Endocrine System Flashcards
(46 cards)
What is a hormone
an organic chemical substance (usually a protein or can be a steroid)secreted by an endocrine gland and carried in the blood stream to its target organ/s.
what do hormones do
they regulate metabolic reactions once reaching their target organ/s.
what is a target organ/tissue
specific cells that respond to a given hormone have receptor sites for that hormone. Can be a single gland/ organ or scattered throughout body.
what is the difference between an endocrine and exocrine gland
An endocrine gland is a vascular ductless gland that secretes hormones which are carried in the bloodstream to target organs
an exocrine gland has ducts which its secreted hormones travel through to where they’re needed i.e. salivary glands
which part of the brain secretes ADH: anti-diuretic hormone and what causes ADH to be released
The hypothalamus, part of brain situated above the pituitary gland.
Osmoreceptors in blood vessels of the hypothalamus detect an increase in osmolarity (low levels of water) of the blood. Hypothalamus responds aby releasing ADH
What is the role of ADH
It helps to conserve water by causing more water to be reabsorbed back into the blood from collecting ducts of the kidney = less water lost in urine
What is the name and role of the ‘master gland’
The Pituitary gland/ Hypophysis
- the chemical coordinator of most of endocrine glands
- attached to hypothalamus at base of brain
Name the 7 hormones secreted by the Pituitary gland
and give the function of ACTH
- Thyroid stimulating hormone TSH
- Follicle stimulating hormone FSH
- Luteinizing hormone LH
- Prolactin
- Growth hormone/ Somatotrophic hormone STH
- Adrenocorticotropic hormone ACTH (stimulates the adrenal cortex to secrete cortisone and aldosterone)
- Interstitial cell stimulating hormone ICSH
Describe the function of growth hormone/STH
Promotes skeletal and muscular growth by stimulating the synthesis of proteins .
Explain the function of Prolactin
- stimulates the production of milk in female mammary glands after birth
- as well as much of the maternal instinct
What is the function of TSH
thyroid stimulating hormone stimulates the thyroid gland to secrete thyroxin.
Explain the function of FSH in female and male
- in females stimulates Oogenesis in ovary i.e. formation of ova (egg)
- in males stimulates Spermatogenesis in testes i.e. sperm formation
what is the function of Luteinizing hormone (2)
- stimulates ovulation from the ovary
2. and formation of the corpus luteum
Name the condition and growth disorder that is caused by hypersecretion of Growth hormone and name one cause of it
Acromegaly
-enlarged terminal skeletal structures
growth disorder: Gigantism
-results in overdevelopment of the skeleton
- cause: tumour in pituitary gland + rare
Name the growth disorder caused by hyposecretion in prepubertal children and features of this disorder
Pituitary dwarfism - underdevelopment of skeleton normal body proportions height ( 91-122cm) sexually immature NOT mentally retarded
What is the function of ICSH
stimulates testes to secrete testosterone
What is homeostasis
The process of maintaining the internal environment in a constant optimal state for cells to function properly despite changes that take place internally and externally
internal environment = tissue fluid+ blood (extracellular fluids)
What factors must stay constant in the internal environment
Carbon dioxide glucose salt water concentration temperature and pH
What is negative feedback
a control mechanism whereby a change from the set point of any factor is corrected by bringing about change in the opposite (negative) direction
i.e. if there is too much of a particular factor a process is set in motion to reduce that factor and visa versa
too little of factor= process is set to make more
What makes up a negative feedback system
- RECEPTOR- detects a change from set point and sends info to the control centre
- CONTROL CENTRE - processes the info and activates corrective mechanisms
- EFFECTOR - responds and corrects change, returning conditions to set point
what happens if homeostasis cannot be maintained
illness or death
List 3 examples of negative feedback mechanisms
- Glucose (blood sugar) concentration in blood i.e. pancreas secretes insulin after eating
- Carbon dioxide concentration in body fluids
- Water and salts (osmoregulation) concentration in body fluids
Explain how insulin lowers blood sugar levels
eight step process
is an example of a negative feedback system
- After eating a meal with carbohydrates, the glucose from the digested food is absorbed from the small intestine into the blood
- this results in increased blood glucose levels above the normal set point
- beta cells detect raised glucose levels when blood passes through the pancreas and respond by secreting insulin into blood
- insulin goes to the liver and muscles, their main target organs
- insulin makes the cell membranes more permeable which enables more glucose to move from blood to cells
- isulin also increases the rate of glucose conversion into glycogen in the cells therefor more glucose can enter
- these processes have lowered the blood sugar levels
- Insulin secreting cells detect the lower glucose levels and stop releasing insulin into the blood.
How does glucagon increase blood glucose
five step process
also a negative feedback system
- blood sugar levels are low in the morning
- Alpha cells in the pancreas detect the low glucose levels and respond by secreting glucagon into the blood
3.Target cells in the liver are where the glucagon causes the breakdown of glycogen into glucose
4 the liver now releases glucose into the blood and increases the blood glucose level
5.Glucagon secreting cells detect the increased blood glucose level and stop releasing glucagon into the blood
