Unit 9 End of Year Review What do animals need to live? O2O2 food ATP Animals make energy using:...
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Transcript of Unit 9 End of Year Review What do animals need to live? O2O2 food ATP Animals make energy using:...
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