BMS1058 - The Liver and Renal System

Question 1

Describe the anatomy of the liver.

Answer 1

Almost completely covered by visceral peritoneum. Completely covered by dense irregular connective tissue layer.

Divided into two principal lobe by falciform ligament (large right lobe and smaller left lobe) which also suspends the liver in the abdominal cavity.

Question 2

What are the major functional cells in the liver? What do they form? What are these 3D structures bordered by?

Answer 2

Hepatocytes - specialised epithelial cells that perform an array of functions.

Form complex 3D arrangements = hepatic laminae. These have plates of hepatocytes one cell thick.
Bordered by hepatic sinusoids (vascular spaces) on either side.

Question 3

What do the grooves in cell membranes between neighboring haptocytes do?

Answer 3

Provide spaces for canaliculi (bile ducts) which hepatocytes secrete bile into.

Question 4

What does bile contain? What is its pH?

Answer 4

Salts, pigments, cholesterol, fats, phospholipids, electrolytes - pH of 7.6-8.6 (alkaline)

Question 5

What is the primary bile salt found in bile? What is it synthesized from? What is it secreted as?

Answer 5

Cholic acid.

Synthesized from cholestero in hepatocytes

Secreted as Na+ salts (increased solubiltiy).

Question 6

What does bile fluid in bile contain? Where does this come from?

Answer 6

HCO3- from the epithelial cells lining the bile canaliculi.

Question 7

Describe the transport of bile

Answer 7

hepatocytes -> bile canaliculi -> bile ductules -> bile ducts -> larger right and left hepatic ducts -> common hepatic duct (leaves liver) -> joins cystic duct from gallbladder to form common bile duct –> bile enters duodenum

Question 8

How much of the bile salts released is reabsorbed and where? How does the bile salts return to the liver?

How mant times is the bile salt pool recycled per day?

Answer 8

Little reabsorption from duodenum.

95% reabsorbed from ileum. 5% lost in faeces.

Bile salts return to liver via portal vein and resecreted by hepatocytes.

Recycled up to 10 times per day.

Question 9

Describe how blood is supplied to the liver.

Answer 9

Hepatic artery (oxygenated blood)

Hepatic portal vein
- brings deoxygenated venous blood from GI tract and spleen into liver.
- blood contains newly absorbed nutrients, drugs and possibly microbes and toxins

Branches form hepatic artety and PV carry blood into hepatic sinusoids. Most of nutrients, oxygen and toxins are taken up by hepatocytes.

Question 10

How does blood move from the lvier back to the heart?

Answer 10

Blood drains from hepatic sinosoids into central vein and eventually passes into the hepatic vein, going back to the inferior vena cava.

Question 11

What destroys worn-out white and red blood cells, bacteria and other foregin matter in the venus blood draining from the GI tract to the liver?

Answer 11

Fixed phagocytes.

Question 12

Describe the structure of a hepatic acinus.

Answer 12

Portal triad - containing a bile duct, hepatic artery branch and hepatic vein branch.

Each lobule is shaped as an oval mass including portions of 2 neighbouring hepatic lobules.

Question 13

What are zone 1 cells? What do they do?

Answer 13

Cells closest to branches of portal triad.
First to receive incoming oxygen, nutrients and toxins from incoming blood.

Take up glucose and store it as glycogen after a meal. Break down glycogen to glucose during fasting.

Question 14

Where are zone 3 cells?

Answer 14

Farthest from braches of portal triad.

Question 15

Between zone 1 and 3 cells, which are the first to show effects of bile obstruction or exposure to toxins?
Which are the first to show effects of impaired circulation?
Which are the first to regenerate?
Which are the frst to show evidence of fat accumulation?

Answer 15

Zone 1 cells - first to show effects of bile obstruction or exposure to toxins

Zone 3 cells - first to show effects of impaired circulation

Zone 1 cells - first to regenerate

Zone 3 cells - first to show evidence of fat accumulation

Question 16

What do zone 2 cells do?

Answer 16

Intermediate between zones 1 and 3

Question 17

What is the smallest structural and functional unit of the liver?

