optional module d: human physiology Flashcards
(327 cards)
1
Q
essential nutrients are grouped into
A
Minerals: for example phosphorus, calcium, magnesium, iron.
Vitamins: for example vitamins A, C, D, K.
Amino acids: for example histidine, tryptophan and others.
Fatty acids: for example certain omega-3 and omega-6 fatty acids
2
Q
what are non essential nutrients
A
ones that can be made by our body eg fructose
3
Q
what can malnutrition be caused by
A
an imbalance
an excess of nutrients
4
Q
the human body cannot synthesise fatty acids and are therefore considered
A
essential
5
Q
examples of fatty acids
A
omega 3 and omega 6
6
Q
what is omega 3 needed for
A
controlling blood clotting and building cell membranes in the brain
7
Q
what is omega 6 needed for
A
lower LDL cholesterol (the “bad” cholesterol) and reduce inflammation), and is protective against heart disease
8
Q
what do the numbers on fatty acids relate to
A
the first double bond counting from the CH3 (methyl, position 1) group of the fatty acid
9
Q
where can you find omega 3 fatty acids
A
in fatty fish, some veg oils, soybean rapeseed, flaxseed, brussel sprouts, kale, spinach, walnuts
10
Q
where can you find omega 6 fatty acids
A
safflower, corn, cottonseed, and soybean oils
11
Q
what are the nine essential amino acids
A
phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.
12
Q
when can tyrosine be synthesised by the human body
A
when phenylalanine is present in the diet
13
Q
which group cannot synthesise arginine
A
infants so must be present in the diet
14
Q
conditionally essential amino acids
A
tyrosine and arginine
15
Q
what elements are most commonly found in the human body
A
oxygen
carbon
hydrogen
nitrogen
16
Q
what is iodine needed for
A
synthesis of thyroid hormones, which can increase basal metabolic rate, affect protein synthesis, and help regulate long bone growth
17
Q
iodine deficiency results in
A
goitre and severe retardation
18
Q
what is calcium and phosphorus necessary for the formation of
A
bones and teeth
muscle contraction
19
Q
sodium and potassium are invovled in the
A
propogation of the nerve impulse
20
Q
can vitamins be synthesised by the human body
A
no must be in the diet
21
Q
two types of vitamin
A
water soluble and fat solublte
22
Q
vitmin sneeded
A
retinol, fat
thiamine, water
cyanocobalamin, water
riboflavin, water
niacin, water
pantothenic acid, water
pyridoxine, water
biotin, water
folic acid, water
ascorbic acid, water
cholecalciferol, ergocalciferol
tocopherols
phylloquinone
23
Q
main causes of malnutrition
A
Deficiency, a diet lacking in one or more particular nutrients.
Imbalance, a diet that has an inadequate intake of a particular nutrient.
Excess, a diet that has a disproportionate intake of e.g. carbohydrates, fats or proteins.
24
Q
what controls appetitie control
A
the appetite control centre in the hypothalamus
25
when the stomach is empty,
gherlin is released, stimulating appetite
26
what happens when food is ingested
the release of peptide PYY3-36 from the small intestine (along with insulin from the pancreas and leptin from adipose tissue) inhibit appetite
27
APPETITE CONTROL CENTRE
D.1
28
BMI=
mass/height^2 (kg/m^2)
29
someone is considered obese when
their bmi is between 25.1 and 29.9
30
consequences of obesity
diabetes type 2
CHD
31
what happens in type 2 diabetes
the beta cells in the pancreas still produce insulin. however these patients still develop insulin resistance, which means that the insulin receptors on the cells are no longer stimulated by insulin.
32
probable causes of type 2 diabetes
High levels of fatty acids in the blood as a result of diets high in fat but low in fibre.
Overweight, especially obesity, associated with a lack of exercise.
Genetic makeup that influences fat metabolism.
33
symptoms of type 2 diabetes
Increased (elevated) glucose levels in the blood urine.
Frequent need to urinate (may lead to excessive thirst).
Tiredness and fatigue.
Some loss of weight.
34
diabetes can increase or decrease your chances of developing CHD
increase
35
hypertension is
blood pressure above the norm
36
what is CHD
a disease in which a substance called plaque builds up inside the coronary arteries. these arteries supply blood with oxygen to the heart muscle.
37
if saturated fatty acids combine with cholesterol it forms
atherosclerosis, which leads to hypertension or angina and heart attacks. can also cause damage to blood vessels increasing the risk of developing even more atherosclerotic plaques
38
prologned starvation can cause
permenant organ damage and death.. Initially the glycogen stores in the liver are mobilised, but once they are depleted the body has to resort to other sources of energy.
39
why does the loss of muscle and adipose tissue occur
by the body's need for caloric intake and to protect the vital systems such as the nervous system and heart muscle. The body breaks down muscles and lipids to generate energy and amino acids. This process is known as catabolysis.
40
consequences of anorexia
BREAKDOWN OF HEART MUSCLE, electrolyte imbalance, skeletal and heart muscle reduction, reduced blood pressure and a slower heart rate. The body can become covered in a fine growth of thin hair. In female patients it can also lead to reduced or absence of menstrual cycles. Extreme cases can lead to death.
