Unit 9 End of Year Review

What do animals need to live?

O2

food

ATP

• Animals make energy using:– food– oxygen

• Animals build bodies using:– food for raw materials

• amino acids, sugars, fats, nucleotides

– ATP energy for synthesis

Getting & Using Food

• Ingest– taking in food

• Digest– mechanical digestion

• breaking up food into smaller pieces

– chemical digestion• breaking down food into molecules small

enough to be absorbed into cells• enzymes (hydrolysis)

• Absorb– absorb across cell membrane

• diffusion• active transport

• Eliminate – undigested extracellular material passes

out of digestive system

intracellulardigestion

extracellulardigestion

stomachkills germs break up fooddigest proteinsstore food

small intestinesbreakdown food

- proteins- starch- fats

absorb nutrients

pancreasproduces enzymes to digest proteins & carbs

liverproduces bile

- stored in gall bladderbreak up fats

large intestinesabsorb water

mouthbreak up foodmoisten food digest starchkill germs

Stomach• Functions

– food storage• can stretch to fit ~2L food

– disinfect food• HCl = pH 2

– kills bacteria– breaks apart cells

– chemical digestion• pepsin

– enzyme breaks down proteins– secreted as pepsinogen

» activated by HCl

But the stomach is made out of protein!What stops the stomach from digesting itself?

mucus secreted by stomach cells protects stomach lining

Ooooooh!Zymogen!

Small intestine

• Function– major organ of digestion & absorption – chemical digestion

• digestive enzymes

– absorption through lining• over 6 meters! • small intestine has huge surface area = 300m2 (~size of

tennis court)

• Structure– 3 sections

• duodenum = most digestion• jejunum = absorption of nutrients & water• ileum = absorption of nutrients & water

Pancreas

• Digestive enzymes – peptidases

• trypsin– trypsinogen

• chymotrypsin– chimotrypsinogen

• carboxypeptidase– procarboxypeptidase

– pancreatic amylase

• Buffers – reduces acidity

• alkaline solution rich in bicarbonate (HCO3-)

• buffers acidity of material from stomach

Explain how this is a molecular example of structure-function theme.

Explain how this is a molecular example of structure-function theme.

small intestines

Liver

• Digestive System Functions– produces bile

• stored in gallbladder until needed• breaks up fats

– act like detergents to breakup fats

Circulatory System ConnectionCirculatory System Connectionbile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

bile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

Absorption by Small Intestines

• Absorption through villi & microvilli– finger-like projections

• increase surface area for absorption

Ooooh…Structure-Function

theme!

Absorption of Nutrients

• Passive transport– fructose

• Active (protein pumps) transport– pump amino acids, vitamins & glucose

• against concentration gradients across intestinal cell membranes

• allows intestine to absorb much higher proportion of nutrients in the intestine than would be possible with passive diffusion

– worth the cost of ATP!

Large intestines (colon)

• Function– re-absorb water

• use ~9 liters of water every day in digestive juices

• > 90% of water reabsorbed– not enough water absorbed

back to body

» diarrhea

– too much water absorbed back to body

» constipation

Why do we need a respiratory system?

O2

food

ATP

CO2

respiration forrespiration

• Need O2 in

– for aerobic cellular respiration– make ATP

• Need CO2 out

– waste product fromKrebs cycle

Optimizing gas exchange• Why high surface area?

– maximizing rate of gas exchange

– CO2 & O2 move across cell membrane by diffusion

• rate of diffusion proportional to surface area

• Why moist membranes? – moisture maintains cell membrane structure– gases diffuse only dissolved in water

High surface area?High surface area!

Where have we heard that before?

Counter current exchange system

• Water carrying gas flows in one direction, blood flows in opposite direction

just keepswimming….

Why does it workcounter current?

Adaptation!

