7: The Endocrine System Flashcards
What is homeostasis?
Homeostasis is the control of body function. It requires the coordinated activity of the nervous and endocrine systems
Describe the actions of the endocrine system:
The actions of the endocrine system are much slower and longer than the nervous system
What chemical messengers does the endocrine system use?
The endocrine system uses hormones as chemical messengers secreted by the endocrine gland
Describe the actions of hormones in the endocrine system:
The endocrine system uses hormones secreted by the endocrine gland. This makes the action less targeted because the hormones are released into the bloodstream, exposing all cells
Describe the cell response to a hormone:
A cell will only respond to a particular hormone if it has a receptor for that hormone. The effect is long term because the hormone is effective for as long as it’s in the bloodstream
Describe the solubility of hormones:
Hormones move around the body in the blood, so need to be soluble in blood, which is a very watery substance. This means hormones need to be water soluble to be able to be soluble in blood
Many hormones are water soluble, making travelling easy. Other hormones are insoluble, so need special carry proteins to transport them
What is half life?
The time a hormone is active in the blood is called its half-life
Describe half life for hormones:
Half life is very variable in hormones. It depends on the activity of enzymes in the blood or liver that break down the hormone
What are receptor proteins?
Cells produce receptor proteins that bind to typically one particular hormone, activating specific cellular metabolic pathways and creating a change in cell behaviour
Water soluble hormones find their receptor in the cell membrane as they are able to pass through the lipid cell membrane and target their receptors intracellularly
What are the roles of hormones?
The roles of hormones are to:
- Regulate metabolism
- Control the rate of chemical reactions
- Help things move across cell membranes
- Regulate water and ion balances
- Vital role in reproduction and growth
What is the role of thyroid hormones?
Thyroid hormones regulate metabolism
What is the role of growth hormones?
Growth hormones control the rate of chemical reactions
What is the role of insulin?
Insulin helps things to move across cell membranes
What is the role of anti diuretic hormone?
ADH regulates water and ion balances
What is the role of oestrogen?
Oestrogen plays a vital role in reproduction and growth
Describe the relationship between the hypothalamus and pituitary gland:
There is a very close relationship between the hypothalamus in the brain and the pituitary gland which secretes hormones
The hypothalamus controls the pituitary
Describe the role of the pituitary gland:
The pituitary gland secretes hormones. It is often called the master gland because it controls many other glands
Describe the structure of the posterior pituitary:
The posterior pituitary develops from a stalk off of the floor of the brain (hypothalamus)
Describe the role of the posterior pituitary
Nerved from the hypophysis extend down into the posterior pituitary and produces neuron or ones that build up in the nerve terminals. When the hypothalamus is activated, these hormones are released into the blood supply and into the general body circulation
Describe the position of the anterior pituitary:
The posterior pituitary is connected to the anterior pituitary by a pocket of epithelial tissues that has disengaged from the oral cavity
Describe the role of the anterior pituitary:
Other nerves in the hypothalamus release neurohormones into their own capillary bed. Capillary vessels carry the neurohormone to the anterior pituitary. These neurohormones act upon he anterior cells either stimulating or inhibiting hormone release. Hormones produced enter the capillary bed and from there enter into the general circulation
What are the hormones of the posterior pituitary?
The hormones of the posterior pituitary are:
- ADH
- Oxytocin
What are the hormones of the anterior pituitary?
The hormones of the anterior pituitary are:
- Growth hormone
- Prolactin
- Thyroid stimulating hormone
- ACTH
- LH and FSH
What is the role of ADH?
More ADH means higher blood pressure and increased blood volume
What is the role of oxytocin?
In pregnant women it causes contractions in the uterine smooth muscle to assist in labour
In lactating females, it causes milk ejection by contraction of the smooth muscle in mammary gland tissue
In non-pregnant women it assists in the movement of sperm after sexual intercourse
In men the role isn’t precisely understood, but it’s thought to link to pair bonding and sperm motility
What controls the secretion of growth hormone?
Growth hormone releasing hormone and growth hormone inhibitory hormone are produced by the hypothalamus and control the secretion of growing hormone. This is typically in response to low blood glucose and other stressors
What is the role of growth hormone?
Growth hormone stimulates growth in most tissues, regulates metabolism and blood nutrient levels
Under secretion- dwarfism Over secretion (children)- giantism Over secretion (adults)- acromegaly
What controls the secretion of prolactin?
Prolactin secretion is controlled by the prolactin releasing hormone and prolactin inhibitory hormone produced by the hypothalamus