Download Lecture 7 Animal Energy Acquisition II: Food acquisition and

Lecture 7 Animal Energy Acquisition
II: Food acquisition and Digestion
Accessory
Pancreatic
duct
Bile duct
Tail of Pancreas
Body of Pancreas
Main Pancreatic
duct
Head of Pancreas
Dr. Shlomoh
Simchon
Duodenum
Junction of bile and pancreatic duct
Esophagus
Fundus
Pyloric sphincter
Duodenum
Antrum
Plicae
Note
07/11
2nd exam: covers lectures 4-7; Tutorials 2-3
Same format as 1st exam
Tutorial 2 and 3 (not tutorial 4)
Will not have lecture 8 will be covered in final
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Review
Neuromuscular Junction
Action
Potential
Ach released
Vessicles
Myasthenia Gravis
Destruction of acetylcholine receptors
by an autoimmune reaction
Ach bind to receptors 
response
Ca Channels
2
Neuromuscular Junction
Events in chemical synaptic transmission
• Neurotransmitter
release is Ca2+dependent
• NMJ events are similar
to other synapses
• EPP is large enough to
depolarize muscle fiber
• EPP produces a
synaptic current that
occurs as Na+ and K+
channels open
simultaneously driving
Vm towards ~0mV
Nerve ending
Block Ach-esterase
Ach released
EPSP-End Plate Pot. (EPP)
Ach bind to receptors
Action Potential
Muscle
3
Excitation-contraction coupling
KEY
DHP = dihydropyridine L-type
calcium channel
RyR = ryanodine receptor-channel
Action potential in t-tubule
alters conformation of DHP
receptor.
DHP receptor opens RyR Ca2+
release channels in sarcoplasmic reticulum, and Ca2+
enters cytoplasm.
Ca2+ released
Myosin thick filament
Distance actin moves
Ca2+ binds to troponin,
allowing actin-myosin binding.
Myosin heads execute power
stroke.
Actin filament slides toward
center of sarcomere.
© 2013 Pearson Education, Inc.
Muscle fiber AP
EC Coupling
Relaxation
4
Relaxed muscle
Initiation of
contraction
5
Isotonic and Isometric Contractions
Isometric
Isotonic
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Lecture 7 Animal Energy Acquisition
II: Food acquisition and Digestion
Accessory
Pancreatic
duct
Dr. Shlomoh
Simchon
Bile duct
Tail of Pancreas
Body of Pancreas
Main Pancreatic
duct
Head of Pancreas
Duodenum
Junction of bile and pancreatic duct
Esophagus
Fundus
Pyloric sphincter
Duodenum
Antrum
Plicae
Functions of the digestive system
•
•
•
•
•
•
Ingestion
Mechanical processing
Digestion
Secretion
Absorption
Excretion
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Some definitions
• Mechanical digestion – cut large particles into small,
without changing molecular structures
Examples: chewing, peristalsis, segmentation,
mixing/churning
• Chemical digestion -- large molecules into small, changing
molecular structures
Examples: enzymatic breakdown of polysaccharides into
disaccharides and then into monosaccharides
• Absorption -- moving simple nutrients from lumen
(external environment) to blood (internal environment)
The digestive system
The three fundamental processes that take place are:
Motility: Contractions of smooth muscle in the wall of the tube that
crush, mix and propel its contents
Secretion: Delivery of enzymes, mucus, ions and the like into the
lumen, and hormones into blood
Absorption: Transport of water, ions and nutrients from the lumen,
across the epithelium and into blood
Note differences among animals.
The digestive systems of humans, dogs, mice, horses, kangaroos and
great white sharks are, to a first approximation, virtually identical. If
you look more carefully however, it becomes apparent that each of
these species has evolved certain digestive specializations that have
allowed it to adapt to a particular diet.
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These differences become particularly apparent when you compare a
carnivore like a dog with a herbivore like a goat or a horse.
Goats evolved from ancestors that subsisted on plants and adapted
parts of their digestive tracts into massive organs which enabled
them efficiently utilize cellulose, the major carbohydrate of plants.
