Kin 131 exam Endocrine system Flashcards
What is a hormone?
A chemical messenger that is secreted into the bloodstream to influence another organ or tissue
What is the endocrine system?
A series of glands throughout the body that produce hormones
Explain the differences between the endocrine system and the nervous system
Signalling mechanisme:
- Endocrine: Chemical
- Nervous: Chemical and electrical
Primary chemical signal:
- Endocrine: Hormones
- nervous: Neurotransmitters
Response time:
- Endocrine: Fast or slow depending on where its traveling from
- Nervous: Imediate
Target cell:
Endocrine: near or far
Nervous: Nearby
Environment interaction:
- Endocrine: internal only
- Nervous: Internal and external
What are the different type of endocrine glands?
A gland is a tissue that secretes a substance
Exocrine glands:
- Secretes substance into a duct
Endocrine glands:
- Secretes directly to the bloodstream
What are paracrine and autocrine substances?
paracrine substance:
- Causes a reaction on the cells around it
Autocrine substance:
- Causes a reaction with the cell that released it
What two substances hormones are made of. What are the different ways they are transported
- Lipid based
- Dont need a vesicle to cross the lipid bilayer of the cell since they are lipid soluble, but a carrier protein is needed once in bloodstream - Amino acid based
- Needs a vesicle to cross the lipid bilayer since their not lipid soluble, but does not need a carrier protein to be transported in the bloodstream
Where are the receptor cells located for water soluble hormones vs lipid soluble hormones?
Water soluble
- Receptors on the outside of the lipid bilayer
Lipid soluble
- Receptors on the inside of the lipid bilayer
What are the ways sensitivity to hormones can change
- Up-regulation
- Target cell becomes more sensitive due to the increase in receptor cells caused by low concentration of that hormone - Down regulation
- target cell becomes less sensitive to the hormone, due to lower numbers of the receptor cells caused by excessive amounts of that hormone
What are the different affects hormones can have
- permissive effect:
- Interaction between hormones where one hormones enables the other to work - Synergistic effect:
- interaction where two hormones amplify each others effects - Antagonistic effect
- When two hormones have opposing effects
What are the 3 different ways hormones are triggered to be released
- Plasma ion concentration
- Detecting a change in concentration of a substance triggering the release of hormones - Neuronal controle
- Neurons stimulates the release of a hormone
- Eg. the adrenal medulla - Another hormone
- One hormone triggers the release of another
- Called a tropic hormone
Ways hormones are removed after they complete their function
- Exretion
- Excreted through ruin - Liver metabolization
- Enzymes in the blood breaking them down to amino acids
- Target cells break them down to their amino acids
Which removal is faster? The removal of amino based hormones or steroid based hormones?
Amino acid hormones are removed quickly
Steroid hormones are removed slowly
Explain the Hormone disorders
AT GLAND
1. Hyper secretion: too much hormone is produced
- Primary: Gland just overproduces
- Secondary: Overstimulation
- Hyposecretion: Too little hormone is produced
- Primary: gland just doesn’t produce enough
- Lack or overinhibition of a stimulus
AT TISSUE
1. Hyper responsive: Target tissue has excessive reposes to hormones to to excessive receptors
- Hyporesponsive: Target tissue has no or little reaction to hormone due to loss or dysfunctional receptors
What are the key organs that secrete hormones
- Pineal gland
- Adrenal gland
- Hypothalamus and pitituary gland
- thyroid
- Parathyroid glands
- Pancreas
- Ovaries
- Testes
Explain the Pineal gland.
Location: In the brain inferior to the thalamus
Function: Production and secretion of melatonin
Release controled by: Hypothalamus
Melatonin:
- Controls our circadian rhythm (sleep wake cycle)
- Melatonin causes us to sleep
- Light stimulus inhibits the production of melatonin
Explain the adrenal gland
- Location: sits onto of the kidneys
- Consists of
1. the adrenal cortex (3 zones)
2. Adrenal medula
Explain the adrenal cortex
- Produces steroid based hormones
- Produces long hormones that regulate long term stress and blood pressure
3 zones:
1. Zona glomerulosa: Produces aldosterone: Hormone that regulates water, water, and bloodpressure in body
- Zona faculata: Produces cortisol: helps the body respond to stress by increasing blood sugar and metabolism, and it also has an anti-inflammatory effect.
