5.2 Hormonal Communication Flashcards
What are hormones ?
Chemical messenger in the endocrine system, that travel in the blood and works alongside the neuronal system to react to change. Can be steroids, proteins, polypeptides are amines.
What are endocrine glands ?
Group of cells which are specialised to secrete chemicals, which are hormone directly secreted into the blood stream.
What is the pituitary gland ?
Produces growth hormones, controlling growth of bones and muscles. Anti-diuretic hormones, which increases reabsorption of water and gonadotrophins, controlling development of ovaries and testes.
What is the thyroid gland ?
Produces thyroxine which controls the rate of metabolism and rate that glucose is used up in respiration.
What is the adrenal gland ?
Produces adrenaline which increases heart and breathing rate and raises blood sugar level.
What is the pineal gland ?
Produces melatonin which affects reproductive development and daily cycles.
What is the thymus ?
Produces thymosin which promotes production and maturation of white blood cells.
What is the pancreas responsible for ?
Produces insulin to convert glucose to glycogen and glucagon to convert glycogen to glucose.
What are the testes responsible for ?
Produces testosterone which control sperm production and sexual characteristics.
What are the ovaries responsible for ?
Produces oestrogen, controlling ovulation and progesterone that prepares the uterus lining for receiving an embryo.
Where are hormones directed to ?
Released in blood to reach target cells. Once bound to their receptors, hormones stimulate target cells to produce a response.
What are steroid hormones ?
Lipid soluble so can pass through lipid component of cell membrane and binds to form hormone-receptor complex.
What are non-steroid hormones ?
Hydrophilic so cannot pass directly through membrane, so binds to specific receptors on cell surface membrane of the target cell.
Hormonal vs neuronal communication ?
-Blood stream
-Relatively slow
-Widespread response
-Response is slow
-Response is long-lasting.
-Permanent and irreversible.
Neuronal vs hormonal communication ?
-Neurones
-Rapid transmission
-Specific parts of body
-localised response
-short-lived response
-effect is temporary and reversible.
Where are the adrenal glands located ?
Top of each kidney and are made up of adrenal cortex (produces vital hormones such as cortisol and aldosterone) and adrenal medulla 9produces non essential hormones like adrenaline)
What are glucocorticoids ?
Include cortisol to help regulate metabolism. Also includes corticosterone that works with cortisol to regulate immune response and supresses inflammatory reactions.
What are mineralocorticoids ?
Main one produced is aldosterone that helps blood control pressure by maintaining the balance between salt and water concentrations .
What are androgens ?
Small amounts of male and female sex hormones are released. Impact is small but is still important.
What hormones are secreted by adrenal medulla ?
Adrenaline responsible for flight or fight.
Noradrenaline responsible for responding to stress, such as increasing heart rate.
What are the two main functions of the pancreas ?
Produces enzymes and releases them into duodenum. Also produces hormones and releases them into the blood.
What are the Islets of Langerhans ?
Small regions of endocrine tissue that are responsible for producing insulin and glucagon and secreting these hormones directly into the blood stream.
What are alpha cells in Islets of Langerhans ?
They produce and secrete glucagon.
What are beta cells in Islets of Langerhans responsible for ?
These produce and secrete insulin.
What is glycogenolysis ?
Glycogen broken down to glucose to increase blood glucose levels.
What is gluconeogenesis ?
Production of glucose from amino acids and lipids.
What is glycogenesis ?
Glucose is converted to glycogen.
What happens when blood glucose concentration falls ?
Alpha cells detect fall and glucagon is secreted. Glycogen is converted to glucose during glycogenolysis. Amino acids are converted to glucose and an uncontrolled amount of glucose enters.
What happens when blood glucose concentration rises ?
Beta cells detect rise and insulin is secreted directly into blood stream.
Increases cellular respiration, converts glucose to glycogen.
Glucose absorbed in cells. Blood glucose levels fall.
What type of protein is insulin ?
Globular protein with 2 polypeptide chains.
What type of protein is glucagon ?
Coiled protein forming an alpha helix.
What is the normal blood glucose level ?
90 mg 100 cm-3
What occurs in the cell when there is high blood glucose levels ?
ATP sensitive K+ pump is closed and the Ca2+ channel is open leading to an influx of Ca2+ ions depolarising cell. This causes vesicles to bind to cell membrane to release insulin via exocytosis. Glucose channels are open which is detected by receptors on mitochondria leading ATP to be synthesised to close ATP K+ pump.
What are some symptoms of diabetes ?
High blood glucose concentration, glucose in urine, excessive need to urinate, excessive thirst, constant hunger, weight loss, blurred vision and tiredness.
What is the coordinated response ?
Body responds to environmental changes through coordinated response between nervous and endocrine system. Eg., fight or flight.
How does hypothalamus coordinate neuronal communication ?
Activates sympathetic nervous system. Impulses activate glands and smooth muscle. This activates the adrenal medulla where adrenaline and noradrenaline is released into the blood stream.
How does the hypothalamus coordinate hormonal communication ?
Activates the adrenal-cortical system by releasing CRF. Pituitary gland secretes hormone ACTH. Acth arrives at adrenal cortex and released approx 30 hormones.
What is the first stage in glycogenolysis ?
Adrenaline is a non-steroid hormone so it is hydrophilic so cannot pass through the membrane. It binds to the receptors acting as a 1st messenger hormone. This causes adenyl cyclase to bind to the inside of the membrane so becomes activated.
What is the second stage of glycogenolysis ?
The activated adenyl cyclase converts ATP to cAMP, which acts as a second messenger.The cAMP phosphorylates protein kinases which activates the enzymes involved in glycogenolysis.
How many times does a human heart beat per minute ?
70 beats per min.
What is the medulla oblongata responsible for ?
Controls heart rate, which is controlled by the autonomic nervous system. Has 2 centres linked to the Sino-atrial nodes in the heart by motor neurones.
What is the neuronal pathway when heart rate increases ?
Impulses are sent through the sympathetic nervous system by the accelerator nerve.
What is the neuronal pathway when heart rate decreases ?
Impulses sent through the parasympathetic nervous system by the vagus nerve.
What are baroreceptors ?
Detect changes in the blood pressure and are found in aorta, vena cava and carotid arteries.
What are chemoreceptors ?
Detect changes in pH and chemicals. Found in the arts, carotid artery and medulla.
How does adrenaline and noradrenaline influence heart rate ?
They increase the frequency of impulses produced by the SAN, speeding up heart rate.
