Specialised animal cells

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Key points

  • Specialised animal cells have components that allow them to complete a specific purpose.
  • Specialised animal cells include red blood cells, sperm, eggs, nerve cells, muscle cells, ciliated cells, and villi.

Video - What are specialised animal cells?

Can you answer these questions based on the video?

1. What are the three main components of animal cells?

2. How many animal cells could fit across the width of a full stop?

  1. A nucleus, cell membrane and cytoplasm

  2. 100

Most cells share features such as having a nucleus, a cell membrane, cytoplasm and mitochondria.

Each type of cell has its own job to do. These cells have special features that allow them to perform their functions effectively.

Red blood cells

Red blood cells carry oxygen around the body, which is needed for They are well suited to this function because:

  • They contain , which carries oxygen molecules.
  • They don't have a nucleus, allowing more space to carry oxygen.
  • They are a flat disc shape with dips on both sides (biconcave). This gives them a large surface area, and the best chance of absorbing as much oxygen as they can in the lungs.
diagram of three red blood cells labelled biconcave

Sperm cells

Sperm are the male sex cell. They are made in the testes after . They join with an egg cell during to form an which can then develop into a new life. The following features make them well suited to this function:

  • A tail moves them towards an egg cell.
  • Many release energy for movement.
  • Part of the tip of the head of the sperm, called the acrosome, releases enzymes to digest the egg membrane to allow fertilisation to take place.
  • The nucleus contains the genetic material for fertilisation.
  • Sperm are produced in large numbers to increase the chance of fertilisation.
a diagram of a sperm cell labelled tail, acrosome, midpiece containing mitochondria, haploid nucleus

Egg cell

Eggs are the female sex cell. They are made in the ovaries before birth. Usually, one egg is released each month during the menstrual cycle, but sometimes this number may be higher. They join with a sperm cell during fertilisation to form an embryo which can then develop into a new life. They are well suited to this function because:

  • The egg cell’s cytoplasm contains nutrients for the growth of the early embryo.
  • The haploid nucleus contains genetic material for fertilisation.
  • The changes after fertilisation by a single sperm so that no more sperm can enter.
diagram of an egg cell labelled cell membrane, cytoplasm, haploid nucleus, mitochondria

Nerve cells

Nerve cells transmit electrical signals in the . They are well suited to their function because:

  • They are thin, and can be more than one metre long in your spinal cord. This means they can carry messages up and down the body over large distances very quickly.
  • Nerve cells have branched connections at each end. These join to other nerve cells, allowing them to pass messages around the body.
  • They have a fatty (myelin) sheath that surrounds them. The fatty sheath increases the speed at which the message can travel.
diagram of nerve cell labelled nucleus, nerve ending, cytoplasm, cell membrane

Muscle cells

Muscles cells are found in bundles which make up our muscles. These cells are able to contract (get shorter) and relax (return to original length). There are different types of muscle cell, each perfectly adapted to its function:

  • Cardiac (heart) muscle cells contract and relax to pump blood around our bodies for our entire lives. They never get tired.
  • Smooth muscle cells make up thin sheets of muscle, such as the stomach lining. They can also be arranged in bundles, or rings, like that in the anus.
  • Skeletal muscle is joined to bones. Its cells contract to make bones move and joints bend.
diagram of the three types of muscle cell

Video - Understanding muscle cells

Find out how a sports therapist uses his knowledge of specialised cells to help his clients

Ciliated cells

Ciliated cells are found in the airways. They have tiny hairs on their tops called which beat in a rhythm. These hairs move mucus containing dust and other particles upwards and out of the airways. Ciliated cells are also found in the . Here the tiny hairs beat to move the egg from the ovaries to the .

Villi

Villi are structures about one millimetre long in the and . Millions of them poke out to absorb digested food and water into the blood. They are well suited to this function because:

  • They have a large surface area.
  • They have thin walls which are only one cell thick.
  • The cells of the lining have tiny hairs to absorb more food and water.
a diagram of a villus with thin walls, network of capillaries and blood vessels labelled

Test your knowledge

Quiz

Test questions

What are the adaptations of red blood cells?

  • Red blood cells contain haemoglobin, which carries oxygen molecules.
  • They don't have a nucleus, allowing more space to carry oxygen.
  • They are a flat disc shape with dips on both sides (biconcave) which gives them a large surface area.

What are the adaptations of nerve cells?

  • Nerve cells are thin and long so they can carry messages all over the body very quickly.
  • They have branched connections at each end to allow electrical signals to pass to other cells.
  • They have a fatty (myelin) sheath that surrounds them and increases the speed at which the electrical signal can travel.