Transcript Document

Wyebank secondary
Grade 10
Life Sciences
Transport in Animals
Khoza M.M
Overview: Transport and Exchange
Every organism must exchange materials with its
environment
Exchanges ultimately occur at the cellular level
In unicellular organisms, these exchanges occur
directly with the environment
For most cells making up multicellular organisms,
direct exchange with the environment is not
possible
Gills are an example of a specialized exchange
system in animals
Internal transport and gas exchange are
functionally related in most animals
Introduction
• The cells of all organisms need energy for their
survival.
• This energy comes from food which need to
undergo cellular respiration to release energy.
• During cellular respiration CO2 also released and
O2 is required.
• As a result of other metabolic activities cells give
off excretory wastes.
• Therefore, there must be a way for the cells organisms to receive food
and get rid off CO2 and other excretory wastes.
• The very small organisms such as the unicellular Amoeba
don’t need a transport system. Different substances diffuse
in and out of their bodies across surface membranes.
• In larger organisms the process of diffusion will occur only up to a few
cells into the body from the surface. Also with skin, fur and feathers
acting as barriers the process is slowed.
• It is inefficient as necessary substances will not reach to cells in
required time.
Simple organisms
When your body is only 2-cell layers thick, you can get
supplies in and waste out just through diffusion
• all cells within easy reach of fluid
Jellyfish
Hydra
Why some animals do not need a transport
system?
• The cells receive food directly from the water in
which they live.
Example: In the phylum porifera (e.g sponges) and
phylum cnidaria (e.g Jelly fish)
Fig. 42-2a
Circular
canal
Mouth
Radial canal
(a) The moon jelly Aurelia, a cnidarian
5 cm
• Also, oxygen enters the cells from the water, and carbon dioxide and
other excretory wastes are shed into the water, by the process of
diffusion.
• In slightly larger animals such as those belonging to the phylum
platyhelminthes (e.g. Planaria), food reaches the cells by means of
pouches in the gut.
• The cells of such animals which do not receive their food by diffusion
from other cells.
• Their supply of oxygen and release of carbon dioxide and other
excretory wastes, are by means of diffusion.
Examples are Porifera and Cnidarians
Why do animals need a Transport
system?
• A transport system carries things to and from one
place to the next.
• Diffusion will occur only up to a few cells into the
body from the surface. Also with skin, fur and
feathers acting as barriers the process is slowed.
• It is inefficient as necessary substances will not reach
to cells in required time.
• In most other animals most of the cells are too far away from the cells
that obtain food, or from those that are in direct contact with the
environment.
• Examples are those that belongs to the phylum Annelida, Mollusca,
Arthropoda and the vertebrates
• This means that diffusion is not good enough to
transport digest food to all the cells;
• it is also inadequate to get rid of carbon dioxide
and other excretory wastes from the cells.
• A special transport system is necessary to
transport digested food, oxygen, carbon dioxide
and other excretory wastes.
• The transport system of animal are each made up of blood tissue,
blood vessels and a heart, making up a circulatory system.
• The pumping action of the heart puts the blood under pressure,
forcing it through its blood vessels and then back again to the heart.
Open and Closed Circulatory Systems
• More complex animals have either open or closed
circulatory systems
• Both systems have three basic components:
• A circulatory fluid (blood tissue)
• A set of tubes (blood vessels)
• A muscular pump (the heart)
Open and closed blood systems
• In an open blood system, blood is pumped from the heart through
blood vessels and reaches interconnected blood-filled spaces or
sinuses called haemocoels.
• The organ lie within these haemocoels and receive their oxygen and
food by diffusion from the blood which bathes (washes) them.
Open Circulatory System
• CO2 and other excretory
wastes are also shed
into the haemocoels by
diffusion.
• This blood, laden with
CO2 and other excretory
wastes enters the heart,
through small openings
on it.
Haemocoel in which
organs are present
• From the heart, the
waste products are
taken to excretory
organs by blood.
• Most molluscs and
arthropoda have an
open blood system
Open Circulatory System
• Open circulatory systems tend to be found in more
inactive animals.
• Most molluscs have an open system, but the highly
active cephalopods (squid and octopus) have
evolved a closed system.
• Insects have avoided limitation of their open
system by their tracheal system for oxygen supply.
Open circulatory system
• Blood vessels lead into a cavity, which leads into a network of interior
channels and spaces.
• Blood moves freely inside the body cavity in all directions.
• Arthropods are a group of animals consisting mostly of insects that
have an open circulatory system.
Open Circulatory System
• Advantage - There is no diffusion barrier.
• Disadvantage - No mechanism for reducing flow to a
specific part of an organ.
Feeding
Energy
Needs
• Why do we need a circulatory
system?
• supplies in
• fuel (sugars)
• digestive system
• oxygen
• respiratory system
• waste out
• CO2
• respiratory system
• need to pick up & deliver the
supplies & wastes around the
body
• circulatory system
Closed blood system
• In a Closed blood system, the heart pumps blood into the large blood
vessels.
• The smallest vessels which branch to form smaller and smaller vessels
• The smallest vessels, called capillaries reach the organs.
• Here food and oxygen from the blood
diffuses into the tissue fluid
surrounding the cells of the organs .
• Also Carbon dioxide and other
excretory wastes diffuses from the cells
into the tissue fluid and then into the
blood.
• The blood is then returned to
the heart from where it is taken to the
 Digestive system to pick
up food.
 Lungs to pick up oxygen and
get rid of carbon dioxide
 and excretory organs to
get rid off excretory wastes
• Earthworms, larger molluscs i.e squids and
octopuses and vertebrates have closed blood
systems.
Closed Circulatory System
• The blood is contained
within a completely closed
system of vessels.
• Vessels form a closed loop,
usually with some sort of
pumping organ like a heart
or contractile vessels.
• Vessels branch into smaller
and smaller tubes that
penetrate (enters) among
the cells of tissues.
Closed Circulatory System
Advantages:
• Fine-scale control over the distribution of blood to
different body regions is possible.
• Muscular walls of vessels can constrict and dilate
(open) to vary the amount of flow through specific
vessels.
• Blood pressures are fairly high and the circulation
can be vigorous (forceful).
• Blood vessels lead from one type of vessel to
another, not into a body cavity (opening).
• Blood flows in one direction, continuously.
• Vertebrates have a closed circulatory system.
Worksheet 1
1. Fill in the missing words
1.1 During cellular respiration also Carbon dioxide released and Oxygen
is
required.
1.2 In some Animals Diffusion is not good enough to transport digest
food to all the cells thus a special transport system is necessary to
transport digest food , oxygen, carbon dioxide and other excretory
wastes.
1.3 Carbon dioxide and other excretory wastes are also shed into the
haemocoels diffusion.
1.4 More complex animals have either open or closed circulatory
systems but both systems have three basic components which are: 2.1
blood tissue; 2.2 blood vessels; 2.3 and a heart.
3. Give the correct biological term in the following
statements
3.1 Here food and O2 from the blood diffuses into
the tissue fluid surrounding the cells of the organs.
Open circulatory system
3.2 Blood vessels lead into a cavity, which leads into
a network of interior channels and spaces. Closed
circulatory system
Comparison of open and closed circulatory
systems
Organisms (/)
Open System
Closed System
Invertebrates
Vertebrates
Location Of blood
Body fluid and
blood freely fills
the body cavity
Efficiency of blood Slow and limited
flow
Blood is contained
in the arteries and
veins
Fast and good
Examples of
organisms
Human being, cow,
Squid, octupus,
gastropoda