41
what is vitamin C known as
L-asbcorbic acid
42
can humans and animals synthesise vitamin c
no
43
what is vitamin c needed for
the production of collagen, found in skin, connective tissues, tendons, blood vessels
44
vitamin c defciency
scurvy
45
main symptoms of scurvy
Bleeding gums, gingivitis or loose teeth. Vitamin C is necessary for the synthesis of collagen, which builds and maintains tissue.
Lack of energy. Loss of weight and extreme fatigue.
Mood swings or depression. Irritability and rapid changes in mood may indicate a severe deficiency. Depression is common.
Chronic joint pain. Bleeding in the joints causes constant pain.
Suppressed immune system. Frequent diseases.
Slow wound healing and bruising. Bruising occurs easily and wounds take a long time to heal.
46
how is RDA calculated
A control group (group 0) does not receive any foods containing vitamin C.
Other groups (groups 1 to 10) get increasing levels of a daily supplement of vitamin C in their diet, e.g. group 1 gets 10 mg of vitamin C per day, group 2: 20 mg vitamin C per day, etc.
The control group will start to develop symptoms of scurvy.
Perhaps also groups 1 and 2 may show some symptoms, but above a certain daily supplement of vitamin C, e.g. 30 mg per day, the guinea pigs do not show the common symptoms of scurvy.
The data collected this way can be used to calculate the amount of vitamin C required by a human.
47
what is phenylketonuria
a genetic disease, a gene coding phenylalanine hydroxylase, an enzyme that catalyses the hydroxylation of phenylalanine to tyrosine, is mutated. This results in the inability to convert phenylalanine into tyrosine. PKU is inherited as an autosomal recessive trait which means that patients with PKU have two recessive (mutated) alleles. As the enzyme can no longer catalyse the last and rate limiting step, phenylalanine accumulates in the body.
48
medical consequences of PKU
Intillectual disability
Reduced growth of the head
Lack of skin and hair pigmentation
Seizures
49
what is the guthrie test
test for phenylketonia
50
what artifical sweetener
aspartame
51
what is vitamin D (calciferol) needed for
the absorption of calcium in the digestive system
52
what is calcium needed for
to build healthy bones
53
what is calcium d deficiency called
osteomalacia in adults (milder)
or rickets in children (more severe)
54
important roles of vitamin d
to maintain skeletal calcium balance by promoting calcium absorption in the intestines and maintaining calcium and phosphate levels for bone formation
55
if a breastfeeding mother has low vitamin d what happens
causes problems with the bone mineralisation of their infants
56
where is vitamin d found
oily fish, salmon, herring and tuna, egg yolk, liver, dairy
57
what does exposing human skin to uv light with a wavelength between 290-310 nm
triggers the synthesis of vitamin d in the skin.
58
where is vitamin d to be stored
fat soluble so liver
59
cholesterol is the precursor of
bile acids, vitamin d and steroid hormones such as progesterone and oestrogen. protects membrane integrity. presence of cholesterol in the cellular membrane enables the cell to change shape and move about.
60
types of cholesterol
Very Low Density Lipoprotein (VLDL), Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL)
61
which type of cholesterol has been linked with developing CHD
LDL
genetic factors and lack of mobility
62
how can you lower total blood cholesterol levels
reducing intake of dietery cholesterol
statin drugs (
63
what do statins do
inhibits the enzyme HMG-CoA reductase, which catalyses the second step in the pathway from Acetyl CoA to cholesterol.
64
what is a balanced diet
a combination of foods that contains all essential and non-essential nutrients in the right proportion. The proportion is key here.
65
what is energy measured in
joules
66
what is the kilojule used for
in food related quantities
67
1 kilocalorie =
4.184 kilojoules
68
total calorie intake value =
120-160 kcal to kg of weight
69
what proportion is protein of the TCV
10-15%
70
what proportion is carb of the TCV
35-60%
71
what proportion is fats of the TCV
35-50
72
amount of fibre =
age in years + 5g
73
how do you calulate the energy in food
burning a known mass of the food to test. The burning food is placed under the test tube with water. The heat liberated by the burning food is absorbed by a known volume of water. The rise in temperature is recorded (Figure 4). The energy value is calculated as temperature rise × mass of water × specific heat capacity of water (4.184 joules/gºC or 1 calorie/gºC).
74
enerfy value =
temperature rise × mass of water × specific heat capacity of water (4.184 joules/gºC or 1 calorie/gºC).
75
what is digestion
the breaking down of food particles into smaller particles. It is controlled by nervous and hormonal mechanisms.
76
why do food particles need to be digested to soluble molecules that can pass through the membranes in the intestinal tissues.
food particles are too large to be absorbed through the intestine walls of the digestive system.
77
how are food particles broken down to soluble molecules to pass through the membranes in the intestinal tissues
the exocrine glands of the digestive system secrete enzymes that hydrolyse large molecules into smaller molecules.
78
what is the autonomic nervous system / nervous control within the digestive processes divided into
the sympathetic and parasympathetic systems
79
what does the sympathetic nervous system do
controls processes involved in responses to danger, while the parasympathetic system controls homeostasis and processes related to rest and digestion.
80
what does the parasympathetic nervous system do
speeds up digestion when food is ingested, while the sympathetic slows it down when there is no food available.
