Endocrine 1 Flashcards
Define hormones
chemical messengers in body
secreted from glands into blood, transported to other parts of the body
synthesized from steroid or amino acids
regulate specific body functions
target other cells in the body through binding to hormone specific receptors
what are the ways that hormones alter targest cell activity
open / close ion channels
stimulate protein synthesis
activate / deactivate enzymes
stimulate cell to increase/ decrease secretory activity
stimulate mitosis (eg. growth hormone)
describe three types of stimuli for hormonal release
describe the mechanisms for regulation of hormone production / release
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Humoral stimuli-
change in ion / nutrients in the blood. - e.g. excess Ca in blood stimulates Thyroid to release Calcitonin.
- Calcitonin inhibits osteoclasts which break down bones and release Ca- thus facilitating Ca uptake / incorporation into bones
- Negative feedback used- as Ca in blood returns to normal, calcitonin inhibited
- Hormonal stimuli-
- release of hormones from one endocrine gland target another endocrine gland, and influence production / release of hormones
- negative feedback- As hormones levels return to normal, they inhibit Releasing hormone example- Hypothalamus releases GnRH (Gonadotrophin Releasing hormone). This hormone stimulates Anterior PG to release LH / FSH, which in turn releases sex hormones
- When sex hormones are at normal levels, this inhibits GnRH and LH/FSH
- When sex hormones fall (e.g. oestrogen + progesterone levels fall at end of monthly uterine cycle), GnRH is then able to be released
- Neural stimuli
- neurons stimulate hormones to be released, when neuronal stimulation stops, so does hormone release.
- e.g. baby suckling on breast stimulates nerves that trigger release of oxytocin which causes milk to be released
- nervous system can have overriding effets on regulation of hormone release
identify between exocrine and endocrine
exocrine - release various secretions / mucous / breastmilk/ digestive juices into epithelial surface of hollow gland (either direct or via a duct)
endocrine- release hormones directly into blood
Briefly describe why the hypothalamus is sometimes referred to as the “master gland’ Use one example of a posterior pituitary gland hormone, and two examples of an anterior pituitary gland hormone in your answer.
Hypothalamus monitors hormones in blood.
When hormones in blood are not within normal limits, hypothalamus regulates release of appropriate ‘releasing hormones’ that then stimulate APG to release trophic hormones which regulate majority of other hormonal responses to return hormone levels in blood back to normal- inhibiting hypothalamus to secrete ‘releasing hormones’ further (Negative Feedback)
2 examples Anterior PG
- Hypothalamus releases GnRH, which stimulates APG to release LH which targets ovaries to trigger ovarian cycle (stimulating secretion of progesterone by corpus luteum)
- Hypothalamus releases Prolactin Releasing Hormone, stimulating APG to release Prolactin which targets Breast glands, stimulating growth of breast tissue and milk production
- Hypothalamus releases Growth Hormone releasing Hormone (GHRH) whih stimulates APG to release GH, which targets most tissues / many organs to promote tissue growth- esp of bones and muscles
Hypothalamus also produces hormones and stimulates release of these hormones via PPG, through neural impulses
- example- Hypothalamus produces oxytocin which is stored in Posterior PG. During childbirth, contractions stimulate Hypothalamus to stimulate PPG (via nerve impulses) to release more oxytocin, which stimulates uterine contractions. positive feedback.
compare and contrast anatomical relationship between Hypothalamus and APG/PPG
APG- supplied with arterial blood that has already passed through Hypothalamus - linked by pituitary portal system. this enables hormones from Hypothalamus to quickly reach APG via blood
PPG- Nerve cells sit between Hypothalamus and PG, whereby hormones produced in cell body (in hypothalamus) and then stored in axon terminal (PPG). Nerve impulse starts in hypothalamus and moves down axon to PPG
identify the overall endocrine functions of the hypothalamus
Control centre for endocrine system
- produces hormones that control release of hormones from APG
- Releasing hormones (stimulate release of specific hormons from APG)
- Inhibiting hormones (inhibit the release of specific hormones from the APG)
- produces 2 hormones that are stored and released by the PG
list the hormones of the Pituitary gland
Anterior Pituitary Gland (FLAT GP)
- Follicle stimulating hormone
- Luteinising hormone
- Adrenocorticotrophic hormone (ACTH)
- Thyroid stimulating hormone (TSH)
- Growth hormone
- Prolactin
Posterior Pituitary Gland
- oxytocin
- anti-diuretic hormone (ADH)
Name the two hormones involved in the homeostasis of blood glucose levels and briefly describe how they regulate blood glucose levels
Insulin
- released by pancreas (combined endocrine and exocrine organ)
- targets most body cells- esp skeletal muscle, liver and fat
- stimulates glucose receptors and use / uptake of glucose, esp in skeletal muscle and fat
- stimulates conversion of glucose to glycogen (glycogenesis)
- stimulates other anaobolic reactions (convert glucose to fat)
- inhibits glucose releaseing processes (glycogenolysis, gluconeogenesis)
- regulated by decreased BGL (increase insulin release) + sympathetic NS / epinephrine + cortisol (inhibit insulin release)
Glucagon
- released by pancreas
- targets liver to stimulate conversion of glycogen to glucose (glycogenolysis)
- also stimulates gluconeogenesis (formation of glucose from non carbon source + lactic actid)
- stimulate liver to release glucose into blood
- regulation
- stimulated by reduced BGL / Sympathetic NS + increasing AA levels
- inhibited by increasing BGL + insulin
- stimulated by reduced BGL / Sympathetic NS + increasing AA levels
