Specialised Animal Cells

Most animal cells are specialised. They have adaptations that help them perform specific functions. Humans are made up of trillions of cells; however, there are only about 200 different types.

  • The process in which cells become specialised is called differentiation

Red Blood Cells

Red blood cells carry oxygen around the body for aerobic respiration. They have no nucleus, so they can contain more oxygen-carrying haemoglobin. As red blood cells have no nucleus, they also have no DNA.

Also, red blood cells are a biconcave disc shape to make them more flexible and allow the cells to move smoothly through the circulatory system. This shape also maximises the absorption of oxygen.

A close up illustration of a red blood cell

Nerve Cells

The function of nerve cells is to carry electrical impulses around the body. A nerve cell has a cell body which contains most of the subcellular structures. There are extensions connected to the cell body:

  • Dendrites receive signals from other neurons and carry them inwards.
  • Axons carry electrical impulses away from the cell body, so they can be received by other neurons.

The axon is covered in a fatty myelin sheath, which increases the speed of nerve impulses.

Nerve cell with two extensions, which are dendrites and axons, which are covered in a fatty myelin sheath

Sperm Cells

Sperm cells are found in males and their function is to pass on the father’s DNA. A sperm cell joins with an egg cell and this is called fertilisation. During fertilisation, the genetic information of the sperm cell and the egg cell combine.

Sperm cells have many adaptations:

  • The genetic information is contained within the nucleus of the sperm cell. Sperm cells are gametes, so they are haploid, meaning that they only contain half the amount of genetic information as a body cell.
  • A sperm cell contains lots of mitochondria because they require a lot of energy to move.
  • The sperm head (acrosome) is full of enzymes which help break down the membrane of the egg cell and break in for fertilisation.
  • Sperm cells have a long tail which helps them to swim. The tail can rotate to propel the sperm cell forward.
Close-up illustration of a sperm cell with its elongated tail and compact head

Muscle Cells

Muscle cells create a pulling force to move parts of the body. They can contract (get shorter) because they contain filaments of protein that slide over each other. Muscle cells have plenty of mitochondria packed into them to provide energy (through respiration) for muscle contraction.

There are three types of muscle in animals:

  • Skeletal
  • Cardiac
  • Smooth
Diagram of the three types of muscle cells in animals - skeletal, cardiac and smooth muscle

Egg Cells

Egg cells are found in females and their function is to pass on genetic material to the next generation. They have a unique cell membrane which only allows one sperm to penetrate through. After fertilisation, the membrane changes so that no more sperm can enter.

Most of the genetic information is contained within the nucleus of the egg cell. Egg cells are also gametes, so they only contain half the amount of genetic information as a body cell.

Close-up illustration of an egg cell showing its nucleus, cytoplasm and cell membrane.
  • Eggs are one of the largest cells in the body

Ciliated Epithelial Cells

Ciliated epithelial cells move particles or fluid over the epithelial surface. They are found in the lungs and fallopian tubes. They have many cilia on the top surface of each cell.

  • In the lungs, these cilia help move mucus out
  • In the fallopian tubes, they help with the movement of the egg cell toward the uterus
Close-up illustration of an epithelial cell showing its distinct nucleus, cytoplasm, and tightly packed neighbouring cells.

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