nutrition in humans Flashcards
(147 cards)
1
Q
y do organisms require food
A
- growth,
- for repair or replacement of worn and damaged tissues,
- as a source of energy
- to maintain health
2
Q
how does food help in organism growth
A
food provides the substances needed for synthesising new protoplasm, cells and tissues
3
Q
how does food help in being a source of energy
A
food has chemical potential energy.
when digested food is oxidised during respiration, the energy from the food is released in the form of ATP molecules.
4
Q
what is ATP used for
A
- (anabolism) chemical reactions that build complex molecules from simpler molecules
- activities such as movement
- maintenance of body temperature
5
Q
3 components that make up food
A
nutrients
fibre
water
6
Q
what are nutrients
A
nutrients are chemical substances in food that nourish the body.
7
Q
what are the 5 groups of nutrients
A
carbohydrates
fats
proteins
minerals
vitamins
8
Q
which 3 groups of nutrients are required in large qwuantities as they supply energy and materials to make new protoplasm
A
carbohydrates
fats
proteins
9
Q
which 2 groups of nutrients are required in small qwuantities as they are needed to maintain normal metabolism. they have no energy value
A
minerals
vitamins
10
Q
what elements are carbohydrates made up of
A
carbon
hydrogen
oxygen
10
Q
what are the 3 main groups of carbohydrates
A
monosaccharides (simple sugars)
disaccharides (complex sugars)
polysaccharides
11
Q
monosaccharide structuring
A
(C H2O) -> general formula
they tend to have 3,5 or 6 carbon atoms
C6H12O6 -> 6 carb atoms 6 waters
12
Q
monosaccharide examples
A
glucose
fructose
galactose
they all have C6H12O6
13
Q
monosaccharide functions
A
- monosaccharide are the chief source of energy in the form of ATP during cellular respiration
- form nucleic acids(DNA) as ribose sugar(backbone of nucleic acid) is a monosaccharide
14
Q
disaccharides structures
A
is made up of two molecules of monosaccharides(simple sugars) joined together.
this is a condensation process involving the loss of water with the resulting establishment of a covalent bond called a glycosidic bond
glucose + monosac -> disach + water
15
Q
disaccharides examples
A
sucrose
lactose
maltose
16
Q
disaccharides functions
A
can become monosaccharides aka a source of energy when it is hydrolysed.
disach + water -> glucose + monosac
breaking a disach into 2 monosach is called hydrolytic reactionn which invloves water
17
Q
polysaccharides structures
A
consists of many monosaccharide molecules joined togetyher. this is called polymerisation
18
Q
polysaccharides examples
A
starch
glycogen
cellulose
19
Q
polysaccharides functions
A
- starch is a storage of carbohydrate in plants. it also hydrolyses to become a source of energy from glucose units.
- glycogen is a compact storage of carbohydrate in animals
20
Q
y is glycogen and starch both ideal storage materials
A
-they are insoluble in water(do not change the osmotic pressure in the cell)
-large molecules(cannot diffuse thru the cell membrane)
- they can be broken down to glucose molecules
- they have compact shapes(occupy less space)
21
Q
what elements are fats made of
A
carbon
hydrogen
oxygen
(although the same as carbohydrates it contains less oxygen in proportion to hydrogen compared to carbohydrates)
22
Q
what is a fat molecule made up of
A
4 molecules
1 glycerol attached to 3 long molecules, fatty acids
23
Q
so what is obtained when fat is hydrolysed
A
fatty acids and glycerol
fat molecule + 3 H2O –lipase–> glycerol + 3 fatty acid
24
what grp is fats under/ i think is interchangeable with
LIPIDS
but if u thought nutirents kudos
25
lipids(fats) functions
- forms part of the **cell membrane*
- efficient source of energy that can be *oxidised* in respiration to CO2 and H2O, liberating *2x as much energy* in the form of ATP as compared to the *same weight in carbohydrates*
- *long term* storage
-*insulating* material beneath the skin, prevent excessive heat loss
- solvent for fat-soluble vitamins
- protect vital organs
- sebum, oily secretion, form on the skin restricting water loss
26
difference between animal fats and plant fats
animal fats are saturated fats
plant fats are unsaturated fats
27
what elements are proteins made of
carbon
hydrogen
oxygen
NITROGEN
sometimes sulfur and phosphorus are also present
28
what are the simpler compounds that proteins are made from
amino acids
29
protein functions
when proteins r digested, amino acids are absorbed into the bloodstream, enter the cells and used to build up different proteins such as,
-> proteins that form part of the protoplasm of new cells(growth) and worn-out cells(repair)
->enzymes of cells
->membrane proteins embedded in phospholipid bilayer
->actin and myosin in muscles
->keratin in hair and nails
->peptide hormones, insulin
-> antibodies that defend the body
30
what is ***kwashiorkor***?????
