THE NEED FOR TRANSPORT - ANIMALS

Multicellular Organisms- Section 6

Animal transport & exchange systems

A large animal has a small surface area relative to its volume

It needs additional absorbing surfaces to take in oxygen & food

Once these substances have entered the body, they need to be carried to each of the cells

- this requires a circulatory system

Learning Outcomes

By the end of this section you will be able to:

- describe the pathway of blood flow through the circulatory system

- identify the chambers of the heart - identify the key structural features of

the three types of blood vessel - describe the components of blood

Structure of the heart• Divided into 4 chambers• - 2 atria & 2 ventricles• Right atrium receives

deoxygenated blood from the body

• - via the vena cava• This blood passes through

the heart• Leaves via the pulmonary

artery• Picks up oxygen in the

lungs• Returns to the heart via

the pulmonary veins• Passes through the heart,

and leaves via the aorta

Heart wall and valves• Left ventricle wall is very

thick and muscular• - to pump blood around

the body• Right ventricle wall is

thinner• - only pumping to the

lungs• The heart has 4 valves• They open and close to

let blood flow through• - ensure blood only

travels in one direction• - stops blood flowing

backwards

Blood Vessels• Arteries • - carry blood AWAY from the

heart• - have a thick muscular wall (to

withstand high pressure)• - usually carry oxygenated blood

(exception is pulmonary artery)• Veins• - carry blood TO the heart• - carry blood at low pressure• - thin walled, but have valves• - valves prevent backflow• Capillaries• - tiny vessels (1 cell thick)• - exchange materials between

blood and cells

Coronary arteries• The heart muscle needs

it’s own blood supply• - provided by the

coronary arteries• These branch off from the

aorta• They spread out all across

the heart• If they become blocked =

coronary heart disease (heart attack)

Blood An average adult has 5 litres

of blood in the body Blood transports useful and

waste substances around the body

E.g. oxygen, CO2, food, urea Blood has the following

components: Platelets - form blood clots White blood cells - involved in the immune

system plasma – liquid part of the blood - carries dissolved substances Blood also contains…..

Red Blood Cells

-Very small and numerous (5.5 million/ml of blood)

- Have a biconcave shape- - provides a larger surface

area- Small and flexible- - can easily squeeze through

narrow capillaries- Cytoplasm is rich in

haemoglobin- - in the lungs, combines with

oxygen to form oxy-haemoglobin

- - at the tissues, oxygen is released

Re-Cap questions

1) Name the four chambers of the heart

2) Name blood vessel A 3) Where has the blood in

vessel A come from? 4) Name the three types of

blood vessel, and describe the differences in their structure

5) Name the pigment in red blood cells, that helps carry oxygen

A

Structure & function of lungs

• Organs of gas exchange• Air passes in through the nose

or mouth• Then passes through the

trachea (windpipe), bronchi, bronchioles

• - and finally into the alveoli (air sacs)

• Trachea and bronchi are lined by tiny hair-like cilia

• - and cells that secrete mucus• - which traps dirt and micro-

organisms• The cilia sweep the mucus

away from the lungs

Gas Exchange• Alveoli are

surrounded by many capillaries

• Alveolus lining is very thin and moist

• Large surface area for exchange

• Breathing in:• - air enters alveoli• - oxygen dissolves in

the moist lining• - then diffuses into

the blood• - blood is now

oxygenated• - CO2 moves in the

opposite direction

Need For Digestion Food is needed for cells to: Give fuel for energy Provide building materials for - growth - repair - fighting infection (antibody

production) Digestion breaks down large

insoluble molecules - into small soluble molecules - much of the digestion is done by

enzymes These molecules can then be

absorbed into the bloodstream

Alimentary Canal A long tube running

from mouth to anus Has several

associated organs connected to it

e.g. liver, pancreas, salivary glands

These organs are connected by tubes or ducts

Pharynx (throat)

Oesophagus

Oesophagus & Peristalsis Oesophagus is a muscular

tube - connects the mouth to the

stomach It’s wall is lined with circular

muscle Contraction & relaxation of

this muscle pushes food along

This is known as Peristalsis This process continues all the

way along the alimentary canal

Small Intestine Where the majority of digestion (&

all absorption) takes place Structure: - very long - folded inner lining - covered in finger-like villi These create a large surface area Each villus has a blood capillary

and lacteal Lining is only 1 cell thick Glucose & amino acids pass into

the capillary Fat digestion products pass into the

lacteal Digestion products absorbed into

the bloodstream

A balanced diet The major food groups

that make up a balanced diet are carbohydrates, fats and proteins

Carbohydrates – provide energy for cell

activities Fats – Energy storage &

insulation Proteins – Provide materials for

growth & repair

Vitamins & Minerals

The lack of a certain vitamin or mineral in the diet can result in a deficiency disease

Vitamin

Food source

Function Effect of Vitamin

deficiency

A Dairy products

& fish

Healthy skin, good vision, strong

immune system

Night blindness

C Fruit & Veg

Growth & repair of skin

Scurvy

D Oily fish & eggs

Calcium absorption – for bone growth

Rickets

Mineral Food source

Function Effect of deficienc

y

Iron Meat & eggs

Helps form haemoglobin

Anaemia

Calcium Dairy products

Hardening bones & teeth

Rickets

Sodium /Potassium

Most foods Muscle contraction /

nerve impulses

Impaired movement

Re-cap questions

1) What is the purpose of : - the cilia - mucus 2) Explain the role of alveoli 3) Describe the mechanism of peristalsis,

with reference to a mouthful of food having been swallowed

4) State three ways the small intestine is suited to it’s role of absorbing digested food