Biology 30 Rock the Diploma Unit notes & Problems
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Transcript of Biology 30 Rock the Diploma Unit notes & Problems
Unit A – Endocrine systemUnit A – Endocrine system
+ whereas the nervous system makes short-term changes to restore homeostasis, the endocrine system works more slowly and tends to make more long-term changes
+ hypothalamus can be considered part of both the nervous and endocrine systems– hypothalamus regulates the pituitary gland, the
master gland, through nerve stimulation– pituitary gland stimulates other endocrine glands
secrete chemicals that affect the nerve activity of the hypothalamus
+ chemical regulators, from the Greek word hormon which means “to set into motion”
– hormones act to speed up or slow down body processes+ produced in one part of the body, but affect another part+ hormones do not affect all cells, only those with the correct
receptor for that particular hormone+ classified according to where they work (activation site)
– most hormones target a specific target tissue e.g. parathyroid hormone (regulates calcium levels) e.g. gastrin (stimulates stomach cells to produce digestive enzymes)
– non-target hormones affect cells throughout the body e.g. human growth hormone (cause long bones to grow) e.g. insulin (produced by the islets of Langerhans in the pancreas, secreted
when blood sugar levels are high & regulates blood sugar) e.g. epinephrine (adrenaline) (produced in times of stress)
+ negative feedback control system– prevents chemical imbalances in the body– when a hormone causes a body response, it triggers
receptors and the response is inhibited, restoring homeostasis
– e.g. pituitary gland produces male LH (luteinizing hormone) activates testosterone production in the testes testosterone levels increase high levels of testosterone inhibits the release of male LH
+ when negative feedback systems fail, medical disorders can result– e.g. gigantism results from a failure to turn off the
production of growth hormone
stimulus•high blood glucose
responding gland•pancreas•Islet βcells
hormone produced•insulin
target•fat cells•liver cells•other cells
effects•conversion of glucose into glycogen
•glucose uptake
result•blood glucose falls
negative feedback•pancreas β cells no longer getting high blood glucose message•stop producing insulin
Numbered:1. Thyroid2. Adrenal Cortex3. Adrenal Medulla4. Pancreas5. Ovaries6. Testes
Not numbered:+ hypothalamus+ pituitary+ parathyroid
+ anterior lobe (towards the front)– produces its own hormones– release of pituitary hormones regulated by the
hypothalamus via other hormones thyroid-stimulating hormone (TSH) protein hormone
÷ stimulates thyroid gland to release thyroxine, which stimulates cell metabolism
corticotrophin adrenal steroid (ACTH) steroid hormone÷ stimulates adrenal cortex to release hormones involved in stress
growth hormone (GH) a.k.a. somatotropin protein hormone÷ targets most cells but effects are most pronounced in bones and
cartilage, promotes growth÷ disorders related to GH
= dwarfism – underproduction of GH= gigantism – overproduction of GH= acromegaly – continued growth of jaw, forehead, fingers and toes
into adulthood÷ production inhibited when hypothalamus releases somatostatin
follicle-stimulating hormone (FSH)÷ in ovaries, stimulates follicle development ÷ in testes, promotes the development of sperm cells
luteinizing hormone (LH)÷ in ovaries, stimulates ovulation÷ in testes, stimulates the production of testosterone
prolactin (PRL)÷ targets mammary glands and stimulates and maintains milk
production÷ production inhibited when hypothalamus releases dopamine
+ located at the base of the neck in front of the windpipe
+ produce hormones involved in regulating metabolism and tissue growth and differentiation– thyroxine
promotes the oxidation of sugars and other nutrients÷ 50% released as heat÷ 50% converted to ATP
control of thyroxine÷ receptors in hypothalamus are informed of low metabolic rate
thyroid-releasing factor (TRF) stimulates pituitary to release TSH carried by blood to thyroid gland thyroid releases thyroxine stimulates cells to use more sugar
÷ high levels of thyroxine inhibits TRF from hypothalamus
+ thyroid disorders– goiter
caused by low levels of iodine, a main component of thyroxine thyroxine no longer completes negative feedback loop TRF keeps being produced, so thyroid keeps being stimulated, causing it to enlarge why table salt contains iodine (iodized salt)
– hyperthyroidism people with high thyroid activity are typically
÷ thin÷ warm, ÷ overactive
excess glucose is converted to heat and ATP– hypothyroidism
people with low thyroid activity are typically÷ less thin÷ intolerant of the cold÷ tend to have dry skin
because excess glucose is converted to fat once glycogen stores are full
+ The parathyroid glands are small glands in the neck that produce parathyroid hormone.