In contrast, dogs evolved from animals that lived on the carcasses of
other animals, and have digestive systems that reflect this history extremely small organs and essentially no ability to utilize cellulose.
Bridging the gap between carnivores and herbivores are
omnivores like humans and pigs, whose digestive tracts attest to a
historical diet that included both plants and animals.
The digestive system of carnivore - is the simplest among
mammals. Other species, even humans, have a more or very much
more extensive large intestine, and ruminants like cattle and sheep
have a large set of for stomachs through which food passes before it
reaches the stomach.
Mechanical methods of feeding
• Fluids
nectar/blood suckers/ milk
aphids; hummingbirds young mammals;
parasites
• Small particles
filter feeders/
cilia/ mucus traps/vacuoles
amoeba, mussels whales, flamingoes
• Large particles
capture and swallow prey/graze
plants/wood borers/scrapers
snakes, birds, deer, termites
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Three phases of digestion
1. Cephalic phase in response to sight, smell , and
thought of food.
2. Gastric phase secretion of acids stimulated directly
by the presence of food in the stomach (mechano
and chemo-receptors).
3. Intestinal phase controlled by many hormones
produced by intestine when food enters
duodenum (cholecystekinin VIP, somatostatin,
enkephalin etc.) Also produces most
neurotransmitters.
Human
digestive
system
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Mouth: Foodstuffs are broken down mechanically by chewing and saliva is added as
a lubricant.
Esophagus: A simple conduit between the mouth and stomach - important but only
marginally interesting.
Stomach: Where the real action begins - chemical digestion of proteins initiated and
foodstuffs reduced to liquid form.
Liver: The center of metabolic activity in the body - its major role in the digestive
process is to provide bile salts to the small intestine, which are critical for digestion
and absorption of fats.
Gallbladder: stores bile.
Pancreas: Important roles as both an endocrine and exocrine organ - provides a potent
mixture of digestive enzymes to the small intestine which are critical for digestion of
fats, carbohydrates and protein.
Small Intestine: The most exciting place to be in the entire digestive system - this is
where the final stages of chemical digestion occur and where almost almost all
nutrients are absorbed.
Colon = Large Intestine: Major differences among species in extent and importance in all animals water is absorbed, bacterial fermentation takes place and feces are
formed. In carnivores, that's about the extent of it, but in herbivores like the horse, the
large intestine is huge and of critical importance for utilization of cellulose.
Digestion Process
GI tract consists of:
• Mouth
• Pharynx
• Esophagus
• Stomach
• Small and Large Intestine
• Anus
Accessory Organs:
• Salivary glands
• Liver  Gallbladder
• pancreas
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The mouth opens into the oral
cavity
• Its functions include:
– Analysis of material before swallowing
– Mechanical processing by the teeth, tongue,
and palatal surfaces
– Lubrication
– Limited digestion
Adaptations for feeding
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Mosquitoes
The females of mosquitoes (blood sucker, depend on
blood as a source of protein for their developing eggs)
have the same set of mouthparts (labrum, mandibles,
maxillae, and labium) that are common to other
insects but are modified. Both the mandibles and
maxillae are blade- or sword-like, with serrated edges,
and their musculature has been radically altered to
allow them to be jabbed into skin.
As blood wells up in the wound, they pump salivary
fluid into it to prevent coagulation. This saliva, which
contains protein, is allergenic, and causes the swelling
and itching that you are all familiar with.
Bird Adaptations - Beaks
There are so many types of bird beaks. The most important
function of a bird beak is feeding, and it is shaped according to
what a bird eats. You can learn more about the behavior of a
bird by looking at the beak and thinking about what it eats. It is
used to find food, pick it up, and ready it for swallowing. Since
birds have no teeth they either swallow the food whole, or bite,
crack, or tear it into bite-sized pieces. They often hold the food
with their feet as they work at it with the beak
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Teeth
Beautiful Smile
• Teeth- provide mechanical digestion of feeding by
breaking, cutting, and tearing up food.
• The increase surface area aids in the chewing
and swallowing process.
