Lecture 39: ENDOCRINE REVISION Flashcards
Endocrine system consists of:
- Endocrine gland that secretes..
- Hormones (chemical messengers), which are…
- Carried in the bloodstream to…
- The target cells upon which they act
If the target cell expresses a specific receptor…
- That hormone will be able to affect it
- And the target cell will be able to respond
Water-soluble hormones:
Water-soluble hormones
- Peptides
- Catecholamines
- Stored until required
- Dissolved in the blood
- Receptors on the cell surface
- Mechanism of action via 2nd messengers
- Speed = milliseconds - minutes
Lipid-soluble hormones:
Lipid-soluble hormones
- Steroids
- Thyroid hormones
- Made from cholesterol as required (not stored)
- Thyroid hormones made in thyroid cells, stored until required
- Bound to carrier protein
- Intracellular receptors
- Alter gene transcription
- Speed = hours - days
Anterior pituitary hormones:
- Growth Hormone
- Prolactin
- Gonadotropic hormones
- Thyroid stimulating
- Adrenocorticotropic hormone
Posterior pituitary hormones:
- Antidiuretic Hormone
- Oxytocin
Posterior pituitary gland:
- Neuron starting from hypothalamus extends to posterior
- Hormone made and synthesised in hypothalamus and stored in axon
- Secretes hormone into posterior pituitary gland
- Main hormone secreted = oxytocin
Oxytocin:
- Fetus moves into birth canal, stretch increase
- Variable = stretch
- Detected by stretch receptors
- Feeds information via nerve fibres back to hypothalamus + pituitary
- Hormone (OT) stimulates muscle
- Stronger, more frequent labour contractions
- Uterine muscle = effector
- POSITIVE FEEDBACK = response increases stimulus
Anterior Pituitary Gland:
- Neuron from hypothalamus only extends to median eminence
Different axes:
- HPG
- HPT
- HPA
Feedback regulation of the anterior pituitary gland:
- Hypothalamus
- Releasing Hormone
- Anterior Pituitary Gland
- Pituitary Hormone
- Target Cell
- Effector
Effects of Growth Hormone:
- Long Term Growth of bones, muscles, and other tissues indirectly via insulin-like growth factor (IGF-1) Stimulates protein synthesis - Short Term Increases blood glucose Increases triglyceride breakdown
Thyroid hormones work via ______ ______.
- Negative Feedback
Effects of thyroid hormone:
- Metabolic effect
- Growth (developmental) effects
- Via nuclear receptors that alter the transcription of genes
C cells (calcitonin) directly sense ______ levels in the blood.
- Calcium
Calcitonin :
- Lowers high Ca2+ levels so that they’re back to normal.
Parathyroid hormone ______ ____ Ca2+ back to normal.
- Raises low
- Kidney hydroxyapatite affected
- Less urinary calcium excretion
Adrenal Glands located at the top of the kidney. Broken into two main parts:
- Cortex: inner, middle, outer
- Medulla : epinephrine, norepinephrine (catecholamines) –> have the same function on target cells
Cortisol Secretion:
- Abnormal stress / daily variation
- Hypothalamus : corticotropin releasing hormone
- AP : secretes adrenocorticotropic hormone
- Adrenal Cortex: Cortisol
- Metabolic effects: increased protein breakdown, fat breakdown, glucose synthesis
- Negative feedback (except during stress response)
- Other effects: helps one cope with stress, long-term: suppresses immune system
Constant Glucose Levels:
- Alpha cells and Beta cells sense and integrate glucose levels
Insulin regulates _____ storage.
- Fuel
Glucagon regulates fuel _____.
- Release
Type 2 Diabetes = _____ of beta cells. Two completely pathways between
- Hypertrophy
Type 1 = ZERO insulin. Type 2 = Insulin level is also lowered
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