its a protein deficiency disease
31
what are minerals?
minerals are *inorganic salts* which *DO NOT* provide energy but are required for normal, healthy development
32
what are some of the minerals needed in large amts
calcium
phosphorus
chlorine
sodium
potassium
iron
cancerous potatoes can sometimes poison infants
33
what are trace elements
trace elements are minerals needed in minute quantities such as
iodine
zinc
manganese
34
calcium function in the body
-in the form of calcium phosphate, is deposited in the bones and teeth *making it hard*
-present in blood plasma, essential in *normal blood clotting*
-chemical changes -> *muscles contract*.
35
iron fucntion in the body
-RBC contains haemoglobin. haemoglobin contains iron and it plays an important part in carrying oxygen around the body
-Mucle cells contain myoglobin. myogllobin contains iron and it plays an important role in storing oxygen in the muscle cells
-iron is needed for enzyme systems in all the body cells
36
what is anaemia
when a person is iron deficient. insufficient haemoglobin is made and the oxygen-carrying capacity of blood is reduced.
37
iodine function in the body (small amts)
it forms an essential part of the hormone *thyroxine* in the thyroid gland in the neck. deficiency in idoine lesads to goitre, swelling the neck.
38
phosphorus function in the body (small amts)
js to form calcium phosphate of bone and teeth, and also for ATP and DNA molecules.
38
what are the 2 grps of vitamins
- fat-soluble vitamins (A,D,E,K) can be stored in the body
- water-soluble vitamins (B,C) cannot be stored, daily intake needed
39
what are vitamins?
grp of organic substances that have these features:
- *not* digested or broken down for energy
- *not* built into body structures (used chemically)
- essential in very *small quantities* or normal health
- needed for *chemical reactions* in cells
40
**vitamin C (ascorbic acid) functions
-needed for formation of *connective* tissues that bind and support other tissues
-necessary for maintaining healthy *epithelial* tissues
-acts as an *antioxidant*
41
what causes scurvy
lack of vitamin C results in scurvy
swollen bleeding gums, poor healing wounds, bleeding under skin
42
where does excessive vitamin C go
excreted in urine
43
**vitamin D (calciferol) functions
- promotes absorption of *calcium* and *phosphorus* compounds from the intestines
- helps in deposition of calcium salts in the *bones* and *teeth*
44
how can we get vitamin D from sunlight
natural fats in the skin are converted to vit D.
45
what happens when vitamin D defiency
tooth weak, bone weak
46
vitamin A(retinol) function
- needed for formation of light sensitive-pigment in the *retina* and for maintaining healthy *epithelial* tissues.
- *carotene* from carrots is converted into vita A
47
deficient in vita A =
poor night vision, dry opaque cornea of eyes
48
What, in the plants, are we unable to digest
the cellulose in the cell walls of plants
49
what is fibre or roughage
the cellulose in the cell walls of plants
50
if fibre or roughage cant be digested how isit removed
it makes it to the large intestine and is egested in the faeces
51
fibre functions in the digestive tract
-prevents constipation
the fibre itself + the bacteria that feeds on it, adds bulk to the shit and helps it retain water. this softens the shit and and shit can come out easy
- fibre stimulates peristalsis
food moves thru the canal because of peristalsis, wavelike muscular contractions of the walls of the digestive tract. soft food does not stimulate the muscles but are by harder substances like fibre.
