B2-Topic 5- Homeostasis 2022 Flashcards
(46 cards)
Where is body temperature controlled in the
body?
Body temperature is controlled by the thermoregulatory centre in the hypothalamus of the brain
How is temperature monitored by the body?
● Thermoregulatory centre has receptors sensitive to blood temperature.
● Skin has receptors sensitive to skin temperature - sends impulses to
thermoregulatory centre.
What physiological changes occur when the body temperature is too high? 2
● Vasodilation - blood vessels near the surface
of the skin dilate - more heat is radiated away.
● Sweating - evaporation of water takes away heat energy from the surface of the skin.
What physiological changes occur when the body temperature is too low? 3
● Vasoconstriction - blood vessels near the surface
of the skin constrict - less heat radiated away.
● Shivering - respiration allows muscles to contract.
It is an exothermic process, so heat energy is
released.
● Sweating stops
What type of reactions are vasoconstriction and vasodilation
transfer energy from the skin to the environment = exothermic
Give the name of the body’s coordination
system which involves hormones
The endocrine system
What is a hormone?2
chemical messenger
secreted by a gland
. It travels in the blood to
a target organ, where it causes a response.
Why is the pituitary gland considered a
‘master gland’?2
It secretes a wide range of hormones,
some of which may stimulate other endocrine glands
What is the role of the pituitary gland in
the endocrine system?4
● Secretes human growth hormone - controls human
growth.
● Stimulates the thyroid gland.
● Stimulates ovulation and the production of oestrogen in the ovaries.
● Stimulates the production of sperm and testosterone in the testes
What is the role of the thyroid gland in
the endocrine system?
Secretes the hormone thyroxine - controls
metabolism, heart rate and body temperature
What is the role of the pancreas in the
endocrine system?
Secretes the hormone insulin - controls
blood glucose levels
What is the role of the adrenal gland in the
endocrine system?
Secretes adrenaline - controls the body’s
‘fight or flight’ response
What is the role of the ovaries in the endocrine
system?
Secrete oestrogen, which coordinates the
menstrual cycle and the development of female secondary sexual characteristics
What is the role of the testes in the endocrine system?
Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics
Which organ monitors and controls blood
glucose concentration?
the pancreas
explain how insulin controls blood glucose (sugar) levels in the body if it is too high.3
pancreas produces the hormone insulin
causes glucose to move from the blood into the cells.
In liver and muscle cells excess glucose is converted to glycogen for storage.by receptors on liver
How does the pancreas respond when blood glucose levels are too low 3
The pancreas secretes the hormone
glucagon.
Glucagon binds to liver cells,
causing glycogen to be converted into
glucose and released into the blood
How is blood glucose concentration controlled using a negative feedback loop? (higher only) 2
When blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas.
● The action of either hormone (insulin or glucagon) helps bring back the concentration to the correct
level.
What is Type 1 diabetes?
an autoimmune disorder
the pancreas does not produce sufficient
insulin to control the blood glucose concentration.
so blood glucose levels are often very
high, leading to excessive urination, tiredness and weight loss
How can Type 1 diabetes be treated?2
Insulin injections before meals - allows
glucose to be converted into glycogen.
● Limiting carbohydrate intake.
● Attempts using pancreas and pancreatic cell transplants; investigations into genetic
engineering of pancreatic cells.
What is Type 2 diabetes?2
the body cells no longer respond to insulin produced by the pancreas.
linked with increasing age and obesity
How can Type 2 diabetes be treated? 4
Following a carefully-controlled diet ● Doing regular exercise ● Losing weight ● Use of drugs which increase insulin production and effectiveness
What is osmosis?
movement of water from a
dilute solution to a concentrated solution
through a partially permeable membrane
ways water is lost from the body?3
● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)
