Endocrine System Flashcards
Pituitary Gland, Pancreas (Diabetes) & Kidney (Nephron & urodynamics)
Function of the endocrine system
A system made up of glands that secrete hormones directly into the blood to maintain homeostasis and regulate the body’s chemical reactions.
Homeostasis
Maintaining a balanced, stable internal environment for among all bodily systems in order for the body to survive and function correctly.
Pituitary Gland
A small pea sized gland found in the brain also known as the master gland as it controls the production and release of other hormones.
Hypothalamus
Controls the pituitary gland
Anterior Lobe
The front half of the pituitary gland which secretes sex hormones such as LH, FSH and growth hormone.
Posterior Lobe
The back half of the pituitary gland which secretes ADH (antidiuretic hormone) & oxytocin (used in childbirth).
Pancreas
A 6-10 inch long tapered organ found behind the stomach with both an exocrine and endocrine function
Functions of the Pancreas
Exocrine function: release pancreatic juices (digestive enzymes) via a duct.
Endocrine function: secrete hormones to regulate blood glucose levels (insulin & glucagon).
Islets of Langerhans
A group of hormone producing cells in the pancreas.
Alpha cells: produce glucagon
Beta cells: produce insulin
Hormonal release of the Islets of Langerhans
Alpha cells produce glucagon (for glycogenolysis)
Beta cells produce insulin (for glycogenesis)
Glycogenolysis
The hydrolysis of glycogen to glucose in the liver (stimulated by glucagon release) to increase blood glucose as a result of low glucose levels in the blood.
Glycogenesis
The formation of glycogen from excess glucose in the liver (stimulated by insulin) to decrease blood glucose as a result of high glucose levels in the blood.
Decreasing blood glucose levels
High blood sugar is detected by the pancreas which then releases insulin (from beta cells).
The liver undergoes glycogenesis and converts the glucose into glycogen for storage.
Blood glucose level decreases back to ‘normal’
Increasing blood glucose levels
Low blood sugar is detected by the pancreas which releases glucagon (from alpha cells).
The liver undergoes glycogenolysis and converts the glycogen to glucose.
Blood glucose levels increase back to ‘normal/.
Negative feedback in the pancreas
Negative feedback ensures that blood glucose levels can remain at homeostasis as the reduction of blood glucose (glycogenesis) can be counteracted by an increase in blood glucose (glycogenolysis)
Diabetes
Diabetes is a non-communicable disease which causes a reduction in the insulin levels produced by the body.
There is two types: Type 1 & Type 2
Symptoms of BOTH diabetes
increases appetite & thirst
unexplained weight loss
blurred vision
frequent urination
tiredness/weakness
Type 1 Diabetes
This is when the body produces NO insulin, and can occur at any age (mainly childhood)
Type 1 Diabetes- Causes
Genetics
Type 1 Diabetes- Treatments
insulin injections
(+ balanced diet & healthy weight)
There is NO CURE
Type 2 Diabetes
This is when your body does not produce enough insulin, mainly occurs in people over 45
Type 2 Diabetes- Causes
Being overweight
Unhealthy diet
Lack of exercise
High blood pressure
Genetics
Type 2 Diabetes- Treatments
Insulin tablets
Diet change
Weight loss
(healthy lifestyle)
There is NO CURE
Role of the Kidney
To filter waste products out of the blood and produce urine
Fibrous Capsule
A thin collagen rich tissue with some elastic and sooth muscle which encloses each kidney to provide it with protection and support the kidney (mass)
Renal Artery & Vein
Renal Artery- The blood vessel which supplies oxygenated blood to the kidneys
Renal vein- the blood vessel which removes deoxygenated blood from the kidneys
Renal Pelvis
Collects the urine as it is produced and passes it into the ureter
Ureter
Muscular tube, which transport urine from the renal pelvis to the bladder
Urine (+contents)
The waste products produced by the kidneys:
Excess Water
Dissolved Salts
Urea
Small Substances (e.g. hormones/ excess vitamins)
Renal Cortex
The outer layer of the kidney found around the medulla.
