Bio 2 unit 3 pt. 1: homeostasis, kidney

homeostasis

maintenance of dynamic equilibrium in the body

• “same state”

regulated internal conditions

• core temperature (not all animals)

• level of metabolic waste products

• blood pH

• blood glucose concentration

• blood osmolarity

• blood pressure

conformers

allow their internal conditions to become similar to the external environment

• Advantage: lower energy expenditure

• disadvantage: less functional in some environment

• regulation and conformation lie at the 2 extreme ends of a spectrum, and most animals fall somewhere in between

Importance of Homeostasis

• maximize enzyme efficency

• temperature affects membrane permeability and how quickly solutes can diffuse

• freezing of water inside a cell can rip cells apart

fever

an intentional increase in temperature initiated by the immune system to fend off pathogens

• occasional departure from homeostasis, adaption

helps maintain homeostasis

• epithelial tissue

• homeostasis control systems

• hormones

epithelial tissue

the interface between internal and external environments

• impermeable barrier

• membrane proteins

hormones

released by the endocrine system promote communication

homeostatic control system

how homeostasis is usually achieved, regulation

• sensor

• integrator

• effector

sensor

detects/senses the variable

Ex: temp

integrator

evaluates incoming sensory information by comparing it to the setpoint and determines if a response is necessary to achieve homeostasis

• hypothalmus

effector

structure or behavor that helps us restore the internal condition

• reduce or oppose the change in internal conditions

  • redundancy is common and adjustments are constantly being made

temperature increase

thermoregulation in animals where:

1. sensors record temperature-by skin, spinal chord, hypothalmus

2. integrator compares sensor input with set point, then instructs effectors

3. effectors change body temperature to return to set point

• blood vessels near the skin dilate, blood flow increases, heat loss from skin surface increases

• sweat glands are stimulated, evaporation for heat loss

• respiratory center is stimulated, panting=heat loss

temperature decreases

thermoregulation in animals where:

1. sensors record temperature-by skin, spinal chord, hypothalmus

2. integrator compares sensor input with set point, then instructs effectors

3. effectors change body temperature to return to set point

• blood vessels near skin constrict, blood flow decreases, heat loss decreases

• shivering: generates heat in muscles

• chemical signals arrive at cells and stimulate increases in cellular respiration and heat protection

negative, antagonistic

homestatic systems are based on _____ feedback and usually work in _____ pairs

Ex: glucose levels; what effectors do

glucose

• blood ___ levles are maintained at a constant level by a negative feedback mechanism

• when blood ___ level is too high, the pancrease secretes isnulin

• when blood ___ level is too low, the pancrease secretes glucagen

heat exchange

critical in animal physiology because individuals that get too hot or too cold may die

overheating

can cause enzymes and other proteins to denature and cease functioning

• may lead to excessive water loss and dehydration

sharp drop in body temperature

can slow down enzyme function and energy production

mechanisms of heat exchange

1. conduction

2. convection

3. radiation

4. evaporation

conduction

direct transfer of heat between two physical bodies that are in contact with each other

convection

a special case of conduction; heat exchanged between a solid and a moving liquid/gas

radiation

transfers heat between two objects that are not in direct contact

evaporation

occurs when liquid becomes a gas; leads only to heat loss

homotherms

keeps body heat constant

• has a thermal neutral zone, has max metabolic rate, comfortable

• “a like heat”

• energetically expensive: higher metabolic rates, bc eat lots of food bc of size

ex: mammals, birds

poikilotherms

allow their body temperature to rise or fall depending on environmental conditions

ex: amphibians, reptiles, fishes

thermal neutral zone

range of external temperatures in which metabolic rate is minimal and does not change with external temps; internal temperature remain relatively constant

• constant

differs

metabolic rate ___ with externam temperature

homotherms evolved thermoregulatory mechanisms

• shivering

• body insulation (fat, fur, feathers), specialized blood flow patterns

• panting and sweating (lose heat in larger animals)

shivering

skeletal movements require ATP hydrolysis

• heat is diven off as a by-product

• maintain heat in the cold

Poikilotherms and body temperature

behavioral regulation

• positioning itself in a suitable environment (sitting on a rock that is in the sun)

more thermoregulation strategies

• small animals that inhibit cold climates lose heat rapidly

• reduce metabolic rate to allow body temp to drop—poikilo

  • hibernation

hibernation

long term state of low body temperature and thermal conformity in the winter

• evolved to benefit from homeothermy and poikilothermy

bundles of arteries and veins

countercurrent heat exchanges occur in these to allow animals to thrive in a wide variety of environments; minimize heat loss

Ex: whale tongue, birds and cold feet, artic fox

whale tongue

heat exchanges in bundles of arteries and veins that minimize heat loss from the ___ to the cold ocean water during feeding

• can also similarly found in flippers

birds and cold feet

1. warm blood from the body’s core travels down leg in an artery, arterial blood

2. arterial blood passes heat to cold blood coming back from foot, veinous blood

3. arterial blood is now cooler and will loose less heat to the environment as it travels thorugh the foot

