Unit 2.1 The Human Body Flashcards
1
Q
2.1.1 Life Processes:
All living things perform essential functions, What are these?
A
MRS GREN: Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition
2
Q
2.1.2 Basic Chemistry
What do chemical changes involve?
A
Chemical changes involve changing the bonds that hold atoms together, they all involve energy transfers.
3
Q
What is the activation energy?
A
The energy required to break chemical bonds, supplied by the collision that occur between molecules as they move randomly.
4
Q
What can affect the rate of a reactions?
A
The higher the temperature, the more frequently these collisions occur and the faster the rate of reaction
5
Q
What is released when new bonds form?
A
Energy
6
Q
What is an Endothermic reaction?
A
More energy is taken in from the environment to break bonds than is released when new bonds are made. e.g photosynthesis.
7
Q
What is an Exothermic reaction?
A
More energy is released when new bonds are formed than is taken in to break bonds. Exothermic reactions usually warm their environment eg. respiration.
8
Q
What is the core temperature of a human?
A
37 degreesC
9
Q
Due to the relatively low concentration fo molecules inside cells, most chemical reactions needed inside humans would not happen quickly enough to sustain life, what do we have to help with this?
A
Biological catalysts called enzymes speed up chemical reactions in living organisms.
10
Q
What differences can be found within molecules?
A
Tiny charge differences
11
Q
What are covalent molecules with dipoles known as?
A
Polar molecules
12
Q
What are polar molecules held together by?
A
Electrostatic forces - they are weaker than ionic bonds but because they form between all the molecules in a substance there are a lot of them and they can have a major effect.
13
Q
What is the best known example of an electrostatic force?
A
Hydrogen bonds.
14
Q
When do hydrogen bonds occur?
A
When hydrogen atoms are covalently bonded to extremely electronegative atoms such as oxygen, nitrogen or fluorine. e.g when oxygenated hydrogen are covalently bonded to form a hydroxyl group, the oxygen always has a greater share of electrons than the hydrogen so the molecules have some polar nature.
15
Q
What type of compound often contain hydroxyl groups giving them a polar nature?
A
Organic compounds.
16
Q
2.1.3 Basic Biochemistry
What are organic molecules?
A
Organic molecules are compounds of carbon.
17
Q
Compounds which are involved in human biochemistry normally contain what?
A
Mainly carbon, hydrogen and oxygen and are often large complex molecules.
18
Q
What are inorganic compounds?
A
They do not contain carbon (there are exception such as carbonate ions or carbon dioxide) and they are usually small (made up of just a few atoms).
19
Q
What are some important inorganic compounds in the body?
A
Water, salts including sodium chloride, and cerium acids and soluble bases (called alkalis)
20
Q
What percentage of your body is water?
A
Between 50-70%
21
Q
Water is an excellent solvent, what does this mean?
A
Many other compounds dissolve in it. Most of the bodies chemical reactions take place in solution in water.
22
Q
Does water have a high or low heat capacity?
A
High heat capacity, meaning it takes a lot of energy to warm it up and a long time to cool down.
23
Q
Water cannot be compressed, therefore what function can it provide in the body?
A
It acts as a protective cushion for vital body organs, for example water makes up an important part of the cerebrospinal fluid that cushions the brain and the amniotic fluid that protects the foetus in the amniotic sac.
24
Q
What are salts, acids and bases called which dissolve in water?
A
Electrolytes
25
What happens to electrolytes when they dissolve in water?
Electrolytes dissociate when they dissolve in water so that their constituent positively and negatively changes particles called ins are able to move about in solution.
26
Can electrolyte in solution conduct electricity?
Yes
27
Salts, acids and bases are important features of body chemistry, what are examples of salts in living organisms?
Sodium and potassium ions from sodium and potassium salts are essential for the conduction of nerve impulses. Nitrate ions are needed for the production of proteins by plants.
28
Salts, acids and bases are important features of body chemistry, what do acids do in living organisms?
Acids transfer hydrogen ions (protons) to water molecules when they are dissolved in water so they are known as proton donors.
29
What is a base?
A substance which contains an ion or molecules which can take up hydrogen ions, they are proton acceptors. If a base is dissolved in water it takes some hydrogen ions from the water molecules and leaves hydroxide ions in the solution OH- ions.
30
What are bases which dissolve in water called?
Alkalis
31
What is the pH of an aqueous solution?
