Hoorcollege 1 Humane fysiologie Endocrinologie
Hormone = chemical substances produced by specialized tissue (gland) and
secreted into the blood circulation to reach a target organ. Are chemical mediators
of intracellular communication.
Intercellular communication
• Synaptic translation
• Autocrine function
• Paracrine function
• Pheromone function
• Allomone function (from one organism to another)
Endocrine signaling
• Source: gland
o No contribution to specificity of target
o Synthesis/secretion
• Distribution: bloodstream
o Universal (almost)
o Importance of dilution
• Non target organ
o Metabolism
o Breaks down
• Target cell
o Receptor: source of specificity
o Responsiveness
▪ Number of receptors
▪ Downstream pathways
▪ Other ligands
▪ Metabolism of ligand/receptor
▪ All often regulated by ligand
In paracrine cell the source is the adjacent cell. And the distribution is the matrix.
Hydrophilic messenger = water-soluble and readily transported via the circulation
Hydrophobic messenger = nearly insoluble in water and distribution presents special
problems. They are bound to carrier proteins. Can diffuse over the membrane of the
cell because they are lipid soluble.
Mostly peptide hormones bind to an GPCR membrane receptors.
Types of cell surface receptors
1. Channel-linked receptors
2. Enzyme-linked receptors (tyrosike-kinine receptors)
3. G-protein-coupled receptors
Intracellular receptors
, • Ligand must be hydrophobic and able to pass directly through the plasma
membrane of the cell
Hypothalamus-pituitary master control center
• Anterior pituitary
o Receives signals from neuroendocrine cell bodies located in
hypothalamus. Produce releasing hormones.
o Signal is transported through blood circulation to pituitary
o Endocrine signaling
o Hormone producing cells increase/decrease their own hormones;
tropic hormones
o Hormones secreted in the circulation and carried to the organs
• Posterior pituitary
o Axons from neuroendocrine cells go through posterior pituitary
o Signal reaches pituitary and hormones are directly released into the
bloodstream
o There is no intermediate step
Hormone secretion follows predictable changes in the environment
• Such as light
• Presence day and night
o Causes change in behavior
• Circadian systems (periodic)
o Two fundamental characteristics
▪ Endogenous rhythmicity with a period of approximately 24 h.
these rhythms persist independently of oscillations in external
factors such as light/dark cycle
▪ The ability to have rhythmicity shifted by external factors such as
light and nutrient intake (entrainment)
▪ Unpredictable factors (stressors) can change behavior
▪ Organs in body are regulated by the hormones
Regulatory feedback loops
• Autocrine feedback
o Endocrine cell produces hormone that also regulates the cell that
produced is
o Normally negative feedback
• Target cell feedback
o The activity of the target cell gives the feedback signal
• Brain regulation
o The activity of the target cell regulates the hypothalamus activity
• Brain and pituitary regulation
o The produced hormone from the endocrine cell regulates the
hypothalamus activity and the pituitary activity
,Homeostasis = self-regulating to maintain the balance for survival
1. Stimulus; produces change in variable
2. Change detected my monitor (receptor)
3. Input; information sent along different pathway to control center
4. Output; information sent along efferent pathway to effector
5. Response of effector feeds back to influence magnitude of stimulus and
returns variable to homeostasis
Endocrine diseases
1. Hormone overproduction
2. Hormone underproduction
3. Altered tissue responses to hormones
4. Tumors affecting endocrine glands
Regulation of water and ions concentration in our bodies
• Balance needs to be maintained
o Concentration into the cell and out of the cell
o Dehydration is example
Dehydration
• Increased osmolarity in extra cellular matrix (ICM)
• Less saliva and dry mouth
• And hypothalamus sends out signal that makes us want to drink
• Water is absorbed and osmolarity decreases
• Heart and kidney are also involved
Dehydration decreases blood pressure. This changes cardio-vascular system. This
increases sympathetic activity. Which causes granular cells of afferent arterioles to
produce renin (enzyme).