Answer 17

Hepatic acinus

Question 18

The gallbladder consists of __ layers. The mucosa is made up of simple ______ epithelium. The wall of the gallbladder lacks a _________. The middle muscular coat consits of _____ muscle fibres. The outer coat is visceral peritoneum.

Answer 18

3
columnar
submucosa
smooth

Question 19

What is the function of the gallbladder.

Answer 19

To store and concentrate bile produced.

In the concentration process, water and ions are absorbed by the gallbladder mucosa.

Contraction of smooth muscle fibres ejects contents of gallbladder into cystic duct.

Question 20

What are the symptoms and cause of jaundice?

Answer 20

Yellowish colouration of the sclerae (whties of eyes), skin and mucous membranes.

Cause: Build up of bilirubin
- formed from the breakdown of haem pigment in old RBCs. transported to liver for processing and excreted in bile.

Shows that liver is not functioning properly.

Question 21

What are the 3 main cateogries of jaundice?

Answer 21

Prehepatic jaundice: excess bilirubin production

Hepatic jaundice: congenital liver disease, cirrhosis of liver or hepatitis

Extrahepatic jaundice: blockage of bile drainage by gallstones or cancer of the bowl/pancreas

Question 22

Why do babies often have jaundice? What is the treatment?

Answer 22

Liver of newborns often function poorly - neonatal jaundice.

Blue light treatment - converts bilirubin into substances the kidneys can excrete.

Question 23

What liver function tests are there?

Answer 23

Blood tests to determne presence of certain chemicals released by liver cells.
e.g. Albumin globulinase, ALT, AST, ALP, GGT, bilirubin

Evaluate and monitor liver disease/damage.

Question 24

Wha are some common causes of elevated liver enzymes?

Answer 24

Non-steroidal anti-inflammatory drugs
Cholerterol-lowering medication
Some antibiotics
Alcohol
Diabetes
Infections
Gallstones
Tumour of the liver
Excessive use of herbal supplements - e.g. comfrey, dandelionroot etc

Question 25

What causes gallstones?

Answer 25

When bile contains either insufficient bile salts or excessive cholesterol. Cholesterol crystallizes to form gallstones. Obstruction to flow of bile from the gallbladder into duodenum.

Question 26

What are the treatments for gallstones?

Answer 26

Gallstone-dissolving drugs Lithotripsy (shock-wave therapy) Surgery - removal of the gallbladder and its contents Post-surgery: - limit saturaed fat and alcohol intake - eat smaller, more frequent meals

Question 27

The principal bile pigment is _______. One of its breakdown products—_______ - gives faeces their normal brown colour. Phagocytosis of aged red blood cells liberates ____ and _____ (which are recycled) and _______ (secreted in bile and broken down in the small intestine). These are all derived from heme.

Answer 27

bilirubin stercobilin iron and globin and bilirubin

Question 28

Describe the carbohydrate metabolism function of the liver.

Answer 28

* Maintenance of normal blood glucose level. * When blood glucose is low, the liver can break down glycogen to glucose. * Liver can convert certain amino acids and lactic acid to glucose. * Liver can convert fructose and galactose into glucose. * When blood glucose is high e.g., after eating a meal, the liver converts glucose to glycogen and triglycerides for storage.

Question 29

Describe lipid metabolism in the liver.

Answer 29

* Hepatocytes store some triglycerides. * Break down fatty acids to generate ATP. * Synthesize lipoproteins, which transport fatty acids, triglycerides, and cholesterol to and from body cells. * Synthesize cholesterol * Use cholesterol to make bile salt

Question 30

Describe protein metabolism in the liver.

Answer 30

* Hepatocytes deaminate (remove the amino group, NH2) from amino acids. * These amino acids can be used for ATP production or converted to carbohydrates or fats. * Toxic ammonia (NH3) is converted into much less toxic urea and excreted in urine. * Hepatocytes also synthesize most plasma proteins e.g., alpha and beta globulins, albumin, prothrombin, and fibrinoge.

Question 31

The liver can detoxify substances such as _______ and excrete ______ into bile (e.g....) It can chemically alter or extrete _____ hormones and ______ hormones (e.g....)