81
divide the digestive processes into three
mechanical control
nervous control
hormonal control
82
examples of mechanical control of digestion
stomach contraction
peristalsis
83
what does hormonal control do
secretin
cholecystokenin
gastrin
somatostatin
84
what does secretin do
release of alklai and regulates water homeostasis throughout the body by acting on the kidney, hypothalamus and pituitary gland.
85
what does cholecystokinin
secretion of pancreatic enzymes
release of bile from gall bladder and pancreatic juice from pancreas
86
what does gastrin do
release of gastric acids and enzymes
87
what does somatostatin do
prevents and release of acid
88
what produces gastrin
g cells in the stomach, duodenum and pancreas, in response to physical stimulation due to the presence of food, as well as to chemical stimulation by protein
89
when gastrin is released...
it stimulates the production of gastric juice by the parietal cells in the gastric glands.
90
what does gastric juice contain
a mixture of water, hydrochloric acid and other inorganic ions, enzymes (pepsin, rennin), mucus, various polypeptides, and intrinsic factor
91
what is intrinsic factor in gastric juice
is necessary for absorbing vitamin B12.
92
effect of the ph of gastric juice
Gastric juice changes the pH of the food content from 6.7 to 2, providing acidic conditions that will enhance digestion.
93
when does gastrin stop being produced
When there is sufficient gastric juice present (around 1 to 1.5 litres), the production of gastrin will stop and therefore so will the secretion of gastric juice.
94
where is secretin produced
by special cells in the small intestine in response to the presence of acid fluid.
95
the presence of gastric acid activates prosecretin into
secretin
96
when secretin is released
it stimulates the production of alkali by the pancreas, neutralising the intestinal components.
97
when is the production of pancreatic juice stopped
via negative feedback when the pH of the intestine reaches 8
98
what produces cholecystokinin
small intestine when food is present there
99
where is bile produced and stored
bile is produced in the liver and stored in the gall bladder
100
bile
is a hunger suppressor and
101
what type of hormone is somatostatin
inhibitroy
102
what secretes somaatostatin
special cells in the stomach, duodenum and pancreas
103
how does somatostatin work
travels through blood to directly inhibit acid producing cells.
104
how does somatostatin work indirectly
by preventing the release of gastrin, CCK and secretin, thus slowing down the digestive process.
105
describe the regulatory stomach feedback mechanism
whereby the presence of acid in the lumen of the stomach stimulates somatostatin secretion, which in turn slows down acid secretion.
106
which system regulates acid secretion
the nervous system
107
what do exocrine glands have
ducts that carry their secretory product to the surface of the body or the lumen of the gut. These glands include the sweat, sebaceous, and mammary glands and the glands that secrete digestive enzymes.
108
how is stomach acid produced
by the combination of hydrogen ions (H+) and chloride ions (Cl-) produced by the epithelial cells (known as parietal cells) of the stomach lining. The release of hydrogen ions through protein carriers is coupled to the intake of potassium ions (K+) from the lumen of the stomach. This process requires energy in the form of ATP
109
what does gastric juice contain
hydrochloric acid and pepsin
110
what is pepsin
a protease that hydrolyses proteins to peptides.
111
where is pepsin
ound in the stomach in an inactive form as the pro-enzyme pepsinogen.
112
what releases pepsin
the chief cells in the lining of the stomach and is activated into pepsin by the presence of acid.
113
what releases hydrochloric acid
by the parietal cells of the stomach, removing 44 amino acids from pepsinogen transforming it into pepsin
114
acid condiitons in the stomach favour...
the hydrolysis reactions by pepsin. the optimum pH for this enzyme is 2
115
benefit of acidic conditions
control pathogens in ingested food. The bacteria present in food cannot survive such acid conditions.
116
benefit of the stomach mucus cover
avoids self-damage
117
when could the stomach produce an excess of gastric acid leading to a gastric ulcer if the mucus layer is damaged
if someone has eaten an excess of spicy foods, excess proteins or has extreme stress
118
symptoms of a stomach ulcer
stomach pain, heartburn, nausea and in some cases presence of blood in the stools.
119
what bacteria could cause stomach ulcers and why
Helicobacter pylori produces toxins that cause continuous gastric inflammation. The inflammatory response by the immune system damages the stomach lining.
120
Ulcers due to H. pylori are treated with a combination of medications:
Amoxicillin: antibiotic that directly inhibits the synthesis of bacterial cell walls.
Clarithromycin: antibiotic that prevents bacteria from growing by inhibiting the translation of peptides in the ribosome, thus inhibiting their protein synthesis.
Proton Pump Inhibitor (PPI): inhibits acidification of stomach.
121
what do Proton Pump Inhibitors do
block the proton pump (hydrogen-potassium-ATPase pump), responsible for the secretion of hydrogen ions (H+) in the stomach. The decrease of H+ into the lumen of the stomach reduces the amount of hydrochloric acid (HCl) produced, which makes the stomach less acidic (Figure 4), making it a suitable treatment of gastric ulcers.
122
polysachharides are digested to
monosacchardies
123
proteins are digested to
amino acids
124
lipids are digested to
short chain fatty acids or longer chain fatty acids
125
monosacchardies are absorbed by the
small intestine
126
monsaccharides destination is
Villus through hepatic portal vein to liver.
