Hormones and reproductive systems Flashcards
What are endocrine glands?
Organs that secrete a hormone into the blood
What are hormones?
Chemical messengers
Regulate processes like growth, development, metabolism, homeostasis and reproductive processes
Name three types of hormones.
Steroid hormones
Peptide hormones
Amino acid derived hormones
What are some steroid hormones?
Testosterone
Oestrogen
Cortisol
What are some peptide hormones?
Growth hormone
Oxytocin
Parathyroid hormone
What are some amino acid derived hormones?
Thyroid hormones
Catelcholamines
What is the pituitary gland?
A small structure at the base of the brain which releases hormones that, in turn, controls the activity of the body’s other hormone glands
What are the 2 hormones released by the posterior pituitary?
Oxytocin
Vasopressin (Anti-diuretic hormone, ADH)
What does oxytocin do?
Controls milk release from lactating breast
Controls uterine contraction at onset of labour
What does vasopressin/ ADH do?
Acts on kidneys to reabsorb water
Regulates blood osmolarity and urine output
Describe the neuro-endocrine reflex that happens with breastfeeding?
Suckling -> Hypothalamus -> Posterior pituitary -> Oxytocin -> Milk squeezed out
What are the 6 hormones secreted by the anterior pituitary?
1) Growth hormone
2) Prolactin
3) Adrenocorticotropic hormone (ACTH)
4) Thyroid stimulating hormone (TSH)
5) Follicle stimulating hormone (FSH)
6) Luteinising hormone (LH)
What do most of the anterior pituitary’s hormones do?
Most of which regulate secretions of tropic hormones
What are tropic hormones?
Hormones from endocrine organs
What are the principle target organs for FSH and LH?
Ovaries and testes
What is the principle target organ for ACTH (Adenocorticotropic hormone)?
Adrenal glands
What is the principle target organ for TSH (Thyroid stimulating hormone)?
Thyroid gland
What are the principle target organs for growth hormone?
Bone
Skeletal muscle
Liver
What are the principle target organs for prolactin?
Mammary glands
How can you remember the anterior pituitary hormones?
FLAT PeG
What are the 5 cell types in the anterior pituitary?
Somatotrophs Lactotrophs Corticotrophs Gonadotrophs Thyrotrophs
What hormone is produced by the cell type, somatotrophs?
Growth hormone
What hormone is produced by the cell type, lactotrophs?
Prolactin
What hormone is produced by the cell type, corticotrophs?
Adrenocorticotropic hormone (ACTH)
What hormones are produced by the cell type, gonadotrophs?
Follicle stimulating hormone (FSH) Luteinising hormone (LH)
What hormone is produced by the cell type, thyrotrophs?
Thyroid stimulating hormone (TSH)
What triggers the release of anterior pituitary hormones?
Hormones from the hypothalamus control release of anterior pituitary hormones
Describe growth hormone.
Synthesised and stored in somatotrophs
Principle targets: bone and skeletal muscle
Stimulates growth in children and adolescents but continues to have important impacts through adult life
What are the direct metabolic impacts of GH on muscle, adipose tissue and liver?
Increased muscle mass
Decrease in fat deposits
Stimulates IGF (insulin-like growth factors) production
What causes growth hormone disorders?
Usually result of pituitary tumour secreting growth hormone
What is gigantism and what is it caused by?
GH excess
Abnormally high linear growth due to excessive action go IGF while epiphyseal growth plates are open (childhood)
Normal body proportions because soft tissue is also impacted
What is acromegaly and what is it caused by?
GH excess
Increased growth hormone later in life after fusion of epiphyses
Course facial features, enlarged hands and feet, protruding jaw, separation of teeth, enlarged tongue and thickened lips, deep voice, cardiomegaly and diabetes
Usually due to pituitary tumour
What is the result of GH insufficiency in adults generally?
No major symptoms
What is the result of GH insufficiency in children?
Pituitary dwarfism Slow growth rate Normal body proportions Poor muscle development Excess subcutaneous fat
Describe the thyroid gland.
Discrete organ, adheres to trachea
2 large, asymmetrical flat lobes connected by isthmus
Rich blood supply
Regulated by hypothalamus and pituitary
What is the functional unit of the thyroid gland? How many are there in each gland?
Follicle
1000s in each gland
Consists of a layer of follicular cells surrounding a colloid-filled cavity
What are the thyroid hormones?
Triiodothyronine (T3)
Thyroxine (T4)
Describe the thyroid hormones.
Amino acid derived hormones
Tyrosine
Iodinated
What 2 principle raw materials are required for thyroid hormone synthesis?
Tyrosines: provided by thyroglobulin and secreted by follicular cells into lumen of follicle
Iodine: essential requirement, pumped into follicular cells against concentration gradient
What is one major advantage of the thyroid hormone system?
Capable of storing many weeks worth of thyroid hormone, coupled to thyroglobulin
If no iodine is available, thyroid hormone secretion will be maintained for a while
Where are thyroid receptors in the body?
Throughout the body e.g. liver, brain, kidney, hypothalamus and pituitary