B5 Flashcards
(165 cards)
1
Q
Give an example of an animal that does not have a skeleton made of hard material.
A
An example of an animal that does not have a skeleton made of hard material is a worm.
2
Q
Give an example of an animal that has an external skeleton.
A
An example of an animal that has an external skeleton is an insect.
3
Q
Give an example of an animal that has an internal skeleton.
A
An example of an animal that has an internal skeleton is a human.
4
Q
What is an insect’s external skeleton made of?
A
An insect’s external skeleton is made of chitin.
5
Q
What are the different forms of internal skeleton?
A
The different forms of internal skeleton are those made only of cartilage e.g.sharks; and those made mainly of bone with some cartilage (outer ear, nose, ends of long bones) e.g. humans.
6
Q
Name and describe 3 different fractures of bones.
A
3 different fractures of bone include simple, compound and greenstick.
7
Q
What can be used to detect fractures?
A
An X-ray can be used to detect fractures.
8
Q
What is a joint?
A
A joint is the place where two or more bones meet.
9
Q
What are bones moved by?
A
Bones are moved by muscles.
10
Q
What are muscles attached by?
A
Muscles are attached by tendons.
11
Q
Where in the body would you find a fixed joint, hinge joint, and ball and socket joint.
A
In the body, you would find a fixed joint in the skull, a hinge joint in the elbow or knee, and ball and socket joint in the shoulder and hip.
12
Q
What are the main bones in the human arm?
A
The main bones in the human arm are the humerus, ulna and radius.
13
Q
What are the main muscles in the human arm?
A
The main muscles in the human arm are the biceps and triceps.
14
Q
Explain why an internal skeleton is advantagous compared with an external skeleton.
A
An internal skeleton is advantagous compared with and external skeleton because it provides a framework of the body, can grow with the body, it is easy to attach muscles and it provides flexibility.
15
Q
Are cartilage and bone living or dead tissue?
A
Cartilage and bone are living tissue.
16
Q
What is the structure of a long bone?
A
A long bone has a head covered with cartilage and a shaft containing bone marrow with blood vessels.
17
Q
Why are long bones that are hollow advantagous?
A
Long bones that are hollow are advantagous because they are stronger and wweigh less.
18
Q
Despite being strong, what can happen to bones following a sharp knock?
A
Despite being strong, following a sharp knock bones can easily be broken.
19
Q
Why are elderly people more prone to fractures?
A
Elderly people more prone to fractures because of osteoperosis.
20
Q
Describe the structure of synovial joints.
A
The structure of synonial joints is synovial fluid, synovial membrane, ligaments are cartilage.
21
Q
What are the types and ranges of movement in a ball and socket joint?
A
Ball and socket joints are found at the shoulder and the hip. They are able to move in all directions, or in all three dimensions.
22
Q
What are the types and ranges of movement in a hinge joint?
A
Hinge joints are found at the elbow and knee and they only allow movement in one direction, or in only one plane.
23
Q
How do the biceps and triceps muscles operate?
A
The biceps and triceps muscles operate by contraction and relaxation of antagonistic muscles to bend and straighten the arm.
24
Q
What are cartilage and bone susceptible to?
A
Cartilage and bone are susceptible to infection.
25
What are cartilage and bone able to do if they become damaged?
Cartilage and bone are able to grow and repair themselves.
26
What does the skeleton start off as in humans?
In humans the skeleton starts off as cartilage.
27
What is ossification?
Ossification is when cartilage becomes ossified as it is slowly replaced by the addition of calcium and phosphorus.
28
How can it be determined whether a person is still growing?
It can be determined whether a person is still growing by determining the amount of cartilage present.
29
Why can it be dangerous to move a person with a suspected fracture?
If someone is thought to have a bone fracture it can be dangerous to move them. Movement might make the fracture more serious - for example, it might turn a simple fracture into a compound fracture. Moving someone with a broken back may damage their spinal cord, leading to paralysis.
30
In a synovial joint, what is the function of synovial fluid, synovial membrane, cartilage and ligaments?
In a synovial joint, synovial fluid is oily and acts as a lubricant to reduce friction. The synovial membrane makes synovial fluid. The cartilage is a soft, smooth substance which allows smooth movement as well as acting as a shock absorber. Ligaments are tough bundles of fibre which hold the bones together.