127
amino acids are absorbed by
the stomach or small intestine
128
stomach amino acids destination
Cells of stomach lining.
129
small intestine amino acids destination
Villus through hepatic portal vein to liver.
130
lipids are asorbe dby
the small intestine
131
lipids destination
Villus through hepatic portal vein to liver.
Lacteal to lymphatic system.
132
adaptations of the small intestine
Increased surface area due to presence of villi and microvilli.
Many mitochondria to provide energy for active transport.
Presence of capillaries in villi for absorption of digested foods.
Presence of lacteal for absorption of absorbed lipids.
Presence of pinocytotic vesicles aid the uptake of fluids.
Presence of tight junctions to ensure molecules do not escape through the membrane, and to maintain a concentration gradient.
Enzymes (peptidases and disaccharidases) bound to epithelial membranes to complete hydrolysis/digestion.
133
what does each villus have
a central lacteal whose function is mainly the absorption of fats, and capillaries that carry the rest of the absorbed molecules to other organs.
134
most capillaries join to form the...
hepatic portal vein tthat carries blood to the liver.
135
what is the structure of cells in the epithelium of the villus adapted to
the absorption of food
136
STRUCTURE OF VILLUS
like d2
137
what is the order of the fiv elayers of the small intestine
mucosa
submucosa
circular muscle layer
longitduinal muscle layer
serosa
138
mucosa
contains the epithelium formed by enterocytes, goblet cells and endocrine cells. Enterocytes are cells that have microvilli; they digest and absorb substances. Goblet cells produce mucus and endocrine cells secrete hormones.
139
submucosa
contains blood vessels and connective tissue.
140
circular muscle layer
smooth muscle arranged in a circular manner.
141
longitudinal muscle layer
smooth muscle arranged in a longitudinal manner.
142
serosa
single layer of epithelial cells with connective tissue.
143
glucose and sodium is co transported via
facilitated diffuseion
144
how is glucose and sodium is co transported via facilitated diffusion
Na+ must first be transported out of the cell by active transport (along the basal membrane). This powers the co-transport of glucose and Na+ into the epithelial cells via the apical membrane. The glucose is then carried along the epithelial cell to a sugar transporter protein that allows its transport into the capillaries, which will carry it to the hepatic portal vein.
145
proteins are digested by WHAT into WHAT
protesases into amino acids
146
how are amino acids co transported with Na+
into the epithelial cells. Amino acid carrier proteins then carry them by facilitated diffusion into the capillaries.
147
fats or lipids are emulsified in the WHAT by WHAT
in the intestines by bile, into smaller droplets which allows lipases to digest them into fatty acids and glycerol
148
glycerol from lipids will
will be absorbed and used in carbohydrate metabolism
149
fatty acids from lipids will
diffuse into the small intestine epithelial cells
150
long chain fatty acids will combine with...
proteins to form chylomicrons
151
what do chylomicrons do
travel to the border of the cell in the smooth endoplasmic reticulum and are expelled by exocytosis to later enter the lacteal, thus entering the lymphatic system
152
what is the point in insoluble fibre
it increases faecal mass, thus stimulating peristaltic movements
153
what is dietary fibre
the non-digestible carbohydrates, especially cellulose, and lignin that are intrinsic and intact in plants.
154
what materials are not absorbed in digestion
cellulose and lignin from plant matter, bile pigments, the remains of intestinal epithelial cells and bacteria. peristalsis of the walls of the large intestine will push the faecal matter toward the rectum and eventually eliminate it through the anus
155
what increases rate of transit of materials through the large intestine
fibre content
156
what does an infection of the intestines cause
inflammation of the epithelial cells lining the intestine. This will reduce the absorption of water
157
what is cholera
a disease caused by the ingestion of food or water contaminated with the bacterium vibrio cholerae. When cholera toxin is released from the bacteria in the infected intestine, it binds to the intestinal epithelial cells (enterocytes), triggering endocytosis of the toxin.The toxin then becomes an active enzyme which activates ions and water to leave the infected enterocytes, leading to watery diarrhea.
158
signs and symptoms of dehydration
dry mouth
swelling of brain
weakness
dizziness
palpitations
drop in blood pressure
decreased urine output
kidney failure
fainting
159
the liver regualtes
the chemical composition of the blood
160
where is the liver
under the diaphragm in the upper right part of the abdomen
161
the liver produces
bile
enzymes
hormones
cholesterol
triglycerides
162
the liver is the site of synthesis of
amino aicds
proteis
163
the liver stores
glycogen
vitamin A, B12, D and K
minerals such as iron and copper
164
the liver is the remova of
toxins from the blood, drugs
165
the liver maintains
blood temp and pressure
166
the liver breaks down
red blood cells / erytrocytes
167
the gall bladder
stores bile and regulation of blood clotting
168
what supplies the liver with oxygentated blood
from the heart through the hepatic artery (branch of the aorta)
169
where does blood leave the liver
through the hepatic vein which carries deoxygenated blood. this vein joins the vena cava, which returns the blood to the heart
170
the hepatic vein
takes blood back to the heart
171
the hepatic artery
takes blood from the heart
172
the portal vein
brings blood from the bowel
173
the liver recieves deoxygenated blood from
from the spleen, stomach, pancreas, gall bladder and intestines through the hepatic portal vein.