4. cold veinus blood from the foot is warmed before it returns to body core

aqueous

the chemical recations that make life possible occur in ___ solutions

electrolyte concentraions

water balance and intimately associated with balancing ___ in the body

electrolytes

compounds that dissociate into ions when dissolved in water

Na+, Cl-, K+, Ca+

most abundant ions of electrolytes

electrolyte imbalance

muscle spasms, confusion, irregular heart rhythms, fatigue, paralysis, or even death are caused by ____

osmoreguation

helps maintain homeostasis by regulation water and solute levels

• controls osmotic pressure

• driven by total solute concentration

• occurs by changing osmotic fradient and opening and closing channel proteins

• regulates osmolarity

• achieved by movement of solutes, particularly electrolyte ions, into and out of the cell with water following passively by osmosis

osmolarity

concentration of all solutes within a solution

• based on the total number of solute particles in a solution, but independent of large macromolecules and cells

• in osmoles per liter

• drives movement of water

ex: 1 mol of NaCl= 1 mol of Na+ and 1 mole of Cl-= 2 osmoles/L

hyperosmotic

Solution A has a higher osmolarity than solution B, then solution A is _____ to solution B

hypoosmotic

solution A has a lower osmolarity than solution B, then solution A is ____ to solution B

isosmotic

solution A has the same osmolarity as solution B, then solution A is _____ to solution B

metabolic water

water produced by complex IV of the ETC during celluar regulation

equal

when water imput and water output ____ homeostasis is maintained

osmotic stress

occurs when the concentration of dissolved substances in a cell or tissue is abnormal

toxic, excreted, renal system, kidneys

many waste products of metaboliss are ___ and need to be ___, which vertebraes do by the ___ and the ___

osmoconformers

in osmotic equilibrium with their environment, match their internal osmotic environment to teh same osmolarity as ocean water, but with different compoution of solutes (urea)

• have extracellular fluids that are isomotic to seawater

ex: sharks and most marine invertebrates, mollusks and crustaceans

osmoregulators

actively maintain a relatively constant blood osmolarity, different than that of the surrounding environment

• active process

• freshwater animals live in a hypoosmotic environment

• salterwater animals live in a hyperosmotic environment

Ex: all “other” invertebrates; bony fish

gills

• blood in its capillaries is in close proximity to the water in the environment

  • important for oxygen uptake, but also means that water and electrolytes can be exchanged here as well

• osmoregulation

50

freashwater and marine fishes that are osmoregulators expend as much as ___% of their resting metabolic energy just on osmoregulation

osmoregulation in freshwater fish

challenges

• tend to gain water by osmosis

• tend to lose electrolytes (ions) by diffusion

Adaptions

• drink little or no water

• excrete large amounts of dilute urine

• actively take up ions through gills

osmoregulation in marine bony fish

Challenges

• tend to lose water by osmosis

• tend to gain electrolytes by diffusion

Adaptions

• drink large amounts of seawater (Na+ and Cl-)

• excrete concentration urine

• actively excrete ions through gills

chloride cells

epithelial cells in teh gills of bony fish that actively transport

• in saltwater fish, it actively pumps Cl- out of the body, Na+ follow gradient, water follows bc of its gradient

• in freshwater fish, it pumps Cl- into the body, Na+ follow gradient, water also follow ions due to osmotic gradietn

chloride cells in saltwater fish

1. Na+/K+ ATPase (in basolateral membrane) transports Na+ out of the cell and k+ into the chloride cell; creates gradient for Na+

2. NKCC transporter (in basolateral membrane) transports Na+, K+, 2 Cl- ions into the cytoplasm of the chloride cell

3. CFTR protein (Cl- channel in apical membrane) allows diffusion of Cl’ out of chloride cell

4. Paricellular Na+ chennels (in tight junctions btwn epithelial cells) allow Na+ moevement between interstitial fluid and the ocean water; diffusion and follow Cl- ions

5. K+ is retured to the interstitial fluid thorugh K+ leak channels in basal lateral membrane

apical, basal, opposite transport

in freshwater fish, locations of the NKCC are in the ____ membrane, CFTR in the ____ membrane, because of ____

euryhaline organisms

can live in both freshwater and sea water

ex: salmon run- salmon migrate from the ocean (saltwater) and swim to the upper reaches of rives (freshwater) to spawn on gravel beds

• orientation of key transport proteins flip depending on the environment

terrestrial animals

always losing water to the enviroment via evaporation and urination (excretion)

urea

• converted from ammonia

• loses little water by osmosis

• used a lot of energy to make proteins to protect cells from high concentrations

• produced in the liver

• eliminated thorugh urine, produced in the urinary system

• less toxic than ammonia, medium toxicity

• soluble in water

salt concentration in sharks

Na+ and Cl- are continually entering intersitial fluid by diffusion thorugh gaps between cells, so salt concnetration increases

• sharks must excrete salt against concentration gradient by rectal gland

shark rectal gland

secretes a concentrated salt solution

ammonia

excess amino acids and nucleic acids are broken down into this via catabolism/deanimation

