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Biology Sem 2 test 1 > Week 3 - Digestion and Excretion systems > Flashcards

Week 3 - Digestion and Excretion systems Flashcards

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1
Q

Function of the digestive tract?

What’s its other name?

A

Ingestion and chemical as well as mechanical digestion

Also called alimentary canal

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2
Q

True or false? Dentition evolved with animals as food sources changed

A

true

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3
Q

mastication?

A

chewing of food

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4
Q

What’s the Buccal cavity? What does it contain?

A

Space between the jaws.

Contains: teeth, tongue, salivary glands and more

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5
Q

What does saliva contain and how does it aid digestion?

A

Salivary amylase - breaks down starch into disaccharide maltose.

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6
Q

What’s the epiglottis? What does it do?

A

Flap of cartilage that prevents the bolus entering trachea instead of oesophogus - so prevents choking.

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7
Q

What’s the bolus?

A

mix of saliva and food being digested

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8
Q

What does the oesophagus contain? And why?

A

Two layers of smooth muscle

This muscle moves bolus along as peristalsis

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9
Q

What’s the process of the bolus moving along the oesophagus?

A

Peristalsis

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10
Q

Main functions of the stomach?

A
  • Storage of injested food
  • Mechanical breakdown of injested food
  • Chemical breakdown of injested food by enzymes and other chemicals secreted in gastric juice.
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11
Q

Why is the stomach wall highly folded?

A

Larger surface area

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12
Q

What does the stomach contains in a lot of the pits of it’s wall?

A

Gastric glands

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13
Q

What are the components of stomach’s gastric juice?

A

Mucus, hydrochloric acid and pepsinogen

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14
Q

What are the three cell types in the stomach wall and what do they secrete?

A

Goblet cells - Mucus
Parietral cells - Hydrochloric acid
Chief cells - Pepsinogen

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15
Q

After what is bolus referred to as Acid chyme?

A

After chemical and mechanical digestion

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16
Q

How does acid chyme leave the stomach?

A

Though the pyloric sphincter into the small intestine.

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17
Q

How is digestion able to occur in a highly acidic stomach?

A
  1. Inactive Zymogen: Pepsinogen has a masking sequence that prevents it binding to substrates and reacting.
  2. But in low PH this triggers masking sequence to come off of active site therefore exposing the active site.
  3. Its now called the active enzyme: pepsin. Which reacts to acid digestion in low PH. In this case 1-2 PH.
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18
Q

What does the pancreas have that allows it to regulate blood glucose levels?

A

a-cells secrete glucogen

B-cells secrete insulin

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19
Q

What is homeostasis?

A

Normal blood glucose level (state of homeostasis)

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20
Q

Steps for blood glucose regulation, when it’s too high?

A
  • Rising blood glucose level
  • High level detected by insulin secreting B-cell of pancreas.
  • Stimulated to release more insulin into blood stream
  • So body cells take up more glucose and the liver takes up excess glucose and stores it as glycogen.
  • Blood glucose declines to set point, stimulation for insulin secretion stops, body returns to state of homeostasis.
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21
Q

Steps for blood glucose regulation, when it’s too low?

A
  • Declining blood glucose level
  • Detected by glucagon releasing a-cells of pancreas.
  • Stimulated to release glucagon into blood stream to get to the liver.
  • Glucagon at the liver converts stored glycogen back into glucose
  • Glucose is released back into blood
    Glucose level rises to a set point, stimulus for glucagon release stops and body returns to state of homeostasis.
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22
Q

Main components of pancreatic juice?

A

Bile salts, pancreatic amylase, lipase, maltase, lactase, mucus and water.

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23
Q

How many litres of pancreatic juice produced daily?

A

2 litres

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24
Q

What does the gall bladder serve as?

A

Reservoir for bile which contains pigment: bilirubin.

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25
Q

What are gallstones?

A

Deposits that form in the gall bladder. Usually occur from high cholesterol diet. Can block ducts requiring surgery.

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26
Q

Features of the liver?

A
  • Self-regenerating
  • Secretes bile - which emulsifies fats during digestion
    Compromised of lobules (Segments of tissue)
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27
Q

Roles of liver?

