ch15

studied byStudied by 0 people
0.0(0)
get a hint
hint

What is excretion?

1 / 125

Tags and Description

Biology

126 Terms

1

What is excretion?

The removal of metabolic waste from the body

New cards
2

What are the 3 main metabolic waste products of the body?

  1. Carbon Dioxide

  2. Bile Pigments

  3. Urea

New cards
3

What blood vessel brings oxygenated blood to the liver?

Hepatic artery

New cards
4

What does the hepatic portal vein do?

Brings deoxygenated blood, rich in digested nutrients, from the small intestine to the liver

New cards
5

What does the hepatic vein do?

Takes deoxygenated blood away from the liver and joins the vena cava

New cards
6

What is a lobule?

Many vertical rows of hepatocytes arranged around a central vein

New cards
7

Where in the body would you find a hepatocyte?

The liver

New cards
8

What are sinusoids?

Capillaries which run along liver lobules

New cards
9

Branches of which two vessels provide blood to the sinusoids?

Hepatic artery and hepatic portal vein

New cards
10

What are canaliculi?

Fine ducts which carry bile from hepatocytes to the main bile duct

New cards
11

In which direction do canaliculi run?

The opposite direction to sinusoids

New cards
12

Where are sinusoids and canaliculi found in lobules?

Running in between columns of hepatocytes

New cards
13

What do Kupffer cells in sinusoids do ?

Phagocytose pathogens and old red blood cells

New cards
14

What adaptations do sinusoids have?

They are dilated and have discontinuous basement membranes, which not only allows for ready exchange of macromolecules but allows them to expand if necessary

New cards
15

How many different metabolic functions are linked to the liver?

500

New cards
16

What adaptations do hepatocytes have?

Lots of mitochondria and an enlarged Golgi apparatus, numerous microvilli in contact with sinusoids to maximise exchange

New cards
17

Why do sinusoids and canaliculi run in opposite directions?

To maximise exchange from hepatocytes

New cards
18

What are the 9 basic functions of the liver?

  1. Gluconeogenesis

  2. Storage

  3. Ornithine cycle

  4. Bile synthesis

  5. Production of plasma proteins

  6. Detoxification of poisons

  7. Synthesis of cholesterol from acetyl CoA

  8. Metabolism of amino acids, fats and carbohydrates

  9. Phagocytosis of old red blood cells

New cards
19

How is bile formed?

It is formed from haemoglobin, which is broken down after being taken from old red blood cells

New cards
20

Where is bile formed?

The liver

New cards
21

Where is bile stored?

The Gall Bladder

New cards
22

How is excess blood glucose stored?

Is converted to glycogen and stored in hepatocytes as granules

New cards
23

How are blood glucose levels increased?

The hormone glucagon (produced at alpha cells in the pancreas) causes hepatocytes to convert glycogen back into glucose, then release it into the blood

New cards
24

What is transamination and where does it occur?

The conversion of one amino acid into another. Occurs in the hepatocytes

New cards
25

What is deamination?

Where amine groups are removed from excess amino acids, forming ammonia and organic carboxylic acids

New cards
26

What happens to the organic carboxylic acids produced during deamination?

They can be respired to give ATP or converted to carbohydrates and stored as glycogen

New cards
27

Why isn't ammonia excreted directly?

It is too toxic

New cards
28

What happens to ammonia produced during deamination?

It is combined with carbon dioxide in the ornithine cycle to form urea

New cards
29

What is the name of the cycle which produces urea from ammonia?

The Ornithine Cycle

New cards
30

What happens to urea after it is synthesised in the liver?

It is released into the blood, before being removed from the body as urine

New cards
31

Where in hepatocytes does the ornithine cycle occur?

Some in mitochondria, the rest in the cytoplasm

New cards
32

What are three things which are broken down from the liver during detoxification?

  1. Paracetamol

  2. Ethanol

  3. Excess insulin

New cards
33

Why is excess insulin broken down by the liver?

Because it can cause hypoglycemia

New cards
34

Why is paracetamol broken down by the liver?

Too much can cause liver and kidney failure

New cards
35

What is paracetamol broken down into?

Several products, which are excreted by the blood, urine and bile

New cards
36

What type of reaction is the conversion of ethanol to ethanal or ethanal to ethanoic acid?

Oxidation

New cards
37

How is ethanol broken down by the body?

It is first oxidised to ethanal, then to ethanoic acid

New cards
38

What is the IUPAC name for acetic acid?

Ethanoic acid

New cards
39

Why must excess alcohol be broken down by the liver?

It can lead to fatty liver disease or liver cirrhosis

New cards
40

What is fatty liver disease?

Where hepatic cell nuclei are displaced by fat-filled vesicles

New cards
41

What is liver cirrhosis?