52
water functions in living things
- essential part of cytoplasm
water is the best known solvent. hence it serves as
- a medium in which various *chemicasl reactions* of an organism occur in, eg, hydrolysis
- a transporter of digested food,salts,vitamins,hormones,excess salt and urea
- a major component of body fluids, blood, lymph and tissue fluiid
HELPs to regulate the body temperature, sweating
-esential reactant in photosynthesis
53
what is a balanced diet
a balanced diet consist of the right amt of carbohydrates, fats,proteins,vitamins,minerals,water and roughage to meet the daily reqs of the body
54
what must a balanced diet contain
enough
- carbohydrates and fats to meet our *energy needs*
- protein of the right kind to provide the essential amino acids to make new cells and tissues for *growth and repair*
- vitamins, dissolved mineral salts, fibre and water
55
Energy for each food
the amt of energy that can be obtained from food is measured in *kilojoules* or kilocalories
- 1g of carbohydrates -> 16kJ of energy
- 1g of fats -> 37kJ of energy
- 1g of proteins -> 17kJ of energy
56
what is basal metabolism
it is the amt of energy needed to carry on vital life processes when the body is in complete rest.
energy to maintain circulation, breathing, body temperature, brain function, essential chemical process in the liver and other organs
(aka base power needed)
57
what is basal metabolic rate
the amount of energy a person completely at rest uses per unit time
58
what does total energy intake have to be sufficient for
*total energy expenditure*
- basal metabolism
- meet the needs of work and other physical activitties
- offset energy lost in heat
59
what is enegry balance
when the total energy intake balances the total energy expenditure
60
what affects the amt of energy we need each day
- climate
- body size
- age
- gender
- health conditions
- activity
61
how does climate affect amt of energy we need each day
more energy is required in colder climates
- a person living in colder climates loses more heat ot the surroundsing compared to one living in the tropics, so more energy is required to maintain body temperature. *basal metabolic rate* is higher.
62
how does body size affect amt of energy we need each day
A smaller body size has a higher metabolic rate than a bigger size.
- the smaller the animal, the greater the energy cost of maintaining a stable body temperature beacuse of a greater surface area to volume ration and thus a greater loss of heat to the surroundings
63
how does age affect amt of energy we need each day
growing children have higher basal metabolic rates than adults
64
how does gender affect amt of energy we need each day
men usually have higher heat production than women of the same body size and age because men tend to have more muscle tissue than fatty tissue, and muscle tissue uses up more energy than fatty tissue
65
how does health conditions affect amt of energy we need each day
there is insufficient thyroxine from an underactive thyroid gland and excessive thyroxine from an overeactive thyroid gland. Thyroxine is a hormone thaty increases metabloc rate
Hence less thyroxine = less energy needed
More = more needed
(thyroxine is the neck thing that needs iodine)
66
how does activity affect amt of energy we need each day
a person who does hard, manual work requires more energy in the form of ATP molecules for muscular activities than one who sits in an office.
67
what are the 3 main world food supply related problmes
starvation, malnutrition and over-nutrition
68
what is starvation
starvation occurs when a human does not receive enough energy from the diet.
to meet basic metabloic needs, the body uses energy reserves(fats, glycogen) when depleted *proteins are used*
msucles made of protein, *muscle wasting*
69
what is malnutrition
malnutirtion results from dietary imbalance. due to dificiency or and excessive intake of a component of food
70
what is over-nutrition
overconsumption of food than required by the body (for its energy needs or for building tissues) resulting in storage the surplus as fat.
