Endocrine system and metabolic reactions Flashcards
WHAT IS GLYCOGENESIS
synthesis of glycogen from glucose
WHAT EFFECT DOES GLYCOGENESIS HAVE ON BGL?
Decreased BGL
WHAT HORMONE STIMULATES GLYCOGENESIS?
Insulin
WHAT IS GLYCOGENOLYSIS?
breakdown of glycogen to form glucose
WHAT EFFECT DOES GLYCOGENOLYSIS HAVE ON BGL?
increased BGL
WHAT HORMONES STIMULATE GLYCOGENOLYSIS?
glucagon and adrenaline
WHAT IS GLUCONEOGENESIS?
synthesis of glucose from glycerol, amino acids and lactic acid
WHAT IS THE EFFECT OF GLUCONEOGENESIS ON BGL
increases BGL
WHAT HORMONES STIMULATE GLUCONEOGENESIS
cortisol and glucagon
WHAT IS LIPOLYSIS?
breakdown of triglycerides into glycerol and fatty acids
WHAT IS THE EFFECT OF LIPOLYSIS ON BGL?
increase BGL
WHAT HORMONES STIMULATE LIPOLYSIS?
adrenaline, cortisol, thyroid hormones, growth hormone
WHAT HORMONE STIMULATES LIPOGENESIS?
insulin
WHAT EFFECT DOES LIPOGENESIS HAVE ON BGL?
decreased BGL
WHAT IS LIPOGENESIS
synthesis of lipids from glucose and amino acids
What is the definition of catabolism?
break down molecules and are intended to produce energy
What is the definition of anabolism?
is the chemical reaction that joins simple molecules together to form complex molecules.
Describe what happens during glycogenesis, the effect it has on BGL, and what hormone stimulates this reaction
- Glycogenesis is the formation of glycogen from glucose and occurs in liver and muscle cells
- If there’s more glucose than needed the molecules of glucose are joined together to form glycogen
- Glycogenesis decreases blood glucose levels when they’re high allowing glycogen to be stored in liver and muscle cells.
- Glycogenesis is stimulated by the hormone insulin.
Describe what happens during glycogenolysis, the effect it has on BGL, and what hormone stimulates this reaction
- Glycogenolysis occurs when blood glucose level is low, causing glycogen stored in the liver to break up to release glucose into the bloodstream
- Causes BGL to increase
- Glycogen stored in skeletal muscle cells is broken down to glucose, to make ATP for that muscle
- main hormones responsible for glycogenolysis are glucagon and adrenaline
Describe what happens during gluconeogenesis, the effect it has on BGL, and what hormone stimulates this reaction
- Gluconeogenesis is the process by which the body produces glucose from lipids and proteins when the BGL drops and glycogen stores are used up the liver.
- Increases BGL
- Gluconeogenesis is stimulated by the diabetogenic hormones (glucagon, growth hormone, epinephrine, and cortisol).
Describe what happens during lipogenesis, the effect it has on BGL, and what hormone stimulates this reaction
- Occurs when the intake of carbohydrates, proteins or fats exceeds the body’s ATP/energy needs.
- results in creation of triglycerides, which are stored in the adipose tissues.
- main hormone responsible is insulin
- decreases BGL
Describe what happens during lipolysis, the effect it has on BGL, and what hormone stimulates this reaction
- Lipolysis is the breakdown (catabolism) of triglycerides into glycerol & fatty acids
- increases BGL
- main hormones involved are adrenaline, cortisol and thyroxine
Where is glycogen stored?
liver and muscles
Name the two products resulting from lipolysis & what they are used for
- Glycerol is converted into pyruvate (pyruvic acid) & enters the Krebs cycle to produce ATP
- Glycerol can also be converted to glucose by gluconeogenesis
- Fatty acids are converted into acetyl coenzyme A (CoA) in the liver, which then enter the Kreb’s cycle to form ATP
- But if the levels of CoA produced are too high for the Krebs cycle to process the liver converts the CoA into ketone bodies
What are ketone bodies (ketones) produced from?
ketones are produced from CoA when levels of CoA produced are too high for the Krebs cycle to process, the liver converts the CoA into ketone bodies
Describe what causes an increase in ketones
Overproduction of ketone bodies occurs in conditions of:
- severe starvation
- uncontrolled diabetes
List the clinical signs & symptoms that would result from excess ketones
- High levels of ketones are toxic, especially to the brain.
- excretion of excess ketones occurs through:
- the lungs giving the breath a characteristic sweet smell of acetone
- the urine (ketonuria)
Explain the clinical significance of excess ketones - state what homeostatic imbalance will occur (you should be able to describe this homeostatic imbalance and the compensatory mechanisms used to attempt to correct it
- Since ketone bodies are acidic, excess production can lower blood pH & cause metabolic acidosis (ketoacidosis)
what is metabolic acidosis and what compensatory mechanisms are used to attempt to correct it?
