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Human Physiology And Practical Skills > Lectures 8-10 > Flashcards

Lectures 8-10 Flashcards

1
Q

Where is the liver in the body?

A

Just below the diaphragm

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2
Q

How heavy is the liver?

A

1-1.5kg in healthy individuals

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3
Q

What are the two major vessels that supply the liver?

A

The hepatic artery (around 20%)

The hepatic portal vein

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4
Q

Blood leaves the liver via what?

A

A number of hepatic veins

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5
Q

How big is the hepatic portal vein?

A

Around 7-8cm

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6
Q

What does the hepatic portal vein carry?

A

Substances absorbed from the intestinal tract into the blood via the vein

Carries water soluble substrates arising from the diet (monosaccharides and amino acids)

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7
Q

What do lymph vessels carry?

A

Products of fat digestion

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8
Q

What are hepatocytes?

A

Liver cells which make up the majority of the liver volume (80%)

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9
Q

What other cells apart from hepatocytes are in the liver?

A

Endothelial cells and macrophages

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10
Q

What do hepatocytes appear as?

A

Hexagonal units (lobules) 1mm across

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11
Q

At each corner of the hepatocyte (lobule) there is a triad of 3 vessels, what are they?

A

Tiny branches of the portal vein, hepatic artery and the bile duct

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12
Q

How does blood flow between hepatocytes?

A

Via sinusoids (like capillaries)

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13
Q

What is metabolic zonation?

A

The different cells in the liver have different functions

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14
Q

What are the main functions of the liver?

A

Main organ of metabolism and energy
Metabolism: concerting food into energy
Energy storage
(Other functions): bile production, storage of iron and vitamins, detoxification

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15
Q

What is a monosaccharide?

A

A basic carbohydrate unit

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16
Q

What are the most common monosaccharides?

A

Pentose (5 carbon atoms)

Hexoses (6 carbon atoms)

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17
Q

Monosaccharides join up to form chains, such as?

A

Disaccharides (2 units)

Polysaccharides (>10 units)

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18
Q

Glucose and monosaccharides circulate freely in blood but what facilitated their entry into cells?

A

Specific carrier proteins

Eg liver cells have GLUT-2 glucose transporter predominantly

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19
Q

What is glycogen?

A

A branched polysaccharide

Stored in cells as granules

Highly hydrated

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20
Q

Why does glycogen branch?

A

It creates more ends for enzymes to operate on

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21
Q

Saturated fats = ?

Mono-unsaturated fats = ?

Poly-unsaturated fats = ? Yeah

A

No double bonds

One double bond

Several double bonds

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22
Q

How are fatty acids transported and why are they transported like this?

A

In the plasma bound to the protein albumin.

As they have long hydrophobic tails which are insoluble in water

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23
Q

What is the purpose of fatty acids?

A

The form in which lipid energy is transported around the body

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24
Q

What is triacylglycerol?

A

3 individual fatty acids and a glycerol

It is the most abundant lipid in the water

Hydrophobic (so carried in plasma as lipoproteins)

Main way fat is stored in the body

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25
Q

What are proteins?

A

Chains of amino acids (20 different types of amino acids)

9 essential in diet (body cannot manufacture)

Water soluble

Can be used as an energy store

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26
Q

Which hormones have a big effect on the live?

A

Insulin and glycogen are released into the hepatic portal vein and so have a big effect on the liver

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27
Q

What cells within the pancreases secret glucagon and insulin?

A

Islets of Langerhans

A-cells = glucagon

B-cells = insulin

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28
Q

When glucose concentration rises above 5 mmol/L what is released?

A

Insulin

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29
Q

Purpose of glucagon

A

To elevate blood glucose

It is suppressed when glucose concentration is high

Glucagon has no important metabolic effect in any tissue other than the liver

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30
Q

Purpose of cortisol

A

Released from the adrenal glands

Strong influence on metabolic pathways which take part in the liver

It stimulates gluconeogenesis

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31
Q

Purpose of adrenaline (epinephrine)

A

Released from adrenal glands

Effects the liver

The net effect of a rise in adrenaline leads to a breakdown of stored fuels triacylglycerol and glycogen

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32
Q

What is a normal blood glucose level?

A

5mmol/L

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33
Q

Brain requires stable glucose levels for fuel, below what mark is dangerous?

A

3mmol/L

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34
Q

What are the 3 major ways glucose enters the bloodstream?