31
Give an example of an organism that doesn't have a circulatory system.
An example of an organism that doesn't have a circulatory system is an amoeba.
32
Give an example of an organism that has an open circulatory system.
An example of an organism that has an open circulatory system is an insect.
33
Give an example of an organism that has a closed circulatory system.
An example of an organism that has a closed circulatory system is a human.
34
What is the difference between an open and closed circulatory system?
In an open circulatory system, blood flows freely through the body cavity, carrying nutrients to. In closed circulatory systems, blood flows through blood vessels (arteries, veins and capillaries) and there is a a heart to push the blood around their body.
35
In a closed circulatory system, what will blood flow in?
In a closed circulatory system, blood will flow in arteries, veins and capillaries.
36
How does heart muscle cause blood to move?
The heart muscle contracts to cause blood to move.
37
What is the heart made of?
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The heart is made of powerful muscles.
38
How is the arm bending and straightening an example of a lever?
The arm acts as a lever when it bends or straightens. The elbow joint is the fulcrum or pivot, the hand moves through a larger distance than the muscles do, the muscles exert a greater force than the load on the hand
39
What supplies the heart muscle with glucose and oxygen?
The coronary artery supplied the heart muscle with gluose and oxygen.
40
Why does the heart muscle need a constant supply of glucose and oxygen?
The heart needs a constant supply of glucose and oxygen so that its muscle cells can respire and continue to contract.
41
What is the pulse?
The pulse is a measure of the heart beat (muscle contraction) to put the blood under pressure.
42
Where can the pulse be detected?
The pulse can be detected in various places including the wrist, ear and temple.
43
Why do many animals need a circulatory system?
Larger, multicellular animals need a circulatory system to transport substances to and from their cells.
44
Describe a single circulatory system.
A single circulatory system is one circuit from the heart.
transport substances to and from their cells.
45
Describe a double circulatory system.
A double circulatory system is two circuits from the heart.
46
Compare the circulatory system of fish and mammals.
Fish have a single circulatory system, but mammals have a double circulatory system. In the circulatory system of a fish, the blood travels from the heart to the gills, where it absorbs oxygen and releases carbon dioxide. It then flows from the gills to the organs and tissues in the rest of the body, and back to the heart. There is just one circuit from the heart. In the circulatory system of a mammal, there are two circuits from the heart:
blood passes from the heart to the lungs - where it absorbs oxygen and releases carbon dioxide - then back to the heart blood passes from the heart to the organs and tissues in the body, and back to the heart.
47
What pressure changes are there in arteries, veins and capillaries?
Blood in the arteries is under high pressure generated by the heart. The blood in veins is under lower pressure than the blood in arteries. The capillaries is where the pressure changes from high to low.
48
How is heart rate linked to activity?
Heart rate is linked to activity. The body's cells need more glucose and oxygen during exercise, and the blood supplies this. The heart rate increases as activity increases.
49
How is heart contraction controlled?
Heart contraction is controlled by groups of cells called pacemakers which produce a small electric current that stimulates muscle contraction.
50
What is commonly used to control heart beat?
Pacemakers are commonly used to control the heart beat.
51
What can be used to investigate heart action?
ECG and echocardiograms are used to investigate heart action.
rrent that stimulates muscle contraction.
52
What hormone increases heart rate?
Heart rate can be increased by the hormone adrenaline.
53
What was the contribution of Galen towards the understanding of blood circulation?
The contribution of Galen towards the understanding of blood circulation was the imprtance of pulse, and the difference between blood in arteries and veins.
54
What was the contribution of William Harvey to the understanding of blood ciculation?
The contribution of William Harvey to the understanding of blood circulation was the circulation.
55
Why does a single circulatory system link to a two-chambered heart?
A single circulatory system (such as in fish) links to a two-chambered heart. One chamber receives blood from the body and the other pumps it back out.
56
Why does a double circulatory system link to a four-chambered heart?
A double circulatory system (such as in humans) links to a four-chambered heart. The right side is involved with moving deoxygenated blood to the lungs, and the left side is involved with moving oxygenated blood to the body.