- Metabolic acidosis is a decrease in blood pH caused by non-respiratory conditions.
Buffer systems - Act quickly to bind excess H+ and increase pH
- Do not remove H+ from the body
Respiratory system - Increasing the rate & depth of breathing increases the exhalation of CO2 and increases pH
Renal system - Acts slowly to increase or decrease the excretion of H+ from the body and hence decrease or increase pH
Describe three uses for amino acids
- Excess amino acids are broken down by the liver &
- Used for production of ATP
- Converted into glucose (gluconeogenesis) & triglycerides (lipogenesis)
One of the end products of amino acid catabolism is urea
- State two tests could be done to check the levels of urea and what elevated levels of this urea would indicate
- The liver converts ammonia (highly toxic) to urea which is excreted in the urine
- Nurses check for urea during urinalysis
- Blood tests - electrolytes & urea (U&E’s), blood urea nitrogen (BUN)
- elevated levels of urea are an indicator of decreased renal function
Define Basal Metabolic Rate (BMR)
the metabolic rate measured under resting/fasting conditions
State four factors that would increase BMR
exercise increases metabolic rate as much as 15 times
- hormones increase basal metabolic rate
- higher body temperature raises BMR
- ingestion of food raises BMR 10-20%
- children’s BMR is double that of an elderly person
List five hormones that increase BMR & explain how each hormone increases BMR
thyroxine, insulin, growth hormone & testosterone
- sympathetic nervous system’s release of epinephrine (adrenalin) & norepinephrine (noradrenalin) increases BMR
- The hormone thyroxine increases BMR it stimulates cell respiration which means cells use more oxygen & produce more ATP
Describe four age related changes to the endocrine system
Growth hormone decreases allowing muscle atrophy
Thyroid gland decreases production of thyroid hormones, which decreases metabolic rate and increases body fat
Pancreas releases insulin more slowly and cells are not as responsive to insulin (insulin resistance)
Ovaries become unresponsive to FSH and LH so decreases oestrogen production
Testosterone levels decline but effects are apparent until very old age
Describe The resistance reaction
- This is initiated mostly by releasing hormones of the hypothalamus. It provides a longer lasting response then the initial sympathetic fight or flight response.
- Resulting in increased secretion of cortisol, growth hormone and thyroxine. The actions of these hormones help the body continue fighting stressors long after the sympathetic response dissipates
Describe initial fight or flight response
the fight or flight response is initiated by nerve impulses from the hypothalamus to the ANS (sympathetic), which includes the release of adrenaline which is from the adrenal medulla.
his quickly provides large amounts of glucose and oxygen to the brain, skeletal muscle and heart
Name the hormone that is produced from the pineal gland and its location
The pineal gland is attached to the roof of the 3rd ventricle
Secretes melatonin
Melatonin contributes to the natural body clock
Describe three actions of PTH
Parathyroid hormone (PTH) is the main hormone which increases blood calcium level. Parathyroid hormone has 3 main functions. 1, stimulates osteoclasts to resorb bone and raise blood calcium. 2, enhances reabsorption of calcium by the kidneys. 3, activates vitamin D to become Calcitriol which is needed to absorb calcium from food.
State three uses for calcium in the body
Precise control of calcium is essential for many functions including: transmission of nerve impulses, muscle contraction and blood clotting
Describe Noradrenaline
noradrenaline primarily works on alpha 1 receptors resulting in vasoconstriction, this leads to increased blood pressure.
Adrenal medulla also releases a much lesser amount of noradrenaline, noradrenaline release
Describe Adrenalin (epinephrine)
adrenal medulla releases adrenaline and noradrenaline when is stimulated by stressful situations and exercise, sympathetic stimulation- fight or flight response
Describe Prolactin
initiates and maintains milk production, levels rise dramatically towards the end of pregnancy.
Describe Luteinising Hormone LH
in females, stimulates the production of oestrogen and progesterone in the ovaries. In males, stimulates the testes to produce testosterone.
Describe Follicle Stimulating Hormone
in females, initiates the development of oocytes (eggs) in the ovarian follicles, stimulates the production of oestrogen. In males stimulates the testes to produce sperm.
Describe Growth Hormone GH
stimulates all body cells to enlarge and divide, major targets are bone and skeletal muscle. stimulates epiphyseal plate so long bones increase in length, increase in muscle mass, tissue repair and breakdown of fat and rise in blood glucose. Control of growth hormone: a releasing hormone from the hypothalamus stimulates the anterior pituitary to release GH.
Name the six hormones produced by the anterior pituitary
Growth Hormone GH Thyroid Stimulating Hormone TSH Adrenocorticotropic Hormone ACTH Follicle Stimulating Hormone Luteinising Hormone LH Prolactin
describe Oxytocin hormone
Oxytocin is released from the axon terminal in the posterior pituitary and it is diffused into the blood vessels. oxytocin travels through the blood to the breast where it stimulates the release of milk from the ducts of the breast. Oxytocin also stimulates contraction of the uterus during labour and breastfeeding.