A

Absorption from the intestines
Breakdown of glycogen in the liver
Gluconeogenesis in the liver

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35
Q

What is gluconeogenesis

A

The synthesis of carbs from other precursors

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36
Q

What is glycogenolysis

A

Liberate carbs, stored in the liver after meals, into the bloodstream

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37
Q

Facts about gluconeogenesis

A

Mainly occurs in the liver

Occurs during periods of: starvation, low-carb diets

3 main substrates for gluconeogenesis are: lactate, glycerol and amino acids

The purpose it to maintain steady blood glucose for the brain

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38
Q

Go over diagrams with recap

A

Around pages 22/23

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39
Q

What is de novo lipogenesis

A

Synthesis of fatty acids from non-lipid precursors (where fatty acids are made)

A pathway for disposing of excess carbohydrates

Leads to liver fat storage and metabolic diseases where there is a high energy diet (because it stores carbs into fats)

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40
Q

In terms of protein metabolism what is the liver the only organ capable of doing

A

Eliminating nitrogen from amino acids

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41
Q

What does amino acid oxidation provide for the liver?

A

About half the livers energy requirements

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42
Q

After an individual has their breakfast what happens in the hours after in their liver?

A

The liver switches from production to storage and utilisation of glucose

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43
Q

After an individual has their lunch what happens to their liver in the hours after?

A

The events that occur at breakfast occur but to a greater extent

Eventually de novo lipogenesis will occur

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44
Q

Basic understanding of what the liver does

A

Releases stored energy at times of high metabolic demand
And
Replenishes energy stores during nutrient excess

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45
Q

What happens in terms of the liver when we exercise?

A

Increase liver glucose output, mainly from glycogenolysis, but also gluconeogenesis

Increase in adipose tissue lipolysis and FFA mobilisation

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46
Q

Look at slides with recap

A

Slides 38 and 39

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47
Q

During exercise what can the liver do with amino acids to turn them into a more useful fuel source for the muscle

A

They can be recycled in the liver to make glucose

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48
Q

What happens to the associated nitrogen that is produced when the liver turns amino acids into glucose?

A

It is excreted via urea in the kidneys

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49
Q

What happens to liver metabolism during exercise?

A

It is not dominant because of reduced blood flow

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50
Q

Slide 42 with recap

A

Diagram one

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51
Q

Name some adaptations the liver undergoes after exercise training

A

More effective at utilising fat for fuel

Reduced liver fat content (good for the sedentary)

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52
Q

What are the parts of the GI tract?

A 
Mouth
Oesophagus
Stomach
Liver
Gall bladder 
Pancreas
Small intestine
Ileum 
Large intestine (colon)
Rectum
Anus
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53
Q

What is the name of the process that occurs where food moves down the oesophagus?

A

Peristalsis

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54
Q

What is in the stomach that helps break down food?

A

Hydrochloric acid
Enzymes
Hormones

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55
Q

What happens in the pancreas?

A

Enzyme production

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56
Q

What is the structure in the liver that secretes something? And what does it secrete?

A

The gall bladder, secretes bile

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57
Q

Is bile an enzyme?

A

No

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58
Q

What is the job of bile?

A

It is important in the emulsification of fats

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59
Q

What is an emulsifier?

A

Breakdown of larger fat molecules into smaller ones, providing a larger surface area for enzymes to act to digest the fats into fatty acids and glycerol

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60
Q

What does the small intestine do?

A

Absorb the things we’ve broken down like carbs and protein

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61
Q

What is the structure in the small intestine that allows us to absorb nutrients

A

Mycrovilli

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62
Q

What is the SA of the small intestine equal to?

A

Tennis court roughly

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63
Q

What is the main function of the large intestine (colon)?

A

To absorb water

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64
Q

What is there on the surface of the tongue? And what is the purpose of this?

A

Tastebuds, part of the reflex where if your food tastes bad or a slimy taste, triggers the spitting/vomiting reflex

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65
Q

What is the structure that prevents your food from going down the trachea?

A

Epiglottis

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66
Q

What does the rectum do?

A

Stores faeces

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67
Q

What does the GI in GI tract stand for?

A

Gastrointestinal

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68
Q

What is the function of the mouth and oral cavity?

A

To breakdown the food to mix it with saliva that contains enzymes that start to breakdown the food

69
Q

What is another function of saliva other than enzymes to breakdown food? (X2)

A

Moistens the food

Protective function - contains lysosine - breakdowns bacterial cell walls to start preventing bacteria from entering the GI tract

70
Q

You have 4 incisors at top and bottom (ones I’m worried about if they’re moving) what is the purpose of an incisor tooth?

A

Cutting food into pieces

Incisors are first teeth to come in

71
Q

How many sets of canine teeth do you have on the top and bottom sets? What’s their purpose?

