W3: Endocrine system Flashcards
What are hormones? (2)
- Substances released into the bloodstream that bind to receptors on cells at distant locations
- Travel long distances
Some neurotransmitters are also hormones
Same exact molecule but they are utilised in a different way
Examples (2)
- Epinephrine and Norepinephrine (neurotransmitters) are responsible for alertness
- The same exact molecules (neurotransmitters) are released into the bloodstream to stimulate the heart to make it beat faster to initiate sympathetic activation
Some neurotransmitters are also hormones
Epinephrine and Norepinephrine are re-named as:
Examples (2)
- Adrenaline and Noradrenaline (hormones)
If we use chemicals to communicate in the brain , CNS and even in spinal cord
they are called
Neurotransmitters
If we use chemicals to communicate everywhere else except the brain and spinal cord (the peripheral nervous system)
They are often referred to
Hormones
Hormones influence: (3)
- Behaviour
- Emotions
- Physical characteristics
Hormones influence social behaviours like (3)
- Bonding
- Parenting
- Sex and reproduction
Endocrine hormones
- A hormone that is released into the bloodstream that affects the functions of cells at some distance from the source of the release
Endocrine system
- System of glands that release hormones in the body
Endocrine signalling (3)
- Communication facilitated by hormones, having their effects by binding to receptors on cells at distant locations in the body
- They either activate or deactivate those glands
- Similar to neuronal signalling but travelling long distances
Most hormones/endocrine system function in accodance to
drive theory
Drive theory put forward that the body maintains
homeostasis
Homeostasis is a state in which a system is
in balance or equilibrium
Drive theory
To maintain homeostasis, everything in the body has a
setpoint
Drive theory
A set point is where (3)
- Point which the system returns to and tries to maintain
- This point is where the body is peak and optimal performance
- If the body is not at this set point, it will increase/decrease hormones to reach and try to maintain it
Endocrine system is responsible for maintaing
Homeostasis and that set point in the body
The hypothalamus - the regulator (2)
- Monitors the levels of hormones and maintains those set points in the body
- maintains homeostasis
Hypothalamus contains several sets of nuclei to (2)
- Regulate functions in the body
- Each nuclei has there individual function to make ensure the body is maintaining those set points
Hypothalamus
Regulation is done via the release of (2)
Hormones in the bloodstream (via the stimulation of the pituitary gland in the hypothalamus)
to maintain homeostasis
HPA is activated for
long-term physiological reaction to stress
HPA axis hormones hypothalamus order (3)
- Hypothalamus releases CRH
- CRH goes to pituiarty gland to release ACTH
- ACTH flows to adrenal cortex to stimulate release of stress hormones (cortisol , epinephrine and norepinephrine)
When the HPA axis is engaged
Typically coincides with the sympathetic nervous system (fight or flight)
So increased… (3)
- Heart rate
- Blood flow
- Respiration
HPA axis suppresses
immune system
Cortisol promotes the release of glucose (blood sugar) by inhibiting
insulin, which helps store glucose to use for energy
Cortisol narrows arteries so increases blood pressure (2)
What happens to the heart and blood flow?
- Epineperhine (adrenaline) is released causing the heart to beat faster
- However, this requires the heart to pump blood with more force (and faster) to get blood through the body due to increased blood pressure
Cortisol release is usually temporary under normal circumstances
Order
- Promotes release of glucose
- Narrows arteries
Extended cortisol release (3) supresses…
- Suppresses immune system
- Suppresses function of the parasympathetic nervous system
- Likelhood of cardiovascular disease
Extended cortsiol release is when..