-> leads to obesity
71
special dietary needs for a pregnant woman
a pregnant woman needs to increase her intake of some substances
- **protein**-rich food (milk, eggs, beans) promotes *rapid foetal tissue growth*
- vegetables rich in **folic acid** promote development of the nervous system
- milk is a good source of **calcium** for one growth
- red meat is a good source of **iron** necessary for haemogloin the blood
72
what does a lactating mother need
increased intakes of
-proteins,
-vitamins
-calcium
73
what is nutrition
the intake of food and the processes that convert food substances into living matter are called nutrition
74
what do growing children up to the age of 12 years require the following extra food substances
- **protein**s for making new tissues
- **iron** for haenmoglobin in red blood cells
- **carbohydrates** as a source of energy in the form of ATP
- **calcium** for growing bbones
- vitamin **A** for disease resistance
- vitamin **D** to help calcification of bones
piccAD
75
5 nutrition processes
ingestion
digestion
absorption
assimilation
egestion
76
ingestion meaning
the intake of food into the body
77
digestion meaning
the process whereby **large, complex food molecules** are broken down to **smaller, simple**, soluble and diffusible molecules so that they can be **absorbed** into the bloodstream
78
absorption meaning
the passage of digested food materials through the **walls of the small intestine** into the bloodstream so that they can be carried to living cells in all parts of the body
79
assimilation meaning
the process whereby some of the absorbed food materials are **converted** into new protoplasm or used to provide energy
80
egestion meaning
The passing out of **undigested** food as **faeces**
81
how do mammals feed
Mammals feed by ingesting complex, **insoluble** organic nutrients in their food which they **digest** into smaller and **soluble** molecules.
82
what is holozoic nutrition
a specific form of heterotrophic nutrition where it basically means digesting solid food
82
does digestion take place in the body cells?
no, digestion is **extracellular**. the nutrients then go back in
82
the entrie alimentary canal
(i) Mouth and buccal cavity
(ii) Pharynx (throat)
(iii) Oesophagus (gullet)
(iv) Stomach
(v) Small intestine (duodenum, jejunum and ileum)
(vi) Caecum and appendix
(vii) Large intestine (colon and rectum)
(viii) Anus
82
y is the alimentary canal so long
its atcl abt 900 cm long 🤓, it fits by coiling. the long alimentary canal gives the food enough time to be **digested and absorbed** into the body
83
theres alot of gaps(abdominal cavity), so how do the organs js like float.
The gut is suspended from the wall of the abdominal cavity by tough connective tissue called **mesentery** that carries blood vessels, nerves and lymphatics that serve the gut.
84
what r the 4 layers of the gut wall
1. Serous coat (serosa) outer-most layer
2. Muscular layer (muscularis mucosa)
3. Submucous coat (submucosa)
4. Mucous coat (mucosa) inner-most layer
85
whats the Serous coat (serosa)
Serous coat (serosa) is an outer covering of loose connective tissue.
86
whast the Muscular layer (muscularis mucosa)
Muscular layer (muscularis mucosa) is made up of two layers of smooth muscles which are responsible for **peristalsis** (slow, sustained and coordinated contractions), which propel food along the gut
- Outer layer of **longitudinal muscles** that run along the length of the canal
- Inner layer of **circular muscles** that run round the canal
87
whast the Submucous coat (submucosa)
Submucous coat (submucosa) is made up of **connective tissue** and blood vessels
88
whats the Mucous coat (mucosa)
Mucous coat (mucosa) is the innermost layer that is folded extensively. It contains cells that line the inside of the canal, forming an **epithelium** that secretes **mucus**.
Functions of mucus:
- It **lubricates** the food so that it moves more easily along the gut.
- It **protects** the lining from attack by **digestive enzymes** which are released into the alimentary canal.
89
3 accesory organs(not in the gut but related to it)
(i) Salivary glands
(ii) Liver and gall bladder
(iii) Pancreas
89
what is antagonistic muscle action in peristalsis
The two sets of muscles work in such a way that when **one contracts, the other relaxes**. This is known as **antagonistic** muscle action.
(i) When the **circular muscle _contracts_**, the **longitudinal muscle _relaxes_**.
--The gut **constricts** (lumen becomes smaller), i.e. it becomes **narrower but longer**.
The food is squeezed and _pushed forward._
(ii) When the **longitudinal muscle _contracts_**, the **circular muscle _relaxes_**.