It is where the nephron start (ultrafiltration)
Renal Medulla
Multiple (6) structures found on the inside of the kidneys around the renal pelvis.
It where the loop of Henley and collecting duct
Nephrons
Millions of microscopic structures found within the kidney which are responsible for filtering the blood
Fluid Movement through the Nephron
Glomerulus
Bowman’s Capsule
Proximal Convoluted Tubule (PCT)
Loop od Henle
Distal Convoluted Tubule (DCT)
Collecting Duct
Blood movement through the nephron
(Renal Artery)
Afferent Arteriole
Glomerulus
Efferent Arteriole
(Renal Vein)
Afferent Arteriole
Blood enters the nephron through the afferent arteriole and them branches off into many small capillaries (glomerulus)
Efferent Arteriole
Glomerulus joins back upto form the efferent arteriole which runs side by side to the nephron to selectively re absorb components into the blood
Ultrafiltration
The difference/smaller lumen size of the afferent/efferent arteriole causes high pressure in the glomerulus.
This forces small molecules such as water, glucose urea and amino acids into the Bowmans capsule
Glomerulus Filtrate
The fluid found in the Bowman cap capsule which contains:
Water
Glucose
Urea
Amino acids
Ions
Which substances are not passed into the Bowmans capsule?
RBC
WBC
Proteins
Because they’re too large to pass into the glomerulus filtrate.
Selective reabsorption
The absorption of selected substances required by the body back into the blood stream (after ultrafiltration)
Proximal Convoluted Tubule (PCT)
ALL glucose is reabsorbed into the blood by active transport
SOME amino acids, vitamins, hormones & some (Na+) Ions reabsorbed into blood (active transport)
Descending Limb of the Loop of Henle
Water is absorbed out of the filtrate by osmosis, causes concentration of ions to increase
Bottom of the Loop of Henle
Filtrate is hypertonic (has a really high concentration of salt)
Ascending Limb of the Loop of Henle
Ions/Salts move out by diffusion and then active transport (to maximise absorption). This causes the glomerulus filtrate to become dilute.
(The ascending limb has thicker walls to reduce water loss from the filtrate.)
Distal Convoluted Tubule (DCT)
Any more ions or water which are needed by the body are now absorbed (what’s absorbed varies based off conditions).
Water is absorbed by osmosis under the action of ADH if required.
If salts are required, Na+ and Cl- are absorbed back into the bloodstream.
Collecting Duct
Any remaining water that is required by the body is absorbed under the action of ADH (osmoregulation).
Any material still not reabsorbed from the glomerulus filtrate will form the urine.
Production & Release of ADH
ADH is produced by the hypothalamus but released by the pituitary gland.
Antidiuretic Hormone (ADH)
Binds to the surface of the plasma membrane (on DCT & Collecting Duct).
This causes vesicles carrying aquaporin to fuse with the membrane.
This leads to the membranes permeability to increase so MORE water is absorbed into the blood
Osmoregulation
The control of water in the blood detected by osmoreceptors and regulated by ADH release.
High Concentration of Water in the Blood
Detected by osmoreceptors in the hypothalamus. Signal sent to pituitary gland.
Pituitary Gland releases LESS ADH into the blood.
Less water is absorbed into the bloodstream. Urine turns pale.
Low Concentration of Water in the Blood
Detected by osmoreceptors in the hypothalamus. Signal sent to pituitary gland.
Pituitary gland releases MORE ADH into the blood.
More water is absorbed into the blood. Urine turns dark/yellow.
Urodynamics
Tests which measure how well the body is at storing and releasing urine.
Urine Flow Rate
(Free Flow Rate)
Patients are asked to urinate into a funnel that is connected to a measuring device.
This measures the amount of urine, rate of flow & total length of time.
Cystometry
The patient is asked to empty their bladder as much as possible.
A small tube (catheter) is placed into the urethra until it reaches the bladder.
Urine left in the bladder is recored.
Fluid/Gas is placed into the bladder via the catheter until the patient feels the need to urinate.
The catheter is linked to a cystometer which measures the bladder pressure.
