Biology

• the main function of the skin is to protect against infection, prevent water loss and regulate temperature
• the epidermis contains melanin which gives us our skin colour
• the dermis has blood vessels that carry oxygen and nutrients around the body
• the hypodermis stores fat and insulates the body from cold temperatures
• hair follicles are found within the dermis and hair grows out through the epidermis
• hair follicles are found within the dermis
• sebaceous glands produce sebum which keeps hair soft and prevents it from becoming dry
• apocrine sweat glands release pheromones into the air when we get hot or scared
• sebaceous glands produce sebum which keeps the skin moisturised
• apocrine sweat glands release pheromones into the air when we get nervous or excited
• eccrine sweat glands release sweat onto the surface of the skin to cool it down
• apocrine sweat glands release chemicals into the sweat to make it smell different depending on what we eat or drink
• eccrine sweat glands release watery sweat when we get hot, this cools down the body by evaporating off the surface of the skin
• the respiratory system is made up of the nose, trachea, bronchioles, lungs and alveoli
• eccrine sweat glands release water to cool us down by evaporating off our skin
• epidermal cells divide by mitosis to replace dead skin cells
• the nose filters the air as it enters the body
• the stratum corneum is made up of many layers of dead keratinocytes that have been pushed towards the surface of the skin
• keratinocytes make keratin, a protein that makes the skin waterproof
• the stratum lucidum contains no blood vessels, so there's no oxygen available for respiration
• the stratum corneum is made up of dead cells that have been pushed to the surface by new ones underneath
• the stratum basale has lots of mitochondria as they need energy for cell division