Unit 2 Flashcards
1
Q
Where are sperm produced in the testes?
A
Sperm are produced in the seminiferous tubules.
2
Q
Which cells in the testes produce testosterone?
A
Testosterone is produced in the interstitial cells.
3
Q
What role do the prostate gland and seminal vesicles play in sperm function?
A
They secrete fluids that help maintain sperm mobility and viability.
4
Q
How do the fluids secreted by accessory glands affect sperm?
A
These fluids keep sperm mobile and alive (viable).
5
Q
What do the ovaries contain in various stages of development?
A
The ovaries contain immature ova.
6
Q
What structure surrounds each ovum in the ovary?
A
Each ovum is surrounded by a follicle.
7
Q
What are the functions of the follicle in the ovary?
A
The follicle protects the developing ovum and secretes hormones.
8
Q
Where are mature ova released?
A
Mature ova are released into the oviduct.
9
Q
What event occurs in the oviduct involving the ovum and sperm?
A
Fertilisation may occur in the oviduct if sperm are present.
10
Q
What is the result of fertilisation between an ovum and a sperm?
A
Fertilisation produces a zygote.
11
Q
Which gland releases the hormones that trigger puberty?
A
The pituitary gland.
12
Q
What stimulates the pituitary gland to release reproductive hormones?
A
A releaser hormone produced by the hypothalamus.
13
Q
Which hormones are released by the pituitary gland at the onset of puberty?
A
Follicle stimulating hormone (FSH), luteinising hormone (LH), or interstitial cell stimulating hormone (ICSH).
14
Q
What is the role of the hypothalamus in the onset of puberty?
A
It produces a releaser hormone that stimulates the pituitary gland to release FSH, LH, or ICSH.
15
Q
What is the role of FSH in sperm production?
A
FSH promotes sperm production.
16
Q
What does ICSH stimulate the production of?
A
Testosterone.
17
Q
How does testosterone contribute to sperm production and male reproductive function?
A
It stimulates sperm production and activates the prostate gland and seminal vesicles.
18
Q
What is the role of negative feedback in regulating testosterone levels?
A
High testosterone levels inhibit FSH and ICSH secretion, maintaining hormonal balance.
19
Q
What marks the first day of the menstrual cycle?
A
The first day of menstruation.
20
Q
Which hormone stimulates the development of the follicle?
A
FSH.
21
Q
What does the follicle produce during the follicular phase?
A
Oestrogen.
22
Q
How does oestrogen affect the endometrium and cervical mucus?
A
It stimulates proliferation of the endometrium and makes cervical mucus easier for sperm to penetrate.
23
Q
What hormonal event triggers ovulation?
A
A surge in LH secretion caused by peak oestrogen levels.
24
Q
Around which day does ovulation usually occur in a 28-day cycle?
A
Around the mid-point of the cycle (typically day 14).
25
What structure forms from the follicle after ovulation?
The corpus luteum.
26
Which hormone is secreted by the corpus luteum?
Progesterone.
27
What is the function of progesterone in the luteal phase?
It promotes further development and vascularisation of the endometrium, preparing it for implantation.
28
How do high levels of ovarian hormones affect the secretion of FSH and LH?
They inhibit FSH and LH secretion through negative feedback.
29
What causes menstruation if fertilisation does not occur?
The corpus luteum degenerates, causing a drop in progesterone, which leads to menstruation.
30
What happens to the corpus luteum and hormone levels if fertilisation does occur?
The corpus luteum does not degenerate, and progesterone levels remain high.
31
What is the purpose of antenatal screening?
To identify the risk of a disorder so that further tests and a prenatal diagnosis can be offered.
32
What are the two types of ultrasound scans offered during pregnancy?
Dating scans and anomaly scans.
33
When is a dating scan typically performed?
Between 8 and 14 weeks of pregnancy.
34
What is the purpose of a dating scan?
To determine the stage of pregnancy and estimate the due date.
35
What is the purpose of an anomaly scan, and when is it carried out?
To detect serious physical abnormalities in the fetus; done between 18 and 20 weeks.
36
What can an anomaly scan detect?
Serious physical abnormalities in the fetus.
37
Why are blood and urine tests carried out throughout pregnancy?
To monitor the concentrations of marker chemicals.
38
What can cause a false positive result in chemical marker tests?
Measuring the chemical at the wrong time during pregnancy.
39
What might an atypical concentration of a marker chemical lead to?
Diagnostic testing to determine if the fetus has a medical condition.
40
What are two types of diagnostic tests used during pregnancy?
Amniocentesis and chorionic villus sampling (CVS).
41
How does CVS differ from amniocentesis in terms of timing and risk?
