2j Coordination and responses (continued...) Flashcards
What temperature is a human body temperature at?
37°C
What are the two systems that control the body?
- endocrine system
- nervous system
What does the endocrine system consist of?
- glands that secrete hormones
What are hormones?
- hormones are chemical substances which produced by endocrine glands which are directly released in the bloodstream and are carried in the blood plasma around the body
Why do hormones only act on certain cells or organs?
- the cells or organs must have the correct receptors (target organs)
Which system is faster?
Nervous system
Which system is chemical and which is electrical?
- endocrine system is chemical
- nervous system is electrical
Which system uses impulses that travel along neurones?
Nervous system
Which system uses hormones secreted by glands?
Endocrine system
Which system controls reactions to body surroundings?
Nervous system
Which system controls processes inside the body?
Endocrine system
Which system is longer lasting?
Endocrine system
Which system is shorter lasting?
Nervous system
Which system is slower?
Endocrine system
Which 3 endocrine glands are male?
- pituitary gland
- adrenal gland
- testes
Which 2 endocrine glands are female?
- pancreas
- ovaries
What does the pituitary gland do?
- makes hormones that control other endocrine glands
- makes growth hormones
What does the adrenal gland do?
- makes adrenaline
- gets the body ready for action in the ‘flight or fight’ response
What do the testes do?
- make testosterone
- this controls the development of male characteristics in puberty
What does the pancreas do?
- makes hormones called insulin and glucagon
- these control the amount of sugar in the body
What do the ovaries do?
- make female hormones called oestrogen and progesterone
- cause the development of female characteristics during puberty and control the menstrual cycle
What is adrenaline’s target organ?
- vital organs (heart, ect.)
What is insulin’s target organ?
Liver
What is testosterone’s target organ?
Male reproductive organs
What is progesterone’s target organ?
Female reproductive organs
What is oestrogen’s target organ?
Female reproductive organs
What is homeostasis?
- the ability to maintain a constant internal environment
What does homeostasis involve?
- keeping certain physiological variables within a normal range, to allow cells to function at optimal conditions
What are 5 examples of homeostasis?
- body temperature
- water balance
- blood pH
- carbon dioxide concentration
- blood glucose levels
What is negative feedback?
When a deviation from the ‘norm’ is detected, it will initiate a response to return the system to its ‘norm’.
What is thermoregulation?
Control of body temperature to ensure optimum temperature for enzymes
What are the dangers if the body temperature becomes too low?
- the reactions become too slow for cells to survive
- hypothermia
What are the dangers if the body temperature becomes too high?
- the body’s enzymes are at risk of denaturing
What is the hypothalamus?
The hypothalamus is the area of the brain responsible for controlling temperature, and in that area the thermoregulatory centre detects changes in the blood temperature
How is a rise in temperature detected?
Rise in temperature is detected by the warm skin thermoreceptors and the thermoregulatory centre
What are the 3 cooling mechanisms?
- sweating
- vasodilation
- behaviours
How is a reduction in temperature detected?
Reduced temperature is detected by the cold skin thermoreceptors and thermoregulatory centre
What are the 4 warming mechanisms?
- increase rate of metabolism
- constriction of arterioles (vasocontriction) in the skin
- contraction of arrector pili muscles
- behaviours
What is vasodilation?
- control the size of the blood vessels (arterioles) near the surface of the skin
What happens if you are too hot (vasodilation)?
If you are too hot, more blood vessels are opened so more blood flows near the skin’s surface and radiates heat to the environment. This results in more heat being lost so the body cools down.
What happens if you are too hot (sweating)?
- sweat is made up of water and salts from the body
- sweat glands open ensuring that water is lost to the skin
- evaporation of this water from the skin uses heat energy which causes a cooling effect on the body
What happens if you are too hot (behaviours)?
- Removing excess clothing, limiting excess movement, air conditioning
What happens if you are too cold (increased rate of metabolism)?
- start to shiver when cold
- shivering is caused by muscle contractions
- this uses respiration which generates heat as a by-product
What happens when you are too cold (vasoconstriction)?
- close blood vessels so the blood does not flow near the skin and does not lose heat energy
- results in less blood being transferred to the skin and more blood transferred to internal organs
- less heat is lost by radiation
What happens when you are too cold (contraction of arrector pili muscles)?
- hairs can stand on end (up)
- traps a layer of air around the skin which is a very good insulator, this stops you losing too much heat
What happens when you are too cold (behaviours)?
- increased movement, huddling, reduction of exposed surfaces.
