Endocrine system

Question 1

What does the endocrine system do?

Answer 1

Produces hormones in endocrine glands scattered around the body and in endocrine cells throughout the body. These hormones diffuse into the blood stream where they are transported to target organs and alter function.

Question 2

Describe the location and function of the hypothalamus

Answer 2

Located in the brain a small area beneath two lobes of the thalamus. controls most endocrine functioning through the pituitary gland by releasing hormones that act on the pituitary gland. It produces its own hormones in the specialised nerves - the neuroendocrine cells which are transported rapidly to the anterior love of the pituitary by the pituitary portal system.

Question 3

Describe the location and function of the pituitary gland

Answer 3

Situated at the base of the brain. Anterior and posterior lobes. Secretes hormones responsible for the homeostasis of many organs in the body. Physically connected to the hypothalamus by the pituitary stalk.

Question 4

What is the function of the pineal gland?

Answer 4

Involved in the body’s biorhythms. Located in the brain. Melatonin secreted here.
10mm in size
Attached to the roof of third ventricle in the brain
Many sympathetic nerve pathways terminate here
Physiological function of the gland is not understood
?? Inhibits gonadotrophin with the timing of puberty

Question 5

What is the function of the thyroid gland?

Answer 5

Influence metabolic activity
Situated in front of the larynx and trachea
Very vascular
Secretes thyroxine, triiodothyronine, calcitonin
T’s have an effect on basal metabolic rate, metabolism of fats, carbohydrates and proteins and the normal functioning of cardiac, nervous and reproductive systems
Calcitonin secreted in response to high levels of calcium and phosphate in the blood, controls levels alongside parathyroid glands

Question 6

What is the function of the parathyroid gland?

Answer 6

Involved in the homeostasis of blood calcium and phosphate levels
Secreted parathyroid hormone (works with calcitonin)
Antagonist to calcitonin: it releases calcium and phosphate form bone and decreases secretion from the kidneys when blood levels of these mineral are low
Also promotes formation of calcitriol in the kidneys which absorbs calcium form the gastrointestinal tract

Question 7

What is the function of the thymus gland?

Answer 7

Release hormones related to the immune system. Activates lymphocytes. Does this by secreting thymopoietin and thymosins.

Question 8

What are the functions of the two adrenal glands?

Answer 8

Involved in autonomic nervous system responses and renal functions. Situated on superior pole on the kidneys. Consists of adrenal cortex and medulla which both have different functions.

Question 9

Where are endocrine cells situated?

Answer 9

Situated in organs such as ovaries and testes, placenta, pancreas and digestive system

Question 10

Discuss the anterior lobe of the pituitary gland

Answer 10

The adenohypophysis produces hormones that have a variety of functions. Anterior pituitary hormones are released in response to the action of the hypothalamus. 6 hormones realised by anterior pituitary are - gonadotrophins, prolactin, growth hormone, thyroid stimulating hormone, adrenocorticotrophic hormone, melanocyte stimulating hormone.

Question 11

Describe the functions of gonadotrophins

Answer 11

Released in response to GnRH from the hypothalamus. Follicle stimulating hormone (FSH) is a gonadotrophin released in the female after puberty to stimulate ovary prdouction. LH is produced to trigger ovulation and maintain the corpus luteum in the ovary. In the male FSH creates sperm and LH is involved in the production of testosterone.