TEETH: size and shape
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Insect eating bat
Vampire bat
FRUIT BATS EATING
The tongue
• primary functions include:
– Mechanical processing
– Assistance in chewing and swallowing
– Sensory analysis by touch, temperature, and
taste receptors
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Saliva
• Water, electrolytes (Na,K, Cl, HCO3)
• Secretion stimulated by thought/presence of
food.
• Decreased by sympathetic nervous system
(NE) – dry mouth when scared.
• Enzyme Amylase starts digesting starch.
• Mucins lubricate food making it easier to slide
down esophagus.
Digestive system complexity
• Depends upon the diet
• Diets high in easily broken down foods, such
as proteins have simple guts
• Diets high in fiber that requires fermentation
by microorganisms much more complicated
and much larger
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Digestive systems
E =Esophagus
St =Stomach:
L = Liver
G = Gallbladder
P = Pancreas
Si = Small Intestine
C = Large Intestine
Cr = crop (birds)
Birds
Birds have a number of features of the digestive system that
distinguish them from mammals. These include the lack of teeth
and a feeding strategy that allows for maximum ingestion of
food in a short time. Some birds can store food in a crop for a
time.
To meet their metabolic needs while remaining as light as
possible (to be efficient flyers), the digestive system of birds has
to be both as light as possible and as efficient as possible. Weight
has been minimized by the loss of teeth &, in many birds, limited
jaw musculature.
Some birds can pass seeds through. As seed-dispersers birds
play an important role in the ecosystem, in fact many seed types
will only germinate after having passed through a bird's system.
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Cattle Digestive System
Cattle belong to a class of animals known as
ruminants. Ruminants are animals that have four
compartments to their stomach. Their small and large
intestine are designed to handle large volumes of
material and large amounts of fiber.
The four compartments of the cattle stomach are
–Reticulm
–Rumen
–Omasum
–Abomasum
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Functions of the stomach
• Bulk storage of undigested food
• Mechanical breakdown of food
• Disruption of chemical bonds via acids and
enzymes
• Production of intrinsic factor
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STOMACH
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STOMACH
• Parietal cells produce
- HCl, stimulated by parasympathetic system (coffee, alcohol
and spices).
- Intrinsic factor for Vit B12 absorption
• Chief Cells produce pepsinogen for digestion of protein
NOTE:
o HCl breaks down peptide bonds, activates gastric enzymes
(Pepsin) and kills bugs in food.
o Goblet cells of the lining of the stomach produce mucus
coats the gastric epithelium preventing these cells from
being digested.
Digestion and absorption in the stomach
• Preliminary digestion of proteins
– Pepsinogen  pepsin
• Permits digestion of carbohydrates
• Very little absorption of nutrients
– Some drugs, however, are absorbed
– Mucous secretion containing several hormones
• Enteroendocrine cells
– gastrin
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Small intestine
• Important digestive and absorptive functions
– Secretions and buffers provided by pancreas, liver,
gall bladder
• Three subdivisions:
– Duodenum
– Jejunum
– Ileum
Intestinal secretions
• Glands at entrance to duodenum produce and
alkaline mucous fluid to neutralize acid in
chime.
• Secretin, gastrin, GIP and digestive enzymes
• Large intestine has no enzyme secretions
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SECRETION FROM INTESTINE
Brunner's glands
Compound mucous glands.
Found primarily in the duodenum.
Stimulated to secrete by:
chemical - stimulation by the food.
nervous - vagal efferent fibers.
hormonal - secretin.
Goblet cells
Found over surface of the small intestine.
Secrete mucus.
Secretion stimulated by the presence of food.
Accessory Organ
• Pancreas
• Liver
• Gallbladder
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Accessory Organ
SECRETION FROM THE PANCREAS
A. Important organic constituents of pancreatic exocrine secretion:
Pancreatic "juice" contains enzymes involved in the digestion of:
Proteins.
Carbohydrates.
Lipids.
Phospholipids.
Ribonucleic acids and deoxyribonucleic acids.
B. Important inorganic constituents of pancreatic exocrine secretion:
BICARBONATE ion, HCO3-. plays a vital role in the normal
digestive process in that it is required to:
Neutralize stomach acid that enters the small intestine.
Provide the proper pH (the digestive enzymes).
