hormones and homeostasis

test is all multiple choice and one data base im pretty sure!! monday november 6

define homeostasis

the maintenance of the internal environment within an acceptable range, despite fluctuations of the external environment, creating a dynamic equilibrium

define a dynamic equilibrium

a stable condition with fluctuating limits

what are the three homeostatic conditions

• body temperature of 37 degrees

• 0.1% blood sugar level

• blood pH of 7.4

what are negative feedback systems?

mechanisms that bring body back to acceptable ranges

what are the three functional components of homeostatic control systems and what do they do?

• a monitor / sensor

  • measure current situation

• a coordinating centre

  • compares current to normal

  • activates mechanism to adjust

• regulator

  • mechanism to restore normal balance

explain how CO₂ concentration in the blood is affected by a negative feedback system?

• chemoreceptors in walls of specific blood vessels can detect if pH is too high or low and increase or decrease breathing rate to adjust

  • monitor: chemoreceptors

  • coordinating centre: medula oblongata

  • regulator: intercostal muscles

what is blood pH maintained by?

carbonic acid-bicarbonate buffer system

• H₂O + CO₂ ←—> H₂CO₃ ←—> HCO₃^- + H⁺

what is called when blood pH is out of homeostatic ranges? what can this cause?

• > 7.35 —> acidosis

• < 7.45 —> alkalosis

• can cause blood proteins and enzymes to ionize and change shape and therefore function

how is low blood pH brought back to homeostatic levels?

H⁺ ions will find HCO₃^- ions and form H₂CO₃, removing free H⁺ ions and increasing blood pH

how is high blood pH brought back to homeostatic levels?

H₂CO₃ ionizes to create more H⁺ ions and lower pH

what is thermoregulation?

maintenance of body temperature within a range that allows cells to function efficiently

how does thermoregulation work for invertebrates vs vertebrates ?

invertebrates: depend on air temperature for thermoregulation

vertebrates: able to maintain body temperature despite surroundings

• thermoreceptors in skin and hypothalamus monitor temperature changes in environment and blood

how does the body return to homeostatic conditions when the organism is too hot? (vertebrates)

• vasodilation: increases blood flow to the skin, bringing heat to be evaporated)

• sweat: evaporation of water from skin requires energy, which is taken from body heat, removing heat from the body

• decreased metabolism: metabolic reactions produce heat

• behavioural adaptations

how does the body return to homeostatic conditions when the organism is too cold? (vertebrates)

• vasoconstriction: blood vessels in skin narrow, decreasing blood flow, and decreasing heat loss to environment

• shivering: muscle contractions produce heat as by-product

• increased metabolism

• fluffing hair or feathers

• thick layer of fat/blubber (insulation)

what is the endocrine system?

a system of glands that secrete hormones to regulate body function

what are hormones and what do they do?

• chemical regulators and messengers

• released by cells in one part of the body and affects cells in other parts of the body to speed up or slow down processes

where are endocrine hormones produced, where are they secreted, and how are they distributed?

• produced in endocrine glands

• secreted in blood stream

• distributed by circulatory system

what cells do hormones affect?

not ALL cells, but only the cells that have a receptor for the particular hormone (target cells)

what are the two types of hormones?

• protein hormones

• steroid hormones

what are steroid hormones made of, and what does this mean about where they bind to the receptor?

• made of cholesterol

• soluble in fat but not in water, meaning it can dissolve through the cell / nuclear membrane

• bind to receptor in the cytoplasm or nucleus to form the hormone-receptor complex

what does a hormone-receptor complex do in steroid hormones?

can switch certain genes on and off by promoting or inhibiting the transcription of genes in the nucleus

give two examples of steroid hormones?

• sex hormones

• cortisol

what 3 things does cortisol affect?

• liver → cortisol activates the gene for glucogenisis

• cells → prevents expression of insulin receptor genes (prevents glucose storage)

• pancreas → inhibits transcription of insulin gene

what are protein hormones made of and how does this affect where they bind to the receptor?

