Endocrine Flashcards
Water soluble hormone act on…
Plasma membrane receptors since it cannot enter cells
Lipid soluble hormones act on
Intracellular and plasma membrane receptors since it can enter the cell
Water soluble hormones are
Protein and amino acid based hormones
Lipid soluble hormones are
Steroid and thyroid hormones
Main types of hormones
1) Protein and peptide hormones e.g. Insulin
2) Amino acid derivatives from tyrosine e.g. Epinephrine, Norepinephrine
3) Steroid hormones e.g. oestrogen, testosterone
Hormone actions on target cells include
- Alters plasma membrane permeability
- Stimulates protein synthesis
- Activates (or deactivates) enzymes
- Induces secretion of other substances(Tropic hormone?)
- Stimulates cell division
Target cells have
Specific receptors which the hormone binds to
Protein/AA-based hormones
Freely dissolved in plamsa
Steroid and Thyroid hormones
Bound to protein carriers
Humoral stimuli
Changes in plasma solute concentrations of ions or
organic nutrients
Neural stimuli
Regulation by the nervous system
Hormonal stimuli
Regulation by other hormones
Positive feedback
enhances the stimulus
Pineal gland secretes
Melatonin
Hypothalamus role is to
Stimulate release of hormones from the anterior pituitary gland (tropic response)
Hypothalamus produces
1) Oxytocin
2) Anti-diuretic hormone (ADH)
3) Corticotropin-releasing hormone
4) Thyrotropin-releasing hormone (TRH)
5) Gonadotropin-releasing hormone (GnRH)
6) Growth hormone-releasing hormone (GHRH)
Melatonin
Helps sustain sleep cycles
Oxytocin
- Stimulates contraction of smooth muscle in uterus
* Secretion at birth (labour) and during breast feeding
Anti-diuretic hormone (ADH)
↑ blood concentration, ↓ blood volume or ↓ blood pressure
Corticotropin-releasing hormone
Stimulates adrenocorticotropic hormone release from anterior pituitary
• Corticotropin-Releasing Hormone (CRH)
• Growth Hormone-Releasing Hormone (GHRH)
• Thyrotropin-Releasing Hormone (TRH)
initiates the
Long lasting response to stress
Pituitary gland role is to
Secretes 9 hormones that regulate most other endocrine glands in the body
Anterior pituitary gland releases
1) Oxytocin
2) ADH
1) Growth Hormone (GH)
2) Thyroid Stimulating Hormone (TSH)
3) Adrenocorticotropic Hormone (ACTH)
4) Prolactin (PRL)
5) Follicle Stimulating Hormone (FSH)
6) Luteinizing Hormone (LH)
7) Melanocyte Stimulating Hormone (MSH)
Posterior pituitary gland releases
1) Oxytocin
2) ADH
Growth Hormone (GH)
- Promotes protein synthesis & growth of body cells
* Influences carbohydrate & fat metabolism
Thyroid Stimulating Hormone (TSH)
Controls production and release of thyroid hormone by
the thyroid gland
Adrenocorticotropic Hormone (ACTH)
Controls hormone production and release by the adrenal cortex
Prolactin (PRL)
Starts/maintains milk production
Follicle Stimulating Hormone (FSH)
- Women: Stimulates the development of ova & production of oestrogen
- Men: Stimulates sperm production
Luteinizing Hormone (LH)
- Women: Stimulates ovulation, formation of corpus luteum & secretion of progesterone
- Men: Stimulates development of interstitial cells of testes & production/secretion of testosterone
Melanocyte Stimulating Hormone (MSH)
Controls production & secretion of melanin
Negative feedback of anterior pituitary gland
1) Stimulus
2) Releasing hormone from hypothalamus
3) Trophic hormone from anterior pituitary
4) Target gland releases target hormone for necessary biological effect
Thyroid gland produces
1) Thyroid Hormone
2) Calcitonin
Thyroid Hormone (TH)
Increases metabolic rate & heat production
Also
• Maintaining blood pressure
• Regulating tissue growth
• Development of skeletal & nervous system
• Reproductive capabilities
Calcitonin
• Stimulates Ca2+ uptake and absorption by bones
• Inhibits osteoclast activity, and thus the release of
Ca2+ from the bone matrix
Thyroid hormone synthesised in
Lumen of thyroid glands
Parathyroid releases
Parathyroid hormone
Parathyroid hormone
Increases plasma calcium by increasing:
• Absorption of calcium by the digestive tract
• Reabsorption of calcium by the kidneys
• Phosphate excretion by the kidneys
• Activity of osteoclasts = more calcium released into the
blood
Thyroid gland stimulus
Humoral stimulus
Stimulus is calcium levels too high
Releases calcitonin which increases uptake and absorption of calcium into bones
Parathyroid gland stimulus
Humoral stimulus
Stimulus is calcium levels too low
Releases parathyroid hormone which activates osteoclasts to breakdown bones and release calcium. Improves absorption of calcium from GI tract and decreases calcium loss in urine.
Pancreas (beta cells) stimulus
Humoral stimulus
Stimulus is blood glucose too high
Insulin increases uptake of glucose into tissue cell and stimulates glycogen formation in liver and muscle
Increases formation of fat
Pancreas (alpha cells) stimulus
Humoral stimulus
Stimulus is blood glucose too low
Glucagon stimulates breakdown of glycogen breakdown and gluconeogenesis in liver. Increase release of glucose into blood
Hypothalamus stimulates
Release of anterior pituitary gland which stimulates release of adrenal cortex.
