5 - MZH - Homeostasis 3 - Hormonal communication and adrenaline Flashcards
What are hormones?
Hormones are messenger chemicals produced by endocrine glands and carried in the blood to cells, tissues or organs on which they act
5 characteristics of hormones
- Effective in small quantities, but often have widespread and permanent effects
- Normally very small molecules
- Often proteins or polypeptides, although some are steroids
- Transported by the blood stream
- Produced by endocrine glands
What are the 2 different types of hormones?
How do they work?
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Protein and polupeptide hormones - e.g. insulin and adrenaline.
- Binds to specific receptors on the cell surface membrane of target cells.
- Hormone/receptor complex triggers a series of changes within the cell producing a specific response.
-
Steroid hormones - e.g. oestrogen and testosterone.
- Lipid soluble so can pass throughphospholipid bilayer.
- Once inside the cell it binds to a specific receptor protein that carries it into the nucleus.
- Here hormone/receptor complex “switches on” a specific gene thereby affection protein synthesis.
What is a endocrine and exocrine gland?
Difference between endocrine and exocrine hormones?
Example?
Endocrine gland = ductless and endocrine hormones are secreted directly into the blood stream e.g. insulin
Exocrine gland = contains a duct. Exocrine hormones are secreted into the duct e.g. sweat
What are all steriod hormones derived from?
Cholesterol
Steroid hormones:
- Why are they transported in the blood?
- Why is the receptor of the target cell in the cytoplasm
- Why can a steroid hormone be called a transcription
- They’re transported by proteni carriers.
- They’re lipid soluble so they can pass through the phospholipid bilayer.
- It affects the level/rate of transcription.
Non steroid hormones:
- Why is the receptor of the target ccell on the plasma membrane?
- What is the role of the second meesenger cAMP?
- They’re not lipid soluble so they can’t pass through the phospholipid bilayer
- Can initiate a range of enzyme controlled reactions inside the target cell
Where are the aderenal glands located?
Above the kidneys
Describe the structure and function of the adrenal glands
Adrenaline is secreted by the adrenal glands.
Outer layer = Adrenal cortex
Inner layer = Adrenal medulla.
Adrenal cortex is divided into 3 distinct layers:
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Zona glomerulosa - outmost layer.
- Secretes mineralocorticoids e.g. aldosterone which helps to control concs of Na+ and K+ in the blood important in maintaining bloof pressure.
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Zona fasciculate - middle layer.
- Secretes glucocorticoids e.g. cortisol.
- Released in response to stress or as a result of a low blood glucose conc.
- It triggers the production of glucose from stored compounds in the liver e/g/ glycogen, fats and proteins.
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Zona reticularis - innermost layer.
- Secretes androgens (sex hormone precursors).
- Cortisol can be secreted from the zona reticularis o molecules which are precursor androgens which can be converted into sex hormones in the ovaries or teste.
Responsible for general regulatory effects and LT adaptations to stress.
Adrenal medulla:
Found in the center of the adrenal glands.
- Secretes adrenaline and noradrenaline.
- Produces catecholamines as well in response to ST stress.
Responsible for short term effects and responses to temporary stimuli.
What type of hormones are produced by:
Adrenal cortex?
Adrenal medulla?
Adrenal cortex = Steroid hormones - They’re all essential hormones. Means it’s more normal maintenence.
Adrenal medulla = Non essential hormones. They’re produced as a response to temporary stimuli e.g. fear
Effects of adrenaline on the body? What does it prepare the body for? (8)
It prepares the body for arousal, fight and flight responses.
How is Adrenaline released?
