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Biology 1.5
Demonstrate understanding o biological
ideas relating to a Mammal as a
Consumer – external – 3 credits
How can I do a good job?
 Check
out what you need to know in your
workbook.
 It is important that you always know where you are
heading and what is expected of you.
 What do you need to do to achieve, get merit?
 What about excellence?
 Keep in mind what you need to be able to do while
you learn your work and ask questions, look up
answers and more information when you need it.
Introduction -A mammal is an
animal
An animal is:
 a multicellular organism - made of many cells

It is heterotrophic, which means it feeds on
other plants and/or animals

capable of moving

respond to factors or stimuli in their
environment, such as temperature, light etc.
Features of a mammal?
A mammal
 Vertebrate – has a backbone
 has four chambered heart
 Has lungs for gas exchange
 homoeothermic - warm blooded
 Has fur and/or hair
 mammary glands - to feed young by
producing milk
Types of mammals
 Monotremes
platypus.
- lays eggs, eg, echidna and
 Marsupials
- pouches, eg, kangaroo,
possum, koala
 Placental
- placenta attaches embryo to
uterus by umbilical cord, eg, cat, dog, lion,
human, rat!
What advantage is it to be
warm blooded?
A
warm blooded animal is able to
maintain a constant body temperature
even in cold weather. This means their
chemical reactions will occur at a
constant rate. Enzymes have very
specific temperature ranges in which they
are most efficient and they are most
efficient between the range of 37⁰C - 40⁰C
Why do animals need to eat?
Animals are consumers. They ingest food to
obtain the nutrients they need for their life
processes – respiration, movement, growth,
chemical reactions (metabolism) that occur
in the body.
 Growth - provide energy and materials for
DNA replication, mitosis and cell division.
 Repair of tissues
 Energy to carry out all the chemical
reactions in cells
What’s the energy used for?
 Energy
is used for growth, reproduction,
excretion, movement, respiration, cell
division, sensitivity and active transport of
substances across the membranes of
cells.
 More detail later…..
Nutrition – the big picture
 Mammals
are multicellular organisms,
and..
 All those cells need food, oxygen and
waste removed
 Cells are tiny, so nutrients must be tiny to
get across the cell membrane.
 This is why food must be digested – to
make food particles small and soluble
An animal cell
Active transport into the cell
Food classes
 When
food is ingested it needs to be
digested. There are different classes of
food and they all have their uses.
 Carbohydrates
 Lipids
 Proteins
 Read and highlight your work book and
answer the questions on pages 10-11.
 Write a list of what each of the three
classes is mostly used for in the cell.
What are the foods broken
down into?
 Proteins
into amino acids
 Carbohydrates into soluble single sugars
 Lipids to soluble fatty acids and glycerol
What are the basics of
digestion?
1.
2.
3.
4.
5.
Ingestion – food taken in the mouth
Digestion – physical and chemical
(enzymes) breaking down of food
Absorption – small soluble food particles
pass from gut into capillaries
Assimilation – small soluble food
molecules enter cells and used for
growth, repair and cellular respiration
Egestion – undigested food such as plant
fibre leaves the anus as faeces
Find out the answers
 What
is the name of the tube food goes
down from the mouth?
 What is the pH of the stomach?
 What is the pH of the secretions from the
gall bladder?
 Where is chemical digestion carried out?
 Where does most of the absorption of
food occur?
 Where is water absorbed?
Define the digestive system
 The
gut or alimentary canal is a long tube-like
system where food is processed along an
assembly line of specialised organs producing
specific enzymes to break the larger molecules
into small soluble ones.
 This is needed so that nutrients can dissolve and
cross from the digestive system into the small
capillaries, and then cross the cell membranes
of cells needing the nutrients.
The different digestive system
of a herbivore
 Cellulose
found in plants is difficult for
mammals to digest as they don’t produce
enzymes needed to break down cellulose
into glucose particles. Herbivores have
micro-organisms in areas of the gut that
produce the enzymes. Their gut is long to
increase the time available for digestion.
The different digestive system
of a carnivore
 Their
digestive system is specialised to
digest protein. It is easily digested as the
enzymes are produced by the mammal
and the gut does not need to be so long.
Omnivores
 They
are neither specialised for cellulose
or protein and their gut is intermediate in
length.
 We are omnivores.
The first step – physical
digestion
 Physical
digestion occurs when food is broken
down into smaller pieces by the teeth or the
muscle action of the stomach wall.