174
what is the hepatic portal vein rich in
amino acids
glucose
vitamins
minerals
and other foods
175
why does the liver have a dual blood supply
because it recieves oxygenated blood from the hepatic artery and deoxygenated blood from the heaptic portal vein
176
how many lobes are there in the liver
4
177
how many lobules does each lobe contain
100,000
178
what does a lobule consist of
a central venule coming from the hepatic vein surrounded by six venules coming from the hepatic portal vein and sex arterioles from the hepatic artery. these blood vessels are connected by sinusoids
179
interlobular vein
branch of hepatic vein carries away deoxygenated blood
180
ateriole
brand of hepatic artery (brings oxygenated blood)
181
interobular vein
branch of hepatic portal vein (brings blood from gut)
182
bile duct
takes bile to gall bladder
183
what are sinusoids
tubes that resemble capillaries but have a discontinuous endothelium
184
layers of sinusoid
incomplete basement membrane
fenestrations
intracellular gap
185
layers of capillaries
continuous basement membrane
endothelial layer
intercellular cleft
186
give differnces between capillaries and sinusoids
very small pores vs fenestrations
continuous basement membrane v discontinuous basement membrnae
cylindircal shape vs definite shape
smaller vs larger
little intracellular space vs large
only small moleucles can pass vs leaky
187
what do hepatocytes do
perform most of the liver functions esp storage and metabolism
188
describe hepatocyteds
These cells are large (around 25 μm) and constitute around 80% of the total liver cells. Their nucleus is round and found in the centre of the cell. These cells are capable of regenerating when exposed to toxic substances. Liver regeneration involves the replication of hepatocytes followed by the replication of other liver cells.
189
liver regeneration
Liver regeneration involves the replication of hepatocytes followed by the replication of other liver cells. Once cell proliferation is completed, the newly divided cells undergo restructuring and reformation of the extracellular matrix to complete the process. During regeneration, liver function is only partially affected. Because human liver cells regenerate it has become possible to use partial livers from living donors for transplantation, thereby increasing the number of organs that are available for transplantation.
190
what are plasma proteins
synthesised in hepatocytes mainly in the rough endoplasmic reticulum (rER) and processed in Golgi complexes.
191
function of hepatocytes
(main liver cells) degradation of toxins
exocrine function in secretion of bile
192
what are kupffer cells
white blood cells (macrophages) that break down red blood cells
193
what do kupffer cells do
involved in the recycling of erythrocytes, as you will see later in this subtopic.
194
what do bile canaliculi do
carry bile to the bile duct that leads to the gall bladder where bile is stored until it is used in the small intestine
195
how is glucose dealt with in the liver
hepatocytes in the liver absorb most of the glucose and store it as glycogen
196
fatty acids in the blood passing through the liver are
absorbed by hepatocytes and metabolised to produce energy in the form of atp.
197
what do hepatocytes synthesise
lipids such as triglycerides, cholesterol and phospholipids.
These lipids can be bound to proteins forming lipoproteins, which are now soluble in blood plasma and can therefore be transported in blood to all the body
198
much of the cholesterol produced by hepatocytes gets
excreted from the body as a component of bile.
199
what do Endoplasmic reticulum and Golgi apparatus in hepatocytes produce
plasma proteins that include fibrinogen used in blood clotting, and albumin that transports hormones and maintains the blood pH.
200
what happens when amino acids are no longer necessary
hepatocytes remove the amine group from the acid group (deamination). The acid group of the amino acid is used to produce energy or new glucose molecules while the amine group is converted into ammonia. As ammonia is toxic, it is transformed into urea, which is then eliminated by the kidneys in urine.
201
FIGURE 1 METABOLISM OF NUTRIENT SIN THE LIVER
D3
202
what is detoxification
the liver gets rid of drugs, hormones and other toxins.
203
what if the liver cannot break down sunstnaces
it attatchces these substances to other organic groups such as a glycerine which allows the kidneys to recognise them as unwanted waste material and are therefore excreted.
204
what is ethanol oxidised into
acetaldehyde, a toxic substance, by the hepatic enzyme alcohol dehydrogenase. Acetylaldehyde is converted into a less toxic substance, acetate, by aldehyde dehydrogenase. Acetate is then broken down to acetyl-CoA that can enter fatty acid metabolism or be used in the Krebs cycle. If acetaldehyde is not broken down immediately, it can combine with proteins that induce liver injury. Excess of alcohol can damage the liver, causing cirrhosis.
205
is cholesterol essential
no, most cholesterol molecules are synthesised in the liver
206
as most animal cells require cholesterol for membrane synthesis,
a small portion is added to the membranes of hepatocytes, and the rest is exported as lipoproteins or bile salts
207
what is cholesterol a precursor for
bile salts, steroid hormones (oestrogen and progesterone) and vitamin D.
208
how is cholesterol synthesis regulated
according to its concentration in cells. This depends on the amount ingested in diet, and the regulation is performed by the hormones glucagon (inactivating its synthesis) and insulin (activating its synthesis).
209
STRUCTURE OF CHOLESTEROL
D3
210
is cholesterol insoluble or soluble
insoluble, so it must be carreid as plasma lipoproteins
211
what is cholesterol carried as
plasma lipoproteins
212
Different combinations of lipids and proteins produce particles of
different densities.
