Endorcrine System Flashcards
describe chemical coordination
a slow, prolonged process of communicating information throughout the body by way of chemicals called hormones
what are endocrine glands
the special glands or tissue that secrete hormones
what is the difference between the chemical and nervous coordination
chemical coordination
- brought about by the endocrine system
- influences metabolic activities of all cells by means of chemicals (hormones)
- hormones travel through the blood system
- conduction is slow
- causes a widespread response in many target organs
- the responses is slow but long lasting
Nervous coordination
- brought about by the nervous system
- regulates the activities of muscles and glands by means of electrical impulses
- impulses conducted by neurons
- conduction is very fast
- chases a specific response in one target organ (effector)
- response is rapid but only lasts a short time
what is a hormone
a chemical substance, usually a protein but sometimes a steroid, secreted by an endocrine gland and carried in the blood stream to its target organs where it regulates metabolic reactions
why don’t hormones last long in the body
because they’re broken down my enzymes
do hormones operate alone
no. they form an integrated system with other hormones as well as with the nervous system
what are some different hormones categorized by chemical structure
peptides, steroids and amines
what is a steroid and what is a amine
steroid - synthesis based on cholesterol substrate carbon atoms arranged in 4 rings
amines - biochemical modifications of a single amino acid (tyrosine)
what are some hormones that are categorized by function
the main category of interest is androgens (male hormones) which occur in both males and females but in higher levels in males.
these include:
- testosterone
- androstenedione
- dihydrotestosterone
in women’s bodies a key function of androgens is to be converted to oestrogen
what are come complications with androgen
hyperandrogenism
and androgen insensitivity
what is a target organ
the specific cells that respond to a given hormone and that have receptor sites. in some cases these are located in a single gland or organ, in other cases they’re scattered throughout the body so many areas are affected
describe an endocrine gland
a small, vascular, ductless gland that secretes hormones which are carried in the bloodstream to their target organs
endocrine glands in the body - label diagram
page 212
what is the hypothalamus and what does it control
a part of the brain, situated above the pituitary gland. it controls the functioning of the autonomic nervous system as well as the release of hormones from the pituitary gland
why is the hypothalamus considered a gland
because some of its neurons secrete the hormone anti-diuretic hormone ADH
what does ADH do
passes down nerve fibres to be stored in the posterior lobe of the pituitary
how does the hypothalamus control the release of hormones
- when hormones from the anterior lobe of the pituitary are needed. the hypothalamus secretes releasing factors that travel in the blood to the anterior lobe, stimulating it to produce and release the required hormones
- when ADH and other hormones are needed, nerve impulses from the hypothalamus stimulate the posterior lobe of the pituitary to release the stored ADH into the bloodstream
why is the pituitary gland called the “master gland”
because it is the chemical coordinator of most of the other endocrine glands
where the pituitary situated
attached stalk and is situated in a small bony cavity in the floor of the cranium called the ‘Turkish saddle’
what’s another name for the pituitary
hypophysis
how is the pituitary made up
made up of two glands
- large anterior lobe is purely glandular and made up of secretory cells
- small prosterior lobe develops from the base of the brain and mainly made up of neurons
what are 7 hormones released from the anterior pituitary lobe
- growth hormone or Somatrophic hormone STH - promotes skeletal growth and muscular growth by stimulating the synthesis of proteins
- thyroid stimulating hormone TSH - stimulates the thyroid gland to secrete its hormone, thyroxin
- adrenocorticotropic hormone ACTH - stimulates the the adrenal cortex to secrete mainly the hormones cortisone and aldosterone
- follicle stimulating hormone FSH - (in females) stimulates oogenesis in the ovary, formation of eggs. (in males) stimulates spermatogenesis in the tests, formation of sperm
- luteinizing hormone LH - (in females) stimulates ovulation, release of an egg, from the ovary
- interstitial cell stimulating hormone ICSH - chemically similar to LH but produced in males to stimulate the testes to secrete testosterone
- prolactin - stimulates the production of milk in the female mammary glands for as long as the baby suckles and it is responsible for much of the maternal instinct
what growth disorders can occur
in prepubertal children:
hyper-secretion
hypo-secretion
in adults:
hyper-secretion
explain hyper-secretion in children
hyper-secretion of growth hormone results in the overdevelopment of the skeleton (a condition known as gigantism)
caused by a tumor in the pituitary gland
is very rare
explain hypo-secretion in children
hypo-secretion of growth hormone results in underdevelopment for the skeleton (condition known as pituitary dwarfism)
caused by a disease of the anterior one pituitary gland
although height is reduced the body proportions are normal
they’re not mentally retarded but often sexually immature
they can be treated by injection of synthetic growth hormone produced genetically by engineered bacteria
explain hyper-secretion in adults
hyper-secretion results in enlarged hands, jawbone and brows ie. all terminal skeletal structures (condition known as acromegaly)
in adults bone can only thicken because the growth points in the long bones are no longer active
what are endocrine glands stimulated by
changes in the composition of blood and they respond by either secreting more or less of their hormones