--The gut **dilates** (lumen becomes larger), i.e. it becomes wider but shorter.
The hollow lumen of the gut is widened for _food to enter_.
90
what is peristalsis
The two layers of smooth muscles cause rhythmic, wave-like contractions of the walls of the gut. Such movements are known as peristalsis and they help to move food along the gut.
91
what is chemical digestion
breaking down of large molecules (proteins, starch, fats) in food into smaller molecules. This involves **hydrolytic** reactions **catalysed** by digestive enzymes.
92
what is physical digestion
breaking up of food into small particles **mechanically.**
93
MOUTH AND BUCCAL CAVITY Structure
not super impt
Food enters the body via the mouth which leads to the **buccal cavity.**
The buccal cavity contains the muscular **tongue**, and is supported by the fixed upper and movable lower **jaws** in which the **teeth** are set in sockets. The jaws bear four types of **teeth**: incisors, canines, premolars and molars.
**Three pairs of salivary glands** open into the buccal cavity via ducts.
94
teeth function in the mouth, mastication
- solid food is broken up into small pieces by the grinding action of the teeth
- physical digestion
- Mastication reduces food to **small particles**, increasing the **surface area** on which enzymes act. Mastication also facilitates **swallowing.**
95
tongue function in the mouth
The tongue **rolls the food** into small, slippery, spherical masses or **boli (sing. bolus).**
96
salivary glands function in the mouth
Food in the mouth stimulates the salivary glands to secrete **saliva.**
97
whats found in saliva and its function
(i) **_Mucus_** which helps to **lubricate** and soften the bolus for **ease of swallowing**
(ii) **_Salivary amylase_** (ptyalin) which **catalyses** the **hydrolysis** of cooked starch to **maltose** (chemical digestion)
(iii) **_Lysozyme_** which **reduces bacterial contamination**
98
whats the pharynx
The pharynx is a common passage for food and air.
99
During swallowing, what occurs to prevent food from passing into the trachea
(i) The **larynx** moves up.
(ii) The opening into the trachea (glottis) is **partly closed** by the contraction of a ring of muscles.
(iii) (epiglottis) flap covers the glottis.
the whole thing is the larynx, then it shifts upwards + ring of musdcle contract = epiglotiss flap cover
100
whats the OESOPHAGUS
The oesophagus is a straight, narrow, thick-walled muscular tube that leads from the pharynx to the stomach.
101
OESOPHAGUS adaptations
The glands of submucosa secrete copious quantities of **mucus** into the lumen(empty space), **lubricating** the passage of the **bolus**.
The bolus is propelled down the oesophagus towards the stomach by a wave of muscular contraction and relaxation known as **peristalsis.**
102
STOMACH Structures
- distensible muscular bag with **thick and well-developed muscular walls.**
- lining of the stomach (mucous coat) has numerous pits, the walls of which are lined with **gastric glands** that produce **gastric juice.**
- **pyloric sphincter** is a circular band of muscle at the lower end of the stomach which **stops solid pieces of food** from passing through.
103
what does gastric juice contain
HCL, pepsin and rennin
104
HCL function in the stomach
Stops the action of **salivary amylase**
**Kills germs** and potential parasites in the ingested food
Initiates conversion of inactive form of pepsin **(pepsinogen)** into **pepsin**
Initiates conversion of inactive form of rennin **(prorennin)** into **rennin**
Provides an **acidic medium** for the action of gastric enzymes
105
what does pepsin do
catalyses the hydrolysis of proteins into **short polypeptides** or **peptides.**
106
what does Rennin do
commences the digestion of milk proteins by
converting soluble CASEINOGEN protein -> insoluble CASEIN protein
the casein is then digested by pepsin
107
so theres so much chemical warfare in the stomach, hows it not getting digested?
Mucus-secreting cells in the **gastric glands** secrete **mucus** that protects the stomach lining and glands from **self-digestion** (autolysis) by pepsin, which could lead to stomach ulcers.