A

2

To tear meat

72
Q

What is the purpose of molars

A

Grind food

73
Q

Because older people can get damaged enamel what must you recommend for their diet

A

Foods that don’t hurt as much to eat, softer foods

74
Q

How many muscles does the tongue have?

A

8

4 extrinsic muscles (attached to bone at the back of the mouth)
4 intrinsic muscles (not attached to bone allow you to move the tongue freely) (their job is to change the shape of the tongue)

75
Q

Where are circumvallate papilla found? And what do they do?

A

The back of the tongue just in front of the tonsils

They contain your taste buds (sweet, sour, bitter, salty) (and umami)

76
Q

What enzymes are in the salivary glands

A

Salivary amylase - breaks down starch

Lingual lipase - breaks down fat

77
Q

Parotid gland produces saliva that is more what?

A

Watery and has enzymes in

78
Q

The sublingual gland and submandibular gland produces what?

A

Saliva that is more mucus (does contain amylase and lipase and water as well)

79
Q

What is the protein in mucus that enables it to do its job?

A

Mucin

80
Q

What signals you to start producing saliva?

A

Sight and smell and taste of food?

Smell is the most powerful one

81
Q

How does peristalsis work in the oesophagus?

A

Muscle contracts behind the food, constricting passageway and pushing food down, muscle relaxes in front of the food to minimise resistance

82
Q

What is the purpose of the Interstitial (ICC) cells?

A

Only found in smooth muscle layer of GI tract

Function is to regulate contraction of the muscles

83
Q

The ICC cells are co-ordinated via what?

A

The sympathetic nervous system in order to control the passage of food

84
Q

In a situation of fear what happens to the GI tract? And why?

A

It stops

So that all the blood can get to your muscles to help with the fight or flight response

85
Q

What’s are the layers of the GI tract?

A

Inner lining - mucosal layer (consists of epithelial tissue moistened by glandular secretion)

Submucosa layer - connective tissue (contains blood vessels)

Smooth muscle layers (circular layer and a longitudinal layer (they enable peristalsis))

Serosa - connective tissue that holds the structure together

86
Q

Why do you need more mucus and lubrication towards the end of the GI tract?

A

As good passes down the GI tract more and more moisture is removed and so the composition of the bolus is getting more dehydrated (could lead to constipation)

87
Q

What is a bolus?

A

Fancy word for food going through GI tract

88
Q

Which part of the GI tract does not secrete enzymes

A

Small intestines (enzymes for this come from elsewhere)

89
Q

What is the purpose of the stomach?

A

To undergo rhythmical contractions to mix food with hydrochloric acid and pepsin to break it down

90
Q

Top of the stomach is called?

Bottom is called?

A

Fundus region

Pyloric region

91
Q

What is pepsin?

A

An enzyme that breaks down proteins

92
Q

What do rugae cells do?

A

Allow the volume of the stomach to expand to you can eat more

93
Q

What does the pyloric sphincter do?

A

Controls the movement of food from the stomach into the duodenum

94
Q

In the stomach lining there are villi, in the villi there are structures called what?

A

Gastric pits

95
Q

What are gastric pits?

A

Indentations of the stomach wall lining (epithelial wall lining) its where you produce hormones acid and pepsinogen

96
Q

What secretes pepsinogen?

A

Chief cells at the bottom of gastric pits

97
Q

What is pepsinogen?

A

An inactive form of pepsin (an inactive form of an enzyme is secreted because if it was the active form it would start acting on the cells before it had even got to the food, damaging the cell lining)

98
Q

What do G cells produce? And where do they secrete them into?

A

A range of hormones (eg gastrin)

They are secreted into the blood supply for the stomach (so that they act on other epithelial cells in order to signal the production of more hydrochloric acid in order to active pepsinogen

99
Q

What do parietal cells produce?

A

They secrete intrinsic factor

(Essential for the absorption of vit B12)

Without intrinsic factor you won’t absorb B12 from the small intestine which can help with respiration and energy metabolism

100
Q

How does hydrochloric acid act on pepsinogen?

A

Turns it into the active pepsin

Pepsin can actually activate itself form pepsinogen

101
Q

What is the other main role of hydrochloric acid?

A

Acts as an anti infective agent

102
Q

Adult humans do not secrete what?

A

Lipase

103
Q

How does the proportion of goblet cells change as you move from the small intestine to the large intestine? And why?

A

It increases, to increase the amount of mucus that is secreted

104
Q

Where are panet cells found? And what role do they have?

A

At the bottom of crypt cells

They have an anti microbial role and to further protect the epithelial layer from absorbing toxins and bacteria etc

105
Q

What are the main enzymes for carbohydrates?