- Zona reticulairis: Produces androgens: Converted to testosterone and estrogen
Explain the adrenal medulla
- Sympathetic neurons communicate directly with it during stress
- Produces amine based hormones (catacholmeins: Epinephrine and norepinephrine)
- Hormones released due to short term stress
Explain the structure of the adrenal gland
The adrenal cortex surrounds the adrenal medulla in the middle
Explain hyper and hypo cortilism
Hyper cortilism (AKA cushingtons syndrom):
- Too much cortisol
- rare
- Symptoms:
1. Round face
2. gain fat in the mid body
- Thinning of extremities
3. Weakness of bones
Hypocortilism (AKA addingtons disease):
- Not enough cortisol
-Caused by damage to the adrenal glands pituitary gland disfunction
- Symptoms:
1. Extreme fatigue
2. Weight and appetite loss
3. Low blood sugar
4. Mood change
Explain the Hypothalamus and pituitary gland
- Location of hypothalamus: Anterior and inferior to the thalamus
- Hypothalamus controls that pituitary gland
- Pituitary gland makes, stores and secretes its own hormones
- ## Pituitary gland influences what hormones it releases and indirectly affects hormones released by other glands
How are the hypothalamus and the pitituary gland connected?
TheyTheirre connected via the infundibulum, which houses the median eminence (where the hypothalamus monitors the blood content outside of the BBB).
How does the hypothalamus communicate with the pituitary gland?
- The hypothalamus comunicates with the posterior pituitary gland via neurons which send signals telling it when and what hormones to release
- It communicates with the anterior pituitary gland via tropic hormones which travel through the hypophyseal portal system (network of blood vessels)
Explain the pituitary gland
- Has 2 lobes, both under the control by the hypothalamus
- Anterior pituitary gland
- Gland that produces and secretes hormones
- No neural connections to the hypothalamus
- Secretes 6 main hormones - Posterior pituitary gland
- Stores and secretes hormones doesn’t synthesize its own
- Hormones produced in hypothalamus and stored here
- Has neural connections
- Releases 2 main hormones: Oxytocin and anti antidietetic hormone
List the 6 hormones produced by the anterior pituitary gland and the 2 from the posterior pituitary gland
Anterior:
- Growth hormone (GH)
- Prolactin (PRL)
- Follicle stimulating hormone (FSH)
- Lutinizing hormone (LH)
- Thyroid stimulating hormone (TSH)
- Adrenocorticotropic hormone
posteriorL
- Oxytocin
- Antidiuretic hormone
Explain the hormones released from the posterior pituitary gland
- Oxytocin:
- Positive feedback loop during labour that causes contractions during labor
- Plays a roll in breast milk ejection - Antidiuretic hormone (ADH)
- Increases blood pressure
- Release in response to high concentration of solutes in the blood sensed by osmoreceptors
- Blood osmolarity too high: Osmoreceptors cause release of ADH = acts on the kidneys decreasing water excretion = increased blood volume and pressure = decrease in blood osmolarity
Explain the first 3 hormones released from the anterior pituitary gland
- Growth hormone (GH)
- Peptide hormone
- Stimulated by growth hormone releasing hormone (GHRH)
- GHRH released by: exercise, stress, low nutrient availability
GH functions: Regulates growth of bones and tissue especially during childhood
- Important in first 2 years of life - Prolactin (PRL)
- Peptide hormone
- Released in response to Prolactin release hormone (PRH)
- PRH is released in response to high estrogen levels
- Also released in response to suckling
- PRL functions: Breast growth and breast milk production - Follicle stimulating hormone (FSH)
- Peptide hormone
- Stimulated by gonadotropin releasing hormone (GnRH)
- GnRH is produced due to levels of reproductive hormones (Estrogen and Testosterone)
- FSH is a type of gonadotropin (hormone that regulates gonad function)
- FSH stimulates the maturation of gametes (ova in females and sperm in males) by promoting the development of follicles in ovaries (egg-containing structures in females) and supporting sperm production in the testes (in males)
Explain the last 3 hormones released from the anterior pituitary gland
- Lutenizing hormone (LH)
- Peptide based hormone
- Stimulated by GnRH
- Triggers release of sex hormones from gonads - Thyroid stimulating hormone (TSH)
- Peptide based hormone
- Stimulated by thyrotropin releasing hormone (TRH)
- TRH is released from the hypothalamus in response to thyroid hormone levels
- TSH acts on the thyroid, stimulating the release of thyroid hormones (T3 and T4)
- Thyroid hormones affect metabolic rate - Adrenocorticotropic hormone (ACTH)
- Peptide based hormone
- Stimulated by corticotropin releasing hormone (CRH)
CRH released by hypothalamus in response to stress
- ACTH acts on the adrenal cortex to increase cortisol levels in the body
Explain the HPA cascade
Stress causes the hypothalamus to secrete CRH causing the anterior pituitary gland to secrete ATCH causing the adrenal cortex to secrete cortisol
Explain the different stress response pathways
2 pathways:
- Short term stress response (sympathetic adrenal medulla pathway):
- used for short term stress
- Adrenal medulla releases epinephrine and norepinephrine - Long term stress response (HPA axis activation)
- HPA cascade occurs resulting in the release of cortisol
- Used for long term stress
Explain the phases of stress
- Alarm phase
- Fight or flight response
- mobilizes resources
- Imediate stress - Resistance phase
- Attempt to deal with the stressor using resources
- if stress continues from alarm phase - Exhaustion phase
- Chronic cortisol levels impact several organs
- If stress continues from resistance phase
In the exhaustion stage are the adrenal glands fatigued?
