Endocrine + homeostasis (Human Bio) Flashcards
What are endocrine glands
glands that secrete hormones into the extracellular fluid that surrounds the cell that make up the glands
Describe the functioning of steroid hormones
Lipid soluble (do not dissolve in water)
Once they are released into the blood, the hormones bind to transport proteins, enabling them to travel in the bloodstream
When they reach target cells, steroid hormones separate from the transport proteins and diffuse across the cell membrane
Inside the cell they combine with a receptor protein in cytoplasm or nucleus
Hormone receptor complex activates genes controlling formation of particular proteins
Transcription is stimulated and therefore protein synthesis
E.g. oestrogen, progesterone
Describe protein/amine hormones
Protein and Amine hormones
Water soluble not lipid soluble, unable to diffuse across cell membrane
Attaches to receptor proteins in membrane of the target cell
Combination of the hormone with the receptor causes a secondary messenger substance to diffuse through the cell and activate particular enzymes
E.g. insulin binds to a receptor protein and leads to an increase in glucose absorption by cell
describe hypothalamus
Regulates body functions (e.g. heart rate, body temperature)
Serves as a connector between the nervous system and endocrine system
Describe relationship between hypothalamus and pituitary gland
Secretes releasing factors, which stimulate the secretion of hormones, or inhibiting factors, which slow down the secretion of a hormone
These factors travel through blood vessels to anterior lobe of pituitary gland
What is the infundibulum
A stalk that joins the hypothalamus and pituitary gland
What does the pituitary gland consist of
Anterior lobe → joined to hypothalamus by blood vessels in infundibulum
Posterior lobe → joined to hypothalamus by nerves fibres
What are some hormones released by anterior lobe
FLAT PiG
Gonadotropins
Hormones that affect the gonads (testes and ovaries)
(Follicle stimulating hormone is released aswell)
Growth hormones
Stimulates body growth, protein synthesis
Thyroid-stimulating hormone (TSH)
Stimulates production and release of hormones from the thyroid gland
Adrenocorticotropic hormone (ACTH) Controls production and release of some the hormones from the cortex of the adrenal glands
Prolactin
Works with hormones to initiate and maintain milk production in females
What are some hormones released by the posterior lobe
Oxytocin
Stimulates contraction of the muscles of the uterus
Also stimulates mammary glands resulting in release of milk during breastfeeding
Antidiuretic hormone (ADH) Causes kidneys to remove water from urine that is forming
Describe causes, symptoms, diagnosis, treatment of Diabetes 1
Cause:
Immune system fault causing the breakdown of beta cells in the Islets of Langerhan of the pancreas which produce insulin
Symptoms: Increased thirst Frequent urination Fatigue Weight loss
Diagnosis:
Blood test
Treatment:
Insulin injections
Describe causes, symptoms, diagnosis, treatment of Diabetes 2
Cause:
being obese or overweight, produces insulin but cells don’t respond (fat affects receptors)
Symptoms: Unexplained weight loss Increased thirst Increased hunger Fatigue Frequent urination
Diagnosis:
Blood test
Treatment:
Managment plan to keep blood glucose level in normal range = e.g. diet, exercise
Describe hypothyroidism
Cause:
Too little thyroxine, iodine deficiency in diet can prevent thyroid gland from making enough hormones
Symptoms
Slow heart rate
Weight gain
Goitre (neck swelling)
Diagnosis:
Blood test
Treatment:
Increase iodine in diet
thyroid hormone tablets
Describe hyperthyroidism (e.g. graves disease)
Cause:
Too much thyroxine due to enlarged thyroid gland therefore produces too much of hormone
Symptoms:
Rapid heart rate
Weight loss
Protruding eyes
Diagnosis:
Blood test
Treatment:
Drugs that block thyroid glands
Example of a positive feedback loop
Childbirth
Labour initiated =by secretion of hormone oxytocin from posterior lobe of pituitary gland
Oxytocin causes contraction of uterus
Contraction pushes baby’s head against the mothers cervix
Stimulation of the cervix causes it to send nerve impulses to the brain, which respond by instructing pituitary gland to secrete more oxytocin
The increased oxytocin makes uterus contract more strongly which push baby’s head more forcibly against cervix, sending more impulses to the brain for oxytocin secretion, making the uterine contractions increasingly intensify
Once baby is delivered, nerve impulses messaged are ceased and positive feedback cycle stop
Describe the role of the liver
Liver is able to convert glucose into glycogen when glucose levels are high like after a meal
And is able to convert glycogen back to glucose if blood glucose is low like during exercise