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The pancreas
• Pancreatic duct penetrates duodenal wall
• Endocrine functions
– Insulin and glucagons
• Exocrine functions
– Majority of pancreatic secretions
– Pancreatic juice secreted into small intestine
•
•
•
•
Carbohydrases
Lipases
Nucleases
Proteolytic enzymes
The liver
• Performs metabolic and hematological
regulation and produces bile
• Histological organization
– Lobules unite to form common hepatic duct to form
common bile duct
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Bile
• Produced in liver stored in gallbladder
• Organic salts made from cholesterol, water salts
and pigments (derived from breakdown of
hemoglobin).
• Important in digestion of fats.
• Highly alkaline.. Neutralizes acids from stomach.
• Breaks down fats into smaller particles for
digestive enzymes to act upon- detergent
function.
Bile Salt
lipid + water  2 phases
Add bile salts in low concentration 
"milky emulsion"
are large
droplets 5,000 Å diameter
add bile salts in high concentration
clear micelle
solution
40 to 50 Å diameter
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Motility of the Alimentary Canal
Propulsion- peristalsis
Mechanical -grinding and stirring
Control of motility by intrinsic (smooth muscle) and extrinsic
(hormones +ACH, -NE)
Peristalsis
• Wave like contractions of the muscles
in the GI tract
• pushes contents
• Moves bolus/chyme with alternating
muscle contraction and relaxation
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Control of the digestive system
• Movement of materials along the digestive tract
is controlled by:
– Neural mechanisms
• Parasympathetic and local reflexes
– Hormonal mechanisms
• Enhance or inhibit smooth muscle contraction
– Local mechanisms
• Coordinate response to changes in pH or chemical stimuli
Coordination secretion and
absorption
• Neural and hormonal mechanisms coordinate
glands
• GI activity stimulated by parasympathetic
innervation
– Inhibited by sympathetic innervation
• Enterogastric, gastroenteric and gastroileal
reflexes coordinate stomach and intestines
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Gastrointestinal secretions
• GIT- Largest endocrine (hormones)and exocrine
(saliva, bile, pancreatic) gland in the body
pH in digestive system
Saliva pH 6.5
Stomach pH 1.5
Small Intestine pH 7-8
What is the importance of pH?
How do you keep these pH?
Secretion
• Saliva secretes water, amylase, salts, bicarbonate
• Stomach secrete acid, HCl, pepsinogen, rennin, intrinsic
factor (Vit B12 absorption)
• Small intestine receives alkaline (bicarbonate secreted
from pancreas and bile)
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Feedback Mechanisms
Nervous
(parasympathetic)
Food
+
HCl
+
Parietal
+
Antrum
Gastrin
Feedback Mechanisms
Hormonal control of Pancreatic secretions
• When chyme reaches the intestine, the
duodenal walls release the hormone, Secretin
into the blood
• When Secretin reaches pancreas, it releases Bicarbonate to neutralize pH of intestine
• When needs are met, switches off
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Feedback Mechanisms
In response to the presence of fat in the meal:
Fat stimulates the intestinal wall to release a hormone
Cholecystokinin (CCK)
gallbladder squirts bile into the intestinal contents
Once fat is emulsified followed by enzymatic action,
CCK not released
Hormones play an important role
Stomach
Protein and fat
HCl
Duodenum
(+)
Protein and fat
digestion products
(-)
Bicarbonate
Intercalated
duct cells
Secretin
Cholecystokinin
Pancreas
Digestive
enzymes
Acinar
cells
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Extracellular digestion and absorption
• Digestion occurs almost entirely in
the lumen
• Absorption involves special carriers
for simple sugars and amino acids
• Fat absorption requires
emulsification
Very little absorption occurs in the stomach because:
•It lacks the villus type absorptive membrane.
•The junctions between epithelial cells are very
tight.
Substances that are absorbed:
•Only a few highly lipid soluble substances example: ethyl alcohol
•Some drugs - example: aspirin.