57
Why is blood under higher pressure in a double circulatory system compared to a single circulatory system?
Blood is under higher pressure in a double circulatory system compared to a single circulatory system so that mterials can be transported more quickly around the body.
58
Describe the cardiac cycle.
One cardiac cycle consists of the atria and then the ventricles contracting so that the blood that has entered the heart is pumped out. This occurs about 70 times every minute and is continuous.
59
Explain the sequence of contraction of the atria and ventricles and the sequence of opening of the semilunar and atrio-ventricular valves.
Deoxygenated blood from the body ebters the right atrium. Oxygenated blood from the lungs enters the left atrium. The right and left atrium contract to pump blood thought the atrio ventricular valves. The right and left ventricles contract and the semilunar valves open allowing blood to be pumped to the lungs and body.
60
How do the pacemaker cells (SAN and AVN) coordinate heart muscle contraction?
Impulses from the SAN cause the atria to contract and stimulate the AVN. Impulses from the AVN cause the ventricles to contract.
61
Name four heart conditions.
There are many heart conditions and diseases, including:
• irregular heart beat
• hole in the heart
• damaged or weak valves
• coronary heart disease and heart attacks.
62
Describe reasons for blood donation.
A blood transfusion may be needed in a medical emergency or during an operation.
63
What are the different blood groups?
The different blood groups are called A, B, AB and O, which are further subdivided into Rhesus positive and negative.
64
What is the function of blood clots at cuts?
The function of blood clots at cuts and appreciate that they sometimes occur abnormally inside blood vessels.
65
Where do blood clots sometimes occur abnormally?
Blood clots sometimes occur abnormally in blood vessels.
66
What drugs can be used to reduce clotting?
Anti-coagulant drugs can be used to reduce clotting.
67
Explain the consequences of a ‘hole in the heart’.
The consequences of a ‘hole in the heart’ are:
• blood can move directly from one side of the heart to the other side of the heart
• less oxygen in the blood
• can require correction by surgery.
68
Explain the consequences of damaged or weak valves in the heart.
The consequences of damaged or weak valves in the heart are: reduced deffective blood circulation, can require replacement by artificial valves.
69
Explain the consequences of a blocked coronary
artery.
The consequences of a blocked coronary artery are: reduces blood flow to the heart muscle, can require treatment by bypass surgery.
70
What devices are there as well as heart transplants?
As well as heart transplants, there are 'heart assist' devices.
71
Describe the process of blood donation.
The blood used in the transfusion comes from stored donor blood. When a donor gives blood their blood group is determined and blood is collected from a vein. It is mixed with an anti-coagulant to stop it clotting, and stored in a fridge.
72
Describe the process of blood transfusion.
A blood transfusion may be needed in a medical emergency or during an operation. When a patient requires a transfusion, their blood group is checked and matched with donor blood. The donor blood is warmed and put into the patient through a vein.
73
What is haemophilia?
Haemophilia is an inherited condition in
which the blood does not easily clot.
74
What drugs are used to control clotting?
Drugs such as warfarin, heparin and
aspirin are used to control clotting.
75
Describe the process of blood clotting.
Platelets in contact with damaged blood vessels, causing a series of chemical reactions leading to the formation of a mesh of fibrin fibres (clot).
76
Explain how a ‘hole in the heart’ results in less oxygen in the blood.
Some people have a ‘hole in the heart’. The septum between the right and left sides of the heart is not complete, and blood can flow from one side to the other. This means that the blood going around the body will carry less oxygen, leading to tiredness and shortness of breath. The hole may be closed by surgery.
77
Why do unborn babies can all have a ‘hole
in the heart’ and do not need a double circulatory
system and why the hole closes soon after birth?
Unborn babies get the oxygen they need from their mother and do not need working lungs. They do not need a double circulatory system, and their heart has a hole between the right and left side. This closes soon after birth so that the double circulatory system can be established. When it fails to close, the baby has a ‘hole in the heart’.
78
Explain the advantages and disadvantages of a heart pacemaker or artificial heart valves over a heart transplant.
A heart transplant is a major operation and there is a shortage of suitable donors. The patient has to take drugs to suppress their immune system for the rest of their life - otherwise the new heart will be rejected by the body. Less difficult operations involve fitting a pacemaker or an artificial valve, and the body is unlikely to reject them. However, they may need to be replaced during the lifetime of the patient.