A
  • Stores iron, vitamin A and D
  • Destroying old red blood cells
  • Produces plasma proteins
  • Breaks down poisons (detoxification)
  • Carbohydrate metabolism (blood glucose control and storage of glycogen
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28
Q

What are the sections of the small intestine?

A

Doudenum - Tube from stomach to small intestine
Jejunum - Tube after Doudenum
Ileum - Tube after Jejunum
Large intestine - after Ileum - wider lumen but shorter than small intestine.
Rectum - Where excretion occurs

29
Q

What do folding villi and microvilli ensure?

A

There is a high SA for efficient absorbtion

30
Q

What do microvilli in intestines have on them?

A

digestive enzymes.

31
Q

What are dips between microvilli called? And what’s in the dips?

A

Called crypts and at their base are stem cells

32
Q

How are carbohydrates absorbed in the small intestine?

A

Broken down into monosaccharides
monosaccharides taken into epithelial cells via microvilli
Then diffuses into capillary through epithelial cells.

33
Q

How are proteins absorbed in the small intestine?

A

Broken down into peptides and then amino acids
Taken into epithelial cells via microvilli
Diffuses into capillary through epithelial cell

34
Q

How are fats absorbed in the small intestine?

A
  • Bile salts attach to fat globules and cluster them together forming emulsification droplets
    .- These are catalysed by lipase into fatty acids like glycerol and monoglycerides from triglycerides
  • Enter epithelial cell via microvilli
  • Triglycerides resynthesized in epithelial cell
  • Triglycerides given a protein cover by Golgi apparatus to form vesicle called chylomicron
  • This enters lymphatic capillary.
35
Q

What’s the site of water absorption?

A

Large intestine

36
Q

Faeces travels along the large intestine to get to the anus.

A

This is true.

37
Q

What is defacation? What can it also be called?

A

Removal of faeces. Can also be called ejestion

38
Q

Why is the gut flora important?

A

Maintains health
Allows faecal transplants to happen
Faeces DNA can be used to identify criminals.

39
Q

What is the Gut microbiota? What happens when it is altered negatively?

A

Collection of micro-organisms living in stomach and intestines.
May cause C diffictile to cause a hard to cure infection

40
Q

Process of microbiota transplant?

A
  1. Donor with healthy microbiota has their stool transferred to a patient with re-occurring c diffictile infection.
  2. This restores a healthy microbiota in the patient’s colon.
41
Q

Basic steps of digestion?

A

Ingestion > Digestion > Egestion

42
Q

What’s excretion? Why are products excreted?

A

Removal of unwanted products from the body.

- some in excess so not required/ some are toxic.

43
Q

Osmoregulation?

A

Control of water and salts in the body.

44
Q

What is the body’s main excretory organ?

A

The kidneys

45
Q

Structure of kidney?

A 
Renal Medulla
Renal cortex
Renal Pelvis
Ureter
(Assign to kidney diagram in powerpoint)
46
Q

Nephron Structure?

A 
(Assign to diagram in powerpoint)
Nephron tubule
Cortical nephron
Juxtamendellary nephron
Renal cortex
Renal medulla 
collecting duct
47
Q

What are nephrons involved in?

A

Regulating water, salt content of blood, urine, PH

48
Q

Structures in Nephron?

A 
Bowman's capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting duct
49
Q

Define Filtration

A

Movement of water and small solutes from blood through the glomerulus across the porous filtration memebrane.

50
Q

What 3 components does the filtrate include?

A

water, small molecules and ions

51
Q

What forces the filtrate across the filtration membrane?

A

Pressure difference

52
Q

What happens in the bowman’s capsule?

A
  • Filtrate moves out of blood supply in glomerulus and is reabsorbed into blood.
  • Secretions from blood move into renal tubule
  • Excretion moves down renal tubule
53
Q

Where are they located? And what do podocytes do?

A

Podocytes on the edge of the glomerulus in the epithelial tissue. Filter the filtrate forced out of the capillary pores by the afferent arteriole’s higher hydrostatic pressure.