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Absorption – villi/microvilli
Structural amplification of surface area
1
Cylindrical
surface area
of lumen
X~10
Surface area
of lumen plus
villi
X~50
Surface are of
lumen plus villi
a plus microvilli
34
Animal food is made up of large organic
molecules that cannot be absorbed
• Fats (MW >> simple sugars and aa’s)
– Usually triglycerides
– Broken down to free fatty acids and monoglycerides
• Carbohydrates (MW up to 1,000,000)
– Mostly starch but also cellulose and other large polymers
– Broken down to simple sugars for absorption
• Proteins (MW 100,000 to 3,000,000)
– Peptide bonds form primary structure
– Broken down to single amino acids or di- and tri-peptides
for absorption
Carbohydrate digestion and absorption
• Broken into monosaccharides
• Facilitated diffusion into epithelium
• Carrier mediated, requires ATP and Na
transport.
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Facilitated diffusion
Absorption across the epithelium- requires presence of
membrane transport protein but no metabolic energy
Intestinal
epithelium
Galactose
Lactose
Lacatase
Glucose
Interstitium
Glucose
Intestinal
lumen
Glucose
Amylase
Maltose
Starch
Maltase
Fructose
Facilitated
diffusion
Sucrase
Sucrose
Fig. 22-28a
Active transport
Most sugars and proteins require energy expenditure for
adequate rates of absorption
Intestinal
lumen
Intestinal
epithelium
Interstitium
+
Sodium
Na
+
Na
+
Na
ATP
ADP + Pi
K
Glucose
Fig. 22-28
Facilitated
diffusion
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Active transport
Most sugars and proteins are co transported with Na ions utilizing a
common Na/K pump and the gradient that drives Na from the lumen
into the cytoplasm of the absorptive cells.
Intestinal
lumen
Intestinal
epithelium
Interstitium
+
Sodium
Na
+
Na
+
Na
ATP
K
ADP + Pi
Glucose
Fig. 22-28
Facilitated
diffusion
Protein digestion and absorption
• Broken into simple amino acids
• Pepsin in stomach(acidic pH); trypsin,
chymotrypsin, caroxypeptidase in small
intestine
• Active transport of aa’s, and di-and tripeptides involved in uptake across epithelium
of GIT
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Fat digestion and absorption
• Also cleaved by hydrolysis (lipase).
• Emulsified to provide increased surface area
for lipases
• Use bile salts to increase hydrophilic
properties.
• Small micelles, cross the cell membrane
• Drain into lymphatic system.
Micelle formation in the GIT
Large Oil Droplet
(triglyceride,
lecithan)
Lipase
Emulsified oil droplets
(triacylglycerol, FFA,
bile salts)
Micelles
(monoglycerides,FFA,
bile salts)
Intestinal
epithelial
cell
Molecules
(monoglyceride,
FFA)
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Monoglyceride and FFA absorption
Free Fatty Acids
Monoglycerides
Monoglycerides + Free Fatty Acids
Protein
Triacylglycerols
Chylomicron
Lacteal
Lymphatics
Subclavian
vein
39
Note
07/11
2nd exam: covers lectures 4-7; Tutorials 2-3
Same format as 1st exam
Tutorial 2 and 3 (not tutorial 4)
Will not have lecture 8 will be covered in final
Field Trip
Dr. Simchon
07/10 (next Monday)
Laboratory Exercise 6 Field trip to Salt Marsh at
Marshlands Conservancy.
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•Learning Benchmarks:
•Describe the environment of the Marshlands
Conservancy, listing and describing some of its
dominant biotic and abiotic features
•Discuss abiotic factors which undergo cyclic
variations on a daily basis and which require
functional responses by organisms experiencing them
•Collect accurate field observations and
measurements
•Describe the zones of the salt marsh, listing their
major features and giving examples of a few plants
and animals found in each
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Get Ready
Make sure you download the SPARKVue app and install it
in your smart phone (or other smart device, such as a
tablet) to record data prior to the field trip (i.e when you
have wifi access).
Shoes (walking), slippery
Long sleeve/pants
Insects, poison ivy
You have to attend (Points off)
Don’t disturb the biome
Please read your lab manual Page 52
41
Because the site is a sanctuary and is protected,
there are rules that must be followed when visiting.