79
Why is it important tp match the blood group of the donated blood to the patient?
It is important to match the blood group of the donated blood to the patient for a blood transfusion to be successful. Unsuccessful blood transfusions can lead to agglutination.
80
Explain how the presence of antigens and antibodies in red blood cells and blood serum determines how blood groups react and therefore whether a blood transfusion is successful.
Red blood cells carry antigens. These are substances that cause an immune response by the body and the production of antibodies. Antigen A and antigen B are two major blood group antigens.
81
Describe which blood groups (A, B, AB and O) have antigens A and B.
Blood groups A and AB have antigen A. Blood groups B and AB have antigen B.
82
Describe which blood groups (A, B, AB and O) have antibodies anti-A and anti-B.
Blood groups B and O have anti-A antibody. Blood groups A and O have anti-B antibody
83
Explain which blood groups can be used to donate blood to which other blood groups.
Someone can receive blood of their own blood group. Someone with blood group O can donate to anyone, because their red blood cells do not carry A or B antigens - they are 'universal donors'. Group AB patients can receive any type of blood, because they do not have anti-A or anti-B antibodies - they are 'universal recipients'
84
Why do most living things need oxygen?
Most living organisms need oxygen to release energy from food.
85
How do small simple organisms, e.g. amoeba and earthworms, take in oxygen?
Small simple organisms, e.g. amoeba and earthworms, take in oxygen through their moist and permeable external surfaces.
86
What do larger, more complex animals have for exchange of gases?
Larger, more complex animals have special organs for exchange of gases, such as gills and lungs.
87
How does surface area affect the exchange of gases.
The rate of diffusion is increased when the surface area is increased
88
Describe the functions of the main parts of the human respiratory system (trachea, bronchus, bronchioles, lungs, alveoli, pleural membranes, ribs, intercostal muscles and diaphragm).
The Trachea (windpipe) leads from the nose and mouth to the two bronchi. The bronchus leads from the trachea to a lung. Bronchiole are smaller tubes inside the lungs leading from the bronchus to the alveoli. The lungs Contain the gas exchange surfaces. The alveoli are tiny air sacs at the end of bronchioles, where gas exchange happens. Pleural membranes allow the lungs to move easily during ventilation. Ribs provide a moveable cage to enclose and protect the lungs. Intercostal muscles allow the ribcage to change in volume for ventilation to happen. The diaphragm works with the intercostal muscles to allow ventilation to happen
89
Explain the terms breathing, respiration, inspiration (inhalation) and expiration (exhalation).
Respiration is the chemical process that releases energy from food in cells. Breathing or ventilation is the process that gets air into and out of the lungs. breathing in (or inhalation) is called inspiration. Breathing out (or exhalation) is called expiration.
90
Describe the direction of exchange of carbon dioxide and oxygen at the lungs and in tissues.
Gas exchange in the lungs happens in the alveoli. Oxygen diffuses into the bloodstream from the air and carbon dioxide diffuses into the air from the bloodstream
91
Name some conditions and diseases of the respiratory system.
There are many conditions and diseases of the respiratory system, including asthma, bronchitis, pneumonia and lung cancer.
92
Why do methods of gaseous exchange restrict amphibians and fish to their habitats?
Frogs and other amphibians have permeable skin. They can take in oxygen through their skin as long as it is moist. This can restrict them to living in moist habitats. It can also make them susceptible to losing a lot of water from their bodies. Fish carry out gas exchange using their gills. These only work when water is forced across the gill filaments, so fish are restricted to living in water.
93
Understand the process of ventilation in terms of changing volume and pressure to include breathing in humans.
When you inhale, the intercostal muscles contract, expanding the ribcage. The diaphragm contracts, pulling downwards to increase the volume of the chest. Pressure inside the chest is lowered and air is sucked into the lungs. When you exhale, the intercostal muscles relax, the ribcage drops inwards and downwards the diaphragm relaxes, moving back upwards, decreasing the volume of the chest. Pressure inside the chest increases and air is forced out.
94
Explain the terms tidal air, vital capacity air and residual air as part of the total lung capacity.