No, the adrenal glands themselves are not “fatigued.” Instead, it is the body’s organs and systems that become fatigued due to prolonged exposure to stress hormones (like cortisol and adrenaline) during the chronic stress response.
Explain the thyroid gland
- Location: Sits on the anterior of the trachea
- Butterfly shaped
- Composed of thyroid follicles which are small protein fluid filled sacs called colloid
- Thyroid hormones are synthesized in the colloid
Thyroid hormones:
- Thyroxin (T4): contains 4 iodine molecules
- Tridothironine (T3): Contains 3 iodine molecules
- both are amino acid hormones, but act like storied hormones (are lipid soluble)
Explain the thyroid hormones
- Tridothyronine (T3) is the active form of the hormone. When Thyroxin (T4) reaches the target tissue it gets converted to T3
- Stimulated by TSH from the anterior pituitary gland
- Function: regulates metabolic rates influencing energy production
Secretion of thyroid hormones T3 and T4 is regulated by TRH and depend on the bodies metabolic needs:
- High metabolism: decreased production
- Low metabolism: increased production
Explain hyper and hypo thyroidism
Hypothyroidism:
- Too much T3 and T4 produced
- Symptoms: Heat intolerance, hyperactivity
weightloss
Hypothyroidism:
- Not enough T4 and T3
Symptoms: swelling of the neck, weight gain, fatigue
Explain the parathyroid gland
- 4 small glands in the back of the thyroid
- Produces parathyroid hormone (PTH)
- PTH production depends on blood calcium level:
1. Low blood calcium: Increased PTH secretion
2. High blood calcium: Decreased PTH secretion
Function: PTH stimulates osteoclast activity and signals to the kidneys to increase calcium absorption
Explain the pancreas
- Location: stomach below the liver
- Has 4 types of pancreatic cells (cells that secrete hormones):
- Alpha cells (20% of cells): Produce glucagon
- beta cells (70% of cells): produce insulin
- Deltan cells (4% of cells): produce somatostatin
- Game cells (1% of cells): produce pancreatic polly peptide
Explain the hormones released from the pancreas
Glucagon:
- Released in response to low blood sugar
- Stimulates glyconeogenasis
- Stimulates glucogenasis
insulin:
- Released in response to high blood sugar
- Stimulates glycogenesis
- Inhibits glucogenasis
- Stimulates use of glucose by body
Somatostatin:
- Inhibits the production of glucose or insulin to regulate blood sugar levels
Pancreatic polypeptide:
- Contributes to feeling full after eating (satiety)
- In brain: reduces appetite
-in GI tract: Slows GI tract emptying
Explain what diabetes is and what type 1 and 2 diabetes is
Diabetes: Disfunction I secretion or insensitivity to insulin
Type 1:
- Autoimune condition where immune cells attack the beta cells of the pancreas therefor insufficient insulin
- Genetic disorder
- body can’t store glucose
Type 2:
- Disorder caused by lifestyle
- Body becomes resistant to insulin
- early stages can be revered by exercise and weightloss
- Exercise increases sensitivity to insulin
Explain the gonads
- Gonads are the reproductive organs (Ovaries and testes)
- Produce sex hormones: Testosterone, Estrogen, Progesterone
Are sex hormone steroid or amino acid based?
Steroid specifically androgens
What is gametogenesis?
Production of sperm in men and eggs in woman
What sex hormones do men and female have?
Everyone has varying levels of all 3
Explain Testosterone
- Primarily released from the testes, but is produced in smaller quantities by the ovaries and adrenal glands
- In the testes, testosterone is produced by leydig cells
- LH stimulates leading cells to produce testosterone
- Testosterone stimulates seratoli cells which creates sperm and produces inhibin
- Inhibit slows down production of FSH, Testosterone inhibits LH and GnRH production
- FSH stimulates seratoli cells aswell
Testosterone: Leads to development of male secondary sex characteristics
Explain Estrogen
- Mainly released from the ovaries, but is produced in small amounts by the testes and adrenal glands
- Also produced by fat tissue
- Produced as estradiol in the granulosa cells of the ovaries then is converted to estrogen
- FSH directly stimulates the graanulosa cells to produce estrogen whereas LH indirectly stimulates them
- granulosa cells stimulate the growth of eggs
- Granulosa cells also produce inhibin which inhibits the production of FSH
Estrogen inhibits the production of LH and GnRH - Estrogen: Development of female secondary sex charecteristics
Explain hyper and hypo androgisme
Hyperandrogisme:
- High levels of androgens
- Caused by: high production from the gonads or overstimulation from the hypothalamus
- Symptoms: Increased acne, hair loss on scalp
Hypoandrogisme:
- To little androgens
- Caused by: underproduction from gonads or under stimulation of the hypothalamus
- Symptoms: decreased body air growth, testes shrink
