Animal Coordination, Control and Homeostasis Flashcards
What are hormones?
A product of cells that circulates in body fluids and produces a specific effect on other cells or tissues
What is a target organ?
A specific organ on which a hormone acts
What are endocrine glands?
Glands of the endocrine system that secrete hormones directly into the blood stream
What are the two ways the body communicates organ to organ?
Hormones (slower response) Nervous system (fast response)
What is the function of the pituitary gland?
Produces hormones that regulate body conditions. These hormones act on other glands and cause them to release hormones
What is the function of the thyroid gland?
Produces thyroxine, which regulates the rate of metabolism, heart rate and temperature
What is the function of the adrenal glands?
Produce adrenaline, used for the ‘flight or fight’ response
What is the function of the ovaries?
Produces oestrogen, involved in the menstrual cycle
What is the function of the pancreas?
Produces insulin, which regulates blood glucose levels
What is the function of the testes?
Produces testosterone, which controls puberty and sperm production
What is the ‘fight or flight’ response?
The brain tells the sympathetic nervous system to start working, which tells the adrenal glands to release adrenaline into the bloodstream. This makes the body more able to respond to a threat, by increasing heart rate and blood pressure among other things. These responses mean the body is more able to run or fight a threat
What responses are caused in the ‘fight or flight’ response?
Adrenaline binds to receptors in the heart, causing it to beat faster and increase blood pressure, increasing blood flow to muscles
Adrenaline binds to receptors in the liver, causing it to break down glycogen into glucose, increasing blood sugar levels
What is homeostasis?
The mechanism that keeps the internal environment constant, so that cells are at optimal conditions to operate
What are the responses when the body is too hot?
Erector muscles relax so hairs lie flat
Lots of sweat is produced
Vasodilation occurs
What are the responses when the body is too cold?
Erector muscles contract
Little sweat is produced
Vasoconstriction occurs
You shiver
How is body temperature controlled?
The hypothalamus contains receptors sensitive to blood temperature in the brain and skin. When a change is detected, it causes a response in the skin
What is vasoconstriction?
Vasoconstriction reduces blood flow near the surface of the skin by constricting blood vessels. This reduces heat loss from the blood by radiation through the skin. It is used in cold weather.
What is vasodilation?
Vasodilation increases blood flow near the surface of the skin by dilating blood vessels. This increases heat loss from the blood by radiation through the skin. It is used in hot weather.
What is osmosis?
The diffusion of water molecules across a semi-permeable membrane