• made of chains of amino acids / modified amino acids

• soluble in water but insoluble in fats (cannot dissolve through cell membrane)

• therefore, attaches to receptor sites on cell membrane

what does the hormone-receptor complex do in protein hormones?

• leads to release of secondary messenger in the cell that can spread through the cell and relay messages

  • ex: cyclic adenosine monophosphate (cAMP)

• these secondary messengers active enzymes in the cell

what two systems make up the body’s control system? how do they help to maintain homeostasis?

nervous - allows body to adjust quickly to environmental changes

endocrine - designed to maintain control over longer durations

what do the hormones created in the hypothalamus do (stored or released?)

• some are stored in posterior pituitary gland

• others control the release of hormones from the anterior pituitary gland

what does the pituitary gland do and what is it controlled by?

• controls other endocrine glands

• produces and stores hormones

• controlled by hypothalamus

  • hypothalamus will stimulate the release of created and stored hormones when necessary

where are the hormones in the posterior lobe made? how do they travel to the posterior lobe? how are they released?

• hormones stored and released in posterior pituitary gland are made by neurosecretory cells of the hypothalamus.

• travel from hypothalamus via specialized nerve cells

• released when nerve response is sent by hypothalamus

give the process of antidiuretic hormone (ADH) release

• created by hypothalamus

• stored in pituitary gland

• osmoreceptors in hypothalamus recognize osmotic pressure

• impulses are sent to pituitary to increase or inhibit the release of ADH into blood stream accordingly

where are the hormones in the anterior lobe made? how are they released? how do the hormones reach the anterior lobe?

• produces its own hormones

• hypothalamus regulates release with inhibiting or release hormones made by hypothalamus

• inhibiting and release hormones are transported through a portal vein

how do TRH and TSH work in tandem?

• anterior lobe produces and stores thyroid stimulating hormone

• TSH is released when hypothalamus releases thyroid releasing hormone

what does TSH stand for, what is its target organ and primary function, and where is it made and stored?

• thyroid stimulating hormone

• target organ: thyroid gland

• primary function: release hormones made in thyroid (T3 and T4)

• site of production and storing: anterior lobe

what does ACTH stand for, what is its target organ and primary function, and where is it made and stored?

• adrenocorticotropic hormone

• target organ: adrenal cortex

• primary function: stimulates release of hormones involved in stress response

• site of production and storing: anterior lobe

what does STH stand for, what is its target organ and primary function, and where is it made and stored?

• somatotropin hormone (growth hormone)

• target organ: most body cells

• primary function: promotes growth

• site of production and storing: anterior lobe

what does FSH stand for, what is its target organ and primary function, and where is it made and stored?

• follicle stimulating hormone

• target organ: gonads (ovaries and testes)

• primary function:

  • females: stimulates follicle development in ovaries

  • males: promotes sperm development in testes

• site of production and storing: anterior lobe

what does LH stand for, what is its target organ and primary function, and where is it made and stored?

• luteinizing hormone

• target organ: gonads (testes and ovaries)

• primary function:

  • females: stimulates ovulation and formation of corpus luteum

  • males: stimulates testosterone production

• site of production and storing: anterior lobe

what is the target organ and primary function of prolactin and where is it made and stored ?

• target organ: mammary glands

• primary function: maintains milk production in lactating females

• site of production and storing: anterior lobe

what does ADH stand for, what is its target organ and primary function, and where is it made and stored?

• antidiuretic hormone

• target organ: kidneys

• primary function: increases water reabsorption in kidneys

• made in hypothalamus

• stored in posterior pituitary

what is the target organ and primary function of oxytocin and where is it made and stored?

• target organ: uterus and mammary glands

• primary function: initiates strong uterine contractions and triggers milk release in lactating females

• made in hypothalamus

• stored in posterior pituitary

what are the cells in the pancreas that produce 2 hormones essential to maintaining homeostatic blood sugar levels, and which hormone does each type produce?

• alpha cells of Langerhans: produce glucagon

• beta cells of Langerhans: produce insulin

what three things does insulin cause and when is it secreted?