108
what is chyme
regular, peristaltic movements of the stomach(churning) mixes up the food and gastric juice into a semi-liquid known as chyme
109
SMALL INTESTINE Structure
The human intestine is about 5 – 6 metres long. There are **two main regions: duodenum and ileum**. In humans a zone intermediate between the duodenum and ileum, the jejunum, is identified.
110
where does most absorption of digested nutrients, i.e. simple sugars, amino acids, fatty acids and glycerol, and water all take place
SMALL INTESTINE
STARPLAYER KING SMALL INTESTINE
110
what does pancreatic juice contain
Pancreatic juice contains sodium hydrogencarbonate (which partly neutralises the acidic chyme) and the enzymes pancreatic amylase, pancreatic lipase and trypsinogen.
110
what does the duodenum do
The duodenum receives bile from the gall bladder and pancreatic juice from the pancreas(from the pancreatic duct)
110
how is sodium hydrogencarbonate similar to bile
they are alkaline, so they neutralise the acidic chyme and provide a suitable medium for the action of pancreatic and intestinal enzymes.
111
Fat digestion in the small intestine
- bile is this green watery shit cuz of bile pigments that are formed from the breakdown of haemoglobin in the liver.
- it contains no enzymes but it has bile salts tat **emulsify fats**, which means to break fats up into fat globules tat greatly increases the **surface area** to speed up digestion from **pancreatic lipase**.
- emulsified fat is hydrolysed by pancreatic lipase to fatty acids + glycerol
111
where is bile made
the liver, but stored in the gall bladder
111
where are brush borders found and whats in the brush border
The **microvilli** of the epithelial cells lining the **villi** of the small intestine have these enzymes bound to them: **enterokinase, peptidases, sucrase, maltase and lactase.** They are called brush border enzymes.
112
Carbohydrate digestion in the small intestine
starch digestion strats in the mouth but only a little, nothing in the stomach
ENTER SMALL INTESTINE:
the remaining starch is **hydrolysed into maltose** by **pancreatic amylase**(found in p juice from pan to duodo)
maltose is hydrolysed to 2 glucose by maltase
lactose is hydrolysed to glucose and galactose by lactase
sucrose is hydrolysed to glucose and fructose by sucrase
113
Protein digestion in the small intestine
it starts in the stoimach
ENTER SMALL INTESTINE:
- trypsinogen from pan juice is converted to trypsin by enterokinase in the brush border. larger polypeptides that reach the small intestine are hydrolysed by trypsin to smaller (shorter) polypeptides.
- The smaller polypeptides or peptides (2 – 3 amino acids) produced are further digested to amino
acids, the end-products, by peptidases.
114
5 adaptations of te small intestine for ABSORPTION OF NUTRIENTS
1. LONG -> sufficient TIME -> large TOTAL SURFACE AREA
2. many VILLI -> increase TOTAL SURFACE AREA
3. epithial lining ONE CELL THICK -> SHHORTEN diffusion distance
4. microvilli -> increase the **surface area to volume ratio of one epithelial cell** -> more brus border enzymes for digestion and carrier proteins
5. dense network of BLOOD CAPILARRIES +LACTEAL -> transport away te nutrients -> maintain a steep concentration gradient of nutrients
6. epitelial cell MANY MITOCHHONDRIA -> release energy IN FORM OF ATP during respiration -> ACTIVE TRANSPORT to absorb nutrients
115
2 different modes of transport across the epithelial cells:
**Passive diffusion** down a concentration gradient from the lumen of the intestine into the epithelial cells for **fructose, glycerol and fatty acids**
**Active transport** against a concentration gradient for **glucose, amino acids, galactose and dissolved mineral salts**
116
Two common types of lipoproteins
low density lipoproteins: LDLs contain 55% cholesterol.
high density lipoproteins: HDLs contain 21% cholesterol
117
Absorption of simple sugars and amino acids
- **simple sugars** and **amino acids** enter the blood capillaries and are carried away from the villi.
- The **capillaries** join up to form veins and these veins unite to form the **hepatic portal vein** that leads directly to the **liver.** The liver plays an important role in regulating the level of nutrients in the blood, especially glucose.
