Body Systems (YEAR 8)
2.1 Body Systems in action
KEY TERMS:
Body system - A group of organs and tissues that work together to perform specific functions necessary for the survival and health of the organism.
Hormone - A chemical messenger produced by glands in the endocrine system that regulates various physiological processes in the body, including growth, metabolism, and mood.
Organ - A structural unit of the body composed of different types of tissues that work together to perform specific functions, such as the heart, lungs, and kidneys.
Tissue - A group of similar cells that work together to carry out a specific function in the body, such as muscle tissue for movement or nervous tissue for transmission of signals.
Cells work together as tissues organs and systems
Cells with similar functions form tissues, and tissues form organs. Two or more organs connected and working together form a body system. Unicellular organisms work alone.
Animals have several body systems
Most animals, such as humans have 11 major body systems.
Circulatory- moves nutrients, gases and waste products around the body.
Nervous- detects, processes and send electric signals
Respiratory- exchanges gases with the environment
Digestive- breaks down and absorbs food
Muscular- allows movement through the use of muscles
Skeletal- provides support and structure to the body and organs
Endocrine- produces the hormones that control growth and development
Excretory- removes body wastes
Reproductive- produces sex cells and supports pregnancy and birth
Immune- protects the body from damage
Integumentary- protects the body from damage
2.2 Tissues and organs in animals
KEY TERMS:
Differentiate- to change to have a particular function
Tissues are specialised cells
Stem cells are beginner cells. The four main types of tissue:
Epithelial - forms the skin and the body’s inner linings
Connective- transports substances to where they’re needed
Muscle - contracts and relaxes to carry out different functions
Nerve - transmits information between the brain and other organs
2.3 Tissues and organs in plants
KEY TERMS:
Epidermis- the outer layer of cells
Vascular tissue- the tissue that transports fluids and nutrients through a plant
Plants have four types of organs
Roots: Anchor the plant and absorb water and minerals from the soil
Stems: Support the plant and house vascular tissues for transport
Leaves: Main site for photosynthesis, exchange of gases, and transpiration
Flowers: Reproductive structures that facilitate pollination and seed formation
Plants have a small number of tissue and organ systems
Plants have two major body systems. The first one is the root system. All organs are underground. This system absorbs the nutrients and water from the soil. The roots are part of this system, as well as any other organs. The second one is the shoot system. This mostly consists of the organs that grow above the ground. These parts of the plant absorb sunlight, and are where photosynthesis happens. Plants also have four tissue systems.
Epidermis- skin of the plant
Vascular tissue- transports fluids and nutrients
Ground tissue- the cells that make nutrients during photosynthesis and store them for later use
Meristematic cells- change to form various organs of a plant and are responsible for growth
2.4 Blood, bones and muscles
KEY TERMS:
blood vessel- a tube such as a vein or artery that carries blood in the body
cartilage- connective tissue that holds bones together
tendon- connective tissue that connects muscle to bone
The circulatory system moves materials around the body
The heart, blood vessels and blood make up the circulatory system. This systems delivers oxygen and nutrients. Oxygen passes from the lungs into the blood, and it is then transported to the heart.
The skeletal system supports and protects the body
The human skeletal system consists mostly of bones and cartilage. Human bones come in all shapes and sizes. Functions of the human skeleton include: support, protection, muscle attachment, blood cell production and mineral storage.
The muscular system allows the body to move
Muscles work by contracting and relaxing. When they contract, they become short and thick. It is the opposite when they relax.
2.5 Energy in, waste out
KEY TERMS:
digestion- the physical and chemical processes that break down the food in your body
enzyme- a chemical that speeds up a reaction
excretion- the elimination of cellular waste in your body.
The digestive system releases the nutrients in food
Humans and other animals need to consume food to obtain the nutrients inside it. Enzymes break down food particles.
The excretory system removes waste from the body.
Kidneys filter blood to remove harmful wastes.
2.6 Human reproduction
KEY TERMS:
embryo- an early stage of development of an unborn baby
fertilise- to join sperm with an ovum
foetus- a later stage of development of an unborn baby
zygote- the first single cell of new life
The human reproduction system produces new life
When a sperm cell fertilises the ovum, a zygote is formed and it quickly divides to become an embryo. After 5 days, the embryo travels down the fallopian tube into the uterus. it develops into foetus where it grows over the course of 40 weeks.
2.7 Plant reproduction
Pistil- the female reproductive organs of a flower
Pollen- the fine powdery substance in the flowers of plants which contains male sex cells
Pollination- the movement of pollen from the male part of the plant to the female part
Stamen- the male reproductive organs of a flower
Flowers contain the reproductive organs of plants
The male reproductive organs of a flower comprise the stamen.
Filament- stalk that supports the anther
Anther- the organ that produces pollen
The female organs of a flower comprise of the pistil.
Stigma- organ where the pollen germinates
Style- the stalk that connects the stigma and ovary
Ovary- organ that stores the female sex cells
Stems and roots are for support, transport and growth
The stem is the main body of a plant. It helps with:
support- helping the plant to stand up
transport- connects the root and shoot systems
growth- allowing buds to grow from the stem.
Roots absorb water and nutrients from the soil. They also anchor the plant to the ground.
Photosynthesis happens in leaves
Leaves are flat, which mean that their surface area is extended, and allows more sunlight to be absorbed. They contain chlorophyll, a green pigment which absorbs sunlight. Leaves have round pores called stomata. They open and close to exchange oxygen and carbon dioxide.
2.8 Organ transplant and technology
KEY TERMS:
ethical- relating to principles about what people think is wrong and right
nobel prizes- world famous awards given each year for academic, cultural and scientific advances
stem cell- a cell that can produce a different type of cell and divide to make more cells
Technology has improved organ transplant medicine
up until now, people have been freezing organs, however this can damage them. Nowadays, they are kept in conditions that can copy the human body.
The human body tries to reject transplanted organs
The immune system is always on the lookout for things that shouldn’t be there, and transplanted organs count as one of them. Doctors try to find a very close match between the donor and the recipient, and anti-rejection is used.