+ Humans have four parathyroid glands, which are usually located behind the thyroid gland
+ control the amount of calcium in the blood and within the bones
+ located above each kidney+ each gland is composed of two smaller glands
– adrenal medulla inner gland, stimulated by sympathetic nerves in times of stress produces hormones that initiate fight-or-flight
response÷ epinephrine÷ norepinephrine
+ adrenal cortex– outer gland, surrounds adrenal medulla– produces two main types of hormones
glucocorticoids – e.g. cortisol÷ affect blood glucose levels
mineralocorticoids – e.g. aldosterone÷ help maintain body fluid levels
+ cortisol – help body recover from stress, increases
amino acid levels in blood – converted into glucose by liver, or used
in protein synthesis to repair damaged cells
– as cortisol levels rise, cells within the hypothalamus and pituitary gland decrease the production of regulatory hormones and cortisol levels drop
+ aldosterone– increase sodium retention and water
reabsorption by the kidney
+ contains two types of cells– digestive enzyme producing cells– hormone producing cells
located in Islets of Langerhans+ produce two hormones
– insulin produced in the beta cells released when blood sugar level is high makes liver and muscle cells permeable to glucose in the liver, excess glucose is stored as glycogen, which helps return blood
glucose levels to normal– glucagon
produced in the alpha cells causes an increase in blood sugar levels after a period of fasting causes blood
glucose to drop promotes the conversion of glycogen back to glucose
+ Several different types of diabetes exist, and there is often confusion on the part of the public about which type is which.
+ Unless “diabetes insipidus” is specified, it is assumed the type of diabetes being discussed is diabetes mellitus.
+ Type I and Type II diabetes are both subtypes of diabetes mellitus.
Diabetes Insipidus Diabetes Mellitus
Also known as:
Type I Juvenile diabetes Insulin-dependent
diabetes
Type II Adult-onset diabetes
Cause: Body does not
make/secrete enough ADH
Beta cells do not produce enough insulin
Tissues do not recognize the effect of insulin
Area of dysfunction: Hypothalamus, or
posterior lobe of pituitary gland
Islet cells in pancreas Body cells
Symptoms:
Large volumes of urine
Dehydration Thirst
Large volumes of urine Dehydration Thirst Weight loss Acetone-scented breath Sweet-smelling urine
Glucose in urine: No Yes Yes
Glucose levels in blood: Unaffected Hyperglycemia Hyperglycemia
Treatment: Anti-diuretic
medications
Insulin replacement via injections
Islet transplants
Medications that make the body more sensitive to insulin
Hormone Source Function Controlled by
Thyroid stimulating hormone (TSH)
Anterior pituitary Stimulates thyroid to produce thyroxine
Thyroxine levels in the blood
Thyroxine Thyroid Regulates metabolism in all cells
Thyroxine levels in the blood
Calcitonin Thyroid Reduces blood calcium Calcium levels in the blood
Parathyroid hormone (PTH)
Parathyroid Increases blood calcium (released from bones)
Calcium levels in the blood
Adrenocortico-tropic hormone (ACTH)
Anterior pituitary Stimulates adrenal cortex to release stress hormones
Cortisol levels in the blood
Cortisol Adrenal cortex Converts amino acids into glucose during stress, reduces inflammation
Glucose levels in the blood
Hormone Source Function Controlled by
Human growth hormone (hGH)
Anterior pituitary Stimulates growth Hypothalamic hormones
Antidiuretic hormone (ADH)
Hypothalamus Promotes water retention by the kidneys
Water/salt balance
Epinephrine (Adrenaline)
Adrenal medulla Prepares body for stress
Sympathetic nervous system
Aldosterone Adrenal cortex Increases salt uptake and water reabsorption
Levels of Na+ and K+ in blood
Insulin Pancreas (β cells) Converts glucose to glycogen and increases cells’ uptake of glucose
Glucose levels in the blood
Glucagon Pancreas (α cells) Converts glycogen into glucose to increase blood glucose levels
Glucose levels in the blood