Tidal volume – the volume of air breathed in or out in one normal breath
Vital capacity – the maximum volume of air that can be breathed out after breathing in as much as you can
Residual volume – the volume of air left in the lungs after breathing out as hard as you can
The total lung capacity is the vital capacity and residual volume added together.
95
Explain how gaseous exchange occurs within alveoli by diffusion between air and blood.
Gas exchange in the lungs happens in the alveoli. Oxygen diffuses into the bloodstream from the air. Carbon dioxide diffuses into the air from the bloodstream. This happens because the concentration of oxygen in the air is higher than its concentration in the blood, and the concentration of carbon dioxide in the blood is higher than its concentration in the air
96
Describe how the respiratory system protects itself from disease by mucus and ciliated cells in the trachea and bronchi.
he respiratory system can protect itself from disease in several ways, for example:
sticky mucus traps dust and pathogens before they can reach the lungs
cells with hair-like cilia waft mucus out of the lungs and into the throat
97
Name 3 causes of lung diseases.
3 causes of lung disases are: 1. Industrial causes (such as asbestosis) 2. Genetic causes (such as cystic fibrosis) 3. Life style (such as lung cancer).
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98
Briefly describe each of the following lung diseases: asbestosis, cystic fibrosis, and lung cancer.
Asbestosis – inflammation and scarring limiting gas exchange. Cystic fibrosis – too much mucus in the bronchioles. Lung cancer – cells grow rapidly reducing surface area in lungs.
99
Describe the tratment for asthma
The treatment for asthma is inhalers.
100
Describe the symptoms of asthma
The symptoms of asthma are difficulty breathing, wheezing, tight chest.
101
Explain why the methods of gaseous exchange of
amphibians and fish restrict them to their habitats:
The methods of gaseous exchange of amhibians and fish restrict them to their habitats because: • the permeable skin of amphibians makes them
susceptible to excessive water loss
• fish gills work by forcing water across the
filaments.
102
Explain how gaseous exchange surfaces are adapted for efficient gaseous exchange
The alveoli have several adaptations for efficient gas exchange. They have a large surface area. They are permeable (they let substances pass through their surface). They have a moist surface (the gases must be dissolved so that they can diffuse across the surface). They have a thin lining, just one cell thick. They have a good blood supply
103
Explain why the respiratory system is prone to diseases.
The respiratory system is prone to disease as it always remains directly in contact with the external environment.
104
Describe what happens during an asthma attack:
uring an astnma attack, the following happens: • the lining of airways becomes inflamed • fluid builds up in airways • muscles around bronchioles contract constricting airways.
105
Describe the position and function of the parts of the human digestive system:
Mouth: Where food enters the alimentary canal and digestion begins
Salivary glands: Produce saliva containing amylase
Oesophagus: Muscular tube which moves ingested food to the stomach
Stomach: Muscular organ where digestion continues
Pancreas: Produces digestive enzymes
Liver: Produces bile
Gall bladder: Stores bile before releasing it into the duodenum
Small intestine - duodenum Where food is mixed with digestive enzymes and bile
Small intestine - ileum Where digested food is absorbed into the blood and lymph
Large intestine - colon Where water is reabsorbed
Large intestine - rectum Where faeces are stored
Large intestine - anus Where faeces leave the alimentary canal
106
Describe the process of physical digestion.
The process of physical digestion is breaking food into smaller pieces by chewing in the mouth and squeezing in the stomach.
107
What happens in chemical digestion?
In chemical digestion the digestive enzymes breakdown large food molecules into smaller ones so they can be absorbed into the blood.
108
Where foes food enter and leave the blood?
Food enters the blood in the small intestine and leaves in body tissues.
109
Explain the importance of physical digestion
The importance of physical digestion is to enable food to pass more easily through the digestive system and to provide a larger surface area.
110
Explain how carbohydrates, proteins and fats are
digested by specific enzymes in the mouth, stomach and small intestine.
Carbohydrates, proteins and fats are
digested by specific enzymes in the mouth, stomach and small intestine.
• carbohydrase breaks down starch to sugar
• protease breaks down protein to amino acids
• lipase breaks down fat to fatty acids and glycerol.
111
What aids protease function in the stomach?
Stomach acid aids protease function.