Gas Exchange on Land• Advantages of terrestrial life

– air has many advantages over water• higher concentration of O2

• O2 & CO2 diffuse much faster through air – respiratory surfaces exposed to air do not have to be

ventilated as thoroughly as gills

• air is much lighter than water & therefore much easier to pump– expend less energy moving air in & out

• Disadvantages– keeping large respiratory surface moist

causes high water loss• reduce water loss by keeping lungs internal

Why don’t land animals

use gills?

Medulla monitors blood• Monitors CO2 level of blood

– measures pH of blood & cerebrospinal fluid bathing brain

• CO2 + H2O H2CO3 (carbonic acid)

• if pH decreases then increase depth & rate of breathing & excess CO2 is eliminated in exhaled air

Hemoglobin• Why use a carrier molecule?

– O2 not soluble enough in H2O for animal needs• blood alone could not provide enough O2 to animal cells • hemocyanin in insects = copper (bluish/greenish)• hemoglobin in vertebrates = iron (reddish)

• Reversibly binds O2

– loading O2 at lungs or gills & unloading at cells

cooperativity

heme group

Circulatory systems

• All animals have:– circulatory fluid = “blood”– tubes = blood vessels– muscular pump = heart

open closed

hemolymph blood

Vertebrate circulatory system

• Adaptations in closed system– number of heart chambers differs

4 chamber heart is double pump = separates oxygen-rich & oxygen-poor blood; maintains high pressure

What’s the adaptive value of a 4 chamber heart?

2 3 4

low pressureto body

low O2

to body

high pressure & high O2

to body

Evolution of 4-chambered heart

convergentevolution

• Selective forces– increase body size

• protection from predation• bigger body = bigger stomach for

herbivores

– endothermy• can colonize more habitats

– flight• decrease predation & increase prey

capture

• Effect of higher metabolic rate– greater need for energy, fuels, O2,

waste removal• endothermic animals need 10x energy• need to deliver 10x fuel & O2 to cells

Mammaliancirculation

What do blue vs. red areas represent?What do blue vs. red areas represent?

pulmonary

systemic

systemic

Cardiac cycle

systolic________diastolic

pump (peak pressure)_________________fill (minimum pressure)

• 1 complete sequence of pumping– heart contracts & pumps– heart relaxes & chambers fill – contraction phase

• systole• ventricles pumps blood out

– relaxation phase• diastole• atria refill with blood

110

____

70

Arteries: Built for high pressure pump• Arteries

– thicker walls • provide strength for high pressure

pumping of blood

– narrower diameter– elasticity

• elastic recoil helps maintain blood pressure even when heart relaxes

Veins: Built for low pressure flow• Veins

– thinner-walled – wider diameter

• blood travels back to heart at low velocity & pressure

• lower pressure– distant from heart– blood must flow by skeletal muscle contractions

when we move » squeeze blood through veins

– valves• in larger veins one-way valves

allow blood to flow only toward heart

Open valve

Blood flowstoward heart

Closed valve

Capillaries: Built for exchange• Capillaries

– very thin walls • lack 2 outer wall layers • only endothelium

– enhances exchange across capillary

– diffusion• exchange between blood

& cells

Exchange across capillary walls

Arteriole

Bloodflow

Venule

Lymphaticcapillary

Interstitialfluid

Fluid & solutes flows out of capillaries to tissues due to blood pressure• “bulk flow”

Interstitial fluid flows back into capillaries due to osmosis plasma proteins osmotic pressure in capillary

BP > OP BP < OP

15% fluid returns via lymph

85% fluid returns to capillaries

What aboutedema?

Capillary

Intracellular Waste

• What waste products?– what do we digest our food into…

• carbohydrates = CHO• lipids = CHO• proteins = CHON • nucleic acids = CHOPN

CO2 + H2O

NH2 =

ammonia

CO2 + H2O CO2 + H2O

CO2 + H2O + N

CO2 + H2O + P + N

|

| ||H

HN C–OH

O

R

H–C–

Animalspoison themselves

from the insideby digesting

proteins!

