Hormones and Sexual Development Flashcards
Endrocrine system
- uses chemicals (hormones)
- greek word ‘hormon’ meaning ‘to excite’
- most hormones synthesised by endocrine glands
- useful for coordinating long lasting changes in the body
Endocrine system hormones
- do not act in isolation
- more than 50 different hormones may be circulating at once
- most hormones bind to receptors on the membrane of target cell
Types of hormone
Amine- synthesised from one amino acid (tyrosine)
Peptide and Protein Hormones made from multiple amino acids
Steroids Hormones made from cholestrol
Pineal gland
- releases melatonin
- increases sleepiness
- influences the sleep/wake cycle
- has role in the onset of puberty
Hypothalamus
- influences the release of hormones by the pituitary gland
Thyroid gland
- releases thyroid hormones
- Thyroxine (T4) and Triiodothyronnie (T3)
- primarily responsible for regulation of metabolism
- help regulate growth and maturation
Parathyroid gland
- releases parathyroid hormone
- regulates calcium levels within the blood and bones
- calcium is element that allows the normal conduction of electrical currents along nerves and causes muscle contraction
Thymus gland
- releases thymosin
- supports the body’s immune system
- particulary active in children to develop lymphoid system
Adrenal cortex
Mineralcorticoids
- reduces the secretion of salts by the kidneys
- controls blood volume and regulates blood pressure
Glucocorticoids
- cortisol stimulates the liver to increase blood sugar
- increases metabloism of proteins and fats for energy
Adrenal Medulla
Adrenaline
Noradrenalime
- these prepare the body for vagarious action especially fight or flight
The Pancreas
- maintains blood sugar levels and releases:
Insulin
- helps glucose move from blood to cells where its used for energy
Glucagon
- releases glucose stored in liver into bloodstream
The ovaries
Oestrogen
- promotes female sexual characteristics
Progesterone
- helps prepare the uterus for/maintain pregnancy
The testes
Androgen’s
- promotes sperm production
- growth on pubic hair
- male sexual characteristics
Tropic hormones
- influence the release of other hormones
- most produced by the anterior pituitary gland
The pituitary gland
- master gland
- fusion of 2 glands which come together during embryological development
- Anterior pituitary (glandular tissue)
- Posterior pituitary (neural tissue)
Anterior Pituaitary
- the same embryonic tissue which formed the roof of the mouth
- during development it pinched off and migrated upward to sit beside the posterioir
Posterior Pituitary
- originated from an outgrowth of hypothalamic tissue on the end of the pituitary stalk
Anterior Pituitary: growth hormone (Somatotropin)
- stimulates growth in childhood and important for maintaining healthy body composition
- in adults improtant for maintaining muscle mass and bone mass
Anterior Pituitary: Thyroid Stimulating Hormone (TSH)
- stimulates thyroid gland
Anterior Pituitary: Adrenocorticotropic Hormone (ACTH)
- increases serotonin of steroid hormones by adrenal glands
Anterior Pituitary: Follicle Stimulating Hormone (FSH)
Females
- increases production of oestrogen an promotes maturation of ovum
Males
- promotes sperm production
Anterior Pituitary: Luteinizing Hormone (LH)
Females
- increases production of progestorone and stimulates ovulation
Males
- increases production of testosterone
Anterior Pituitary: Prolactin
Females
- promotes milk production after childbirth
- can affect sex hormone levels from the ovaries in women and testes in men
Posterioir Pituitary: Oxytocin
- milk releases in nursing mothers
- contols urine contractions
- some aspects of parental beh
- sexual pleasure
Posterioir Pituitary: Vasopressin (Antidiuretic Hormone)
- constricts blood vessels and raises blood pressure
- decreases blood volume
What controls the anterior pituitary?
- blood borne factors released by hypothalmus
What controls the posterior pituitary?
- nerves originating from the hypothalmus
Hormone regulation
- nervous system
- non hormonal chemicals in blood
- hormones (secreated in pulses)
Feedback
- hypothalamus and anterior pituitary sense when there is enough of a artiular hormone in blood circulation
- stop releasing their trohic hormones (negative feedback)