Stimulus is stress
Corticotropin-releasing hormone (CRH) released from hypothalamus, stimulates anteriors piturtary to release adrenocorticotropin (ACTH), stimulates adrenal cortex to release cortisol. Cortisol is anti-inflammatory, increases blood glucose, promotes protien and fat conversion into glucose (gluconeogenesis), and more fuel to deal with stress
Renin-angiotensin-aldosterone system
Stimulus is low blood pressure
Causes renin to be released from kidney which converts angiotensinogen into angiotensin causing vasoconstriction. Angiotensin stimulates aldoterone release from adrenal cortex, cauing sodium reabsorption at kidney, increased water reabsorption by osmosis which increases blood volume –> negative feedback
Thymus secretes
Thymic Hormone which is a range of collective substances
Pancreas (exocrine and endocrine) duct cells produce
1) Bicarbonate neutralise
2) Stomach acidity
Pancreas (exocrine and endocrine) cells produce
Digestive enzymes
Alpha cells produce
Glucagon (a hyperglycaemic hormone)
Beta cells produce
Insulin (a hypoglycaemic hormone)
Acinar cells produce
Pancreatic juices for digestion
Glucagon
1) Elevates blood glucose
2) Major target is the Liver, where it promotes…
• Glycogenolysis
• Gluconeogenesis
• Release of glucose to the blood
Insulin
- Lowers blood glucose
- Enhances membrane transport of glucose into fat & muscle cells
- Inhibits glycogenolysis & gluconeogenesis
- Participates in neuronal development, learning & memory
Cortex produces
Cortical steroid hormones
Medulla produces
Epinephrine & norepinephrine
Adrenal cortex produces the hormones
1) Mineralocorticoids
2) Glucocorticoids
3) Gonadocorticoids
Mineralocorticoids
Regulate H2O and minerals in the blood (BP + volume)
• E.g. Aldosterone
• retains NaCl, bicarbonate & H2O by the kidneys
• ↑ excretion of potassium
Glucocorticoids
- Regulate metabolism and stress response
- E.g. Cortisol –
- promotes protein & fat breakdown, increases blood glucose
- Maintain BP by ↑ action of vasoconstrictors
- ↓ inflammation & depresses the immune system
Gonadocorticoids
Sex Hormones
• E.g. Androgens, Estrogens, Progesterone
Adrenal medulla produces the hormone
1) Catecholamines
• Epinephrine & Norepinephrine
• Also known as Adrenaline/Noradrenaline
Catecholamines
Released in response to stress, they cause:
• ↑ blood glucose & fatty acid levels
• ↑ blood vessel constriction
• ↑ heart rate
• Blood to be diverted to the brain, heart and skeletal muscle
Gonads produce
1) Oestrogen
2) Progesterone
3) Testosterone (& Inhibin)
Gonads
Develop gametes (ova & sperm)
• Maturation of the reproductive tract at puberty
• Development of secondary sexual
characteristics
Female gonads are ovaries and male gonads are
testes
Testosterone
• Maturation of reproductive organs • Appearance of secondary sex characteristics & sex drive • Necessary for normal sperm production • Maintains organs in functional state
Oestrogen and progesterone
• Maturation of reproductive organs • Appearance of secondary sex characteristics • Breast development & cyclic changes in lining of uterus • Increased flexibility of tissues involved in labour (Relaxin)
The heart produces
Atrial Natriuretic Peptide
Atrial natriuretic peptide
Reduces BP, blood volume and blood Na+ concentration
The kidneys produce
1) Erythropoietin
2) Renin
Erythropoietin
Signals production of red blood cells
Renin
Starts the Renin-Angiotensin mechanism
The liver produces
Angiotensin
Angiotensin
Stimulates secretion of aldosterone, to increase Na+ and water retention by kidneys
The gastrointestinal tract cells produce
1) Gastrin
2) Secretin
Gastrin
Stimulates release of HCl
Secretin
Stimulates liver & pancreas to produce bicarbonate
Adipose Tissue produces
Leptin
Leptin
Is involved in appetite control, and stimulates increased energy expenditure
The skin produces
Cholecalciferol
Cholecalciferol
Is the precursor of vitamin D
A stressor
Any stimulus that produces a stress response
Stress benefits
- Increased oxygen and glucose
- Increased activity of respiratory and cardiovascular systems
- Glucagon from pancreas increases metabolism
- Functions not useful for ‘Fight or Flight’ are inhibited
- Enhanced attention, motivation and memory
Stress disadvantages
Stressors can cause illness when they:
1) Severely disrupt a person’s life
2) Are uncontrollable
• Prolonged stress (at least 6 months) can deplete the body’s resources
• Chronic stress can also lead to development of diseases & illness
Stress response
1) Perception of stressor
2) Activation of the Hypothalamic-PituitaryAdrenal Axis (HPA axis) results in the secretion of:
• Epinephrine & Norepinephrine
• Adrenal Steroids – glucocorticoids & mineralocorticoids
3) Suppression of non-vital functions
Short-term stress response
- Increased heart rate
- Increased blood pressure
- Liver converts glycogen into glucose and release glucose into the blood
- Dilation of bronchioles
- Changes in blood flow patterns leading to decreased digestive system activity and reduced urine output
- Increased metabolic rate
Long-term stress response
- Retention of sodium and water by kidneys
- Increased blood volume and blood pressure
- Proteins and fats converted to glucose or broken down for energy
- Suppression of immune system
General adaptation syndrome
• Controlled by hypothalamus
• Systemic, response to challenge on homeostasis
and returns balance, physical manifestation
coordinated
General adaptation syndrome steps
1) Initial flight or fight response (ALARM) Epinephrine & Norepinephrine (catecholamines)
2) Resistance (stress longer than few hours) Cortisol
3) Exhaustion resources depleted, systemic damage