An irreversible condition where hepatocytes are replaced by fibrous scar tissue

New cards
42

What enzyme do hepatocytes contain to break down hydrogen peroxide?

Catalase

New cards
43

What can ethanoic acid be used for?

In cellular respiration or to build up fatty acids

New cards
44

What are the two important homeostatic functions kidneys perform?

Osmoregulation, excretion

New cards
45

What is the main thing that kidneys filter from the blood?

Urea and other nitrogenous waste products

New cards
46

What two things do kidneys help maintain in the blood?

pH and water potential

New cards
47

What artery provides blood to the kidneys?

Renal artery

New cards
48

What vein removes blood from the kidneys?

Renal vein

New cards
49

What part of the Vena Cava does the Renal vein drain into?

Inferior Vena Cava

New cards
50

How much blood passes through the kidney every minute?

About 90-120 cm3

New cards
51

How much blood does the kidney filter a day and how much urine does this produce?

180 dm3 of blood and 1-2 dm3 of urine

New cards
52

What are the filtering structures within the kidneys called?

Nephrons

New cards
53

What tubes take urine away from the kidneys to the bladder?

The ureters

New cards
54

What tube takes urine from the bladder to be excreted?

Urethra

New cards
55

What parts of the kidney nephron form the pyramids?

Loop of Henle and collecting duct

New cards
56

What levels of urea does blood leaving the nephrons have compared to that entering it?

Much lower urea levels

New cards
57

Why might levels of blood glucose decrease slightly in the nephrons?

Because some is used in active transport during selective reabsorbtion

New cards
58

What are the three main areas of the kidney?

Cortex, Medulla, Pelvis

New cards
59

Which of the cortex and medulla is darker in colour? (in the kidneys)

Cortex

New cards
60

What parts of the nephron are in the cortex?

Bowman's capsule, distal convoluted tubule, proximal convoluted tubule

New cards
61

What parts of the nephron are in the medulla?

Loop of Henle and collecting duct

New cards
62

Where in the nephron does ultrafiltration occur?

Bowman's Capsule

New cards
63

What two structures filter blood in the Bowman's Capsule?

Walls of the capillaries and the basement membrane

New cards
64

What is ultrafiltration?

Blood being forced out of the walls of the capillaries in the glomerulus by the high pressure, with larger parts (such as red blood cells) being retained and water and ions passing into the nephrons

New cards
65

Describe the process of Ultrafiltration

-Blood flows into the glomerulus from the afferent arteriole, which is wider i diameter than the efferent arterial. -This difference in diameter ensure blood in the capillaries of glomerulus is under increased/ high pressure. -This forces the blood out of though the capillary walls. The endotheliaum of the capillaries has lots of gaps so liquid and small molecules can go through into the bowmans capsule.

  • The basement membrane is made of glycoproteins and collagen fibers which act as a filter for large proteins and RBC as they too large to pass through. -Epithelial cells of the bowmans capsule called podocytes have finger like projections which ensure fluid can pass into the lumen of the bowmans capsule and dont let any protiens or RBC (that have managed to get through) into the tubule itself.

New cards
66

What specialised cells act as a filter in the walls of the Bowman's Capsule?

Podocytes

New cards
67

How are podocytes specialised for their function?

They have extensions called pedicels, which wrap around the capillaries and form slits to ensure that large molecules do not leave the capillaries

New cards
68

Which of the afferent and efferent arterioles is wider and why?

Afferent, in order to create high blood pressure within the Glomerulus

New cards
69

Where does (selective) reabsorption take place

Proximal Convoluted tubule

New cards
70

What substances are moved from the PCT back into the blood via active transport?

Glucose, amino acids, vitamins, hormones and around 85% of sodium chloride and water

New cards
71

What adaptations do cells lining the PCT have?

  1. Covered with microvilli to increase the surface area over which substances can be reabsorbed

  2. Many mitochondria to provide ATP for active transport

New cards
72

Describe the process and mechanisms of selective reabsorption

  • Na+ ions are pumped out of the PCT into the capillaries using active transport which requires energy, this creates a low concentration of NA+ ions in the epithelial cells.

  • Na+ ions move back into epithelial cells from the filtrate using facilitated diffusion down a concentration gradient

  • A co-transporter protien is used to transport the NA+ ion which then allows glucose and amino acids to be transported into the epithelial cells, The glucose and amino acids move into the capillaries by facilitated diffusion or active transport

  • Ions and H2O move into the epithelial cells via osmosis down a concentration gradient.

New cards
73

Whats a limiting factor for selective reabsorption? in terms of glucose being found in your urine.

If there is lots of glucose in the flitrate (eating sugary food), there may not be enough proteins to transport it into the epithelial cells, so it doesnt all get absrobed. Proteins become the limiting factor.

