete because toxic

1-ammonia (most toxic, requires lots water)‘ammonotelic’ (NH3)

2-urea (need 10% of water of NH3, but costs ATP)‘ureotelic’ (2N)

3-uric acid (white pasty substance, low solubility, need 1% water as NH3) ‘uricotelic’ (4N)

-Three main ways to dispose:

-Disposal depends on water availability

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Knut Schmidt_Nielsen 1997

40Excretion of Nitrogeneous waste

Knut Schmidt_Nielsen 1997

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Excretion of Nitrogeneous waste

-ammonia converted to non-toxic glutamine in the body for transport

-ammonia toxic because -increases pH, -competes with K+ for ion transport, -alters synaptic transmission

(14-31)

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Osmoregulatory MechanismsApical surface (faces lumen and outside world)Basal surface (faces body and extracellular fluid)

- Active movement of ions/salts requires ATP- Movement of water follows movement of ions/salts

(14-11)

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END

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