CVS can be carried out earlier in pregnancy but has a higher risk of miscarriage.
42
What is done with the cells obtained from CVS or amniocentesis?
They are cultured to produce a karyotype to diagnose a range of conditions.
43
What does a karyotype show?
An individual’s chromosomes arranged as homologous pairs.
44
What factors are considered before proceeding with diagnostic testing?
The element of risk and the potential decisions to be made if a test is positive.
45
What is meant by the term “autosomal recessive”?
A disorder expressed only when both alleles are recessive.
46
What is meant by “autosomal dominant”?
A disorder expressed when only one dominant allele is present.
47
What does “incomplete dominance” mean in genetics?
When the phenotype is a blend of the two alleles because neither is completely dominant.
48
What is a sex-linked recessive disorder?
A disorder linked to the X chromosome, often affecting males more than females.
49
What is the difference between genotype and phenotype?
Genotype is the genetic makeup; phenotype is the physical expression of the genes.
50
What is an allele?
A version of a gene.
51
Define dominant.
An allele that is expressed in the phenotype, even when only one copy is present.
52
Define homozygous
Two identical alleles for a gene.
53
Define heterozygous
Two different alleles for a gene.
54
Define carrier.
A person who has one copy of a recessive allele but does not express the trait.
55
What is the difference between autosomes and sex chromosomes?
Autosomes are all chromosomes except the sex chromosomes; sex chromosomes determine biological sex (X and Y).
56
What is PKU and how is it diagnosed?
A genetic disorder diagnosed by postnatal screening; it involves a test for high levels of phenylalanine.
57
What causes PKU at the genetic level?
A substitution mutation resulting in a non-functional enzyme.
58
What is the result of the enzyme being non-functional in individuals with PKU?
Phenylalanine cannot be converted into tyrosine, leading to its accumulation.
59
How is PKU managed after birth?
Individuals are placed on a restricted diet to limit phenylalanine intake.
60
What is the main difference between male and female fertility patterns?
Males show continuous fertility, while females show cyclical fertility.
61
How long are women fertile during the menstrual cycle?
Women are only fertile for a few days during each menstrual cycle.
62
What physical signs indicate a woman's fertile period?
A woman’s body temperature rises by around 0.5°C after ovulation and cervical mucus becomes thin and watery.
63
Why do men show continuous fertility?
Men produce sperm continually in their testes, which is why they are continuously fertile.
64
How does body temperature change after ovulation?
Body temperature rises by around 0.5°C after ovulation.
65
What change occurs in cervical mucus around ovulation?
Cervical mucus becomes thin and watery, aiding sperm movement.
66
How do some fertility drugs stimulate ovulation?
Some fertility drugs prevent the negative feedback effect of oestrogen on FSH secretion, stimulating ovulation.
67
What effect do drugs that mimic FSH and LH have on ovulation?
Drugs that mimic FSH and LH can stimulate ovulation.
68
What is a potential side effect of using ovulatory drugs?
A potential side effect is super ovulation, which may result in multiple births or be used to collect ova for IVF.
69
What is artificial insemination and when is it used?
Artificial insemination is when semen is inserted into the female reproductive tract and is used especially when the male has a low sperm count.
70
Why might semen be collected over a period of time for artificial insemination?
Several semen samples are collected over time to increase sperm count for insemination.
71
What is intra-cytoplasmic sperm injection (ICSI) and when is it used?
In ICSI, a single sperm head is injected directly into an egg; used when sperm are defective or very low in number.
72
Describe the basic procedure of in vitro fertilisation (IVF).
In IVF, eggs are surgically removed, fertilised with sperm in a dish, and after division, transferred to the uterus.
73
What is the role of hormone treatment before egg collection in IVF?
Hormone treatment stimulates the ovaries to produce multiple eggs.
74
What is pre-implantation genetic diagnosis (PGD) used for in IVF?
PGD is used to identify single gene disorders and chromosomal abnormalities in embryos before implantation.
75
At what stage of development are fertilised eggs transferred to the uterus in IVF?
Fertilised eggs are transferred to the uterus when they have formed at least eight cells.
76
What is the biological basis of barrier methods of contraception?
Barrier methods physically block sperm from reaching the egg.
77
How do intra-uterine devices (IUDs)
prevent pregnancy?
IUDs (intra-uterine devices) prevent implantation of a fertilised egg and may also inhibit sperm movement.
78
What are two types of sterilisation procedures used for contraception?
Sterilisation procedures include vasectomy in males and tubal ligation in females.
79
How does the combined oral contraceptive pill prevent pregnancy?
The oral contraceptive pill mimics negative feedback, preventing the release of FSH and LH and thereby stopping ovulation.
80
What hormones are found in the oral contraceptive pill?
