The endocrine system Flashcards
what is The endocrine system
it’s composed of ductless glands which produce hormones
* Hormones control and affect many body functions and organs as well as behavior
* Each gland produces specific hormones
what are Hormones
- Hormones are chemical messengers
- Secreted into the blood by a particular gland
types of hormones
- Some hormones are made of protein (insulin)
- Some hormones are steroids (adrenocorticoid hormones)
- Others are glycoproteins (FSH, LH, TSH)
- Or derivatives of single amino acids (T4 and T3)
why hormone affect only some cell
because They affect only the cells which
have receptors for that
hormone
what is Endocrine glands
- Ductless gland
- Produces hormones
- Hormones travel straight to the bloodstream from the gland
Role of hormones
Affect the behaviour and function of different areas of the body E.g.
* Correct growth
* Changes during puberty
* Menstrual cycle
* Pregnancy
* The menopause
* Response to stress and danger
* Proper functioning of the kidneys and digestive system
Hormone release
- The release of a hormone in response to another hormone or chemical being present in the blood is controlled by a negative feedback loop
- A decrease in the amount of metabolite results in the secretion of less hormone and vice versa
what is the Pituitary gland
- Located at the base of the brain
- Closely connected to the hypothalamus
- Anterior and posterior lobes
what are the hormones controlled by Anterior pituitary
1-Human growth hormone (HGH)
2-Melanocyte-stimulating hormone (MSH)
3-Thyrotrophin (TSH)
4-Adrenocorticotrophin (ACTH)
5-Prolactin/lactogenic hormone
6-Lutenising hormone (LH)/Interstitial cellstimulating hormone (ICSH)
7-Follicle stimulating hormone (FSH)
what is Human growth hormone (HGH) responsible for
Regulates height and growth
Hypersecretion = gigantishm
Hyposecretion = dwarfism
what is Melanocyte-stimulating hormone (MSH) responsible for
Stimulates production of melanin in basal layer of the skin
what is Thyrotrophin (TSH) responsible for
Controls thyroid gland
what is Adrenocorticotrophin (ACTH) responsible for
Controls adrenal cortex
what is Prolactin/lactogenic hormone responsible for
Production of milk during lactation
what is Lutenising hormone (LH)/Interstitial cellstimulating hormone (ICSH) responsible for
1-Stimulates ovaries to produce the corpus luteum and progesterone
2-Stimulates sperm production
what is Follicle stimulating hormone (FSH) responsible for
Stimulates the ovaries to produce oestrogen and stimulates sperm production
what does Posterior pituitary secret
1-Antidiuretic hormone/vasopressin (ADH)
2-Oxytocin
what is Antidiuretic hormone/vasopressin (ADH) responsible for
Regulation of water absorption in the kidneys
Hyposecretion = diabetes insipidus
Hypersecretion = oedema
what is Oxytocin responsible for
1-Contracts mammary glands when suckling begins to release milk
2-Contraction of uterine muscles to during childbirth
what is Thyroid gland
- Located in the neck
- Composed of the left an right lobe
- Secrete thyroxine and
triiodothymine in response to TSH
from the anterior pituitary - Secretes calcitonin
what does the thyroxine and triiodothymine do
- Stimulate tissue metabolism and maintains BMR
function of calcitonin
- Maintenance of calcium and phosphorous balance
what is Parathyroid glands
- 4 glands located in the neck
- Secrete parathormone
parathormone function
- Maintains calcium levels in the plasma
- Stimulates calcium reabsorption in the kidneys
- Activates vitamin D
what is Adrenal glands
- Located on top of each kidney
- Divided into the adrenal cortex and adrenal medulla
hormones that Adrenal cortex produced
1-Mineralocorticoids – Aldosterone
2-Glucocorticoids – Cortisol and cortisone
function of Glucocorticoids – Cortisol and cortisone
- Produced in response to ACTH
- Metabolises carbohydrates, fats and proteins
- Hypersecretion - Cushing’s syndrome
function of Mineralocorticoids – Aldosterone