The pH of an aqueous solution is a measure of the concentration of the hydrogen ions in the solution.
32
If a solution has the same concentration of hydrogen ions and hydroxide ions what is it? what is its pH
Neutral, pH 7
33
If a solution has a pH below 7, what is it?
Acidic, it has more hydrogen ions than hydroxide ions
34
If a solution has a pH above 7, what is it?
Alkaline, it has more hydroxide ions than hydrogen ions in it.
35
Different fluids in the body have different pHs: What is the pH of the following:
Blood, Cerebro-spinal fluid, Pancreatic juice, Bile, Saliva, Urine and Vaginal Fluid
```
Blood = 7.35 - 7.45
Cerebro Spinal Fluid = 7.4
Pancreatic Juice = 7.1 - 8.2
Bile = 7.6 - 8.6
Saliva = 6.35 - 6.85
Urine = 4.6 - 8.0
Vaginal Fluid = 3.5 - 4.5
```
36
2.1.3.1 Carbohydrates:
| What do carbohydrates include?
Sugars, starches, glycogen and cellulose.
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What is the most common carbohydrate
The simple sugar called glucose?
38
What is the structure of glucose?
Glucose contains 6 carbon atoms joined together.
39
What are glucose molecules used in, in the body?
Glucose molecules are then in by the cell of your body and used cellular respiration to provide the energy needed for all the reactions that take place in your cells.
40
What are complex carbohydrates made up of?
Complex carbohydrates are made up of long chains of sugar molecules.
41
Name some examples of complex carbohydrates?
Glycogen is a complex carbohydrate stored in the muscles and the brain.
starch if important in our diets because it is uneasily digested complex carbohydrate.
Cellulose is a very important complex carbohydrate that makes up the cell walls of plants - we cannot digest cellulose so it plays an important role as fibre in our digestive system
42
What percentage of our body mass is carbohydrate?
the body cannot store much carbohydrate, it makes up up 2-3% of your body mass.
43
What percent of organic matter in the body do proteins account for?
Over 50%
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What are the building blocks of proteins called?
Amino acids.
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Joining together amino acids into long chains forms what?
Peptides
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What associates to form proteins?
Peptide chains.
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What are protein molecules often folded into?
Complex 3D shapes which are important for the way they function.
48
What is important for holding together the 3D shapes of the protein molecules?
Hydrogen Bonds.
49
A healthy adult body consists of what percentage of protein?
About 12-18%
50
Proteins that are involved in chemical reactions, enzymes or which bind to receptors such as hormones and antibodies are known as what?
Functional proteins
51
Proteins which form the bulk of many tissues are known as what?
Structural Proteins, for examples action and myosin in muscle or keratin in the skin.
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2.1.3.3 Lipids:
| What percentage of the body mass do lipids make up?
Lipids are organic compounds and mae up 18-25% or more of the body masss?
53
Lipids are hydrophobic, what does this mean?
They do not dissolve in water or watery solutions.
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What are triglycerides made up of?
Triglycerides are made up of 3 fatty acids joined to a molecule of glycerol. The type of lipid is determined on the combination of fatty acids.
55
What are triglycerides good stores of in the body?
Triglycerides are highly concentrated energy stores for the body. The provide more then twice as much energy per gram as carbs or proteins.
56
What are phospholipids?
Phospholipids are triglycerides where one of the fatty acids is replaced by a phosphate group - this results in a polar molecules, important role in the cell membranes.
57
What are steroids?
Steroids are another type of lipid here the molecules for a ring structure.
58
What important functions do steroid hormones have in the body?
Steroid hormones are very important in controlling the body responses to stress, sexual development and in reproduction.
59
What is an important steroid?
Cholesterol, which is manufactured by the liver and also found in animal products such as meat, cheese and eggs. Cholesterol is vital for brain functioning and the production of many hormones.
60
What are the information molecules of the cell?
Nucleic acids - they carry information needed to form new cells.
61
The information is carried in the form of a code molecule of what?
DNA deoxyribonucleic acid
62
What is another nucleic acid which is used to carry the DNA code into the body of the cell and use it to make proteins?
RNA ribonucleic acid
63
DNA and RNA are both large polymers made up of long chains of nucleotides, what is each nucleotide made up of?
A sugar, a nitrogen-containing base and phosphoric acid. the arrangement of the nucleotides determines the structure of the molecule.
64
What shape do the long strands of DNA form?