HPA does not regulate itself and does not stop releasing cortisol and not going through negative feedback loop
Extended cortisol release suppresses functions of the parasympathetic nervous system
Gonna experience (3)
- Experience anxiety
- Issues with digestion
- Sexual dysfunction
Extended cortisol release
Since heart is requirng more effort to get blood where it needs to go to the body and working against the high blood pressure
Increased risk of
- Cardiovascular disease
Extended cortisol release
Cardiovascular disease is when.. (2)
- The heart begins to wear
- Blood vessels damage
Cortisol released in daily intervals to give you energy as there is (2)
certain days you need more energy to function than others
HPA axis does engage itself throughout the day without the need of stress as it is part of homeostasis
Diurnal cortisol curve - normal (2)
- In normal, huge peaks of cortisol in the morning to get energy to get you up in the morning - HPA axis engaged in the morning
- Throughout the day, cortisol stops getting released and HPA is not engaged to near 0 levels
Diurnal cortisol curve - chronic stress (2)
- Morning cortisol release increases and it is later
- Still have elevated levels of cortisol during later in the day (not near 0 levels in normal cortisol curve)
Dorr et al. (2015)
Cortisol
Method (3)
- Had university students
- Assessed levels of stress and dirunal (daily) cortisol release from HPA axis
- Compared regular compared to exam week
Dorr et al. (2015)
Results - Stress
- Those in exam condition students were more stressed compared to control -regular week condition
Dorr et al. (2015)
Cortisol
Results - Stress (2)
- Sig difference in amount of cortisol body releases in the morning between exam and control condition
- Slightly higher cortisol release in students waking up during exam week (cond) than control week
Cortisol release is normal
Cortisol awakening response - (2)
- This response is maintained by the circadian rhythm (internal clock to know when the morning is) in the hypothalamus
- Provides initial boost of energy in the morning
Too much cortisol release can be bad! (7)
- Stress increases morning cortisol release
- Adaptive long-term
- Maladaptive long-term
- Anixety
- Sexual Dysfunction
- Cardiovascular disease
- Suppresses immune system
Ghrelin hormone (2)
- Elicits feelings of hunger
- Synthesis and release in the stomach
Leptin hormone (2)
- Inhibits eating
- Synthesised and released by fat
Ghrelin and Leptin both regulated by
the hypothalamus
Thyroid glands - maintained by the hypothalamus
are located in the
neck
Thyroid glands
Pituitary releases (thyroid-stimulating) hormone
The thyroid glands secrete thyroxine which maintains.. (3)
- Metabolic rate
- Digestion
- Heart Rate
Hypothyroidism (2)
Thyroid does not produce enough thryoxine
Low heart rate, stomach digestion is slow
Hyperthyroidism (2)
Thyroid gland produces too much thyroxine
Heart rate very high
Melatonin is released in the dark to tell you
- when to sleep
Melatonin is suppressed by
exposure to light (sunlight or any light)
Melatonin controls the
sleep/wake cycle
Melatonin is released by the
pineal gland
Lledo et al. (2012) - Melatonin
Method (2)
- Got rabbits to live in either complete darkness, light or light + yellow filter (filtering out blue light)
- Measured melatonin level in the eyes
Lledo et al. (2012) - Melatonin
Results (3)
- Got rabbits to live in light environment, lower melatonin release than darkness and light + yellow filter
- Darkness and light + filter is not sig differently
- Blue light filters are effective in reducing and stopping the increase melatonin release
Circadian rhythm
Circadian rhythm is responsible for
scheduling the release of these hormones
Biological clocks
Circadian rhythm is regulated by the (2)
endocrine system
Circadian rhythm is responsible for scheduling the release of these hormones
Circadian rhythm
Secretion of hormones to maintain (2)
sleep/wake cycle
Circadian rhythms
Secretion of hormones to maintain sleep/wake cycles - (4)
- Thyroid hormones - maintain metabolism
- Cortisol awakening response
- Melatonin release
- Growth hormones (secreted during sleep; repair muscles)
Circadian rhythms secrete hormones based on the time of the day
Circadian keeps track of the day via the
the suprachiasmatic nucleus (SCN) in the hypothalamus
Oxytocin is involved in reproductive functions (3)
Causes contraction of the uterus during birth
Released in response to stimulation of nipple, causing lactation
The reflex can become conditioned to environmental stimuli, leading to the release of oxytocin in response to the sight of a baby or the sound of a crying baby
In the brain oxytocin and vasopressin affect: (2)
Social recognition (hippocampus)
Pair bonding
