Endocrine system Flashcards
What are hormones?
Chemical messengers of the body
Act on specific target cells
Transported via bloodstream to most cells in the body.
Give examples of glands in the body
- Hypothalamus
- Pineal
- Pituitary
- Thyroid
- Parathyroid
- Thymus
- Adrenals
- Islets of Langerhans in pancreas
- Ovaries or testes
What does the hypothalamus do?
- Between cerebellum and brainstem
- Houses pituitary gland and hypothalamus
- Regulates
1. Temperature
2. Fluid volume
3. Growth
4. Pain and pleasure response
5. Hunger and thirst
What are the hormones in the hypothalamus?
- Corticotropin – releasing (CRH)
- Thyrotropin – releasing
- Growth hormone – release
- Gonadotropin – releasing
- Somatostatin – inhibits Growth Hormone GH and Thyroid stimulating hormone TSH
What does the pituitary gland do?
AKA hypothesis
- Sat beneath hypothalamus and connected
- Termed master gland – regulates and control glands
- Divides into
1. Anterior pituitary gland – stimulated by hormones
2. Posterior pituitary gland - synaptic process stimulates using terminals of hypothalamic neurons
What are the two divisons of the pituitary gland?
- Anterior pituitary gland – stimulated by hormones
- Posterior pituitary gland - synaptic process stimulates using terminals of hypothalamic neurons
Explain the negative feebback loop of hormone
- Hypothalamus detects changes in bloodstream
- Releasing hormones to pituitary gland
- Get to target gland
- Hormone levels increase
- Hormones are used
- Hormone levels reduces
- Feedback – positive or negative
What hormones are released from anterior pituitary?
- Growth hormones – promoting growth of bones and muscles
- Prolactin – stimulates lactation
- Stimulating (tropic) hormones
1. TSH – thyroid hormones
2. FSH – follicle stimulating hormones - gametes
3. LH – sex hormone
4. ACTH – steroid hormones like cortisol in adrenal gland
What hormones are released from the posterior pituitary?
- ADH – anti diuretic hormone – on kidney and reduces urine output
- Oxytocin – acts on uterus/breast – uterine contractions and milk release
What hormones are released from the kidney?
- **1,25 dihydroxyvitamin D **– stimulates calcium absorphtion from intestine
- Renin – activates Renin-Angiotensin system
- Erythropoietin – increases red blood cell production
What hormones are released from the ovaries?
- Oestrogen
- Progesterone – important in menstrual cycle and maintaining pregnancy
What hormones are released from the testes?
Angrogens and Testosterone
- both important for secondary sexual characteristics and sperm production
What hormones are released from the thymus?
Releases thymosin and thymopoietin
- Affects maturation of T lymphocytes – response to infection and immune response
What hormones are released from the pineal gland?
Secretes melatonin
- Role in sleep/wake cycles, body temperature and sleep
- Ageing and fertility also effected here
What hormones are released from the thyroid gland?
Needs iodine to function so takes from blood stream
- Produces thyroid hormone and calcitonin
Thyroid functions:
- Increase metabolic rate
- Increase heat production
- Regulate metabolism
Calcitonin function:
- Lowers blood calcium levels
What are two cells that effect hormones in thyroid glands?
- Follicular cells – excretion of T3 and T4 increasing basal metabolic rate, increasing heat production and regulating metabolism of nutrients
- Thyroid C cells – calcitonin – lowers blood calcium and phosphate levels
How do T3 and T4 cells function from thyroid glands?
- increasing basal metabolic rate
- increasing heat production
- regulating metabolism of nutrients
What is the Hypothalamic-pituitary-thyroid axis?
- Neurotransmitter to hypothalamus
- TRH to pituitary
- TSH to thyroid
- T3 and T4 (via liver) cells to target organs
What do parathyroid glands do?
- Embedded in thyroid gland
- Chied cells secrete parathyroid hormone – increases blood calcium levels
What od adrenal glands do and secrete?
- Secrete steroid hormones – cortisol (from zone fasciculata) and aldosterone (from zone glomerulosa) from cortex
- Adrenaline and noradrenaline from the medulla
- Zone reticularis releases adrenal sex hormones
What hormones are secreted from the adrenal cortex?