213
high density lipoproteins (HDL) contian more
protein
214
low-density lipoproteins (LDL) contain more
lipids
215
where are LDL's and HDL's produced
plasma, however a small amount is synthesied in the liver.
216
function of LDL
to transport cholesterol from the liver to the organs.
217
function of HDL
to transport cholesterol from tissues to the liver
218
fats can deposit in arteries causing an...
atheroma or plaque
219
what are atheromas or plaques caued by
white blood cells (foam cells) and LDL, where molecules of LDL deposit in the blood vessels and can become oxidised. This will cause atherosclerosis of the walls of the arteries
220
atherosclerosis
narrowing of arteries due to plaque
221
arteriosclerosis
hardening of arteries
222
what can atherosclerosis cause
cardiovascular disease and stroke
223
what happens if the artery leading to the artery (coronary artery) is clogged
the cells of the heart will not receive enough oxygen and can therefore die. These cells are replaced by fibres causing coronary heart disease (CHD). If the artery leading to the head (carotid artery) is affected, this can lead to a brain stroke.
224
which cholesterol is considered 'good'
HDL as it removes LDL from blood by transporting it to the liver and helps to maintain the endothelium of the blood vessels, thus avoiding coronary heart problems.
225
what are bile salts
emulsify fats
226
what is emulsification
breaking fats down into smaller droplets to increase their surface area to allow enzymes to work better
227
where are bile salts synthesised
by the liver from surplus cholesterol, and may be modified by bacteria in the intestines.
228
Bile salts are ______ from the ______ into the ______
reabsorbed from the
intestines into the
liver
229
bile salt aid in the
digestion and absorption of dietary lipids and fat-soluble vitamins.
230
the liver produces how much bile a day
on elitre
231
bile travels from the liver to where
carried by the bile canaliculi to the bile duct, which carries it to the gall bladder to be stored.
232
composition of bile
97% water
bile salts
cholesterol
fatty acids
bilirubin (from breakdown of erythrocytes)
inorganic salts
233
what can diseases of the liver be caused by
pathogens, metabolic problems, toxins such as drugs or alcohol.
234
what is jaundice
Jaundice is a condition where the skin and white of the eyes turn yellow
235
what is jaundice caused by
the presence of bilirubin in extracellular fluid.
236
bilirubin is produce from
haemoglobin breakdown in erythrocyte recycling in the liver. The metabolism of haemoglobin accounts for 65% to 80% of the total bilirubin production.
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what does bilirubin in blood irreversabily bind to
albumin (a plasma protein), forming conjugated bilirubin that travels to the liver, which removes it from the plasma.
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what happens when the liver is not able to remove the bilirubin from blood
its level may rise (especially in the unconjugated form) and the skin and eyes may begin to appear jaundiced.
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when does jaundice occur
Increased destruction of red blood cells.
Immaturity in the conjugation of bilirubin (greater in premature babies).
Genetic diseases (e.g. Gilbert syndrome).
Defects in the secretion of conjugated bilirubin from hepatocytes (in liver damage).
Defects in transit of bilirubin to intestines (e.g. with bile duct obstruction).
can also be caused by the use of drugs, genetic factors, malaria or anemia.
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a high level of bilirbin in the blood is a sign of
liver malfunction
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effects of jaundice
range from clinically unnoticeable to severe brain damage and even death. Jaundice is usually a symptom of hepatitis or liver cancer.
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what is cirrhosis
a disease where the damaged liver tissue is replaced by scar tissue, as shown in Figure 2. Not only does this affect the functioning of liver cells, but also interferes with the blood supply to these cells.
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symptoms of cirrhosis
weakness, fatigue, jaundice and bruising.
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liver biopsy will
confirm the presence of scars
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tretment of cirrhosis
no cure. liver transplant
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what causes cirrhosis
Excessive alcohol or drug consumption may cause liver cirrhosis. Other causes of cirrhosis include chronic viral hepatitis B or C, chronic bile duct obstruction, fatty liver disease, excess of iron, cystic fibrosis and Wilson’s disease.
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Why should alcoholics be entitled to receive a liver transplant?
Everybody has the right to live.
They can change their lifestyle and stop drinking.
They might be the only support for a family.
Many people care for them.
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Why should they not receive a liver transplant?
They caused the liver damage by their own choice of drinking.
They must put up with the consequence of their own reckless attitude.
Other people deserve the transplant more.
They can relapse back into drinking and damage the new liver.
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what does the structure of the cardiac muscle cells allow
propagation of stimuli through the heart wall.
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where is the nucleus of the cardiac muscle cell found
in the centre of the cell
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what do cardiac muscle cells have a lot of
mitochondria and glycogen granules
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how is cardiac muscle different to skeletal muscle
it has numerous, short, cylindical cells, arranged end to end resulting in long branched fibres
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what is an inteercalated disc
the attatchment site between cardiac muscle cells. appears as a linear structure transverse to muscle fibre
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what do intercalated discs represent
the attatchment site between adjacent cells.
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what do intercalated discs contain
adhering junctions between cells that hold cells together and gap junctions, which allows communication between cells
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what are gap junctions
arrays of densely packed protein channels that permit intercellular passage of ions and small molecules. Electrical activation of the heart requires cell-cell transfer of current via gap junctions.