112
Why do large molecules need to be broken down into small molecules in digestion?
Large insoluble molecules need to be broken down into small water-soluble molecules in digestion so they can be absorbed into the blood.
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113
Describe how small digested food molecules are
absorbed into the blood plasma or lymph in the small intestine.
Small digested food molecules are
absorbed into the blood plasma or lymph in the small intestine by diffusion.
114
Explain how bile, from the gall bladder, improves fat digestion.
Bile is secreted into the small intestine where it has two effects. It neutralises the acid providing the alkaline conditions needed in the small intestine, and it emulsifies fats providing a larger surface area over which the lipase enzymes can work
115
Explain why the pH in the stomach is maintained at acidic levels, whereas the pH in the mouth and small intestine is alkaline or neutral.
The stomach produces hydrochloric acid. It kills many harmful microorganisms that might have been swallowed along with the food. The enzymes in the stomach work best in acidic conditions – at a low pH. The enzymes in the mouth and small intestine work best in alkaline or netral conditions.
116
Describe the breakdown of starch.
The breakdown of starch is a two step process involving the breakdown of starch into maltose and maltose into glucose.
117
Explain how the small intestine is adapted for the
efficient absorption of food.
The small intestine has a large internal surface area for absorption to happen quickly and efficiently.
118
Explain the difference between egestion and
excretion.
Excretion is the removal of waste products from the body. It is different from egestion - which is the removal of undigested semi-solid waste (faeces) from your anus.
119
What are the names and positions of the main organs of excretion?
The main organs of excretion are the lungs, • kidneys and skin.
120
What do the kidneys excrete?
The kidneys excrete urea, water and salt in urine.
121
What is the amount and concentration
of urine produced affected by?
The amount and concentration of urine produced is affected by water intake,
temperature and exercise.
122
Where is carbon dioxide produced by respiration removed from the body?
Carbon dioxide produced by respiration is removed from the body through the lungs.
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123
What is the importance of maintaining a constant concentration of water molecules in blood plasma?
For the cells of our body to work properly, it is important that their water content is maintained at the correct level.
124
Explain how kidneys work.
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The kidneys work by filtering blood at high pressure and water and useful substances are reabsorbed.
125
Where is rea that urea, produced in the liver (from excess amino acids), removed from the blood?
Urea, produced in the liver (from excess
amino acids), is removed from the blood by the kidneys.
126
Explain why the amount and concentration of urine
produced is affected by water intake, heat and
exercise.
The kidneys maintain our water balance by producing urine of different concentrations.
When the water level of our blood plasma is low, more water is reabsorbed back into the blood and the urine becomes more concentrated. When the water level of our blood plasma is high, less water is reabsorbed back into the blood and our urine is more dilute.
127
Explain why carbon dioxide must be removed from
the body.
Carbon dioxide must be removed from
the body due to the toxic effect of high levels.
128
Explain how the structure of the kidney tubule
(nephron) is related to filtration of the blood and
formation of urine.
The structure of the kidney tubule
(nephron) is related to filtration of the blood and formation of urine. It has a filter unit of glomerulus and capsule, a region for selective reabsorption and a region for salt and water regulation.
129
Explain the principle of a dialysis machine and how
it removes urea and maintains levels of sodium and glucose in the blood of a patient with kidney failure.
In a dialysis machine, ‘dirty’ blood (high in urea) is taken from a blood vessel in the arm, mixed with blood thinners to prevent clotting, and pumped into the machine. Inside the machine (separated by a partially permeable membrane) the blood flows in the opposite direction to dialysis fluid, allowing exchange to occur between the two where a concentration gradient exists. Dialysis fluid contains a glucose concentration similar to a normal level in the blood and a concentration of ions similar to that found in normal blood plasma. It contains no urea. As the dialysis fluid has no urea in it, there is a large concentration gradient - meaning that urea moves across the partially permeable membrane, from the blood to the dialysis fluid, by diffusion. As the dialysis fluid contains a glucose concentration equal to a normal blood sugar level, this prevents the net movement of glucose across the membrane as no concentration gradient exists. As the dialysis fluid contains an ion concentration similar to the ideal blood plasma concentration, movement of ions across the membrane only occurs where there is an imbalance.