They are coiled into a double helix.
65
2.1.4 Enzymes:
| What are enzymes?
Enzymes are proteins that act as biological catalysts, speeding up chemical reactions by lowering the activation energy without being affected themselves.
66
What determines an enzymes active site?
The tertiary or quaternary £D structure of a proteins
67
What is the active site?
The active site its an area of the enzyme that binds to a specific molecule or type of molecule (the substrate) to catalyse a reaction.
68
What happens when a substrate(s) binds to the active site?
The binding of the substrate or substrates to the active site of the enzyme lowers the activation energy so the reaction takes place more easily.
69
How much faster can an enzyme catalysed reaction take than the same reaction occurring without enzymes?
Enzyme catalysed reactions take place between 100 million to 10 billion times more rapidly than the same reactions occurring without enzymes.
70
What are anabolic reactions?
Enzyme catalysed reactions building up bigger molecules from smaller ones.
71
What are catabolic reactions?
Enzyme catalysed reactions that break larger molecules into smaller ones.
72
What do the names of enzymes normally end in?
The suffix -ase eg. amylase found in human saliva
73
How are enzymes classified?
According to the type of chemical reaction they catalyse. E.g. oxidase add oxygen to a compound, lipase break down triglycerides
74
What controls wether an enzyme is active or inactive?
Substances within the cell may either enhance or inhibit the action of an enzyme. The chemical environment within a cell controls wether enzymes are switched on or off, giving control over which reactions take place in a cell at any one time.
75
2.1.5 Basic Cell Biology:
Cells are the basic unit of most living organisms,
Why are many of the billions of cells in the human body specialised or adapted?
To carry out particular functions in the body - for example the cells of the retina in the eye are sensitive to light and then cells which make up the muscle of your heart contract around 70 times a min without tiring and the white blood cell of the immune system make antibodies or engulf pathogens.
76
What are the different levels of organisation in the human body?
Specialised cells work together to form tissue and several tissues together form organs. Several organs working together to carry out a bodily function are known as an organ system and finally all the organ systems working together make up the body.
77
What is the name of the membrane that surrounds a typical human cell?
Known as the cell surface or plasma membrane.
78
What can be found inside the membrane?
Inside the membrane is a jelly like liquid called cytoplasm - it contains most of the materials needed to cary out day to day cellular processes.
79
What is usually the largest organelle in a cell?
The nucleus, it can be seen with a light microscope.
80
What does the nucleus do?
The nucleus contains the DNA required to control the functions of the cell - the nucleus organises and directs reactions and controls the cells division and replication
81
What does the nucleus look like?
It is often spherical in shape and it is surrounded by a double membrane containing lots of holes or pore so it can communicate with the rest of the cell.
82
What can be found inside the cell?
Inside the nuclear membrane is deoxyribose nucleic acid (DNA), the genetic material which codes for the characteristics of the organism and is passed on when the cell divides.
83
What are chromosomes?
When the cell is not dividing the NDA is bonded to protein to form chromatin, which forms the structures men in cell replication, the chromosomes.
84
What does Ribonucleic acid do?
RNA translates the genetic code from DNA into instructions for making proteins in the cytoplasm of the cell
85
What is the extra dense area of almost pure DNA which seems to be involved in producing RNA for the ribosomes?
The nucleolus
86
What is the structure of the cell surface (plasma) membrane?
Double layer of phospholipids with other molecules floating in it, including proteins and cholesterol as well as glycolipids and glycoproteins, molecules that combine a carbohydrate with a protein or a lipid.
87
What can the proteins act as?
Pores letting substances into or out of the cell.
88
What can the level of cholesterol effect?
How flexible the membrane is
89
The carbohydrate part of the glycoproteins and glycolipid molecules stick out of the membrane, what do they act as?
They act as part of the cell recognition system.
90
The mitochondria are the powerhouse of the cell. What happens in the mitochondria?
A complex series of biochemical reactions release energy in the form of ATP from the respiration of food.
91
What can ATP be used for?
ATP can be used to drive all the other functions of the cell and ultimately the entire organism.
92
What do mitochondria also include that is unusual for an organelle?
The contain their own genetic material so when a cell divides the mitochondria replicate themselves
93
What type of membrane do the mitochondria have?
The have a double membrane the outer one is a selectively permeable barrier while the inner membrane has many folds to increase the surface area on which chemical reactions occur.