Name the two hormones released from the posterior pituitary and state where they are produced
The two hormones are produced in the hypothalamus, these two hormones are stored in the posterior pituitary. The hormone is released when an action potential travels down the axon of the neurosecretory cells.
Describe the structure and location of the pituitary gland
Small glands that lies in a hollow of the sphenoid bone
Connected to the hypothalamus by the infundibulum, it is controlled by the hypothalamus.
The pituitary consists of an larger anterior lobe and a smaller posterior lobe, is the size and shape of a pea.
describe how other hormones can trigger hormone secretion
many endocrine glands are themselves stimulated by hormones, thyroid stimulating hormones from the anterior pituitary gland stimulates the thyroid gland to produce thyroxine.
describe how levels of chemicals in the blood can trigger hormone secretion
some endocrine glands secrete their hormone in direct response of changing levels of critical ions and nutrients. For example, parathyroid glands detect low levels of blood Ca2+ and increase their release of parathyroid hormone (PTH)
describe how signals from the nervous system triggers hormone secretion
Sympathetic nervous system sends impulses to stimulate the adrenal medulla to release adrenaline (epinephrine)
three stimuli that trigger hormone secretion
- signals from the nervous system
- levels of chemicals in the blood
- other hormones
Describe the difference between endocrine & exocrine glands and give an example of each type of gland
Exocrine glands secrete their products (e.g. sweat, pancreatic enzymes) into ducts. The ducts then carry the secretions to the target site
Endocrine glands secrete into interstitial fluid, then diffuse into the blood
Explain why water soluble hormones cannot be administered via the oral route
water soluble hormones are destroyed by digestion (so insulin cannot be taken orally must be injected)
Explain the difference in receptor location for both water soluble hormones and lipid soluble hormones
Water soluble hormones circulate freely in the blood and bind to receptors on cell membranes then alter the activity of intracellular enzymes
Lipid soluble diffuse through the cell membrane and bind to receptors within target cell, directly activate genes in cell which results in the formation of new proteins which alter cells activity
describe Antidiuretic hormone
osmoreceptors in the hypothalamus detects an increased concentration of solutes in the blood (haemorrhage, diarrhoea, excess sweating). They transmit excitatory impulses to the neurosecretory cells. Neurosecretory cells generate nerve impulses that cause the release of ADH from vesicles in the axon terminals in the posterior pituitary.
State the stimulus for secretion of the hormones that regular BGL’s
Adrenaline, so that glucose is available for an emergency
Growth hormone, by stimulating lipolysis so that lipids are available for growth leaving glucose to be available for the brain
Cortisol, which makes additional glucose available to deal with stress situations
State five ways that the endocrine system maintains homeostasis
Altering metabolism. Regulating growth and development. Regulating reproduction. Regulate circadian rhythms. Regulates activity of smooth muscles, cardiac muscle and glands.
Name the organ that has both endocrine & exocrine functions
The pancreas
Explain how hormones are inactivated and excreted from the body
Most hormones are inactivated by the liver and excreted by the kidneys or in the faeces
Name the two hormones that control blood calcium levels
Parathyroid Hormone (PTH) Calcitonin
Describe two actions of calcitonin
Describe two actions of calcitonin
sustains normal levels of calcium and phosphate by, increasing absorption of calcium and phosphate from the intestine, and enhancing the actions of parathyroid hormone which resorbs bone.
Name the two hormones that specifically regulate BGL’s
Insulin, the dominant hormone after eating, lowers blood glucose levels (it production is increased when blood glucose levels are high)
Glucagon, the dominant hormone of the fasting state, raises blood glucose levels (its production is increased when blood glucose levels are low)
Name the three stages of the stress response
initial fight or flight response
the resistance reaction
exhaustion
Describe Exhaustion
occasionally the resistance stage fails to combat the stressor and the body moves into the stage of exhaustion, but the hormones of the resistance reaction (cortisol, growth hormone and thyronine) continue to release
Define basal metabolic rate (BMR)
Basal metabolic rate is the metabolic rate measured under resting/fasting conditions
State four factors that would increase BMR
Factors the affect metabolic rate and thus the production of body health; exercise increases metabolic rate as much as 15 times; hormones increase basal metabolic rate
Describe Thyroid Stimulating Hormone TSH
TSH from the anterior pituitary stimulates the thyroid gland to produce thyroxine, thyroxine is a hormone which increases the basal metabolic rate.
Describe Adrenocorticotropic Hormone ACTH
hypothalamus releases corticotropin releasing hormone (CRH), the anterior pituitary releases adrenotropic hormone (ACTH) adrenal cortex releases cortisol increasing BGL by stimulating gluconeogenesis and lipolysis assisting other hormones with vasoconstriction to increase BP, helps maintain sympathetic response and acts as an anti-inflammatory.
What is calcitriol also known as?
Bioactive vitamin D
