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Chapter 6
Distribution of materials
Blood circulatory system of mammals
 Transport of materials to and from the cells of tissues (eg,
brain, muscles) is carried out by a blood circulatory system
 The circulatory system consists of:
 Blood vessels: arteries, veins, capillaries
 The heart: a muscular pump to keep the blood moving
 Refer to Figure 6.4 pg 131
Components of blood
Blood is made up of many components:
 Plasma
Is about 90% water, the rest is molecules dissolved in the water
Makes up about 55% of blood
Refer to table 6.1 pg 132 for the dissolved molecules of plasma
 Blood cells
 Red blood cells (erythrocytes)- contain haemoglobin- the ‘oxygen
carrying’ component of blood.
 White blood cells (leucocytes)- part of the immune system, combat
infection. There are different types of WBC’s.
 Platelets- involved in clotting of the blood
Vessels to transport blood
 Arteries- carry blood away from the heart.
 Have thick walls to withstand blood pressure pumped out of heart, however,
these walls are too thick to allow easy movement of substances in and out of
blood and tissue
 Smaller arteries are called arterioles
 Veins
 Transport blood back to the heart
 Have thin walls, blood is under lower pressure as it has travelled further
from the heart
 Veins have valves that prevent the backflow of blood (think about blood
travelling from your feet back to your heart)
 Capillaries
 Thin walled small blood vessels- walls are 1 cell thick, allowing for easy
passage of substances in and out of blood
 Heart  Arteries  Arterioles  Capillaries Venules  Veins 
Heart
Questions
 Quick check pg 136 1-3
 When you finish, read through pages 129-136 paying
particular attention to the diagrams
 Next we will be going through answers to the homework
questions from pgs 125-126
The heart
 The heart is effectively 2 pumps joined together
 The right side receives blood from around the body and pumps
it to the lungs to receive O2 and drop off CO2
 The left side receives blood from the lungs (O2 rich) and
transports it to the body via the main artery- the aorta
Pathway of blood in the heart
Aorta  the body  inferior vena cava & superior vena cava  RIGHT
ATRIUM tricuspid valve  RIGHT VENTRICLE  pulmonary
artery Lungs Pulmonary vein  LEFT ATRIUM  bicuspid
valve  LEFT VENTRICLE  Aorta
Italics = blood vessel
CAPITALS = significant structure in the heart
Inside the heart
 The ‘septum’ separates the right and left sides from each
other
 Each side has two chambers- an atrium and a ventricle.
 The two atria have thin walls as their job is to ‘receive’ blood
into the heart
 The ventricles have thick walls as their job is to pump blood.
(LEFT ventricle has the thickest as it has the bigger job to do)
 Pulmonary artery & vein = responsible for blood traffic
between heart & lungs
Heartbeat
 Average adult HR between 60 & 90 beats per minute
 Rhythmic beating controlled by a ‘pacemaker’ called
sinoatrial node- electrical impulse that spreads throughout
the heart
Different circulatory systems
 Closed: blood remains in blood vessels at all times (things
may enter and leave it but the blood stays)
 Open: blood is sometimes in vessels and sometimes in tissues
The lymphatic system
 When O2 and nutrients leave capillaries some fluid escapes.
 The lymphatic system ‘picks up’ this fluid and returns it to
the blood stream- it is a ‘one-way’ system
 The lymphatic system does not have a pump- it relies on
valves to prevent backflow, muscular movements, pressure
from nearby blood vessels.
Transport of nutrients
 The products of digestion need to be transported to cells in a
form that is small enough to cross the cell membrane
Enter the body as
Digested to
Polysaccharides
Simple sugars (eg
glucose)
Fats
Glycerol & fatty acids
Proteins
Amino acids
 Questions 4-10 pg 142
Transport of gases
 Blood transports O2 to cells and takes CO2 away
 Gas exchange occurs at sites where O2 enters and CO2 is
removed (or vice versa) eg at cells, at the lungs
 http://www.vcaa.vic.edu.au/vce/studies/biology/biologystd.pdf
Pharynx and Larynx
 When we breathe in, air passes through the pharynx (throat)
and the larynx (voice box)
Trachea
 After the larynx, air travels down the trachea (windpipe)
which is reinforced with rings of cartilage to ensure that it
does not collapse
Bronchi & bronchioles
 Air moves from the trachea into 2 bronchi (singular = bronchus)
 If the trachea can be compared to a tree trunk then each bronchus
is a very large branch coming off the trunk.