 This increases the surface area available for
the enzymes in chemical digestion to work on
which increases the overall efficiency of the
digestive process.
 This breaks proteins into soluble amino acids,
carbohydrates into soluble single sugars such
as glucose, lipids to soluble fatty acids and
glycerol.
 The cells use these for energy and growth.
Teeth
Teeth
 Four
different types of teeth:
1. Incisors
2. Canines
3. Molars and premolars
 See your workbook pg 16.
 The different teeth have different
functions – list these next to the names.
 Note the different movement of the jaw
on pg 18.
 Complete pg 19
What are the similarities between the
teeth of mammals?





Herbivores and carnivores both have teeth in their
mouths involved in physical digestion.
They both have three types of teeth, incisors,
canines and molars.
The teeth play a major role in physical digestion of
food.
The teeth are firmly anchored into sockets of the
jawbone and they consist of the same basic parts
of enamel, dentine, pulp and cement.
However, their shape, structure, number and
position vary, depending on what the mammals
diet mainly consists of.
What differences are there between
the teeth of mammals? Carnivores:
 Canines
to catch
 Canines tear food
 Canine penetrates with great force
 Canine length can pierce vital organs
 Incisors cut or scrape flesh away from bone
 Molars are sharp
 Jaw moves up and down
Herbivores:
 Plant
material is tough
 Reduced number of incisors in upper jaw
 No canines in upper jaw
 Canines in lower jaw reduced in size and
not sharp
 Molars are large and flat to grind plant
material
 Jaw chews from side to side
Differences discussed for E
 Carnivores
eat meat and so they can
efficiently do this, their teeth have adapted
in several ways to aid with catching, killing
and eating other live animals.
 Firstly, their canines are long, sharp, and
together with the jaw can generate great
force. Their length allows them to puncture
vital organs and their sharpness effectively
tears and rips flesh from their prey’s bones.
 The incisors are sharp and used to cut and
scrape flesh from bones.
 The molars are also sharp and act like scissors
to cut meat up as the carnivore chews.
 Herbivores
in contrast have adapted teeth
to allow them to break up tough plant
material such as cellulose.
 They generally have fewer incisors in their
upper jaw and canines are absent. They
are sharp, chisel-like and located at the
front of the jaw to enable the mammal to
bite and ingest the grass/leaves.
 Canines are present in the lower jaw, but
significantly reduced and blunt in
comparison to the carnivore’s razor sharp
canines. They are used to bite only when
chomping plant material.
 The
large, flat, molars have a large
surface area to crush, grind and break
plant material into small pieces that can
be easily swallowed and worked on by
digestive enzymes so they are at the rear
of the jaw and have large, sharp ridges
with thick enamel to grind the cellulose
fibres.
 The plant material needs constant
mastication to separate the fibres and
break open plant cell walls.
Why are teeth important in the
physical digestion of food?
 These
adaptations allow the mammals to
extract energy from the food they consume in
order for them to survive and not develop a
deficiency disease. Herbivores need to break
down the tough cellulose cell wall of the plant
to access the available energy. Their modified
molars and jaw allows them to do this.
 Carnivores on the other hand need to be able
to catch, kill, tear, and rip flesh off other
animals. Thus they need teeth that can tear
and rip at flesh so they can access energy
stored in the food to carry out life processes.
 Food
must be fully digested by the
digestive enzymes. Enzymes work most
efficiently on small pieces of food with
large surface areas. Small pieces of food
also move more easily through the
digestive system and are less likely to cause
blockages.
Tooth Structure
Enzymes
 Enzymes
are proteins that speed up or
catalyse chemical reactions in living things.
 Digestive enzymes are secreted by various
organs of the digestive system to chemically
digest food particles into smaller particles.
 They are specific for a particular reaction
 They have optimal pH requirements.
 They are affected by temperature – many
having a optimal temp of 37⁰C.
Chemical digestion in the mouth
 When
food is taken into the mouth the
salivary glands found in the cheeks and under
the tongue release saliva which is mixed with
the food as it is chewed.
 The pH of saliva is around neutral, pH 6.4 to
7.4
 Saliva contains an enzyme called amylase.
 Amylase breaks down starch (a long chain of
glucose molecules) into glucose.
 Saliva also contains mucin, a slimy substance
that moistens and softens food.
Do carnivores have amylase?
 Only
omnivores and herbivores have
amylase in their saliva.