lots!verylittle

cellular digestion…cellular waste

Nitrogen waste Aquatic organisms

can afford to lose water ammonia

most toxic

Terrestrial need to conserve

water urea

less toxic

Terrestrial egglayers

need to conserve water need to protect

embryo in egg uric acid

least toxic

Mammalian System

• Filter solutes out of blood & reabsorb H2O + desirable solutes

• Key functions– filtration

• fluids (water & solutes) filtered out of blood

– reabsorption• selectively reabsorb (diffusion) needed

water + solutes back to blood

– secretion• pump out any other unwanted solutes to

urine

– excretion• expel concentrated urine (N waste +

solutes + toxins) from body

blood filtrate

concentratedurine

Mammalian kidney

Proximaltubule

Distal tubule

Glomerulus

Collecting ductLoop of Henle

Aminoacids

Glucose

H2O

H2O

H2O

H2O

H2O

H2O

Na+ Cl-

Mg++ Ca++

• Interaction of circulatory & excretory systems

• Circulatory system– glomerulus =

ball of capillaries

• Excretory system– nephron– Bowman’s capsule– loop of Henle

• proximal tubule• descending limb• ascending limb• distal tubule

– collecting duct

How candifferent sectionsallow the diffusion

of different molecules?

Bowman’s capsule

Na+ Cl-

Nephron: Filtration

• At glomerulus– filtered out of blood

• H2O

• glucose • salts / ions• urea

– not filtered out• cells • proteins

high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vessel

high blood pressure in kidneys force to push (filter) H2O & solutes out of blood vessel

BIG problems when you start out with high blood pressure in systemhypertension = kidney damage

BIG problems when you start out with high blood pressure in systemhypertension = kidney damage

Nephron: Re-absorption

Descendinglimb

Ascendinglimb

• Proximal tubule– reabsorbed back into blood

• NaCl – active transport

of Na+

– Cl– follows by diffusion

• H2O

• glucose

• HCO3-

– bicarbonate– buffer for

blood pH

Descendinglimb

Ascendinglimb

Nephron: Re-absorption

Loop of Henle descending limb

high permeability to H2O many aquaporins in

cell membranes

low permeability to salt few Na+ or Cl–

channels

reabsorbed H2O

structure fitsfunction!

Nephron: Re-absorption

Descendinglimb

Ascendinglimb

Loop of Henle ascending limb

low permeability to H2O

Cl- pump Na+ follows by

diffusion different membrane

proteins

reabsorbed salts

maintains osmotic gradient

structure fitsfunction!

Nephron: Re-absorption

Distal tubule reabsorbed

salts H2O

HCO3-

bicarbonate

Nephron: Reabsorption & Excretion Collecting duct

reabsorbed H2O

excretion concentrated

urine passed to bladder impermeable

lining

Descendinglimb

Ascendinglimb

Osmotic control in nephron

• How is all this re-absorption achieved?– tight osmotic

control to reduce the energy cost of excretion

– use diffusion instead of active transportwherever possible

the value of acounter current exchange system

Summary

• Not filtered out – cells proteins– remain in blood (too big)

• Reabsorbed: active transport– Na+ amino acids– Cl– glucose

• Reabsorbed: diffusion– Na+ Cl–

– H2O

• Excreted– urea– excess H2O excess solutes (glucose, salts)– toxins, drugs, “unknowns”

whyselective reabsorption

& not selectivefiltration?

nephron

low

Blood Osmolarity

blood osmolarityblood pressure

ADH

increasedwater

reabsorption

increasethirst

high

pituitary

ADH = AntiDiuretic Hormone

low

Blood Osmolarity

blood osmolarityblood pressure

renin

increasedwater & saltreabsorption

in kidney

high

angiotensinogenangiotensin

nephronadrenalgland

aldosterone

JGA

JGA = JuxtaGlomerular Apparatus

Oooooh,zymogen!

nephron

low

Blood Osmolarity

blood osmolarityblood pressure

ADH

increasedwater

reabsorption

increasethirst

renin

increasedwater & saltreabsorption

high

pituitary

angiotensinogenangiotensin

nephronadrenalgland

aldosterone

JuxtaGlomerularApparatus