Liver is producing angiotensinogen in plasma, this is converted in ANG I in plasma by
renin. This is then converted into ANG II by ACE (enzyme). This eventually results in
water and salt retention
Kidney
• Nephron has different parts
• On different places is diffusion of water
, Hoorcollege 2 Humane fysiologie Hart & circulatie
Myocyten moeten in bepaalde volgorde samentrekken. Dit komt door het elektro
potentiaal
Sinus knoop = op overgang vena cava superior en rechter atrium. Genereert
actiepotentiaal.
P golf = activatie atrium
Via atrium potentiaal naar de AV knoop via het myocard. AV zal worden
geactiveerd worden. Activatie midden in p golf.
Spontane depolarisatie AV langzamer dan sinusknoop
Polarisatie zal doorgegeven worden aan his bundel en dan uiteindelijk aan purkinje
vezels. Zorgt uiteindelijk voor QRS golf wat het activeren van de ventrikels is.
Meten actiepotentiaal
• Isoleren myocyten in een badje
o Meten van membraan potentiaal = verschil binnen en buiten de cel
o Binnen Kalium veel en buiten weinig
o Membraan laat selectief Kalium door, kalium naar buiten om
osmotische waarde gelijk te houden → osmotische kracht
o Binnenkant cel wordt negatiever omdat alleen positieve ion naar
buiten kan → elektrische kracht
o Elektrochemische gradiënt bepaalt membraan potentiaal voor
bepaald ion
o Hebt ook natrium → buiten veel en binnen weinig
o Ionen balans bepaald wat membraan potentiaal wordt
Bij rust membraan potentiaal (diastole)
• Na en Ca kanalen gesloten
• K kanalen open → bepaald membraan potentiaal
• Als cel beetje depolariseert gaan Na kanalen open
o Membraan depolariseert verder
• Maar andere K kanalen gaan dan ook nog open
o Membraan repolariseert
• Later ook Ca kanalen open
o Depolariseert weer
• Actie potentiaal = verandering membraan potentiaal in de tijd
o Komt door kanalen die niet tegelijk open zijn
• Kanalen gaan na korte tijd weer dicht
• Upstroke = snelle stijging membraan potentiaal door opening Na kanalen
(fase nul)
o Ion instromen = negatief, ion uitstroom = positief
• Nodge = snelle repolarisatie door opening K kanalen (fase 1)
Hormone = chemical substances produced by specialized tissue (gland) and
secreted into the blood circulation to reach a target organ. Are chemical mediators
of intracellular communication.
Intercellular communication
• Synaptic translation
• Autocrine function
• Paracrine function
• Pheromone function
• Allomone function (from one organism to another)
Endocrine signaling
• Source: gland
o No contribution to specificity of target
o Synthesis/secretion
• Distribution: bloodstream
o Universal (almost)
o Importance of dilution
• Non target organ
o Metabolism
o Breaks down
• Target cell
o Receptor: source of specificity
o Responsiveness
▪ Number of receptors
▪ Downstream pathways
▪ Other ligands
▪ Metabolism of ligand/receptor
▪ All often regulated by ligand
In paracrine cell the source is the adjacent cell. And the distribution is the matrix.
Hydrophilic messenger = water-soluble and readily transported via the circulation
Hydrophobic messenger = nearly insoluble in water and distribution presents special
problems. They are bound to carrier proteins. Can diffuse over the membrane of the
cell because they are lipid soluble.
Mostly peptide hormones bind to an GPCR membrane receptors.
Types of cell surface receptors
1. Channel-linked receptors
2. Enzyme-linked receptors (tyrosike-kinine receptors)
3. G-protein-coupled receptors
Intracellular receptors
, • Ligand must be hydrophobic and able to pass directly through the plasma
membrane of the cell
Hypothalamus-pituitary master control center
• Anterior pituitary
o Receives signals from neuroendocrine cell bodies located in
hypothalamus. Produce releasing hormones.
o Signal is transported through blood circulation to pituitary
o Endocrine signaling
o Hormone producing cells increase/decrease their own hormones;
tropic hormones
o Hormones secreted in the circulation and carried to the organs
• Posterior pituitary
o Axons from neuroendocrine cells go through posterior pituitary
o Signal reaches pituitary and hormones are directly released into the
bloodstream
o There is no intermediate step
Hormone secretion follows predictable changes in the environment
• Such as light
• Presence day and night
o Causes change in behavior
• Circadian systems (periodic)
o Two fundamental characteristics
▪ Endogenous rhythmicity with a period of approximately 24 h.