94
When is ATP able to release energy?
ATP is able to release energy wen it undergoes enzyme catalysed hydrolysis to form adenosine diphosphate ADP and inorganic phosphate molecule.
95
How can ATP be reformed?
ATP can be reformed from ADP and phosphate in a process which needs an input of energy - this is what happens in cellular respiration.
96
What is the endoplasmic reticulum?
The ER is a three dimensional network of membrane bound sacs and tubes that spreads through the whole cytoplasm. the network links with the membrane around the nucleus.
97
What is the rough ER?
The outside of the RER is encrusted with granules called ribosomes. The ribosomes make the proteins and the ER isolates and transports these proteins once they have been made. Some of the proteins such as digestive enzymes and hormones are not needed by the cell which has made them so they are secreted. Most other proteins are needed within the cell.
The RER has a large surface area giving it lots of space for the synthesis of all the proteins needed allowing it to store and transport proteins both around the cell and from the inside to the outside.
98
If a cell secretes a lot of material such as those producing the digestive enzymes in the lining of the gut, what will it have a lot of?
It will have a lot of RER.
99
What is the Smooth Endoplasmic reticulum involved in?
The SER isn't covered in ribosomes, it is involved in synthesis and transport but synthesis and transport of steroids rather than proteins. lots of SER are found in the testes and the liver.
100
What is the golgi body made up of?
The golgi body is made up of stacks of parallel flattened membrane pockets which link with but are not joined to the RER.
101
How are the golgi bodies formed?
Proteins are transported from the RER in small vesicles which pinch off the RER and fuse to form the pockets of the golgi body itself. Carbohydrates are added to the proteins to form glycoproteins which is the main substance secreted from the cell.
Mucus is an example of a glycoprotein.
102
What are Lysosomes?
Lysosomes appear as dark spherical bodies in the cytoplasm of most cells and contain a powerful mix of digestive enzymes. Lysosomes frequently fuse together with each other and with membrane bound vacuoles containing either pathogens or obsolete organelles.
the enzymes break down the contents into molecules that can be reused.
103
What is apoptosis?
Apoptosis is where lysosomes rupture to release their enzymes to destroy the entire contents of a cell if it is damaged or not working.
104
What cells and where can centrioles me found in?
Animal and fungal cells but not plant cells near to the nucleus in pairs.
105
What is each centriole made from?
Each centriole is made up of nine bundles of tubules.
106
What do the centrioles do?
Centrioles pull apart to produce a spindle of microtubules which help move the chromosome apart when the cell is dividing.
107
What are cilia and flagella?
Cilia and flagella are common moving structure found in many cells.
108
What are the differences between cilia and flagella in terms of length, numbers and purpose
Cilia length = 5-10 micrometers
Flagella length = 100 micrometers
Both lash backwards and forwards. In cilia the movement may be pit to other uses but in flagella it is used to move the whole cell.
Cilia are found in much greater numbers whereas a single flagellum can move a cell. EG. in the lungs millions of cilia waft mucus up from the lungs whereas a single flagellum move a sperm towards an egg.
109
What is the cytoskeleton?
The cytoskeleton is a feature of all eukaryotic cells - it is a dynamic 3D wed like structure that fills the cytoplasm made up of microfilaments, proteins fibres and microtubules about 20nm in diameter. microtubules are made from proteins and are found both singly and in bundles throughout the cytoplasm.
110
What is the function of the cytoskeleton?
The cytoskeleton performs several vital functions it gives the cytoplasm structure and keep the organelles in place. it is closely lined with cell movement and transport within cells. Many of the proteins involved are closely related to actin and myosin, the contractile proteins in muscle.
111
What are vacuoles?
Vacuoles are not permanent features of animal cells, they are membrane linked enclosures of cell sap which are formed and lost as needed.
112
Do all cells have vacuoles?
Some cells have them for example white blood cells form vacuoles around pathogens which are engulfed and digested but most do not.
113
Individual cells in the human body usually work together, what are they attach to each other at?
Cell junctions.
114
2.1.6 Cell reproduction and growth:
| How many chromosomes do normal human body cells have? what is the exception?
46 chromosomes arranged in 23 pairs - the exception is the ova and the sperm.
115
What do the chromosomes contain?
The chromosomes contain around 25,000 - 30,000 genes which control the physical and chemical characteristics of your body.
116
Why do cell need to reproduce?