Answer 31

alcohol drugs e.g. penicilin thryoid steroid e.g. oestrogens and aldosterone

Question 32

Which vitamins and minerals does the liver store?

Answer 32

Vitamins A, B12, D, E and K (liver plays a role in activating vitamin D) Iron and copper

Question 33

What is the function of the Urinary system?

Answer 33

Regulate blood composition, pH, volume and pressure Dispose of waste (nitrogenous waste, drugs, environmental toxins etc) Maintain blood osmolarity Produce hormones - calcitrol and erthropoietin

Question 34

What is the urinary system composed of?

Answer 34

2 kidneys 2 ureters Urinary bladder Urethra

Question 35

Describe the anatomy of the kidney.

Answer 35

Parenchyma - renal cortex + renal pyramids of renal medulla 1 million nephrons Filtrate formed by nephrons drains into large papillary ducts. Papillary ducts drain into minar and major calyces. Each kidney has 8-18 minor and 2-3 major calyces. Once filtrate enters calyces it becomes urine.

Question 36

Each nephrone recives one _____ arteriole. What is the glomerulus? Glomerular capillaries reunite to form an ______ arteriole. The renal nerves are part of the _________ division of the ANS. Most are _________ nerves - they regulate the blood through the kidney by causing vasodilation/vasoconstriction.

Answer 36

afferent (towards) Glomerulus = tangled, ball-shaped capillary network efferent (away from) sympathetic division vasomotor nerves

Question 37

What is a nephron? What are its parts?

Answer 37

Function unit of the kidneus. Renal corpuscle: - where blood plasma is filtered - glomerulus - glomerular capsule/owman's capsule Renal tubule: - filtered fluid passes into it - proximal convoluted tubule - loop of Henle - distal convoluted tubule Renal cortex: - renal corpuscle and both convoluted tubules Renal medulla - nephron loop

Question 38

Distal convoluted tubules of several nephrons empty into a single ______ duct. These ducts unite and converge into seeral hundred large ________ ducts. These ducts drain into ______ calyces. Both types of ducts extend from the renal ____ to the renal ____ pelvis.

Answer 38

collecting duct papillary ducts minor calyces cortex pelvis

Question 39

What nitrogenous wastes do the kidney excrete?

Answer 39

- Urea and ammonia (from the deamination of AAs) - Creatinine (from breakdown of creatine phosphate) - Uric acid (from catabolism of nucelic acids) - Urobilin (from breakdown of haemoglobin)

Question 40

What ions do the kidneys regulate in the blood?

Answer 40

Sodium, Potassium, Calcium, Chloride and Phosphate

Question 41

How does the kidney regulate blood pH?

Answer 41

Extreting variable amounts of H+ ions in urine. Conserving bicarbonate ions (to buffer H+ ions)

Question 42

The kidney produces which 2 hormones?

Answer 42

* Calcitriol - the active form of vitamin D, helps regulate calcium homeostasis. * Erythropoietin - stimulates the production of red blood cells.

Question 43

What does the kidney use to regulate blood glucose levels?

Answer 43

Uses tlutamine in gluconeogenesis - can release glucose into blood.

Question 44

Increased _____ in the kidney increases blood pressure. This is known as the _____-angiotensin-_________ pathway.

Answer 44

Renin Renin-angiotensin-aldosterone pathway.

Question 45

What is aldosterone secreted by? What does it do?

Answer 45

Secreted by adrenal coretex in the adrenal glands. Regulates Na+ and K+ homeostasis.

Question 46

What are the 3 layers that surround each kidney?

Answer 46

Deep layer - renal capsule Middle layer - adipose capsule Superficial layer - renal fascia

Question 47

How is urine production? (what are the 3 steps?)

Answer 47

1. Glomerular filtration 2. Tubular reabsorption 3. Tubular secretion

Question 48

What happens in glomerular filtration?

Answer 48

Water and most solutes in blood plasma move across the wall of glomerular capillaries. They are filtered and move into glomerular capsule and then renal tubule.

Question 49

What happens in tubular reabsorption?