• muscle cells to absorb more glucose from bloodstream

• hepatocytes and muscle tissue to convert glucose to glycogen

• convert glucose to fat in fat tissue

• secreted when blood sugar levels are high

when is glucagon secreted, what does it cause, and what is it’s target tissue?

• secreted when blood sugar levels are too low

• travels through body, but target tissues are the liver

• causes hepatocytes to convert glycogen into glucose and release it into blood

what does it mean if someone has diabetes mellitus and what can it lead to?

• when a person does not produce enough insulin, or does not react to it

• can lead to hyperglycaemia (high blood glucose)

what are some side effects of diabetes mellitus?

(DR BNCK)

• death

• retinal damage

• blood vessel damage

• nerve damage

• comas

• kidney failure

what are the signs of diabetes mellitus?

• high glucose levels in urine

• this prevents water reabsorption in kidneys

• leads to frequent urination

• leads to constantly being thirsty / craving sugary drinks

when is type I diabetes typically diagnosed, what does it mean about the individual, what is the cause, and what are the treatments?

• typically diagnosed as a child

• individual does not make insulin / insufficient levels of insulin

• causes: autoimmune disease resulting in the destruction of beta islets of Langerhans by the body’s own immune system

• treatment:

  • insulin injections

  • pancreas transplant

  • diet

when is type II diabetes typically diagnosed, what does it mean about the individual, what is the cause, and what are the treatments?

• occurs / diagnosed later in life

• insufficient levels of insulin are produced / body has become less sensitive due to deficiency of insulin receptors or glucose transporters

• causes:

  • obesity

  • age

  • family history

  • lifestyle

• treatment:

  • regulated diet

    • reduced sugar intake

    • smaller, more frequent meals

    • high fibre (slows glucose absorption)

  • excercise

  • meds to increase insulin production and decrease blood glucose levels

what is gestational diabetes?

• temporary, develops during pregnancy

• increased risk that mother and child will develop type II diabetes

how do the nervous and endocrine system respond to the body’s need for more glucose and oxygen to produce more ATP during stressful situations?

• nervous: increase heart rate and diverting blood to needed muscles

• endocrine: releases hormones that take longer to respond, but have a more sustained response

how is glucagon and insulin secretion affected during the body’s stress response?

• glucagon: secretion increases - converts glycogen to glucose so more ATP is available to deal with situation

• insulin: secretion decreases - so glucose does not leave blood stream

where is the adrenal gland located and what two glands does it contain?

• location: above kidneys

• 2 glands:

  • adrenal cortex

  • adrenal medulla

where is the adrenal medulla located in the adrenal glands, what regulates it, and what hormones does it produce?

• location: inner gland

• regulated by nervous system

• produces:

  • epinephrine

  • norepinephrine

where is the adrenal cortex located in the adrenal glands, what regulates it, and what 3 classes of hormones does it produce?

• location: outer casing

• regulated by other hormones (ACTH)

• hormone classes:

  • glucocorticoids

  • mineralocorticoids

  • sex hormones

what are glucocorticoids do in the immune response and give an example, outlining its function.

• involved in suppressing inflammation in the immune response

• ex: cortisol

  • increases the amount of amino acids in the blood which can then be broken down into glucose for energy or used for protein synthesis

  • cortisol increases glucose uptake by the brain, and reduces it in the muscles so the brain can respond to stress

give an example of mineral corticoids and what it does?

ex: aldosterone

• increases Na⁺ retention and water reabsorption in the kidneys

give an example of sex hormones produced in the adrenal cortex

• androgens

  • including testosterone and estrogen precursors

what are three problems created by long-term stress and what could it cause?

• high blood sugar

  • alters osmotic balance leading to increased fluid uptake by blood and increased blood pressure

• increased blood pressure

  • possible rupture of blood vessels

• increased heart rate

  • can lead to higher blood pressure

  • possible destruction of heart muscle

what three glands affect metabolism (in the every day definition)

• thyroid gland

• parathyroid gland

• anterior pituitary

where is the thyroid located, what two important hormones does it produce, and what is its function?

bonus: what other hormone does it produce and what does it do?