what is the difference between exocrine endocrine glands
exocrine glands - their secretions are carried in ducts to where they are needed (eg. salivary glands, liver, pancreas)
endocrine glands - don’t have ducts and their secretions are carried in the blood stream to their target organs
• the hormones are bonded to the target cells (meaning they’re rapidly transported to all parts of the body)
draw a diagram or an endocrine and exocrine gland
page 212/ slide 6
when does the posterior lobe release ADH
when osmoreceptors in the hypothalamus detect an increase in the osmolarity of the blood, nerve impulses stimulate the posterior lobe to release stored ADH
what is the role of ADH
• helps to conserve water if the body is dehydrated
- it does this by causing more water to be reabsorbed back into the blood from the collecting ducts of the kidney so less water is lost in urine
what disorder can occur in relation to ADH
lack of ADH secretion causes diabetes insipidus (a condition characterized by the loss of large quantities of dilute urine 5-10 liters a day)
where is the thyroid gland situated
the two lobes of the butterfly shaped thyroid gland are found on either side of the trachea just below the larynx (voice box) in the front of the neck
label thyroid gland diagram
page 214
what hormone is secreted by the thyroid gland
thyroxin
what is needed for the production of thyroxin and where can it be found
iodine, found in sea food, sea salt and iodized salt
what can happen when your iodine levels are low
a goitre may develop
what are the functions of the thyroxin
- it increases the basal metabolic rate (and therefore body heat production) in all body cells. it does this by controlling the rate of cellular respiration
- it promotes normal functioning of the
heart - it promotes normal functioning of the nervous system. thyroxin increases nervous activity and sharpens alertness and reflexes
what disorders can occur in relation to the thyroid
hypothyroidism ie. producing too little thyroxin causes a low metabolic rate
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• in children this results in cretinism - a condition in which a child does not grow physically, has immature sexual development and is mentally retarded
• in adults this results in myxoedema - a condition of mental and physical sluggishness ie. low blood pressure, heart rate and respiratory rate
hyperthyroidism ie. producing too much thyroxin causes a high metabolic rate
- high body temperature with profuse sweating
- increased heart rate, blood pressure and respiratory rate
- muscular tremor and nervousness
- swollen thyroid gland - a different goitre know as exopthalmic goitre
how are levels of thyroxin in the blood kept constant
this is done by a control mechanisms known as negative feedback
- to bring this about the thyroid and pituitary glands interact as follows
• the pituitary detects a decreased level thyroxin in the blood, so it secretes more TSH
• the TSH stimulates the thyroid to secrete more thyroxin, returning it’s level to normal
• the higher the level of thyroxin inhibits further secretion of TSH from the pituitary
• the negative feedback mechanism will therefore ensure that the level of thyroxin in the blood is kept at the correct level at all times
negative feedback diagram - draw and label
page 215
what are your adrenal glands and where where are they found
adrenal glands are 1 pyramid shaped gland on the top of each kidney.
each adrenal gland is made up of the inner medulla and outer cortex
what does the adrenal cortex secrete
a group of steroid hormones - cortisone, aldosterone and reproductive hormones
what does cortisone do
it increases the body’s ability to resist stress of all kinds. it is anti-inflammatory and anti-allergic
what does aldosterone do
it causes increased reabsorption of sodium ions - it therefore helps to regulate the electrolyte levels of body fluids
how is cortical activity controlled
low levels of aldosterone cause the hypothalamus to trigger a complex chain of reactions in an attempt to restore homeostasis eg.
- the hypothalamus secretes releasing factors to stimulate the anterior lobe of the pituitary gland to release the hormone ACTH
- ACTH travels in the blood to the adrenal cortex which is stimulated to release aldosterone and other hormones
what does ACTH control
the levels of the hormones in the blood by way of negative feedback
what does adrenal medulla secrete
adrenalin
what are some effects of adrenalin
- increased blood pressure
- vasoconstriction enables more blood to go to the skeletal and cardiac muscles - increased blood sugar levels
- provide fuel for energy release - increased oxygen content in blood
- breathing rate and despite of breathing is increased which means extra oxygen is needed for respiration - increased heart rate
- results in more blood with higher levels of glucose and oxygen going to muscles - increased skeletal muscle tone
- enables the muscles to respond quickly
what other effects does adrenalin have
• dilation if pupils
- better vision
• increased sweating
- for increased cooling of body
• reduction of digestive system activity
• increased mental alertness
- to be aware and think how to cope in emergency situations
why is the pancreas an unusual gland
it functions as both an exocrine and endocrine gland
what is the pancreases endo/exocrine function
exo - the secretion of pancreatic juice, which flows along the pancreatic duct into the duodenum where it helps in chemical digestion
endo - the secretion of hormones by groups of cells called islets of Langerhans. these islets are scattered throughout the pancreas. the hormones they secrete pass directly into the blood stream
label the diagram secretions from the pancreas
page 219
what hormones are secreted by the islets of Langerhans
there are two types of cells secreting two types of hormones
- alpha cells - secrete glucagon
- beta calls - secrete insulin
label structure of pancreatic tissue
page 219
what are the functions of glucagon and insulin