To make more cells so the body can grow. to replace worn out or old cells and to form the special sex cells, the ova and sperm.
117
What is normal cell division called?
Mitosis.
118
What is the first phase of mitosis?
G1 phase: The cell spends a long time functioning normally - this can be between several hours or several months.
119
What is the second phase of mitosis?
S Phase: The cell enters a stage where it replicates chromosomes.
120
What is the third phase of mitosis?
G2 phase: the cell continues to grow for a few hours until mitosis.
121
What is the forth phase of mitosis?
The chromosomes divided by mitosis followed by the division of the cytoplasm to form two cells. This form 2 identical daughter cells.
122
What are phases G1, S and G2 also know as collectively?
Interphase.
123
What happens overall in mitosis?
Each parent cell divides to form 2 genetically identical daughter cells which are an exact copy of the parent cell so they are clones. This happens as part of the regular cell cycle.
If a cell has 2 pairs of chromosomes (4 in total), firstly each chromosome is copied and the cell splits into the two daughter cells each with 4 chromosomes identical to the parent cell.
124
How long can the cell cycle take?
The cell cycle can take anywhere from several hours in rapidly dividing cells for example an embryo to many years in the body of an older person. The main difference in the length of the cell cycle is always the length of time the cell remains functioning normally before dividing.
125
What is the cell cycle controlled by?
The cell cycle is controlled by a number of chemical signals made in response to different genes. The control is brought about at a number of checkpoints where the cell cycle moves from one phase to the next .
126
What happens once the cells have divided?
They differentiate - different genes are switched on or off as the cells become specialised.
127
What happens when control of the cell cycle is lost?
A tumour will develop. All forms of cancer involve rapid uncontrollable cell growth and reproduction, and the checkpoints on the cell cycle are therefore an important target area for the pharma industry.
128
What is the other cell division called?
Meiosis.
129
Where does meiosis take place?
Meiosis only takes place in the ovaries and testes during the production of the ova and sperm.
130
What happens in meiosis?
In meiosis one cell divides into two as in mitosis but then immediately divides again producing 4 daughter cells each of which contains only half the number of chromosomes as the parent cell, so 23 chromosomes. When an ovum is fertilised by sperm the resulting cell has the normal number of 46 chromosomes in 23 pairs, one from each parent.
131
2.1.7: Specialised cells and tissues:
Tissues are made up of a large number of cells, specifically adapted to carry out a particular function what are some of the main types of tissues?
Epithelial tissue, connective tissue, muscular tissue and nervous tissue.
132
What and where is the epithelial tissue found?
Epithelial tissue is a cellular tissue found in the skin and many other body areas.
133
What does the epithelial tissue provide?
Epithelial tissue provides a lining membrane or covering for the surfaces of many structures and organs in the body inc the skin, lining of the digestive system, lining of the reproductive tract and the lining of the urinary bladder. if an organ or organ system has contact with the outside world it will be lined by epithelial cells.
134
What is the difference between a simple epithelial and a compound epithelium?
A simple epithelium is a single layer of cells and a compound epithelium involves cells arranged in several layers.
135
There are different forms of each of the main types of epithelium - what is an example of one?
Some epithelial cells are ciliated - covered with a layer of cilia which moves in waves to move substances about - this is found in the respiratory tract and fallopian tubes. In the breathing system environmental factors such as tobacco smoke and polluted air can stop the cilia moving
136
What is the endothelial tissue?
Endothelial tissue is the tissue that lines the closed circulatory system which doesn't not open onto the outside world. The form extremely smooth lining in the blood vessels which helps prevent the formation of blood clothes which might in turn bloc blood vessels.
137
What does connective tissue do?
Connective tissue supports, binds and connects tissues of the body together.
138
What are the major types of connective tissues?
Bone, cartilage and fibrous tissues which mae up ligaments and tendons
139
What is adipose tissue?
Adipose of fatty tissue is made up of cells filled with fat. it forms a food reserve provides insulation and can be protective for these reasons it is fund particularly under the skin and around the major organs.
140
What is areolar tissue?
Areolar tissue is the most widely distributed connective tissue in the body. It is a soft, pliable tissue that cushions and protects the body. it appears as a thin delicate transparent skin around and between major organs of the body.
141
What is the yellow elastic tissue?
Yellow elastic tissue consists of yellow fibres which can stretch, they are found in the walls of arteries and in the bronchi and alveoli of the lungs.