 Carnivores do not have amylase.
 Carnivores eat protein material from other
animals. Mammals do not store their excess
glucose as starch as plants do. Animals
store their excess glucose as glycogen in
the liver and the rest is changed to fat.
 So, no starch is found in animal cells so
carnivores do not need starch-digesting
enzymes.
Peristalsis in the oesophagus
 There
are special muscles that go around the
oesophagus as well as down its length, the
circular and longitudinal muscles.
Digestion in the stomach
 Physical
and chemical digestion occurs in
the stomach.
 Physical digestion – thick muscular walls of
the stomach are constantly contracting to
mix the food with the gastric juices to
produce chyme.
 Stomach pH is very acidic pH 1 to 2. The
acid is produced by cells in the stomach
wall. It kills bacteria, makes the protease
work and stops amylase.
 Cells in the stomach wall also produce
protease enzymes to digest proteins into
amino acids.
The action of protease
How come the stomach
doesn’t get digested?
 The
stomach wall is lined with a layer of mucous
to protect it against the action of enzymes and
acid.
Renin and baby milk
 Baby
mammals rely solely on milk for all
their energy and nutrient needs.
 Baby mammals produce an enzyme in
their stomachs that makes milk protein
turn into solid.
 As renin coagulates milk, it can be used to
make cheese.
The completion of digestion
 The
liver produces bile which is stored in the gall
bladder. pH 7.5-8.0
 The gall bladder releases bile via the bile duct
into the duodenum, the first part of the small
intestine.
 Humans produce 1L of bile a day
 Bile is alkaline and neutralises stomach acid.
 Bile breaks up large globules of fats and oils (with
a small surface area) to form a suspension of
many small droplets (large SA). This increases
the surface area to volume ratio for chemical
digestion.
 It
is green and it acts like a detergent –
emulsification – enables enzymes in the
duodenum to dissolve fat.
 Also contains salts which help break up
the fat globules to increase the surface
area.
 Peristalsis in the duodenum helps to mix
the chyme with the bile and the enzymes,
enabling rapid and complete digestion.
 See work book pg 30-33
The pancreas
 The
pancreas produces pancreatic juice
that is released into the duodenum
through the pancreatic duct.
 It contains several enzymes that work best
in the alkaline conditions provided by
bile.
 Amylase digests starch
 Lipase digests fats
 Trypsin completes the digestion of
proteins.
Absorption in the Ileum
 Peristalsis
moves digested nutrients and leftover
waste to the ileum, where absorption into the
bloodstream occurs.
 The surface area of the ileum is increased by
the folding of the internal wall into millions of
tiny finger like villi. The villi cells also have
microvilli, which are microscopic folds of the
surface membranes of the cells.
 The epithelium (lining of the ileum) is very thin.
 This all ensures rapid transfer of digested
nutrients from the ileum to the blood.
 Digested
proteins and
carbohydrates are
absorbed into the blood
capillaries by diffusion
and active transport,
which requires energy.
 Capillaries have thin
walls.
 Capillaries join the
hepatic portal vein
which takes the nutrients
to the liver for storage.
 Digested fats go into the
lacteal which joins to the
lymph vessel which goes
into the blood stream.
Other facts
 Most
of the water is absorbed in the small
intestine with the remaining absorbed in
the colon.
 Lots of mitochondria in the cells of
digestive system because lots of energy is
needed.
 Lots of blood directed to the intestines
after a large meal – don’t exercise.
The large intestine – colon and
rectum - egestion




Peristalsis moves undigested food (mostly
cellulose) into the colon (large intestine). The
second half of the colon secretes mucus that
binds the wastes together and lubricates them
so they pass through easily.
Water is absorbed.
Millions of bacteria ferment some of the
carbohydrates. The bacteria release fatty
acids that can be used as energy and help
minerals absorption.
Faeces pass into the rectum, and is egested
through the anus when the anal sphincter
relaxes.
Homework
 Write
1.
2.
3.
4.
a paragraph on the causes of these:
Bowel cancer
Constipation
Diarrhoea
Find out what the appendix is
Assimilation
 Following
absorption into the bloodstream
nutrients can be assimilated:
 Used by body organs to make new substances
 Used by cells for energy
 Stored until needed, eg, glycogen is how
glucose is stored in the liver.
 Broken down into other substances, eg amino
acids not used by the body are broken down
into urea and excreted by the kidneys.