A

Amylase (breaks down starch glycogen and dextrin into smaller disaccharides and) (breaks these down into maltose and glucose)
The sugar maltose is broken down by the enzyme maltase, maltose is broken down in glucose and galactose
Lactose is the specific enzyme to breakdown the sugar in milk, broken down into glucose and galactose
Sucrase breaks down sucrose (the product of maltose) into glucose

106
Q

What are the main enzymes for proteins?

A

Pepsin

Chimatripsin and tripsin (breakdown polypeptides into dipeptides)

Caboxy peptidase (break off individual amino acids)

Amino peptidase (break off individual amino acids)

107
Q

Can bike be reabsorbed into the small intestine?

A

Yes

108
Q

What is another job of bile?

A

To neutralise the acidic contents from the stomach

109
Q

Water soluble nutrients like glucose and amino acids and water soluble vitamins pass form the villi into where

A

The capillaries in the centre of the villi

110
Q

The capillaries from the centre of the villi then go where?

A

From the intestines direct to the liver via the hepatic portal vein

111
Q

What is the hepatic portal vein the control for?

A

Water soluble nutrients

112
Q

What does the lymphatic system control the absorption of?

A

Fat soluble nutrients

113
Q

Lipids, triacylglycerides, cholesterol and phospholipids are packaged into what?

A

Lipoproteins

114
Q

Do lipoproteins go directly to the liver?

A

No, they pass around the entire body via the lymphatic system first, so they can have their fat taken up by peripheral cells before it goes back to the liver

115
Q

What are the three colons in the large intestine?

A

The ascending
The transverse
The descending

116
Q

Main role of the large intestine

A

Water reabsorption

117
Q

Where are your kidneys

A

At the back just above the hip bone

118
Q

What does the kidney do?

A

Acts as a filter for the plasma component of the blood, however most proteins do not get filtered apart from albumin

119
Q

What is the whole point of the kidney?

A

To balance the ion composition of the blood

120
Q

How does our urine get from the kidneys to the bladder?

A

Ureters

121
Q

What are the two main structures within the kidney?

A

The cortex and medulla

122
Q

What are the structures called that filter the ureters?

A

Nephrons (there are millions of nephrons within the kidney)

123
Q

What is the anatomy of the renal system?

A

Two kidneys (urine formation)

Just above the kidney is the adrenal gland (important in secreting hormones that regulate kidney function)

Then the left and right ureters (take urine from the kidneys to the bladder)

Bladder (where the urine is stored)

A muscular valve at the base of the ladder that control the release of that urine

Finally taken to the urethra to be excreted from the body

124
Q

Where does the reabsorbed blood from the kidney go?

A

Passes back in the renal vein and goes back up to the heart

125
Q

Kidneys have an excellent blood supply

A

About 0.5% of total body weight is made up of kidneys but about 20% of cardiac output goes through them
Kidneys process plasma portion of blood by removing substances from it and in a few cases by adding substances to it
Works with cardiovascular system (and others) in an integrated manner

126
Q

The blood flow into the kidneys is regulated by what?

A

Hormones

127
Q

Renal system blood flow pathway

A

Aorta -> renal artery -> efferent arteriole -> glomerulus -> efferent arteriole -> peritubular capillaries and vasa recta -> renal vein -> inferior vena cava

128
Q

Facts about the nephron

A

Total of about 2.5 million in the 2 kidneys
Each nephron consists of 2 functional components:
- the vascular component (blood supply)
- the tubular component (contains what will eventually become urine)
The mechanisms by which kidneys perform their functions depends upon the relationship between these two components

129
Q

What are podocytes

A

A special type of endothelial cells found around the glomerulus and bowmans capsule

130
Q

What happens to calcium that is bound to proteins? And what % of calcium in the blood is bound to proteins?

A

50% is bound to proteins and calcium that is bound to proteins is not filtered

131
Q

Important hormones in kidneys

A

Parathyroid hormone (PTH) - important in controlling water reabsorption

Angiotensin - controlling the afferent and efferent arterioles (whether they’re contracted or relaxed), determines how much blood is filtered

132
Q

What are the three basic renal processes?

A

Glomerular filtration (GFR)

Tubular re-absorption

Tubular secretion

133
Q

Glomerular filtration rate is very high

A

Around 180litres/day of plasma

134
Q

How is GFR controlled?

A

By afferent and efferent arterioles

Sympathetic vasoconstrictor nerves

Anti diuretic hormone (controls amount of water reabsorbed)

Series of hormones know as the Renin angiotensin antiogensinigen system (RAAS) - this controls how much is filtered

As well as a unique system of upstream and downstream arterioles

Auto regulation

135
Q

What does auto regulation do?