118
Absorption and transport of fatty acids and glycerol
fatty acids and glycerol enter the blood capillaries of the villi. but they recombine/condense to form fats again
fats mix with cholesterol and coated with proteins in epi -> **lipoproteins** droplets callked **chylomicrons**
passed into **lacteal** -> mix w colourless **lymph** -> milky **chyle**
119
major function of the large intestine
absorb **water** and **dissolved mineral salts**. The undigested material is stored temporarily in the **rectum** before it is discharged as faeces through the **anus**. The removal of undigested material from the body is called **egestion or defaecation.**
120
assimilation meaninhg
The products of digestion are carried around the body in the blood. From the blood, cells absorb and use glucose, fats and amino acids. This uptake and use of food is called assimilation.
120
secondary active transport of glucose/galactose
sodium/glucose transporter takes up glucose / galactose against its concentration gradient by coupling its transport
-> facilitated diffusion into blood stream
121
how does glucose become energy
Glucose is **oxidised** to carbon dioxide and water during cellular respiration. This process releases energy in the form of ATP molecules
121
how fructose enter the epithelial cell
it enters the epi cell via facilitated diffusion
-> facilitated diffusion into blood stream
122
what hhappens to Amino acids which enter the cells
Amino acids which enter the cells are condensed into proteins,
123
insulin function
increasing **permeability** of cell membrane to glucose
->increasing the rate of glucose uptake by cells via facilitated diffusion
stimulating the **condensation** of **excess glucose** to glycogen for storage in liver and muscles
increased **oxidation** of glucose during respiration
promoting conversion of carbohydrates to **fats**
123
whhats deamination?
excess amino acids r deaminated. thhe amino grp (N2) is removed -> form ammonia -> canged to urea -> excreted by kidney via urine
carbon-containing compound is leftover -> used for aerobic metabolism -> ATP or converted to glucose-> stored as glycogen in the liver and muscles.
123
3 associated vessels to the liver
the **hepatic portal vein** which brings digested food substances from the gut
the **hepatic artery** which brings oxygenated blood and nutrients to the liver from the heart
the **hepatic vein** which brings deoxygenated blood from the liver back to the heart
123
what do thhe beta () cells of the islets of Langerhans in the pancreas do
The beta () cells of the islets of Langerhans in the pancreas detect the high blood glucose concentration and secrete the hormone insulin.
124
wat happens when blood glucose level rises above 160 mg per 100 cm3 blood,
excess glucose is excreted by the kidneys in urine. This is known as diabetes mellitus.
124
wat happens when blood glucose level may fall below 80 mg per 100 cm3 blood.
The glycogen store in the liver is broken down to **glucose**. This is stimulated by the hormone **glucagon**, secreted by the alpha () cells of the islets of Langerhans in the pancreas.
124
what can liver cells do
- convert excess carbohydrates to fats
- remove cholestrol from blood and breaking it down
- hydrolysis of fats into fty acid + glycerol
124
wat happens when blood glucose level may fall below 40 mg per 100 cm3 blood.
the brain cells are adversely affected, leading to coma.
125
what happens to old rbc
rbc gets engulfed by macropphages and releases haemoglobin
globin is the protein part and its broken down to its amino acids
iron in the heme is taken out and stored in the liver and reused.
The remaining part of the heme molecule -> biliverdin -> bilirubin, a yellowish pigment that becomes part of bile, a substance produced by the liver.
126
wat does liver do to hormones
The liver is the primary site for the absorption and recycling of hormones. Steroid hormones such as the sex hormones (oestrogen and testosterone), insulin, glucagon, adrenaline and thyroid hormones are degraded in the liver.
127
cirrhosis of the liver causesd
High doses of alcohol may lead to cirrhosis of the liver, a disease in which liver cells are damaged and replaced with fibrous tissue.
127
effects of alcohol consumption on the brain
- slows down the function of the brain and nervous system. Electrical signals take a longer time to travel to or from the brain.
- self-control is reduced.
- increases the reaction time
