Core and Extended

*

*Cells in organisms

become

specialised to

perform certain

functions

*If similar cells

work together

they form a tissue* These cardiac(heart) muscle cells are

all the same

* They work together, forming cardiac muscle tissue

*

*Tissues work together

to perform a

specialised function

*They form an organ,

like the heart

*The heart is made of

cardiac muscle

tissue, connective

tissue and nerve

tissueThis is a sheep’s heart cut

open.

Look at the different types of

tissue present.

*Various organs work

together forming an

organ system

*The heart works

with the blood

vessels and the

blood forming the

circulatory system

*Organ systems make

up organisms!

*Over the next two

years we will learn

about some of the

organ systems in your

body

Go over the levels of organisation table on page 6

**You need to know some examples of specialised cells in

plants and in animals

*Specifically we will look at Ciliated epithelial cells, muscle

cells and red blood cells in animals and Root Hair cells

and Xylem vessels in pants

*We come back to these cells now and then through the

syllabus, so look out for them

*We will also see other specialised cells as we do other

topics; again make a note of them

*Lets look at the examples…

**The passages into the lungs have a clever system to

keep dust, bacteria and other small particles from

reaching the lungs

*These passages are lined with cells that make mucus,

called Goblet cells, and with ciliated cells

*Small particles are trapped in the mucus

*Cilia are small cytoplasmic

extensions at one end of

the cell

*Protein fibres move these

cilia like a wave

*This movement carries the

mucus out of the airways

to the back of the throat

*it is swallowed here – and

the acid in the stomach

should kill any pathogens

(disease causing

organisms)

Cytoplasm

Cilia move

in waves

forming a

current

Mucus is

moved along

nucleuscilia

Cell surface membrane

Use this information to label the drawing in your notes

**Earlier we saw a picture of

cardiac muscle

*There are different types of

muscle cells but their function is

the same: they contract to bring

about movement

*To allow this this muscle cells are

elongated and have protein fibres

in them that can shorten the cell

*When you contract your biceps all

the cells in the muscle have

shortened

This is smooth muscle

which we find in the

gut for instance

Note how all the cells

are elongated

Can you see the

nuclei?

This is Skeletal muscle. It attaches to bone, so your biceps

muscle looks like this.

The stripes are because of overlapping regions of proteins.

Note how the nuclei are squashed to the edge of the cell

because of the protein fibres in the cytoplasm

*Most of your blood is made of

red blood cells

*The red colour comes from a

pigment in these cells called

haemoglobin

*Red blood cells transport

oxygen from the lungs to body

cells where it is used to make

energy during respiration.

*Oxygen combines with

haemoglobin to form

oxyhaemoglobin

*Note the shape of the red blood cells: they are

dented on both sides

*This is described as biconcave – “bi” means twice and

“concave” means dented

*This shape gives the cells a larger surface area so

they can absorb more oxygen

*Red Blood cells are also really small so they can fit

into the tiny capillaries

*Being small makes the surface area large compared

with the volume

*They have no nucleus to make more room for

haemoglobin

This is a very high

power picture of a

capillary with red

blood cells inside

When red blood

cells are looked at

under a light

microscope they

look as if the centre

is empty because it

is so thin the light

comes straight

through

*These cells are part of the nervous system

They have a long cytoplasmic extension that carries

messages as electrical impulses

These are called nerve fibres

The cytoplasm is continuous so the impulse can move

continuously

This impulse could be carrying a

message from the brain to a muscle

The muscle will then contract

The nerve fibre is surrounded by a fatty

substance called the myelin sheath

This insulates the fibre so the impulse travels faster

The nucleus is found in an area called

the cell body

*

There are male and female gametes

These are cells specialised for reproduction

Each contains only half a set of chromosomes

1/2

1/2

*So when they combine at fertilisation the new

organism has a complete set of chromosomes

1/2

1/2

Complete set

of

chromosomes

Sperm cells These are the male sex cells

The nucleus has half a set of

chromosomes

It is in the head

Sperm cells

The male sex cell swims to the

female sex cell

So it has a tail

And in this region

there are many

mitochondria to

make energy

Egg cells These are the female sex cells

The nucleus contains half

a set of chromosomes

Egg cells

There is a lot of

cytoplasm to store

nutrients and

provide organelles

to the new cell

after fertilisation

Egg cells

The cell is

surrounded by a cell

surface membrane

Which is

surrounded by a

layer of

protective jelly

*If you look under

a microscope at

the very tip of a

root you will see

small “hairs”

*Their function is

to absorb water

from the soil

*Root hairs are

cytoplasmic extensions

from cells lining the

outside of the root; they

are called epidermal cells

*The extensions increase

the surface area for water

absorption

Label the diagram in your notes and use arrows to show where

water enters the root hair cell

*Once water has been absorbed into a plant it moves

through xylem Vessels to other parts of the plant

*Xylem vessels form columns all the way through a

plant

*Xylem vessels are elongated cells

that are places end to end to form a

long tube

*the walls between the cells fall

away so the tube is continuous and

there is no resistance to water

movement

*Plant cell walls are made of

cellulose but in xylem they are

thickened with lignin

*This is often stained red in slides so

xylem vessels have thick red walls

This is what xylem

vessels look like in the

centre of a root

Note how thick the

walls are and that they

have been stained red

*The lignin makes the cell

wall impermeable, so the

contents of the cells die

*This means that the lumen

is hollow and there is no

cytoplasm so no resistance

to water flow

*Lignin is strong so xylem

vessels also provide plants

with support

Note the way these xylem vessels have

rings of lignin thickening

Now go over your notes and highlight the

important parts