These rules are designed to protect the habitat and
the plants and animals so that they can function in a
natural environment. When visiting the site please
do the following:
Say on the trails. Do not venture into the marsh.
Do not bring food onto the trails.
Try to be quiet and do not disturb the animals or
other visi
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Describe
oCommunity
oSuccession
oDisturbance
oMicroclimatology
oDiversity
oTrophic levels
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Ecology
Ecology is the scientific study of the processes
influencing the distribution and abundance of
organisms, the interactions among organisms, and
the interactions between organisms and the
transformation and flux of energy and matter.
Ecosystem
the complex of living organisms, their physical
environment, and all their interrelationships in a
particular unit of space.
Interaction between living and non living.
An ecosystem is a complex set of relationships
resources, habitats and residents of a region.
Includes people, wildlife, fish, shellfish, trees,
wetlands, water, and other living and non-living
entities that are necessary for the ecosystem to
function.
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Ecosystem (biome)
Ecosystems (short for ecological systems) are
functional units that result from the interactions
of abiotic, biotic, and cultural components. All
ecosystems are "open" systems in the sense that
energy and matter are transferred in and out.
The Earth as a single ecosystem constantly
converts solar energy into organic products, and
has increased in biological complexity over time.
Biome are the living things in the ecosystem
Ecosystem
Natural ecosystems, made up of abiotic factors (air,
water, rocks, energy) and biotic factors (plants,
animals, and microorganisms). The Earth s biosphere,
including the atmosphere (air), hydrosphere (water),
and litosphere (land), between living things and their
physical and chemical environments. The flow of
energy and matter through ecosystems, therefore, is
regulated by the complex interactions of the energy,
water, carbon, oxygen, nitrogen, phosphorus, sulfur,
and other cycles that are essential to the functioning of
the biosphere.
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Trophic Levels (biotic factors)
Sun
Producers
(plants)
Heat Loss
Herbivores
(primary
consumers)
Carnivores
(secondary
consumers)
Decomposers
Heat Loss
What are the functions of fungus in an ecosystem
45
Be careful! If you are on wet rocks they may be
slippery. Don’t go into the water, and should a sensor
become tangled find your instructor before attempting
to retrieve it.
Only the depth/temperature, thermocline sensor can be
completely submerged. Keep the other sensors out of
the water except for the measuring end. Don’t let any of
the connectors or the Pasco interface get wet.
Stay with your group at all times. Only the person
assigned to gather information should leave if the
instructor is needed.
91
Factors shaping evolution
Abiotic:
Light (Sun)
Temperature (Sun, atmosphere)
Gases
Water availiblity
Water properties: salinity, pH, ion composition
Biotic factors
Competition
Predation
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Tide
Water level rise and fall (what cause it?)
High tide: water level increase, organisms will be
immersed in water
Low tide: organisms expose to air
Salinity changes: evaporation
Adaptation:
Thinking about the salt marsh and the
intertidal zone
What examples did you observe of:
oShort-term, rapid physiological responses:
oMedium-term, physiological and anatomical
adaptation:
oLong-term, evolutionary adaptations:
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Thinking about the salt marsh and the
intertidal zone
What examples did you observe of:
o Thermal challenges in the salt marsh zones:
o Osmoregulatory challenges in the salt marsh zones:
o Energetic challenges in the salt marsh zones:
o Oxygen-related challenges in the zones
Salt marsh zones
48
Marshland Conservancy Sampling Site
Site
1
2
3
4
5
7
Description
Small pond crossed by walking bridge;
sample from bridge
shore directly off beach
shore directly off beach
salt pannel
stream flows into upper marsh at this
location
stream flows into upper marsh at this
location
98
49
Measurements
Salinity: use refractometer
Conductivity
Dissolve O2 Concentration
Temperature
pH
Depth-Temperature: use Thermocline
100
50
Please observe
o Diversity
-Disturbance
-Forest- trees, sunlight
-Low marsh: salt Spartina Adaptation:
secrete extra salt + high internal osmolarity
o Defense mecahnisms in plant:
-Color
-Smell
-Poison (poison ivy)
-Thorns
o Microclimatology
51