both hormones okay a role in controlling the level of blood glucose/sugar in the blood
what is a normal glucose concentration in the blood
3.5-5.5 mmol/litre of blood
what is glucose
a simple sugar derived from digesting carbs. it’s the primary source of cellular energy. it is transported throughout the body in the bloodstream and can’t enter the cells without the aid of insulin
what does insulin and glucagon do
insulin - lowers blood sugar level
glucagon- raises the blood sugar level
(they’re an antagonistic pair)
how does insulin lower blood glucose levels
• after a meal containing carbs, glucose is absorbed by the small intestine and moves into the blood
• as this blood passes through the pancreas, the beta cells detect the raised glucose levels and respond by secreting insulin
into the blood
• in the main target organs (liver and muscles) the effects include:
- making cell membranes more permeable to glucose which enables more glucose to leave the blood and enter the cells
- increasing the rate at which glucose is converted into glycogen in the cells, which encourages more glucose to enter the cells
- these processes take glucose out of the blood which lowers the blood glucose levels
- the drop in glucose level is detected by the insulin secreting cells which then stop releasing insulin into the blood
how does glucagon increase the blood sugar levels
- the glucose level is low when waking up in the morning or after exercise
- as this blood passes through the pancreas, the glucagon secreting cells (alpha cells) detect the low glucose and respond by secreting glucagon into the blood
- the glucagon affects the liver cells (not muscle cells) by causing the breakdown of stored glycogen into glucose
- as a result the liver releases glucose into the blood increasing the blood glucose level
- the increase in glucose level is detected by the glucagon secreting cells as the blood flows through the pancreas. as a result they stop releasing glucagon into the blood
what is sugar diabetes
a chronic disease characterized by high levels of glucose in the blood
what is type 1 diabetes
insulin dependent
usually starts in childhood and accounts for about 5-10% of all diagnosed cases
what are the initials symptoms of type 1 diabetes
- tiredness
- procuring if large quantities of dilute urine containing glucose as the kidneys can’t reabsorb all the extra glucose from the renal tubules
- great thirst due to loss of so much liquid
what causes type 1 diabetes
- it’s an autoimmune disease as the body’s immune system destroys the beta cells which produce insulin
- this results in the pancreas failing to produce insulin so glucose remains in the blood instead of moving into the cells (causing a condition known as hyperglycemia)
how is type 1 diabetes treated
it’s a life long disease and has no cure however if the patient is highly disciplined, with the proper diabetic management and regular exercise the disease can be controlled
- daily insulin injections
- test blood sugar levels frequently
short term effects if not following this routine include: thirst, nausea, vomiting, dehydration, dizziness and coma
the long term goals of treatment are to prolong life, reduce symptoms and prevent diabetes related complications such as blindness, kidney failure, heart attacks, amputations and stroke
what is type 2 diabetes
non-insulin dependent
usually starts in adulthood and is directly influenced by lifestyle
accounts for 90-95% of cases
symptoms tend to develop more gradually
what increases the chance of developing type 2 diabetes
- increasing age
- a diet high in sugars fats and over processed food leading to overweight and obesity (the cuss elf 87% of diabetic)
- lack of exercise
what causes type 2 diabetes
type 2 develops when the body produces less insulin or in unable to use the insulin correctly
faulty insulin receptor cells (condition known as insulin resistance)
how can type 2 diabetes be treated
- balanced diet
- eating low Gi carbs
- losing weight and regular exercise
- oral drugs or insulin intake
what are the warning signs for the onset of diabetes
- increased thirst
- frequent urination
- blurred vision
- tingling or numbness of hands and feet
- slow healing wounds
- frequent infections
who is most prone to developing diabetes
women
what are the gonads and what do they do
reproductive organs
testes in males
ovaries in females
they produce gametes (sex cells) and secrete large quantities of sex hormones
what do the ovaries secrete
oestrogen and progesterone
what are the functions of oestrogen
it is responsible for:
1. a rapid increase in the rate of physical growth during puberty
2. appearance of the secondary sex characteristics of females during puberty
• maturing of the reproductive organs and keeping them in a functional state
what does oestrogen along with progesterone do
Promotes cyclic changes in the endometrium during the menstrual cycle ie. it prepares the endometrium for pregnancy, it becomes more vascular and glandular and the cells become swollen with nutrients
what happens when levels of oestrogen increase
The release of FSH and LH are inhibited
How does some birth control tablets work
They inhibit the release of FSH - with no FSH, no egg can be formed therefore no pregnancy can occur
what are the functions of progesterone
- together with oestrogen promotes cyclic changes in the endometrium
- during pregnancy it helps maintain the endometrium in a functional state
where are the testes and what do they secrete
in the scrotum
they secrete testosterone
what are the functions of testosterone
it is responsible for:
- a rapid increase in the rate of physical growth during puberty
- appearance of the secondary sex characteristics of females during puberty
- maturing of the reproductive organs and keeping them in a functional state
- sex drive
what disorders of the reproductive hormones can occur
hyper-secretion which causes
• the premature onset of puberty in children
• masculine features become evident in adult woman (condition known as virilism)