Question 12

Discuss the production of prolactin

Answer 12

Produced in the puerperium to initiate and maintain the production of breast milk in response to signals from the hypothalamus

Question 13

Describe the function of growth hormone

Answer 13

Produced in response to growth hormone release hormone (GHRH) form the hypothalamus.
Stimulates the growth of many tissues and organs in the body such as bones, muscles,mother kindness and liver

Question 14

Describe the function of thyroid stimulating hormone

Answer 14

Affects the development and production of hormones by the thyroid gland.
Released in response to thyrotrophin relaxing hormone

Question 15

Describe the function of adrenocorticotrophic hormone (ACTH)

Answer 15

Released in response to corticotrophin releasing hormone from the hypothalamus
Stimulates blood flow to the adrenal glands and the production of steroids

Question 16

Describe the function of melanocyte stimulating hormone

Answer 16

Affects skin pigmentation

MSH also released in reaction to corticotrophin releasing hormone

Question 17

Describe the posterior lobe of the pituitary gland

Answer 17

The neurohypophysis
Composed of specialised secretory cells and nerve fibres
Two hormones secreted from posterior lobe: oxytocin and anti diuretic hormone
Neither is produced by getting posterior pituitary but in the hypothalamus then passed along nerve fibres to the pituitary where they are stored and released when needed

Question 18

Describe oxytocin

Answer 18

Produced in hypothalamus secreted from posterior pituitary
Involved in uterine contraction and contraction of myoepithelial cells surrounding the alveoli of the breaths during lactation

Question 19

Describe antidiurectic hormone

Answer 19

Released when a decrease in fluid volume in the blood is detected by the hypothalamus
Acts on nephrons in the kidney to re absorb water resulting in less being lost by urine
Also a powerful vasoconstrictor so important in maintainence of blood pressure

Question 20

Outline the blood supply to the thyroid gland

Answer 20

Superior and inferior thyroid arteries

Venous blood drains into the internal jugular veins through gets thyroid veins

Question 21

What is hypothyroidism?

Answer 21

Under active thyroid (doesn’t produce enough hormones)
Maternal hypothyroidism can result in cretinism in the fetus (hearing and language difficulties, mental retardation, growth retardation)
Screened for in the UK

Question 22

What is hyperthyrodism? Effects on pregnancy?

Answer 22

Over active thyroid,produces too many hormones
Associated with pre eclampsia, pre term labour and low brith weight
Drugs for hyperthyroidism pass placenta and breast milk

Question 23

What does the adrenal cortex secrete?

Answer 23

Glucocorticoids
Mineralcorticoids
Gonadocortocoids

Question 24

What are glucocorticoids?

Answer 24

Cortisol and corticosterone, essential for life hormones
Released by stimulation of ATCH from the anterior pituitary gland
Wide ranging affects on the body
Formation of ATP
Involved in metabolism of glucose and carbohydrates
Cause blood vessels to be sensitive to chemicals that cause vasoconstriction so are involved in maintainence of blood pressure
Can function as anti inflammatories
Can suppress immune response when necessary

Question 25

What are mineralcorticoids?

Answer 25

Aldosterone | Involved in reabsorption of sodium from the distal convoluted tubule of the kidney

Question 26

What are Gonadocortocoids?

Answer 26

Oestrogen and androgen Female sexual behaviour and in changes in body shapes in males at puberty Normally secreted in very low levels compared to those released by the gonads

Question 27

What does the adrenal medulla secrete?

Answer 27

Enclosed by the cortex Component of sympathetic nervous system Adrenaline Noradrenaline

Question 28

Describe adrenaline and noradrenaline

Answer 28

Secreted when there is an expectation of an instant action. Fight or flight response Help body deal with stressful situations Increase cardiovascular function, muscular contraction while decreasing digestive function

Question 29

What is a stressor?

Answer 29

Any agent of stimuli that produces stress | Pain, lack of control, unfamiliar envorinment

Question 30

What is the midwives roles in stressful situations?

Answer 30

Invaluable in reducing stress by giving support and increasing women's confidence to help women's tension and anxieties Help balance psychological imbalances Educate women about the process of labour and give her control in decision making.

Question 31

What hormone actions occur in stressful situations?