142
Is blood a connective tissue?
Blood is also sometimes regarded as a connective tissue because it consists of blood cells and blood plasma which connect many areas of the body.
143
If there is movement anywhere in the body, what tissue is involved?
Muscular tissue, - they can contact and relax and as a result it can produce movement.
144
What is the major difference between muscle fibres and elastic connective tissue?
When Elastic tissue is stretched it can recoil to its original size, but muscle fibres can contract without having to be stretched first.
145
What are the 3 main types of muscular tissue in the body?
Skeletal muscle, smooth muscle and cardiac muscle.
146
What is skeletal muscle?
Most skeletal muscles move bones of the skeleton. It is also called voluntary muscle or striped muscle because you can control what it does and it appears striped under a microscope.
147
What it smooth muscle composed of?
Smooth muscle is composed of elongated, spindle-shaped cells in muscles we cannot voluntary control.
148
Where is smooth muscle found?
Smooth muscle is found in the walls of hollow internal structure such as blood vessels and most of the internal organs such as the stomach, bladder and respiratory passages. It is also found in the skin, attached to hair follicles. Smooth muscles move substances through pathways in the body.
149
What does cardiac muscle consist of?
Cardiac muscle consists of a branching network of cells that are linked electrically and mechanically to function as a unit.
150
Is skeletal or cardiac muscle more powerful?
Cardiac muscle is much less powerful than skeletal muscle but its much more resistant to fatigue.
151
What makes the heart beat and controls the rate of contraction?
It has an intrinsic rhythmic contraction which makes the heart beat but all responds to the autonomic nervous system and to hormones, which can speed up or slow down the rate of contraction.
152
What is nervous tissue designed to do?
Nervous tissue is specifically designed to carry electrical messages within the body.
153
What does the cell body of a nerve cell contain?
The cell body contains the nucleus which doesn't divide or replicate in the way most other cells do.
154
What can damage to the cell body lead to?
Damage to the cell body may lead to degenerate of the entire neurone, damage to a collection of neurones may lead to paralysis for example when the spinal cord is cut.
155
What are axons?
Neurones have projections of varying lengths called axons, there are nerve fibres
156
What function does the synapse have?
A synapse is a gap between neurones which nurse impulses cross. Chemicals called neurotransmitters move across the gap and start up a new impulse in the next neurone.
157
What functions do neurotransmitters have?
They can inhibit or prevent nerve impulses from eating a cell or they can stimulate and cause a new one.
158
What is the term membrane applied to?
The term membrane its applied to any thin sheet of tissue which forms a lining for various structures and organs. Some are made of epithelial tissue and some are made of connective tissue.
159
The epithelial tissue membranes include:
Mucous membranes, serous membranes and cutaneous membranes.
160
What do the mucous membranes line?
Mucous membranes line a body cavity that opens directly to the exterior, like the entire digestive, respiratory and reproductive tracts and most of the urinary tract.
161
What special cells do mucous membranes contain?
Mucous membranes contain special special goblet cells that secrete sticky fluid called mucus. - this prevents body cavities from drying out.
162
What does the epithelial layer in the membrane of the gut secrete?
Some of the enzymes needed digestion and is the site of food and fluid absorption.
163
What are the serous membranes made of?
The serous membranes are made up of flattened cells which contain watery diluted mucus called serous fluid.
164
What body cavities do the serous membranes line?
They line body cavities that do not open directly to the interior and provide a smooth, mist gliding surface for when organs move onto or across each other. E.g are the pericardium which covers the heart, the pleura which line the lung cavities and the perineum which lines the abdominal cavity and covers the abdominal organs.
165
What is the cutaneous membrane?
The Skin.
166
What do the connective tissue membranes include?
Synovial membranes and meningeal membranes.
167
What is the synovial membrane?
Synovial membranes lack an epithelium layer and line structure hat do not open directly to the exterior. They are found lining joint cavities to lubricate the movement of bone against bone or form fluid filled sacs called bursae between ligaments, tendons and bones.
168
What are the meningeal membranes?
These cover and protect the surface of the brain and spinal cord.
169
What causes disease to occur?
Disease occurs when for whatever reason some of the body cells tissues or organs do not work normally.
170
What are acute diseases?
A disease or disorder which comes on rapidly and is accompanied by distinct symptoms.
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What are chronic diseases?
Chronic diseases are a long lasting disease which often gradually gets worse.