54
Q

Function of loop of henle and features aiding it’s function?

A

Reabsorbs water from filtrate.

  • Solute concentration gradient from top of loop to bottom causes water to move out of the filtrate as it moves down the descending branch.
  • Ascending branch is impermeable to water.
55
Q

What are the percentages of water reabsorption for different parts of the kidney?

A

-Proximal convoluted tube reabsorbs 65-70% of water
-Loop of henle reabsorbs another 25%
(both of these aren’t water regulation as its evening out water concentration not increasing it in blood).
Distal tube and collecting duct reabsorb less than 10% but under regulatory conditions. (Increasing water level in blood).

56
Q

Process of regulation in the loop of Henle?
(This isn’t simplified but you have simplified version in kerensa notes probably and you can make one from powerpoint or AQA book)

A
  1. At base of ascending tubule - sodium and chloride ions diffuse out of tubule into tissue fluid - this reduces water potential of surrounding tissue.
  2. As fluid moves down the descending limb - the water potential inside the tubule becomes lower.
  3. As the fluid ascends up the ascending limb towards the cortex - water potential inside the tubule increases.
  4. Higher up the tubule - sodium and chloride ions are actively transported out into the surrounding tissue fluid. - This reduces water potential of surrounding tissue.
  5. The wall near the top of the ascending limb is impermeable to water - so water cant leave the tubule. Means the fluid in the ascending limb loses salts but not water.
  6. A consequence of the movement of salts from the ascending limb is that water moves out of the descending limb by osmosis - into surrounding tissue fluid where water potential has become lower.
  7. Also, sodium and chloride ions diffuse into the descending limb from the surrounding tissue. - As the concentration of these ions is higher in tissue than in tubule. Which therefore decreases the water potential in the tubule.
57
Q

What is osmoregulation?

A

Control of water and salts in the blood. Can lead to issues with osmosis.

58
Q

Hypertonic?

A

Too little water, too many salt (ions) so imbalance

59
Q

Isotonic?

A

Same amount of water and salt, balanced in equalibrium

60
Q

Hypertonic?

A

Too much water, too little salts so imbalance

61
Q

Osmosis?

A

Net movement of water molecules from area of higher concentration to an area of lower concentration, down a a WATER POTENTIAL gradient across a partially permeable membrane?

62
Q

What does ADH stand for?

A

Anti-diuretic hormone

63
Q

Process of what does ADH does and causes?

A
  • Produced by Neurosecretory cells in hypothalamus
  • Released into the blood and binds to receptors on the wall of the collecting duct.
  • Causes chain of enzyme-controlled reactions to occur.
  • Aquaporins inserted into collecting duct cell surface membrane.
  • Therefore more water can be re-absorbed back into bloodstream by epithelial cells via osmosis.
64
Q

How is water content regulated when there’s too much salt or sweating? What is the urine like?

A

Water content of blood low > Brain produces more ADH > High volume of water reabsorbed by kidney > Urine output low (small volume of concentrated urine).

65
Q

How is water content regulated when too much water has been consumed?

A

Water content of blood high > brain produces less ADH > Low volume of water reabsorbed by kidney > urine output high (large volume of dilute urine).

66
Q

Re-worded osmoregulation when there’s too little water in blood?

A

Too little water > Increased release of ADH > more water re-absorbed in nephron > Lower volume of urine but more concentrated.

67
Q

Simplified osmoregulation when there’s too much water in blood? Effect on urine?

A

Too much water > decreased release of ADH > less water re-absorbed by nephron > Greater volume of urine but more dilute.

68
Q

Regulation of blood volume and pressure when osmotic pressure is increased?

A

Osmoreceptors detect increased osmotic pressure > ADH from posterior pituitary secreted to blood vessels > Causes them to vasoconstrict > Increases blood volume and pressure.

69
Q

Regulation of blood volume and pressure when osmotic pressure is decreased?

A

Baroreceptors detect decreased osmotic pressure > ADH secreted from posterior pituitary > increases reabsorption of water in kidney > Increases blood volume and pressure.

Biology Sem 2 test 1 (7 decks)

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