The pill contains synthetic oestrogen and progesterone.
81
How does the mini pill (progesterone-only) prevent pregnancy?
The mini pill thickens cervical mucus, making it harder for sperm to enter.
82
What is the function of emergency hormonal contraceptive pills?
Emergency pills prevent or delay ovulation.
83
Up to how many hours after unprotected sex can emergency contraception be taken?
Emergency contraceptives can be taken up to 72 or 120 hours after unprotected sex, depending on the type.
84
In what order does blood flow through the major types of blood vessels starting from the heart?
Blood flows from the heart → arteries → capillaries → veins → back to the heart.
85
What happens to blood pressure as blood moves away from the heart?
Blood pressure decreases as blood moves away from the heart.
86
Why does blood pressure decrease as blood travels through the circulatory system?
Because of the increased resistance and branching of blood vessels, especially in the capillaries.
87
What is the name of the inner lining found in all blood vessels?
Endothelium.
88
What surrounds the endothelium in blood vessels?
Layers of connective tissue and smooth muscle.
89
Describe the structure of the artery wall.
Arteries have an outer layer of connective tissue with elastic fibres and a middle layer of smooth muscle also containing elastic fibres.
90
Why do arteries have elastic fibres in their walls?
To stretch and recoil, accommodating the surge of blood after each heart contraction.
91
How do the walls of arteries respond to the surge of blood from the heart?
They stretch and then recoil to maintain blood flow.
92
What is vasoconstriction, and how does it affect blood flow?
Vasoconstriction is the contraction of smooth muscle in arteries, reducing blood flow.
93
What is vasodilation, and how does it affect blood flow?
Vasodilation is the relaxation of smooth muscle in arteries, increasing blood flow.
94
What is the primary function of capillaries?
To allow the exchange of substances between blood and tissues.
95
Why are capillary walls thin?
To facilitate the exchange of materials such as gases, nutrients, and wastes.
96
How do the walls of veins compare to those of arteries?
Veins have a much thinner muscular wall than arteries.
97
What structural feature of veins prevents the backflow of blood?
Valves.
98
Why do veins have thinner muscular walls than arteries?
Because the blood pressure in veins is lower and they don’t need to withstand high pressure surges.
99
What process causes plasma to move from capillaries to tissue fluid?
Pressure filtration.
100
What substances are supplied to cells by tissue fluid?
Glucose, oxygen, and other essential substances.
101
How do waste materials like carbon dioxide leave the cells?
By diffusing into the tissue fluid, then into capillaries for excretion.
102
What happens to most of the tissue fluid after exchange with the cells?
It returns to the blood.
103
What role do lymphatic vessels play in tissue fluid regulation?
They absorb excess tissue fluid and return it as lymph to the circulatory system.
104
What is the difference between tissue fluid and blood plasma in terms of composition?
Tissue fluid lacks plasma proteins, which are too large to pass through capillary walls.
105
Why are plasma proteins not present in tissue fluid?
Because they are too large to be filtered through capillary walls during pressure filtration.
106
What is cardiac output?
6. Through which blood vessels do the ventricles pump blood?
107
How is cardiac output calculated?
It is calculated using the formula: Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV).
108
What does heart rate represent in the cardiac output equation?
Heart rate is the number of heartbeats per minute.
109
What does stroke volume represent?
Stroke volume is the volume of blood pumped out of the ventricle with each heartbeat.
110
Do the left and right ventricles pump the same volume of blood?
Yes, the left and right ventricles pump the same volume of blood.
111
Through which blood vessels do the ventricles pump blood?
The right ventricle pumps blood to the lungs via the pulmonary artery, and the left ventricle pumps blood to the body via the aorta.
112
What happens during diastole?
During diastole, blood returning to the atria flows into the ventricles.
113
What is the role of atrial systole in the cardiac cycle?
Atrial systole transfers the remaining blood from the atria to the ventricles.
114
What causes the AV valves to close?
Ventricular systole increases pressure in the ventricles, causing the AV valves to close.
115
What occurs during ventricular systole?
Ventricular systole pumps blood out of the ventricles through the semi-lunar (SL) valves.
116
What causes the SL valves to open?
The increased pressure in the ventricles during systole causes the SL valves to open.
117
What causes the SL valves to close during diastole?
In diastole, the higher pressure in the arteries causes the SL valves to close.
118
How are heart sounds produced?
The opening and closing of the AV and SL valves produce the heart sounds.
119
Which valves are involved in producing heart sounds?
The AV valves (first sound) and SL valves (second sound) are involved in the heart sounds.
120
Where is the sino-atrial node (SAN) located?
The SAN is located in the wall of the right atrium.
121
What is the function of the SAN?