 Assimilation is the process by which food is
absorbed and used
The role of the liver in
assimilation of digested nutrients
 Glucose,
amino acids, fatty acids, glycerol,
vitamins and minerals all enter the hepatic
portal vein and go to the liver.
 The liver stores vitamins and minerals.
 Glucose is stored as glycogen until needed.
When needed it is converted back into
glucose.
 Unwanted amino acids are broken down
(deanimated) and urea is produced.
 Fatty acids and glycerol are stored for
energy.
From the liver to the blood
 When
the nutrients are needed they are
released from the liver and go into the
hepatic vein.
 The blood then travels around the body in
the main circulatory system.
 Urea also travels the same way.
 Nutrients are absorbed by cells as
required.
 Urea goes to the kidney and is turned into
urine, stored in the bladder and removed.
Cow digestion - herbivore
A
foregut herbivore
 Digestion mostly in stomach
 Ingestion and physical digestion – grip grass
between incisors and lower horny plate
and rip  long tongue pushes food to back
 Large flat surfaces of molars with ridges
grind food.
 Diastema enable tongue to move food
around to make sure thoroughly chewed
 Food in stomach is regurgitated to be
chewed again – chewing the cud. Helps
digest cellulose.
 Saliva
doesn’t contain amylase. Stomach
has 4 parts –rumen, reticulum, omasum,
abomasum,. They have a small intestine
and a caecum, large intestine and colon.
 Chemical
digestion :
 fermentation – bacteria in stomach and
caecum. Bacteria are anaerobic and
produce carbon dioxide and methane
gas.
 Enzymes – produces as in humans.
 Peristasis can go in reverse in the
oesophagus!
 Rumen
– bacteria, muscular contractions,
pH 5.5 to 7, temp 37-40.
 Reticulum – regurgitates food
 Omasum – folded to absorb water and
salts.
 Abomasum – true stomach – digestive
enzymes, pH 2-3, 38.6 degrees.
Rabbit digestion
 For
homework – find out the way that a
rabbit gets food and digests food.
 It’s a bit different – stomach acid kills
bacteria, little digestion occurs in the
stomach, caecum and colon are long,
top and bottom incisors with diastema,
amylase in mouth, trypsin, amylase and
lipase present in intestines.
 Then they do something a little strange….
Transport
 Once
the food is digested it is transported
to the liver. Food travels into capillaries,
then veins back to the heart. The heart
pumps the blood out through Arteries.
 Capillaries are important – tiny vessels that
enter the tissues of the body and are
close to the cells. The capillaries transport
the blood cells and the fluids in which all
of the nutrients are carried.
 Cool resources
Function of circulatory system
The circulatory system consists of the heart, blood
and blood vessels. It transports:
 gases, like oxygen from the lungs to cells around
the body and carbon dioxide from the cells to the
lungs.
 nutrients like glucose.
 wastes from cells to organs that play the role of
eliminating them.
It also :
 contains cells that fight infections and defend
against foreign bodies.
 Maintains the pH levels and ionic concentration of
fluids in the body.
 Helps maintain the body temperature, this is
especially important in warm blooded animals like
humans.
The need for oxygen
 Oxygen
is need by all living cells for cellular
respiration to release energy from food.
 Cellular respiration is aerobic, requires oxygen.
 The equation:
 There
are many chemical reactions that occur.
Where does the oxygen come
from?
 The
lungs is the most important organ to provide
oxygen for respiration.
 Oxygen dissolves in the fluid lining of the alveoli
and the oxygen diffuses into the blood.
 Oxygen is carried on the red blood cell and is
released in the tissues.
 It then diffuses into the cells where it is used for
respiration.
Where does respiration occur?
 Respiration
occurs within mitochondria.
 Some
of the chemical reactions take
place on the many inner folds of the
mitochondria, the cristae. The may folds
give it: a large surface area for enzymes,
many enzymes can be present in one
mitochondria, and a high rate of
respiration
Why cellular respiration?





Cellular respiration involves the breakdown of
glucose molecules by respiratory enzymes
which convert glucose into carbon dioxide and
water.
The energy released in the process is captured
by ATP which is then used to provide energy for
all cell processes.
It is essential to make larger molecules
(metabolism) and enables muscle cells to
contract so that mammals can move.
It is also necessary for active transport of
chemicals.
The mammal could not survive without
respiration as it wouldn’t be able to move, geed
grow or repair itself.
Done!