A

Maintains blood supply and so maintains GFR. Also prevents high pressure surges damaging the kidneys

136
Q

High hydrostatic pressure at glomerular capillaries is due to what?

A

Short, wide afferent arteriole

137
Q

Low hydrostatic pressure is caused by what?

A

A long narrow efferent arteriole

138
Q

If you want to increase your GFR what happens?

A

You would ensure that you’re afferent arteriole is dilated

139
Q

A low concentration of angiotensin does what?

A

Contracts the efferent arteriole, so then more plasma is being filtered

140
Q

A high concentration of angiotensin does what?

A

Means the afferent arteriole contracts, so less blood is coming into the glomeluli, so less plasma is being filtered

141
Q

What controls the reabsorption of ions from the proximal convoluted tubule and back into the peritubular capillaries that are surrounding the proximal convoluted tubule?

A

Oncotic pressure

142
Q

What is oncotic pressure?

A

The pressure due to the higher concentration of proteins within the peritubular capillaries (which has lots of proteins in) compared to the filtrate (which has no proteins in)

143
Q

Structure of proximal tubules

A

Extensive brush border on surface

Re-absorption is rapid

Glucose and chlorine are co-transported coupled with sodium transport down the electrochemical gradient for sodium, requires energy

144
Q

General rule in kidney about sodium and water

A

Wherever sodium goes, water follows

145
Q

Rewatch recap at 40 minutes left

A

Fucking hard

146
Q

Lots of transport proteins have what? And what does this mean?

A

A limited number of binding sites, once all of the binding sites are occupied you cannot have any more glucose binding. This means whatever else is left passes down into the loop of Henley

147
Q

How is sodium absorbed back into the bloodstream?

A

Via active transport mechanisms

Nutrient transporters such as glucose and amino acids

Specialised sodium channels that only carry sodium called ENAC channels, occurs down the concentration gradient

148
Q

What is the proximal tubule very permeable to?

A

Sodium, so ions flow down gradient across membranes

149
Q

The electrical gradient caused by sodium moving across the proximal tubule also draws what across?

A

Chlorine

150
Q

What has the fluid in the convoluted tubule had removed?

A

Majority of its sodium, chloride, glucose and amino acids

Meaning fluid is more concerted than what it was

151
Q

Where does potassium reabsorption take place?

A

The loop of Henley

152
Q

What happens due to the countercurrent exchange?

A

Potassium ions leave the loop of Henley at the deepest part

153
Q

Where does the majority of potassium reabsorption occur?

A

The deepest (lowest) part of the loop of Henley

154
Q

What % of sodium ions are reabsorbed?

A

99%

155
Q

If you have a high potassium diet, what happens to the majority of the potassium? And why?

A

It is excreted in the loop of henley

There is a very tight homeostatic control over the amount of potassium in the body

156
Q

What is the main function of the loop of Henley and the collecting duct is?

A

Is the reabsorption of water and sodium ions

How you control the concentration of your urine

157
Q

Where do sodium ions move out of? And where are they reabsorbed?

A

The ascending loop of Henley via ENAC channels

The descending loop of Henley

158
Q

Why is this cyclical movement of sodium important?

A

For water re-absorption

159
Q

Where does water re-absorption occur? In the kidneys

A

At the most distal part of the medulla

160
Q

Sodium recycling only goes on where in the kidneys?

A

The medulla

161
Q

What controls the active reabsorption of sodium in the distal convoluted tubule

A

Anti diuretic hormone

162
Q

What else does anti diuretic hormone control?

A

The reabsorption of water

163
Q

How does ADH control the reabsorption of water?

A

By deciding how many ENAC channels are open in the epithelial cells of the distal convoluted tubule

164
Q

What happens when ADH binds to its receptor? And how can this affect the concentration of urine?

A

It causes these aquaporin channels to move to the aclical membrane, so you have more aquaporin channels in the aclical membrane, so you get more water being transported

More dilute urine = more ADH opens more aquaporin channels

165
Q

What does the macular denser do?

A

Recognised when you have a low concentration of sodium ions in the tubule

166
Q

What is the difference between the efferent and afferent arterioles?

A

Afferent arteriole brings blood to the glomerulus

Efferent arteriole takes blood away from the glomerulus

167
Q

What does the renal proximal tubule contain?

A

The proximal convoluted tubule

Loop of Henle

Distal convoluted tubule

168
Q

What is the function of the proximal convoluted tubule?

A

Regulates the pH of the filtrate by exchanging hydrogen ions for bicarbonate ions in the filtrate

Secretes organic acids such as creatine into the filtrate

Human Physiology And Practical Skills (5 decks)

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