5.1.4 Hormonal Communication Flashcards
Define cell signalling
Communication between cells that allows cells to work together to trigger a response or a reaction inside the cell
Compare the nervous system and endocrine system’s response
Nervous System
- fast response
- short lived
Endocrine System
- generally a slower response
- generally a longer lasting effect
Give key aspects of hormones
- chemicals made in endocrine cells
- may be steroids, proteins, glycoproteins, polypeptides, amines or tryosine derivatives
- made from stimulated gland
- reach target organ via blood
- can be made + stored for rapid release
- can have an effect on different target organs
Name glands and the hormones they secrete
Pituitary gland: ADH, FSH, LH, Growth Hormone
Thyroid gland: Thyroxine
Thymus: Thymosin
Adrenal gland: Adrenaline
Pancreas: Insulin, Glucagon
Ovaries: Oestrogen, Progesterone
Testes: Testosterone
Define hormone
Molecules secreted by endocrine glands into the blood, communicating with specific target tissues
Define target tissue
A group of cells that have specific complementary receptors on their plasma membranes to a specific hormone
Define endocrine gland
Ductless gland that secretes hormones directly into the blood
Define exocrine gland
Glands that have ducts and secrete molecules into the duct to transport it to where it is used
Explain hormonal communication
- Hormones are secreted into the blood
- They’re transported in the blood
- Detected by target cells or tissues by receptors
Explain key aspects of steroid based hormones
- non polar
- lipid soluble
- can pass through phospholipid bi-layer + plasma membrane
- receptors inside the cell
- form hormone receptor complex + affect gene expression
- e.g. testosterone, oestrogen, progesterone
Explain key aspects of non-steroid based humans
- hydrophilic
- not lipid soluble
- cannot pass through phospholipid bi-layer + plasma membrane
- bind to receptors on the outside of plasma membrane
- cause changes in the cell by the activation of enzymes + production of 2nd messengers
What does the pancreas do?
Exocrine
- secretes pH8 juice + digetive enzymes (amylase/lipase) into ducts
- Pancreatic secretions go into dudoenum
Endocrine
- Islets of Langerhans monitor blood glucose concentration
- beta cells secrete insulin
- alpha cells secrete glucagon
- directly into blood
Explain the structure of Islets of Langerhans
- lightly stained and form large spherical clusters
- secrete hormones direclty into the blood stream
- Beta cells - stained blue, secrete insulin
- Alpha cells - stained pink, secretes glucagon
- pancreatic acini - secrete digestive enzymes
What is glycogenesis, glycogenolysis and gluconeogenesis
- gluconeogenesis = making glucose from other molecules in the liver
- glycogenesis = making glycogen from glucose in the liver
- glycogenolysis = hydrolysing glycogen into glucose in the liver
Explain how insulin causes glycogenesis
- Insulin binds to specific protein receptor
- Chemical released
- Causes more glucose transport proteins to be inserted into the cell surface membranes of liver and muscle cells
- Increases permeability of liver + muscle cells to glucose by allowing more facilitated diffusion of glucose in
- Insulin activates enzyme to convert glucose into glycogen
- Steep glucose diffusion gradient maintained
- More respiration of glucose to produce ATP
Explain how blood glucose level is decreased
- B cell receptors in pancreas detect a change
- B cells in pancreas secrete insulin