Answer 49

Filtered fluid flows through renal tubules and collecting ducts. Tubule cells reabsorb around 99% of filtered water and solutes, which return to blood as it flows through peritubular capillaries and vasa recta.

Question 50

Describe Tubular secretion

Answer 50

Filtered fluid flows through renal tubules and collecting ducts. The cells in these secrete other materials into the fluid (e.g. wastes, drugs, excess ions). Solutes and the fluid that drain into minor and major calyces and renal pelvis consitute urine and are excreted.

Question 51

The rate of urinary excreition of any solute is equal to what?

Answer 51

rate of glomerular filtration + rate of secreition - rate of reabsorption

Question 52

What are 3 types of UTIs? How are they treated?

Answer 52

Urethritis: inflammation of the urethra Cystitis: inflammation of the urinary bladder Pyelonephritis: inflammation of kidneys Treatment: - antibiotics - cranberry juice - prevents E.coli attachment to lining of bladder

Question 53

What is Glomerulonephritis?

Answer 53

Common cause: allergic reaction to streptococcal bacterial toxins Glomeruli become inflamed and swell with blood. Filtration membranes allow blood cells and plasma proteins to enter filtrate. Urine contains many erythrocytes and proteins Glomeruli may be permanently damaged leading to chronic renal failure.

Question 54

What are 2 Nephrotic syndromes?

Answer 54

Proteinuria and Hyperlipidemia

Question 55

What is Proteinuria?

Answer 55

Protein in the urine - increased permeabilitiy of filtration membrane - albumin escpaes into urine - decreases blood colloid somotic pressure - oedema - ankles, feet, eyes, absomen

Question 56

What is Hyperlipidemia?

Answer 56

High blood levels of cholesterol, phospholipids and triglycerides. Loss of albumin. ASsociated with several glomerular diseases of unknown cause and systemic disorders (e.g. diabetes mellitus)

Question 57

What is renal failure? What are the causes? Outcomes?

Answer 57

Decrease or cessation of glomerular filtration. Causes: Low blood volume Decreased cardiac output Damaged renal tubules Kidney stoens Outcomes: - oedema due to salt/water retention - metabolic acidosis as cannot excrete acidic substances - urea build up in blood - K+ levels rise --> cardia arrest - anaemia as cannot produce enough erythropoietin for adequate RBC production - kidneys no longer able to convert vitamin D to calcitriol

Question 58

What happens in stage 1 of renal failure? Treatment?

Answer 58

eGFR above 90ml/min (normal) but other tests suggest there may be some kidney damage. Unlikely to have symptoms. Some ppl have high b.p., swelling in hands and feet, UTIs. TREATMENT: try to slow down kidney damage for as long as possible

Question 59

What happens in stage 2 of renal failure? Treatment?

Answer 59

eGFR is 60-89ml/min Other sign of kidney damage -e.g. in ultasound, protein and blood in urine. Others show similar symptoms to stage 1. TREATMENT: Try to slow down kidney damage for as long as possible. Keeping blood pressure in a healthy range and manage blood glucose in diabetics.

Question 60

What happens in stage 3 of renal failure? Treatment?

Answer 60

eGFR 30-59ml/min Damage is mild-moderate. Kidneys begining to struggle filtering waste and extra fluid out of blood. Symptoms: swelling hands and feet, tiredness and weakness, trouble sleeping, muscle cramps, foamy urine and urine frequency, dry and itchy skin TREATMENT: Medication for b.p. and diabetes, exercise, kidney-friendly diet

Question 61

What happens at stage 4 of renal failure? Treatments?

Answer 61

eGFR is 15-29ml/min Severe damage. Waste products building up in blood. Health issues worsen e.g. high blood pressure, anaemia, heart disease TREATMENT: medication, dialysis, transplant

Question 62

What happens at stage 5 of renal failure? Treatment?

Answer 62

eGFR is less than 15ml/min Kidneys have stopped working or are close to stopping. Comorbid conditions: anaemia, hypertension, buildup of acid, difficulty breathing, swollen legs TREATMENT: dialysis, transplant