130
Explain how the concentration of urine is controlled by the antidiuretic hormone (ADH), released by the pituitary gland.
The concentration of urine is controlled by the antidiuretic hormone (ADH), released by the pituitary gland. ADH increases permeability of kidney tubules so
more water is reabsorbed back into the blood. ADH production is controlled by a negative feedback mechanism.
131
Explain how the body responds to increased carbon dioxide levels in the blood.
The body responds to increased carbon
dioxide levels in the blood by detecting levels in the brain and increasing the rate of breathing.
132
Describe the function of the scrotum.
The function of the scrotum is that it keeps the testes outside the body where the temperature is better for sperm development.
133
Describe the main stages of the menstrual cycle:
The main stages of the mentrual cycle are: • menstruation – uterus lining breaks down (period)
• thickening of uterus lining
• ovulation – egg released by ovary,
134
Are fertilisation and pregnancy guaranteed for all couples?
Fertilisation and pregnancy are not guaranteed for all couples.
135
Describe 3 causes of infertility.
3 causes causes of infertility are:
• blockage of fallopian tubes or sperm ducts
• eggs not developed or released from ovaries
• insufficient fertile sperm produced by testes.
136
How can pregnancy can be achieved in some cases for couples struggling to conceive?
In some, but not all, cases pregnancy can be achieved with the help of fertility treatment.
137
Understand reasons for checking foetal development.
The reasons for checking foetal development are to monitor the development of the foetus and check for any abnormalities.
138
Name and locate human endocrine glands and name the hormones produced.
Human endocrine glans include the ovaries which produce oestrogen and progesterone and the testes which produce testosterone.
139
Describe the role of hormones in the menstrual cycle.
The role of hormones in the menstrual cycle are:
• oestrogen causes the repair of the uterus wall
• progesterone maintains the uterus wall
• FSH (follicle-stimulating hormone) stimulates an
egg to develop
• LH (luteinising hormone) controls ovulation.
140
Where are FSH and LH released?
conceive?
FSH and LH are released by the pituitary gland in the brain.
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141
Explain treatments for infertility.
Treatments for infertility to include: • artificial insemination, which involves inserting sperm into the woman’s uterus.
• FSH may be used to encourage the production of several mature eggs. • “in vitro” fertilisation (IVF) involves fertilising an egg outside the woman’s body and then implanting it into her uterus.
• egg donation can be used in IVF.
• surrogacy, which involves implanting a woman’s fertilised egg into another woman’s uterus. This surrogate mother carries the baby until it is born and then gives it to the biological mother.
• ovary transplants, where the woman receives an ovary from her identical twin, as there will be no problems with organ rejection. It may also work if, for example, the woman’s ovaries were removed and frozen before cancer treatment - and then transplanted back into her body.
142
Explain the arguments for and against infertility treatments.
Fertility treatments increase a woman's chance of becoming pregnant, although the treatment may not always work. On the other hand, because the treatment boosts the production of mature eggs, multiple conceptions sometimes occur, with twins or triplets being expected. This increases the risk of complications in pregnancy and childbirth, and may lead to premature or underweight babies.
143
Describe how foetal development can be checked to identify conditions such as Down’s syndrome using amniocentesis and chromosomal analysis.
In amniocentesis, doctors guide a thin needle through the woman’s abdomen and into the amniotic fluid around the developing foetus. Ultrasound is used to make sure that the needle goes to the correct place, and a sample of amniotic fluid is taken. The fluid contains some cells from the foetus, and the chromosomes in these cells can be examined for abnormalities. Down’s syndrome, for example, is most often caused by having an extra copy of chromosome 21.
144
Explain why foetal screening raises ethical issues.
Foetal screening raises ethical issues. Invasive diagnostic tests, such as amniocentesis, are usually only offered to women when there is a significant risk that their baby may have a serious condition or abnormality. There is a small risk of miscarriage (losing the baby) - around 1 in 100 tests. Where a test is positive for a certain abnormality, the parents of the unborn baby will face the difficult decision of whether to have the baby or abort it.
145
How can fertility in humans be controlled?
Fertility in humans can be controlled by the artificial use of sex hormones such as the contraceptive pill and fertility drugs.