- Aldosterone – effecting sodium absorption and loss of potassium by kidney to retain water, regulates blood volume and blood pressure
- Cortisol – affecting metabolism, regulating blood sugar levels, affects growth, anti-inflammatory action and decreases effects of stress
- Dehydroepiandrosterone and androstenedione – converted to testosterone in periphery
What does aldosterone do?
effecting **sodium absorption and loss of potassium **by kidney to retain water, regulates blood volume and blood pressure
What does cortisol do?
affecting metabolism, regulating blood sugar levels, affects growth, anti-inflammatory action and decreases effects of stress
What does Dehydroepiandrosterone and androstenedion do?
converted to testosterone in periphery in adrenal cortex
What hormones are secreted from the adrenal medulla?
**- Secrete – epinephrine and norepinephrine (adrenaline and noradrenaline)
- Serve as neurotransmitters for sympathetic nervous system
- Involves win stress response (fight or flight)
How does the control of aldosterone affect blood pressure?
- Regulated by blood pressure in the kidney
1. When fall in blood pressur
2. kidney detects
3. hypotension so **renin angiotensin system **
4. **producing renin **hormone triggering
5. angiotensinogen **transforms to angiotensin I **
6. using angiotensin converting enzyme to then make **angiotensin II **
7. making **use thirty and vasoconstriction **
8. so blood pressure rises
9. also produces aldosterone so **higher sodium and water retention **
What are the main functions of the pancreas?
- Located behind the stomach between the spleen and duodenum
- 2 major functions
1. Production of digestive enzymes
2. Release of two hormones insulin and glycogen
What are the components of pancreatic tissue?
- Islets of Langerhan
- Alpha cell – glucagon produced – hyperglycymic hormone – increase glucose levels
- Beta cell – insulin production – hypoglycymic hormone – reduce levels of glucose
- Outside islet is exocrine cells for digestive enzyme production
How does the pancreas respond to Hypoglycaemia ?
low glucose levels
- Glucose level in blood stream
- Liver registers – need glucagen to increase glucose (stimulate break down of glucogen transform into glucose)
How does the pancreas respond to Hyperglycaemia ?
high glucose levels
- Glucose high in blood stream – liver registers
- Insulin is released – makes glucose go into cells to reduce sugar in blood stream
- Insulin also stimulates the formation of glycogen from glucose by glycogenesis
- Also gluconeogenesis – transformation of amino acids, proteins and lipids into glucose
What is gluconeogenesis?
Hyperglycaemic mechanism to increase glucose levels
Transformation of amino acids, proteins and lipids and glycerol into glucose
What is glycogenolysis?
Stimulating** break down of glycogen** this transforms into glucose (increases blood sugar levels)
What is glycogenesis?
**Formation of glycogen from glucose **– to reduce levels of blood sugar levels
What does insulin do?
- Hormone Protein
- Attach to cell receptors and glucose can enter the cell – via insulin passageways
- Can have insulin resistance due to damaged shape of insulin so not complementary to cell
- Insulin **reduces glucose levels **in the blood
What does growth hormone do?
promoting growth of bones and muscles
What does prolactin do?
Stimulate lactation
anterior pituitary
State stimulating tropic hormones in the anterior pituitary gland
- TSH – thyroid hormones
- FSH – follicle stimulating hormones - gametes
- LH – sex hormone
- ACTH – steroid hormones like cortisol in adrenal gland
What does ADH do?
– anti diuretic hormone
– on kidney and reduces urine output
posterior pituitary
What does oxytocin do?
- acts on uterus/breast
- uterine contractions and milk release
posterior pituitary
what does 1,25 dihydroxyvitamin D do?
kidney
stimulates calcium absorphtion from intestine
What does renin do?
activates Renin-Angiotensin system
when thirsty
low blood pressure
kidney
What does erythropoitin do?
kidney
- increase red blood cell production
What does progesterone do?
important in menstrual cycle and maintaining pregnancy
ovaries
What doe thymosin and thymopoietin do?
- Affects maturation of T lymphocytes
- response to infection and immune response
- thymus
What does melatonin do?
-pineal gland
- Role in sleep/wake cycles, body temperature and sleep
- Ageing and fertility also effected here
What does thyroid hormone do?
- Increase metabolic rate
- Increase heat production
- Regulate metabolism
- thyroid gland
What does calcitonin do?
- lowers blood calcium levels
- thyroid
What do follicular cells do?
– excretion of T3 and T4
- Basal metabolic rate
- increasing heat production
- regulating metabolism of nutrients
What do thyroid C cells do?
– calcitonin – lowers blood calcium and phosphate levels
What does aldosterone do?
- effecting sodium absorption
- loss of potassium by kidney
- retain water, regulates blood volume and blood pressure
- kidney - adrenal cortex
What does cortisol do?
- affecting metabolism
- regulating blood sugar levels
- affects growth
- anti-inflammatory action
- decreases effects of stress
- adrenal cortex
