Hormones and homeostasis Flashcards
What is homeostasis?
The ability to maintain a constant internal environment
What does the hypothalamus monitor?
The temperature of the blood
What happens if the hypothalamus detects change in the temperature of the blood?
It sends signals via neurones to other organs, which will bring the temperature of the blood back to normal
Name 3 main ways the body controls the temperature
- sweating
- shivering
- controlling blood near skin surface
What do organs work together to keep constant?
Conditions in the tissue fluid around cells
What would happen if we didn’t have skin?
- wouldn’t be able to maintain a constant body temperature
- difficult for enzymes to react at optimum temperature
What would happen if we didn’t have lungs?
- gaseous exchange wouldn’t be possible
- no alveoli —> less efficient respiration
How do sensory neurones help with homeostasis?
- detect changing levels of solutes in blood
- signals go to hypothalamus
- feedback signals sent to organs
Explain what happens when the body is too cold
- capillaries vasoconstrict (reduces heat loss by radiation)
- hair erector muscles contract, hairs stand up, traps layers of air (reduce heat loss by reducing convection)
- no sweat is released
Explain what happens when body is too hot
- capillaries vasodilate (enlarge)
- higher blood flow at skin surface means increased radiation
- hair erector muscles relax, hairs flat, increased convection at skin surface
- sweat glands secrete sweat
- increased heat loss via evaporation
What does the liver control?
Levels of solutes in blood
What do the lungs control?
Exchange of carbon dioxide + oxygen
What do the kidneys control?
Water content of blood
What does the skin control?
Heat loss/gain
What do the intestines control?
Soluble foods and water
Where is insulin produced?
Pancreas
Where is adrenaline produced?
Adrenal glands
What is the pituitary gland controlled by?
Hypothalamus
What is a hormone?
- chemical messenger
- travels in the plasma
- travels to a target cell/organ
- initiates a change
Why is testosterone important?
For secondary sexual characteristic development
What hormones are produced in the ovaries?
Oestrogen and progesterone
What are is the effect and oestrogen/progesterone?
- make female secondary sexual characteristics develop
- involved in fertility/menstrual cycle
What 3 hormones are produced in the pituitary gland
- Follicle Stimulating Hormone (FSH)
- Luterizing Hormone (LH)
- Anti Diuretic Hormone (ADH)
What are is the effect of FSH and LH?
Effects fertility in the womb
What is the effect of ADH?
Acts on kidneys to control amount of water excreted in the urine
What hormones does the pancreas secrete?
Insulin and Glucagon
What is the effect of insulin?
Tells liver to convert glucose to glycogen, stored in liver + muscles
What is the effect of glucagon?
Tells liver to convert glycogen to glucose, released into blood
What is the effect of adrenaline?
binds to receptors in the heart + makes heart beat faster and harder
What is diabetes caused by?
Pancreas cells not producing insulin
What is hyperglycaemia?
Too much glucose in the blood
What is hypoglycaemia?
Too little glucose in the blood
What are the effects of hypo and hyperglycaemia?
- both can negatively affect respiration
- affects blood concentration levels
- potentially damage cells
How do you get Type 1 diabetes?
Inherited
How do you get Type 2 diabetes?
Developed - obesity, lifestyle, stress
What hormone does the pancreas release if the person has hypoglycaemia?
Glucagon
Speed of action endocrine vs nervous
endocrine = slow, nervous = fast
Type of message endocrine vs nervous
endocrine = chemical, nervous = electrical impulse
method sent endocrine vs nervous
endocrine = via the blood (dissolved in plasma), nervous = along neurones
Response to the message endocrine vs nervous
endocrine = only target cells respond (even though message sent all over the body), nervous = sent directly to muscle or gland (not all over the body)
Role in the body endocrine vs nervous
endocrine = controls longterm processes (e.g. reproduction, growth), nervous = used when a fast response is needed