257
what is the refractory period
where the cells cannot contract for a second time
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purpose of refractory period
ensres that the contraction or systole of the heart is separated by a resting period or diastole
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what causes the heartbeat
the pontaneous rhythmic contraction of cardiac muscle
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where does the contraction causing the heartbeat start
sinoatrial node (SA), a group of specialised cardiac muscle cells found where the superior vena cava joins the right atrium. Signals from the sinoatrial node that cause contraction cannot pass directly from atria to ventricles.
Instead the impulse spreads along the atria to the atrioventricular node (AV), from where it spreads to the ventricle. There is a delay between the arrival and passing on of a stimulus at the atrioventricular node. This delay allows time for atrial systole before the atrioventricular (tricuspid and bicuspid or mitral) valves close. The blood therefore leaves the atria to the ventricles when the atrial systole occurs.
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what does the dealy between the arrival and passing of a stimulus at the AV node gives time for
the atria to contract before the AV valves close
262
what forms the bundle of his
specialised fibres grouped to form a bundle in the interventricular walls
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what does the bundle of his split into
two branches that go to the left and right ventricles, leading to purkinje fibres. these carry the impulse at a very high speed
264
what is the ventricular contraction called
the systole
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what is the diastole
when the heart is relaxed
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what part of the heartbeat is the closing of the AV valves
the first part
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what is the second part of the heartbeat
the closing of the semilunar valves
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what is an action potential
an electrical event associated with different concentrations of ions across membranes.
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what does the plateau of the action potential in cardiac muscle do
prevents the heart from contracting before time
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what is the plateau in action potential
due to the balance between the potassium ions leaving the cell and the calcium ions coming in. This phase maintains depolarization for a longer time.
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why are pacemaker rhytms considered myogenic not neurogenic
as one action potential is completed, immediately another action potential is generated in the membrane, even in the absence of nerve impulse.
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what is heart rate
number of times the heart contracts in one minute (bpm) obtained through pulse
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normal heart rate
50-100 bpm
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factors that increase heart rate
gender
physical activity
body size
temperature
altitude
posture
stress
eating
sodium and calcium ions inblood
drugs
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factors that decrease heart rate
age
potassium ions
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bradycardia
heart beating too slowly
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tachycardia
heart beating too quickly
278
arrhythmia
heart beating irregualrly
279
what does a pacemaker consist of
a battery powered generator (that sends out electrical impulses) and wires with electrodes to connect to the heart muscle. If the pacemaker senses that the heartbeat is above a certain rate, it will stop sending signals to the heart. The pacemaker can also sense when the heartbeat slows down too much. It will automatically turn back on and start pacing the heart again.
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how is a pacemaker inserted
A small cut is made on the left side of the chest or abdomen and the generator is placed under the skin at this location. The pacemaker can have one lead leading to the right atrium or two leads, one to the right atrium and another to the right ventricular walls (Figure 1). Another type of pacemaker also includes a lead to the left ventricle.
281
what does an ECG do
check the electrical activity of the heart
282
how are the resulsts of an ECG displayed
amplified in the ECG machine and displayed on an oscillosocope or recorded on moving paper
283
what does an ecg graph show
voltage variations over time
284
what is the r-r intercal between successive beats allowing the calculation of the heart rate
difference between peaks
285
what is blood pressure
the pressure of blood on the walls of an artery during a systole. (highest value recorded) and a diastole (lowest value).
286
during the heart contraction blood flows
out of the heart at a high pressure through arteries
287
when is blood pressure lowest
heart relaxation (diastole)
288
what measures blood pressure
sphygmomanometer
consists of a inflatable cuff and measuring device
289
HOW TO TAKE
BLOOD PRESSURE
290
what is hupertension
high blood pressure
291
what is hypotension
low blood pressure
292
causes of hypertension
gender
obesitu
age
lack of exercise
caffeine
alochol
smoking
sodium
stress
anxiety
genetic
293
consequences of hypertension
stroke
blindness
arteriosclerosis
heart attack/failure
kidney failure
294
stroke as consequence of heart attack
occurs due to a reduced or interrupted supply of blood to the brain. The brain does not get enough oxygen or nutrients, which causes brain cells to die.
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blindness as consequence of heart attack
can happen because of the ruptured capillaries in the retina or optic nerve or damage to the area of the brain responsible for processing images.
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arteriosclerosis as consequence of heart attack
s the hardening of arteries, restricting the flow of oxygen and nutrients to tissues. Atherosclerosis is a special kind of arteriosclerosis. It is caused by the damage of arteries and subsequent formation of scar tissue. A plaque is formed when cholesterol and other lipids build up on this scar tissue. The plaque makes platelets release factors that cause the formation of a clot over the plaque, forming a thrombus. The thrombus blocks the flow of blood to tissues, causing thrombosis. If a thrombus (or clot) occurs in the coronary artery, the supply of blood and oxygen to the areas of the heart muscle is blocked. This causes irregular heartbeats and can lead to coronary heart disease (CHD).
297
what is epidemiology
investigates all the factors and effects that determine the presence or absence of diseases and disorders in a population.
298
what is CHD
the name for decreased blood flow and oxygen to the heart muscle caused by narrowed heart arteries. It is also called cardiac ischemia or ischemic heart disease.