• toxic because it raises pH; high toxicity

• animals directly excrete this or convert it into other nitrogen containing compounds that are then excreted; needs water to be excreted

• soluble in water

• low energy

• excreted in urine or diffusion

ex: bony fish elminite by diffusion in gills

uric acid

converts ammonia into water insoluble ___

• saves water, precipiates from solution and has a semi solid paste

• requires a lot of energy

• low toxicity

• synthesized with nucleic acids

• excreted by feces

water, environment, development

waste pathway depends largely on the available ______ to organisms and can change by ____ or throughout ___

animals need to

1. eliminate nitrogen-containing waste products of metabolism (animals typically urea)

2. maintain the appropiate water and electrolyte balance that allows their bodies to function

kidney

responsible for filtering urea out of the body and solutes out of the blood, producing urine and adjusting its concentration

• located at the lower back, outside body cavity

• made out of nephrons

ureter

tube that connects the kidney’s to urinary bladder; transports urine formed in the kidney

bladder

stores urine and allows controlled release

renal vein

carries filter blood away from kidnes

renal artery

carries blood containing nitrogenous wastes to the kidneys

20

with each heart heart beat, about ___% of blood passes through kidneys

nephron

basic function unite of the kidney

• made out of tubules with few distinct regions

• where urine is produced

• each is associated with a network of capillaries

cortex

outer region of the kidney

• contains the glomerulus and convoluted tubes

medulla

kidney’s inner region

• contains loop of Henle and collecting ducts

Renal pelvus

where urine in the nephrons drains to

filtration

fluid from blood under pressure is filtered

• first step of urine production

• located first in the glomerulus then the Bowman’s capsule

• has a filtration barrier that bloock blood cells and large blood proteins/large molecules to remain in blood and let everything else, small solutes and water through to enter the nephron

  • solutes move by bulk flow driven by pressure from blood into tubule

• no energy is used

filtrate

water and solutes that are filtered and enter the capsule

glomerulus

a set of capilaries in the nephron

Bowman’s capsule

membranus sac

Afferent Atriole

carries blood to the capillaries in the glomerulus

efferent arterial

where blood leaves the capillaries int the clomerulus to the renal vein

flow of filtrate

1. bowman’s capsule

2. proximal convoluted tubule

3. loop of Henle

4. Distal convoluted tube

5. collectingd duct

6. renal pelvis

7. ureter

8. urinary bladder

proximal convoluted tubule

nearest to the renal corpuscle and twisted tube

• its epithelial cells reabsorb nutrients, ions, and water from the filtrate into the blood

• reabsorb electrolytes with active transport

distal convoluted tubule

further away from glomerulus and renal corpuscle and twisted tube

• reabsorbs ions and water in a regulated manner

• helps maintain water and electrolyte balances according to the body’s needs

descending limb

permeable of water but impermeable to urea

• passive

thick portion of ascending limb

impermeable to water but actively transports electrolytes out of the filtrate

think portion of ascending limb

vasa recta

• descending and ascending vessels arranged in a counter current organizations

• blood vessels flowin to the ___, down arm and back through the cortex in the other

• helps maintain constant gradient in both water and solutes and kidneys

limbs of loop of henle

• thickness affect permeability

• run parallel

• opposite directions

• two

flow of blood

1. Renal Artery

2. afferent arteriole

3. glomerulus

4. efferent arteriole

5. pertubular capillaries and vasa recta

6. renal vein

renal corpuscle

filters blood, forming a filtered pre-urine (ions, nutrients, water, and waste)

• size selective filtration to enter nephrone

loop of henle

establishes a strong osmotic gradient in the interstitial fluid surrounding the loop

1. descending tube is permeable to water and releases water to interstitial fluid in tissue because it has higher osmolarity; passive and rapid

2. thin ascending limb permeable Na and Cl and releases to interstitial fluid by passive transport

3. thick ascending tube actively transports Na Cl out of the tube

• continuted movement of Na and Cl ouut of filtrate back into interstitial fluid

• after this it goes into distil convluted tube in cortex as hypoosmotic to interstitial fluid/blood

colleccting duct

may reabsorb more water to maintain homeostasis

nephron regions

• renal corpsucle

• proximal tube

• loop of henle

• distal tube

• empties into the collecting duct

isotonic

filtrate of bowman’s space is ____ to the blood

reabsorption

useful ions and molecules are transported form the tubular filtrate back into the surrounding bodily fluids

• water follows by osmosis

• begins in the proximal convoluted tube, 2/3s of NaCl and water are filtered, glucose, AA, and many other molecules needed by the body are reabsorbed in the PCT

• many molecules enter/exchanged through cotransporters across basal to blood becauseof gradients

• requires energy

• helped by microvilli

• filtrate→ epithelial→interstitial fluid→ blood vessels

• filtrate volume becomes 60L out of the 180 L

concentration gradient

ion and water movement is driven by a _____ in the interstitial fluid for reabsorption