New cards
74

Where does most selective reabsorbtion of water occur in the kidney?

The proximal convoluted tubule and descending limb of the Loop of Henle

New cards
75

Where does the selective reabsorbtion of ions and glucose occur in the nephron?

The ascending limb and DCT

New cards
76

How are ions and glucose selectively reabsorbed in the nephron?

By active transport, and by diffusion at the very bottom of the Loop of Henle

New cards
77

Why is it useful that the water potential of blood in the capillaries near the Loop of Henle is low?

Allows water to be reabsorbed more easily from the Loop of Henle

New cards
78

Explain what happens in the loop of henle?

  • The descending limb walls are permeable to H2O, so water passes out via osmosis down a concentration gradient, as the loop runs down deeper into the medulla

  • As the filtrate reaches the bend the fluid is very concetrated, theres a low w.p in medulla, so NA+ AND CL- ions move out by diffusion down a concentration gradients

  • As the filtrate moves further up the ascending limb the ions need to use actively pumped out against a concentration gradient

  • Some pumped out diffuse back into the descending limb to help with the concentration gradient.

New cards
79

Why do ions leave via diffusion at the bottom of the Loop of Henle?

Water potential is very low

New cards
80

Why does water leave the descending limb of the Loop of Henle via osmosis?

Water potential is high due to the high amounts of ions which are reabsorbed in the PCT

New cards
81

Why must ions be actively transported out of the ascending limb of the Loop of Henle?

Because water potential is higher than at the bottom

New cards
82

Would a desert animal have a longer or shorter Loop of Henle and why?

Longer, so more ions can be actively pumped out and so that they can reabsorb more water. Have a greater water potential

New cards
83

Which part of the nephron is impermeable to water?

Ascending limb of the Loop of Henle

New cards
84

What type of diffusion multiplier is used in the Loop of Henle?

A countercurrent flow system

New cards
85

Explain what the Distal Convoluted Tubule does

It balances the water needs of the body. Areas where the permeability of the walls of the tubules varies with the level of ADH. They have many mitochondria to carry out active transport. If the body lacks salt, sodium ions can be pumped out of the DCT

New cards
86

Explain what the Collecting Duct does

Passes down the concentrated tissue fluid of the renal medulla. Its the main site where the concentration and volume of of the urine is determined. Water moves out of the collecting duct by diffusion down a concentration gradient as it passes through the renal medulla. As a result urine becomes more concentrated. The permeability of the Collecting duct is controlled by the level of ADH

New cards
87

How is water reabsorbed from the collecting duct?

There is a high concentration of ions outside the collecting duct due to its proximity to the ascending limb of the Loop of Henle, so water can leave via facilitated diffusion through aquaporins

New cards
88

What is the function of the kidney pelvis?

It is a chamber where urine collects before passing into the ureters

New cards
89

When would urine be more concentrated?

When the body is dehydrated

New cards
90

What gland is ADH released from?

The posterior pituitary gland

New cards
91

What parts of the nephron does ADH affect?

The DCT and collecting duct

New cards
92

How does ADH work?

It affects the permeability of the walls of the DCT and collecting duct to water, allowing more or less to leave depending on ADH concentration. It does this as ADH triggers aquaporins to be placed in their cell membranes

New cards
93

What is an aquaporin?

A transport or channel protein for water molecules

New cards
94

What cells monitor the water potential of the blood?

Osmoregulators

New cards
95

Where are osmoregulators found?

The hypothalamus

New cards
96

How can the hypothalamus affect blood water potential?

By sending nerve impulses to the posterior pituitary gland in order to stimulate it to produce more or less ADH

New cards
97

What gland produces ADH?

The hypothalamus

New cards
98

What does the term osmoregulation mean in terms of the kidneys?

The maintenance of a stable water potential in the blood and tissue fluid

New cards
99

What type of feedback system is the one involving ADH?

Negative feedback system

New cards
100

Does ADH act via a secondary messenger?

Yes

New cards

Explore top notes

note Note
studied byStudied by 101 people
Updated ... ago
5.0 Stars(2)
note Note
studied byStudied by 13 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 3 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 47 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 33 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 61 people
Updated ... ago
5.0 Stars(2)

Explore top flashcards

flashcards Flashcard27 terms
studied byStudied by 35 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard35 terms
studied byStudied by 124 people
Updated ... ago
5.0 Stars(6)
flashcards Flashcard44 terms
studied byStudied by 33 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard61 terms
studied byStudied by 32 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard59 terms
studied byStudied by 117 people
Updated ... ago
5.0 Stars(4)
flashcards Flashcard39 terms
studied byStudied by 5 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard48 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard52 terms
studied byStudied by 413 people
Updated ... ago
5.0 Stars(2)