299
what is heart disease caused by in LEDC
viral or bacterial infection and nutritional deficinies
300
what is heart disease caused by in MEDC
hypertension
high fat diets
cigarette smoking
sedentary lifestyles
301
what could genetic dispostiion to CHD be caused by
insulin resistance sydnrome
chances of diabetes
elevated triglyceride
HDL cholesterol concentrations
302
what is ventricular fibrillation
the interruption of the electrical impulses that control heartbeat. This can be caused by the loss of blood flow to the heart or a heart attack. It often begins with ventricular tachycardia (rapid heart beating) and leads to low blood pressure because the ventricles are not able to pump hard enough. The symptoms are chest pain, dizziness, nausea, heartburn, fluttering heartbeat, fainting, coma, nerve function loss, changes in mental function and eventually death.
303
benefit of cpr
CPR can keep oxygenated blood flowing to the brain and other vital organs until more definitive medical treatment can restore a normal heart rhythm. It is quite a simple procedure that can be done by anyone if a doctor is not found in the proximity. To learn CPR properly, you can take an accredited first-aid training course, including CPR and how to use an automated external defibrillator (AED). After calling for emergency medical help, this is what you need to do:
304
CARRYING OUT
CPR
305
Hormones are not
secreted at a uniform rate and exert their effect at low concentrations.
306
hormones can be
steroid or peptide
307
what glands are involved in the production of hromones
pituitary gland
hypothalamus
thymus
thyroid
parathyroid
oancreas
ovaries
mammary glands
adrenal glands
kidneys
testes
308
most hormones are regualted via
negative feedback mechanisms
309
hormones are involved inthe regulation and control of
Metabolism
Development
Homeostasis
Digestion
Excretion
Sleep
Reproductive cycles
Growth
Secondary sexual characteristics
Sensory perception
Mood
Hunger
Birth
Lactation
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major endocrine glands
pituitary
pineal
thymus
thyroid
adrenal
pancreas
testes and ovaries
311
what are hormones
chemical messengers secreted by cells or glands of the endocrine system that control and regulate the activity of other cells or glands in other parts of the body.
312
which hormones are the steroid hormones
the sex hormones (oestrogen, progesterone, testosterone) and those from the adrenal cortex (aldosterone, cortisol and estradiol).
313
what are the protein hormones
all except cortisol oestrogen progesterone testosterone
314
negative feedback def
is seen when the output of a pathway inhibits inputs to the pathway.
315
Synthesis (hormones)
the rate of production can be regulated by positive or negative feedback.
316
delivery (hormones)
n endocrine glands, this is regulated by blood flow.
317
elimination (hormones)
hormones are metabolised and excreted once their half-life is over.
318
steroid hormones are generally synthesised from
cholesterol in the ovaries or testes and in the adrenal glands
319
are steroid hormones polar
no they are fat soluble, they can pass through the phosopholipids of the cell membrane
320
what do steroid hormones do once inside the cell
some bind to a receptor in the cytoplasm and others to a receptor in the nucleus
When the steroid hormone joins a receptor in the cytoplasm, two receptor subunits join together to form one functional DNA-binding unit that can enter the cell nucleus. Once in the nucleus, the receptor-hormone complex binds to specific DNA sequences and regulates transcription of its target genes.
When the steroid hormone binds to the receptor inside the nucleus, the receptor undergoes a conformational change that renders it activated to recognise and bind to specific nucleotide sequences. When the receptor-hormone complex interacts with DNA it alters the transcriptional level (responses can be either activating or repressing) of the associated gene.
The RNA produced is translated into new proteins, for example, enzymes involved in different metabolic processes. This method of action is relatively slow as it involves synthesis of proteins
321
what do peptide hormones do
bind to receptors in the plasma membrane of the target cell. They cannot enter the cell as they can't pass through the cell membrane. Binding of hormones to membrane receptors activates a cascade mediated by a second messenger inside the cell.
The sequence of events that results in hormone action is relatively rapid.
322
what is epinephrine
peptide hormone produced by the adrenal glands in response to stress and during exercise
323
waht does epinephrine do
attatches to receptors on the membrane of the heart cell called adrenergic receptors which are coupled to a g protein. when the epinephrine joins the adrenergic receptor, the G-protein sends a message to the enzyme adenylyl cyclase. This in turn leads to the activation of the secondary messenger, cyclic adenosine monophosphate (cAMP), which induces smooth muscle relaxation, producing vasodilation and increased contraction of the cardiac tissue.
324
what is somatotropin
protein hormone synthesis by the anterioir pituitary gland. involved in the regualtion of bone and muscle growth. HGH is sometimes used in sports to induce anabolic effects.
325
adverse effects of anabolic steroid hormones
Increase in size of testes and ovaries, impaired spermatogenesis, growth of breasts in males.
Psychiatric disturbance.
Toxic to the liver.
Dyslipidemia (raised LDL and triglycerides and reduced HDL).
Hypertension.
Increased coagulation and platelet aggregation.
Exaggerated left ventricle growth.
326
what happens when HGH is mixed with testosterone
It has been proven that HGH significantly reduces body fat mass and increases body cell mass and sprint capacity when administered together with testosterone.
327
D.5 Hormones and metabolism
Hypothalamus and pituitary gland
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