 Smaller and smaller branches exist throughout the lungs
Trachea  bronchus  bronchioles  alveolar duct  alveolar sac
 alveoli
There are around 300 million alveoli in our lungs. These are the site
of gas exchange.
Transport of wastes
 Wastes are produced by metabolic activity. [For instance,
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when protein is metabolised (broken down) in a cell
ammonia is formed]
Removal of wastes is called excretion
CO2 excreted via lungs (breathing out)
Nitrogenous wastes (eg urea) excreted via kidneys
Ammonia is converted to urea or uric acid depending on how
much water is available.
The urinary system in animals deals with waste products such
as urea
The urinary system
 In humans, the urinary system consists of 2 kidneys, 2
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ureters, a bladder, and a urethra
Kidneys: filter the blood and remove wastes
Ureter: transports urine from kidney to bladder
Bladder: stores urine
Urethra: transports urine from bladder to outside the body
Kidneys
 Functional units of the kidneys are called ‘nephrons’
 Each kidney contains about 1 million nephrons
Refer to page 152
Read page 153-154 together
Transport in plants
 The plant transport system consists of phloem and xylem
 Xylem transports water and dissolved minerals
 Phloem transports sucrose (produced by photosynthesis) to
other regions of the plant
Movement of water in xylem
 Water is absorbed by root hairs, moves through the cortex
(layer of tissue between hair and xylem) and into the xylem
 How can trees be up to 100 m tall?
 When stomata open, water loss occurs as vapour evaporates
from them.
 As water evaporates from mesophyll cells, water from the
xylem moves into mesophyll cells. This sets off a ‘chain reaction’
where water is drawn up the xylem
 All of this is possible because water molecules like to ‘stick
together’ a property called ‘cohesion’
Movement of organic substances
through phloem
 Soluble (dissolvable in water) organic substances are
transported by phloem tissue from the leaves (where they are
made) to other parts of the plant (that don’t photosynthesize)
 Transport also occurs between storage sites (where excess
sugars are stored) to parts of the plant requiring energy
 This process is called translocation
 Sugars exit the phloem via active transport and move into
cells for storage or immediate use.
Gaseous exchange in plants
 CO2 is needed for photosynthesis
 CO2 must enter the plant from the air surrounding it
 Stoma (or stomata- pl) are the gateway for CO2 to enter
Stomata: gateways in leaves for
gaseous exchange
 Stomata are surrounded by 2 guard cells which can be either
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‘turgid’ or ‘flaccid’
Turgid: high water content- cell is upright and ‘full’ of water
Flaccid: lower water content- cell is ‘relaxed’
See picture pg 164
When guard cells are turgid, the stoma is open and allows
CO2 to enter
Open Stomata: potential loss of water
vapour
 When stomata are open, water loss occurs. Under ordinary
conditions, the concentration of water vapour in the area
surrounding the stoma will be lower than in the cells of the
stoma, therefore water will move from area of high conc, to
the area of low conc.
 Under dry conditions, there is the potential for this water
loss to become excessive as water will move at a faster rate.
 Some plants have adaptations to protect from excess water
loss (eg sunken stomata)
Gaseous exchange across root hair
surfaces
 Living cells in roots require O2 for respiration
 Soil has spaces containing air that can diffuse into root hairs
Excretion in plants
 Plants have a higher tolerance for fluctuations in their
environment (ie the build up of toxic substances) than
animals do.
 In plants, ergastic substances is the term used (instead of
excretory products) This term refers to the products of
photosynthesis as well as waste products.
 Wastes are often stored in vacuoles (dissolved in water) and
cell walls
 Plants are able to shed parts of themselves to rid themselves
of wastes- eg shedding of some leaves. (imagine animals
needed to lose part of their body to get rid of wastes)
Comparison of plants & mammals
Plants
Mammals
Are ‘heart-less’- oxygen
enters via diffusion or as a
result of photosynthesis
Do not have ‘bulk’ transport
of oxygen
Make their own food via
photosynthesis at locations
around the plant
Have a heart and continuous
supply of oxygen via the
circulatory system
Have haemoglobin in RBCs
that carries oxygen
Have ‘bulk intake’ of food
and oxygen which requires
transport around the
organism