these rhythms persist independently of oscillations in external
factors such as light/dark cycle
▪ The ability to have rhythmicity shifted by external factors such as
light and nutrient intake (entrainment)
▪ Unpredictable factors (stressors) can change behavior
▪ Organs in body are regulated by the hormones
Regulatory feedback loops
• Autocrine feedback
o Endocrine cell produces hormone that also regulates the cell that
produced is
o Normally negative feedback
• Target cell feedback
o The activity of the target cell gives the feedback signal
• Brain regulation
o The activity of the target cell regulates the hypothalamus activity
• Brain and pituitary regulation
o The produced hormone from the endocrine cell regulates the
hypothalamus activity and the pituitary activity
,Homeostasis = self-regulating to maintain the balance for survival
1. Stimulus; produces change in variable
2. Change detected my monitor (receptor)
3. Input; information sent along different pathway to control center
4. Output; information sent along efferent pathway to effector
5. Response of effector feeds back to influence magnitude of stimulus and
returns variable to homeostasis
Endocrine diseases
1. Hormone overproduction
2. Hormone underproduction
3. Altered tissue responses to hormones
4. Tumors affecting endocrine glands
Regulation of water and ions concentration in our bodies
• Balance needs to be maintained
o Concentration into the cell and out of the cell
o Dehydration is example
Dehydration
• Increased osmolarity in extra cellular matrix (ICM)
• Less saliva and dry mouth
• And hypothalamus sends out signal that makes us want to drink
• Water is absorbed and osmolarity decreases
• Heart and kidney are also involved
Dehydration decreases blood pressure. This changes cardio-vascular system. This
increases sympathetic activity. Which causes granular cells of afferent arterioles to
produce renin (enzyme).
Liver is producing angiotensinogen in plasma, this is converted in ANG I in plasma by
renin. This is then converted into ANG II by ACE (enzyme). This eventually results in
water and salt retention
Kidney
• Nephron has different parts
• On different places is diffusion of water
, Hoorcollege 2 Humane fysiologie Hart & circulatie
Myocyten moeten in bepaalde volgorde samentrekken. Dit komt door het elektro
potentiaal
Sinus knoop = op overgang vena cava superior en rechter atrium. Genereert
actiepotentiaal.
P golf = activatie atrium
Via atrium potentiaal naar de AV knoop via het myocard. AV zal worden
geactiveerd worden. Activatie midden in p golf.
Spontane depolarisatie AV langzamer dan sinusknoop
Polarisatie zal doorgegeven worden aan his bundel en dan uiteindelijk aan purkinje
vezels. Zorgt uiteindelijk voor QRS golf wat het activeren van de ventrikels is.
Meten actiepotentiaal
• Isoleren myocyten in een badje
o Meten van membraan potentiaal = verschil binnen en buiten de cel
o Binnen Kalium veel en buiten weinig
o Membraan laat selectief Kalium door, kalium naar buiten om
osmotische waarde gelijk te houden → osmotische kracht
o Binnenkant cel wordt negatiever omdat alleen positieve ion naar
buiten kan → elektrische kracht
o Elektrochemische gradiënt bepaalt membraan potentiaal voor
bepaald ion
o Hebt ook natrium → buiten veel en binnen weinig
o Ionen balans bepaald wat membraan potentiaal wordt
Bij rust membraan potentiaal (diastole)
• Na en Ca kanalen gesloten
• K kanalen open → bepaald membraan potentiaal
• Als cel beetje depolariseert gaan Na kanalen open
o Membraan depolariseert verder
• Maar andere K kanalen gaan dan ook nog open
o Membraan repolariseert
• Later ook Ca kanalen open
o Depolariseert weer
• Actie potentiaal = verandering membraan potentiaal in de tijd
o Komt door kanalen die niet tegelijk open zijn
• Kanalen gaan na korte tijd weer dicht
• Upstroke = snelle stijging membraan potentiaal door opening Na kanalen
(fase nul)
o Ion instromen = negatief, ion uitstroom = positief
• Nodge = snelle repolarisatie door opening K kanalen (fase 1)