- Regulates salts in the body
- Hypersecretion – kidney failure, high blood pressure
- Hyposecretion – Addison’s disease, muscular atrophy and weakness
Adrenal androgens
: male sex hormones mainly dehydroepiandrosterone (DHEA) and testosterone * All have weak effects, but play a role in early development of the male sex organs in childhood, and female body hair during puberty
- Oestrogen is a female sex hormone. It controls female reproduction and sexual development, including the development of female characteristics such as the growth of breasts
Adrenal medulla functions
- Functions to support the sympathetic nervous system
- Secretes adrenaline and noradrenaline
- Known as the stress hormones
- Prepare the body for fight or flight
- Speed up heart rate and slow down digestive and urinary systems
- Increases blood pressure and blood sugar level
- Adrenaline is a powerful vasoconstrictor
Pancreas secrets
- Insulin
- Secreted by beta cells
- Responsible for allowing glucose in the blood to enter the cells
- Glucagon
-Secreted by alpha cells - Prevents blood glucose levels dropping too low
- Stimulates the conversion of stored glycogen to glucose
what are Ovaries
- Located either side of the uterus
- Secrete oestrogen and progesterone
- Responsible for female sexual characteristics
- Malfunctions can lead to polycystic ovarian
syndrome
what are Testes
- Located within the scrotum, behind the penis
- Secrete testosterone
- Responsible for male sexual characteristics and sperm production
- Hypersecretion in females can leave to amenorrhoea
what is the Pineal body
- Pea shaped gland located in the centre of the brain
- Secretes melatonin
- Controls body rhythms associated with natural periods of light and darkness e.g. sleep patterns
- Malfunctions – jet lag feeling, depression
what is Thymus
- Located in the thorax behind the sternum
- Part of both the lymphatic and endocrine systems
- Secretes Thymic factor (TF), Thymic humoral factor (THF), Thymosine and Thymopoietin
- It is part of the immune system * Appears to promote development of T lymphocytes
- Malfunction leads to lowered immunity and/or stress
what happens to thymus After puberty
the thymus starts to slowly shrink and become replaced by fat
the thymus cycle
1-Thymus Before birth and throughout childhood, the thymus is instrumental in the production and maturation of Tlymphocytes
2-Once you reach puberty, the thymus starts to slowly shrink and become replaced by fat.
3-By age 75, the thymus is little more than fatty tissue
Diabetes Mellitus have 2 types
- Type 1 - Insulin dependent; Juvenile onset
- Type 2 - Insulin resistant; Adult onset
what is Diabetes Mellitus
- Metabolic disorders characterized by a high blood sugar level over a prolonged period of time.
the difference between type 1 and 2 diabetes mellitus is
type 1 doesn’t produce insulin but type 2 does but inefficiently
what is Graves disease
- An autoimmune disease
- Causes hyperthyroidism/overactive thyroid
- Immune system attacks the thyroid causing it to produce more thyroid hormone than required
- Usually affects people between ages 30-50
- More common in women
what are Graves disease - symptoms
- Fast and irregular heartbeat
- Frequent bowel movements or diarrhea
- Enlargement of the thyroid gland
- Change in menstrual cycles
- Heat intolerance
- Bulging eyes
- Nervousness or irritability
- Tiredness or muscle weakness
- Trembling hands
- Trouble sleeping
- Weight loss
what is Myxoedema
- Caused by severe hypothyroidism
- Characterised by thickening of the skin and laboured speech
- Can also lead to low oxygen and high carbon dioxide levels in the blood
- Causes include:
- Surgical removal of the thyroid
- Medications that affect the hormone system, such as some for cancer treatment
- Radiation therapy to treat cancer
what is Acromegaly
- Enlargement of bones and hands, feet and face
- Often accompanied by headache, muscle pain and emotional disturbances
- Caused by overproduction of growth hormone