• location: base of neck in front of trachea

• hormones:

  • thyroxin (T4)

  • triiodothyrine (T3)

• function: regulate body metabolism, growth, tissue differentiation, thermoregulation

• also produces calcitonin which acts on bone cells to lower the amount of calcium in blood

what does T4 stand for, what are its target cells, what does it do, where is it made and when is it secreted?

• T4 = thyroxin

• target cells: almost all in the body, but mainly metabolically active ones

• higher metabolic rates support protein synthesis and growth, and in increased generation of body heat

• made in thyroid gland

• secreted when you are cold to stimulate heat production

what is hyperthyroidism and what does it result in?

• people who secrete higher levels of thyroxin will breakdown sugars and other nutrients at a faster rate

  • 60% of glucose oxidized is released as heat

  • other 40% is converted to ATP and used in daily activity

• these individuals don’t gain weight easily

what is hypothyroidism and what are its symptoms?

• people who produce lower levels of thyroxin do not break down sugars as quickly

• excess blood sugar is converted to glycogen and stored as fat

• symptoms (FFWICC)

  • fatigue

  • forgetfulness and depression

  • weight gain

  • impaired brain development in children

  • constipation

  • cold all the time

how is the release of T4 and T3 controlled by negative feedback?

1) low T4 levels activate hypothalamus

2) hypothalamus releases TRH to anterior pituitary

3) anterior pituitary releases TSH which goes to thyroid

4) thyroid releases T3 and T4

5) high T4 levels inhibit release of TRH

what is the parathyroid gland? what do they respond to? what do they produce?

• 4 small glands within the thyroid gland

• respond directly to chemical changes in their immediate surroundings

• produce parathyroid hormone (PTH) which regulates blood calcium levels

what does PTH stand for and what does it do? what do abnormally high levels of this hormone cause?

• parathyroid hormone

• function:

  • kidneys and intestines absorb more calcium

  • calcium is released by bones

• abnormally high levels can cause prolonged breakdown of bones

how doe PTH help with activation of vitamin D?

• vitamin D is produced by skin cells from exposure to UV light and is an important component of several hormones

• vitamin D is required for calcium absorption from food in the intestines

where is growth hormone (somatotropin) secreted and what is it’s function?

• secreted by the anterior pituitary gland

• GH stimulates growth factors produced by the liver which stimulate cell division in growth plates causing the elongation of the skeleton

• also stimulates protein synthesis by increasing amount of amino acid uptake by cells and stimulating ribosomes

• causes an increase in muscle mass

where is leptin secreted and what does it do?

• secreted by adipose tissue (fat tissue)

• acts on the hypothalamus in the brain and controls appetite

what group of cells in the hypothalamus is the circadian rhythm dependent on?

superchiasmatic nuclei (SCN)

how is cortisol released in the morning?

• when light enters the eye and hits the retina, the information travels to the SCN via the optic nerve

• this signals the hypothalamus to cause the release of hormones, such as cortisol, to increase blood sugar

what controls the release of melatonin and where is it released? what is derived from?

• the SCN control release of melatonin by the pineal gland

• derived from the neurotransmitter serotonin

what are the effects of melatonin?

• drop in body’s core temperature during sleep

• melatonin receptors in kidney decrease urine production throughout the night

• has a role in regulating hypothalamus and thus effects hormonal secretions

what is the importance of sleep?

• GH and testosterone are high during sleep, so important for growth and your immune system

• allows for repair and rejuvenation of body systems

• allows for brain to process information and turn short-term memories into long-term memories

name the 6 hormones secreted by the anterior pituitary lobe

PLS FAT

• prolactin

• luteinizing hormone

• somatotropin (growth hormone)

• follicle stimulating hormone (FSH)

• adrenocorticotropic hormone (ACTH)

• thyroid stimulating hormone (TSH)

name the two hormones stored and secreted by the posterior pituitary lobe

• antidiuretic hormone

• oxytocin