Topic 7: Animal Coordination, Control and Homeostasis Flashcards
What is the endocrine system?
A network of glands that produce and secrete hormones into the bloodstream
What is a hormone?
A cell signalling molecule produced by endocrine glands and released into the blood and travels to a target organ and binds to receptors on effectors initiating a response
Describe the endocrine system
Uses hormones, hormones travel in the bloodstream to the target organ, slower response and lasts until all hormones have broken down which takes a long amount of time
Describe the nervous system
Uses nerve impulses, nerve impulses travel via neurones to the effectors, faster response and lasts until the nerve impulse stops which takes a short amount of time
What is the pituitary gland?
Described as the ‘master gland’ and endocrine gland that produces hormones which control other glands
What are the adrenals glands?
Endocrine glands that produce adrenaline
Where are the adrenal glands located?
Above the kidneys
Where is adrenaline?
A hormone produced by the adrenal glands that is involved in the ‘fight or flight’ response
What are the effects of adrenaline on the body?
Increases heart rate, blood pressure, blood flow to muscles and blood glucose levels
How does adrenaline increases heart rate and blood pressure?
Secreted by the adrenal glands, travels in the blood to the heart, binds to specific red on cells in the heart, causes heart muscle to contract more forcefully and frequently so heart rate and blood pressure increases
How does adrenaline increases respiration at muscle tissues?
Adrenaline binds to specific receptors on cells in the liver, triggers breakdown of glycogen stores and release of glucose so blood glucose levels increases, increase heart rate causes greater blood blood flow to muscles and muscle cells receive more oxygen and glucose for respiration
What is negative feedback?
A corrective mechanism that allows only small shifts from a set point and it reverse a change in conditions
What is the thyroid gland?
Endocrine gland that produces thyroxine
Where is the thyroid gland located?
In the neck
What is thyroxine?
A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature
What is metabolic rate?
The rate at which biochemical reactions occur in cells
How is thyroxine released?
Hypothalamus secretes TRH, TRH stimulates secretion of TSH from pituitary gland and TSH stimulates the release of thyroxine from the thyroid gland
Hat does TRH stand for?
Thyrotropin releasing hormone
What does TSH stand for?
Thyroid-stimulating hormone
How does a negative feedback system controls blood thyroxine levels?
If blood thyroxine levels increase above a set point, TRH and TSH secretions is inhibited, less thyroxine is produced by the thyroid gland so thyroxine levels return to normal and if blood thyroxine levels decreases below a set point, TRH and TSH secretion is increased, more thyroxine is produced by the thyroid gland so thyroxine levels return to normal
How do the ovaries act as an endocrine gland?
They secrete oestrogen into the bloodstream
How do the testes act as an endocrine gland?
They secrete testosterone into the bloodstream
What is homeostatic?
The maintenance of a stable internal environment in the body despite fluctuations in internal and external conditions
Why is homeostasis important?
To ensure optimum conditions for enzymes and cellular processes in the body
What three conditions within the body that must be controlled by homeostasis?
Temperature, blood glucose concentration and water levels
What is thermoregulation?
The maintenance of core body temperature
Why must body temperature be controlled?
Enzymes work best at their optimum temperature, deviations from this optimum temperature decrease the rate of enzymes-controlled reactions
What is the optimum temperature for enzymes in the human body?
37C
What does the maintenance of an ideal body temperature depend on?
A negative feedback system involving: receptors, hypothalamus and effectors
Where are temperature-sensitive receptors located?
Skin - epidermis (outer layer) and dermis (below epidermis)
Hypothalamus
What is the function of receptors in the skin and I’m the hypothalamus?
They detect changes in blood temperature and send information to the hypothalamus
What is the function of the hypothalamus?
It coordinates information from the receptors and sends instructions to the effectors
What is the function of the effectors?
They produce a response to counteract the change in blood temperature and return it to the set point
What are the responses of the body to an increase in temperature above 37C?
Vasodilation, sweating and erector muscles relax, hairs lie flat
What structure produces sweat?
Sweat glands found in the dermis
How is sweat released from the skin?
Pores in the epidermis release sweat onto the skins surface which then evaporates
How does sweating help to reduce body temperature?
Heart energy is used to evaporate sweat, increased heat transfer from the skin to the environment decreases body temperature
What is vasodilation?
Dilation of blood vessels near the skin surface, blood flows closer to the skin surface and greater heat loss to the surrounding
What are the responses of the body to a decrease in temperature below 37C?
Vasoconstriction, shivering, hair erector muscles contract and little sweat is produced
How does shivering help to increase body temperature?
Involuntary contraction of muscles generates heat energy from respiration
How does the contraction of hair erector muscles help to increase body temperature?
Hairs stand on the end creating pockets of air between hairs and a layer of insulation
What is vasoconstriction?
Constriction of blood vessels near skin surface, less blood flows close to the skin surface and less heat loss to the surroundings
Which organ is responsible for the maintenance of blood glucose concentrations?
Pancreas
How are blood glucose concentrations controlled?
Controlled by the hormones insulin and glucagon which are secreted by the pancreas
What does insulin and glucagon are antagonistic hormones mean?
They have opposite effects which counteract one another
What is the role of insulin in the regulation of blood sugar levels?
Causes liver and muscle cells to increase their uptake of glucose from the blood and glucose is converted into glycogen, a storage molecule