146
Explain how negative feedback mechanisms affect
hormone production in the menstrual cycle.
Negative feedback mechanisms affect the production of hormones in the menstrual cycle. High levels of one hormone may inhibit (prevent) the production of another hormone. FSH (follicle-stimulating hormone) stimulates the ovaries to release oestrogen. High levels of oestrogen then inhibit the further production of FSH - an example of negative feedback. Oestrogen also stimulates the release of LH (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone. High levels of progesterone then inhibit the further release of LH - another example of negative feedback.
147
Explain how fertility can be reduced.
Fertility can be reduced by the use of
female hormones (contraception) which prevent
ovulation by mimicking pregnancy – inhibiting FSH
release.
148
How can growth can be measured?
Growth can be measured as an increase in height or mass.
149
What factors determine a person’s final height and mass?
A person’s final height and mass is
determined by a number of factors, including:
• their genes
• diet and exercise
• hormones
• health/disease.
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150
Describe the main stages of human growth and
identify them on a human growth curve.
The main stages of human growth are:
• infancy (up to 2 years)
• childhood (from 2 to 11 years)
• adolescence (puberty) (from 11 to 13/15 years)
• maturity (adulthood) (the longest stage)
• old age (above 60/65 years).
151
Why is it sometimes necessary to replace body parts with biological or mechanical parts?
Due to disease or trauma, it is sometimes necessary to replace body parts with biological or mechanical parts.
152
Name some mechanical replacements that are used outside the body.
Some mechanical replacements such
as the heart and lung machine, kidney dialysis and
mechanical ventilators are used outside the body.
153
Where can organs be donated from?
Organs can be donated by living or
dead donors.
154
What are extremes of height are usually caused by?
Extremes of height are usually caused by genes or hormone imbalance.
155
Do different parts of a foetus and a baby grow at the same or different rates?
Different parts of a foetus and a baby grow at different rates.
156
Understand why a baby’s length, mass and head size are regularly monitored during their first months: to provide early warning of growth problems.
Different parts of a foetus and a baby grow at different rates. A baby’s length, mass and head circumference are monitored regularly during the first 6 months after birth. These results are plotted on a growth chart so that any significant difference from the normal range can be detected. This provides the opportunity for an early warning of growth problems.
157
Explain possible causes of the increase in life
expectancy during recent times.
Possible causes of the increase in life
expectancy during recent times include: less
industrial disease, healthier diet and life style, modern treatments and cures for disease and better housing.
158
What are th problems in the supply of donor organs?
The problems in the supply of donor organs are:
• shortage of donors
• tissue match
• size and age.
159
What are the problems of using mechanical replacements?
Problems of using mechanical replacements include size, power supply, materials used and body reactions.
160
Describe the ethical issues concerning organ
donation.
People may be unwilling to donate their organs - either as living donors or after they die. The families of potential dead donors may be unwilling to agree to their loved one’s organs being used for transplants. Some people believe that giving or receiving a transplant is wrong.
161
Explain why donors can be living and what makes a
suitable living donor.
A living donor may be used where the body contains more than one replacement organ, such as a kidney, or where there is a lot of the material needed, such as bone marrow. A thorough medical, surgical and psychological assessment is carried out to establish whether donors are fit and healthy.
162
Describe the criteria needed for a dead person to be a suitable donor.
Doctors must be careful to match a donated organ to the correct recipient. Not only must the organ be a suitable size and age, it must match the recipient’s tissues. These difficulties mean that not everyone who needs a transplant will get one.
163
Where is human growth hormone produced and what is its function?
Human growth hormone is produced by the pituitary gland and it stimulates general growth especially in long bones.
164
Describe possible consequences of more people
living longer, on a personal and national level.
Possible consequences of more people living for longer on a personal level is that it may be more difficult for younger people to find jobs if some older people are still working in old age, while other older people may be unable to enjoy life fully if their health fails them. On a national level an increasing population of older people may place burdens on the health system and the pension system
165
Describe problems with transplants.
Problems with transplants include rejection and imuno-suppressive drug treatment. Tissue matching is done to ensure the recipient receives a donated organ with a tissue type similar to their own. Immuno-suppressant drugs are given to the recipient (and must be taken for the rest of their life)