Answer 31

Corticotrophin releasing hormone released from hypothalamus This releases ACTH from anterior pituitary which acts on the adrenal cortex to secrete large amounts of cortisol with an increase in aldosterone These initiate the fight or flight response This affects normal action of uterus

Question 32

Describe the endocrine cells in the ovaries

Answer 32

Release of progesterone and oestrogen are responsible for reproductive cycle Development of female characteristics Continuation of pregnancy Preparation for breastfeeding and lactation Inhibin Inhibits FSH and LH Relaxin Relaxes pelvic ligaments in pregnancy and helps in cervical dilatation

Question 33

Describe endocrine cells in the testes

Answer 33

Testosterone is synthesised | Responsible for development and maturation of spermatozoa

Question 34

Describe endocrine cells in the placenta

Answer 34

Human chorionic gonadotropin initially maintains the corpus luteum until the placenta is fully functional Then oestrogen, progesterone, human placental lactogen etc

Question 35

Describe endocrine cells in the digestive tract

Answer 35

Hormones secreted to regulate the release of digestive enzymes

Question 36

Outline the role of prostaglandins

Answer 36

Present in most tissues and have a varied role thought to influence the female reproductive tract, pituitary function, body temperature in response to inflammatory response

Question 37

Outline hormonal action

Answer 37

Hormone identifies its target cell by the presence of specific receptors on the cell membrane The hormone binds to receptors and chemically alters he metabolic processes of the target cell Hormones transported in the blood Endocrine glands very vascular easy for hormones to easily pass into blood stream

Question 38

How does hCG effect pregnancy?

Answer 38

Maintains the corpus luteum until he oak cents is formed Causes changes in appetite, sleep patterns and food tolerance Once levels of hCG decrease the symptoms reduce

Question 39

How does FSH and LH secretion change in pregnancy?

Answer 39

From posterior pituitary - lessens as cyclical reproductive cycle not required

Question 40

How do prolactin levels change in pregnancy?

Answer 40

Rise from early in pregnancy in preparation for lactation

Question 41

How do cortisol levels change in pregnancy?

Answer 41

From adrenal glands, Increase in second trimester Involved in many metabolic processes

Question 42

How do corticosteroids effect pregnancy?

Answer 42

Increased in pregnancy | Thought to be implicated in the development of straie gravidarum, glucosuria and raised blood pressure

Question 43

How do oestrogen levels change in pregnancy?

Answer 43

Rise dramatically during pregnancy Act on liv to release proteins and cholesterol (required by breasts and to produce prolactin) Involved in uterine oath and blood supply

Question 44

How do progesterone levels change in pregnancy?

Answer 44

Increase in threefold Acts on smooth muscle of blood vessels, gastrointestinal and renal system. Inhibits uterine contraction until uterus is ready at term

Question 45

How do relaxin levels change in pregnancy?

Answer 45

Released by corpus luteum and ,after by the placenta Highest levels in first trimester Works alongside progesterone

Question 46

How does the endocrine system change in labour?

Answer 46

Both maternal and fetal endocrine systems are thought to be involved in the initiation of labour Cortisol levels in talk adrenal gland rise towards term This increases levels of oestrogen in mother which causes oxytocic receptors on uterine muscle to form Oxytocin then releases form posterior pituitary gland Prostaglandins also involved although exact mechanism is unknown.

Question 47

How does the endocrine system change in the postnatal period?

Answer 47

With expulsion of placenta many hormone levels drop dramatically Drop in oestrogen allows prolactin to act on alveoli in breast Prolactin and oxytocic levels remain high to maintain breastfeeding Oxytocin levels also maintain contractions to minimise blood loss

Question 48

Discuss the endocrine system in the neonate

Answer 48

Largely functional in term neonate Hormones related to reproduction are not formed until puberty During second half of pregnancy adrenal gland produces cortisol resulting in maturation of many organs in preparation for extra uterine life Liver increases glycogen, storage of this prevents hypoglycaemia for the first days of life Surfactant in lungs are under control of cortisol, oestrogen, adrenaline and thyroid hormones Thyroid hormones and noradrenaline used in metabolism of brown fat in thermoregulation