5.1.4 - Hormonal Communication Flashcards
What is the endocrine system?
It is made up of glands that secrete chemical messengers called hormones into the blood stream to bring about a designated response
What hormones does the pituitary gland secrete?
- Growth hormone (controls growth of bone and muscle)
- Anti-Diuretic Hormone (increases reabsorption of water in kidneys)
- Gonadotropins (controls development of ovaries/testes)
What hormones does the hypothalamus secrete?
Located near the pituitary gland
Secretes hormones (tends to be releasing hormones) to tell pituitary gland to start/stop making hormones
Links nervous system with the endocrine system
Keeps body balanced in stable state
What hormone does the pineal gland secrete?
Melatonin - affects reproductive development and daily cycles
What hormone does the thyroid gland secrete?
Thyroxine - controls metabolic rate and the rate of glucose use in respiration + promotes growth
What hormone does the thymus secrete?
Thymosin - promotes production and maturation of white blood cells
What hormone does the adrenal gland secrete?
Adrenaline - increases heart + breathing rate and blood sugar levels
What hormones does the pancreas secrete?
Insulin - converts excess glucose into glycogen in the liver
Glucagon - converts glycogen into glucose in the liver
What hormone does the testes secrete?
Testosterone - controls sperm production and secondary secular characteristics
What hormones does the ovary secrete?
Oestrogen - controls ovulation and secondary sexual characteristics
Progesterone - prepares uterus lining for receiving and embryo
Oestrogen + Progesterone - controls ovulation and secondary characteristics
Name all of the endocrine glands
- Hypothalamus
- Pituitary Gland
- Pineal Gland
- Thyroid gland
- Thymus
- Adrenal Gland
- Pancreas
- Ovary
- Testes
Why are hormones chemical messengers?
They carry information from one body part to another
What form can hormones be?
- Steroids
- Proteins
- Glycoproteins
- Polypeptides
- Amines
- Tyrosine Derivatives
Why can hormones be secreted?
Due to:
- Change in concentration of a particular substance (e.g. blood glucose concentration)
- Another hormone
- Nerve impulse
Once a hormone is secreted, what happens after?
- It is transported in the blood plasma all over the body
- The hormone diffuses out of the blood
- Bind to specific receptors for it (found on membrane/in cytoplasm of target cell in target organ)
- Once bound, hormone stimulates target cell to produce a response
What are the two types of hormones that determines the way it causes its effect on a target cell?
Steroid Hormone
Non-Steroid Hormone
How does a steroid hormone work?
- Since it is lipid soluble, it can pass through the lipid layer of a membrane
- Binds to steroid hormone receptors to form a hormone-receptor complex (found in cytoplasm/nucleus - depends on hormone)
- HRC acts as a transcription factor which facilitates/inhibits the transcription of a specific gene
Steps of the function of a steroid hormone
- Lipid-soluble steroid hormone passes through membrane
- Received by receptor protein in cytoplasm forming HRC
- HRC attaches to DNA
- Instructions for synthesis of polypeptide
- Polypeptide synthesised by ribosomes and mRNA
What is an example of a steroid hormone?
Oestrogen
How does a non-steroid hormone work?
- Since it is hydrophilic, it cannot pass through the cell membrane
- It binds to receptors on the cell surface membrane of the target cell
- This triggers a cascade reaction mediated by second messengers
What is an example of a non-steroid hormone?
Adrenaline
Why is hormonal communication slower?
Hormones are not directly released onto target cells therefore it is slower and a less specific form of communication
How is hormonal communication longer lasting?
Hormones are not broken down as quickly as neurotransmitters therefore they have a longer lasting and widespread effect
What is the difference in communication between hormonal and neuronal communication?
Hormonal: hormones
Neuronal: nerve impulses
What is the difference in transmission between hormonal and neuronal communication?
Hormonal: by bloodstream + relatively slow
Neuronal: by neurones + fast
What is the difference in travelling between hormonal and neuronal communication?
Hormonal: hormone travels to all body parts but only target organs respond
Neuronal: nerve impulses travel to specific part of the body
What is the difference in response between hormonal and neuronal communication?
Hormonal: slow + widespread + often long lasting
Neuronal: fast + localised + short-lived
What is the difference in the effect between hormonal and neuronal communication?
Hormonal: may be permanent + irreversible
Neuronal: temporary + reversible