The SAN sets the rate at which the heart contracts.
122
What is meant by the SAN being auto-rhythmic?
Being auto-rhythmic means the SAN generates impulses on its own without external signals.
123
What happens after impulses spread through the atria from the SAN?
Impulses from the SAN spread through the atria, causing atrial systole.
124
What role does the atrio-ventricular node (AVN) play?
The AVN delays the impulse, allowing the atria to finish contracting before the ventricles contract.
125
Through which structure do impulses travel from the AVN to the ventricles?
Impulses travel from the AVN down fibres in the central wall of the heart.
126
What is the result of impulses traveling through the walls of the ventricles?
These impulses cause the ventricles to contract (ventricular systole).
127
What device detects electrical activity in the heart?
An electrocardiogram (ECG) detects the electrical impulses generated by the heart.
128
What does an ECG measure?
An ECG measures the electrical activity of the heart over time.
129
Which wave on an ECG corresponds to atrial systole?
The P wave corresponds to atrial systole.
130
Which wave corresponds to ventricular systole?
The QRS complex corresponds to ventricular systole.
131
How does the autonomic nervous system influence the heart rate?
The autonomic nervous system (ANS) regulates heart rate by influencing the SAN.
132
What neurotransmitter does the sympathetic nerve release, and what is its effect?
The sympathetic nerve releases noradrenaline, which increases heart rate.
133
What neurotransmitter does the parasympathetic nerve release, and what is its effect?
The parasympathetic nerve releases acetylcholine, which decreases heart rate.
134
What happens to blood pressure in the aorta during ventricular systole?
Blood pressure increases during ventricular systole.
135
What happens to blood pressure during diastole?
Blood pressure decreases during diastole.
136
What instrument is used to measure blood pressure?
A sphygmomanometer is used to measure blood pressure.
137
How does a sphygmomanometer measure systolic pressure?
Systolic pressure is detected when the cuff deflates and a pulse is first heard.
138
How does it measure diastolic pressure?
Diastolic pressure is detected when the cuff pressure drops and the pulse sound disappears.
139
What is a typical blood pressure reading for a young adult?
A typical reading is 120/80 mmHg.
140
What health condition is associated with consistently high blood pressure?
Hypertension is the condition of having consistently high blood pressure.
141
What major disease can hypertension lead to?
Hypertension is a major risk factor for diseases such as coronary heart disease.
142
What is atherosclerosis?
A condition where fatty material accumulates beneath the endothelium of arteries, forming a plaque or atheroma.
143
What materials accumulate to form an atheroma or plaque?
Cholesterol, fibrous material, and calcium.
144
Where does the atheroma form within the artery?
Beneath the endothelium.
145
How does atherosclerosis affect the structure and function of the arteries?
The artery thickens, loses elasticity, and its lumen narrows, reducing blood flow.
The artery thickens, loses elasticity, and its lumen narrows, reducing blood flow.
146
What happens to the diameter of the artery’s lumen as the atheroma grows?
It becomes reduced.
147
How does atherosclerosis influence blood pressure?
It increases blood pressure due to restricted blood flow.
148
Name four cardiovascular diseases that can result from atherosclerosis.
- Angina
- Heart attack (myocardial infarction)
- Stroke
- Peripheral vascular disease.
149
How can an atheroma lead to the formation of a thrombus?
By rupturing and damaging the endothelium, which triggers clotting.
150
What is the role of clotting factors in thrombosis?
They activate a cascade that converts prothrombin to thrombin.
151
Which enzyme is formed from prothrombin in the clotting cascade?
Thrombin.
152
What does thrombin convert fibrinogen into?
Threads of fibrin.
153
What is the function of the fibrin mesh in clotting?
It clots the blood, seals the wound, and provides a scaffold for scar tissue.
154
What is the medical term for a blood clot formed in this way?
Thrombus.
155
What is an embolus?
A thrombus that has broken loose and is traveling in the bloodstream.
156
What can happen if a thrombus becomes an embolus?
It can block a blood vessel.
157
What is the consequence of a thrombosis in the coronary artery?
Myocardial infarction (heart attack).
158
What is the consequence of a thrombosis in an artery in the brain?
Stroke.
159
What is peripheral vascular disease?
Narrowing of arteries due to atherosclerosis outside the heart and brain.
160
Which part of the body is most commonly affected by peripheral vascular disease?
The legs.
161
Why does pain occur in the leg muscles during peripheral vascular disease?
Due to limited oxygen supply.
162
What is deep vein thrombosis (DVT)?
A blood clot in a deep vein, usually in the leg.
163
What serious condition can result if a DVT breaks off?
Pulmonary embolism.
164
What is cholesterol and what are its functions in the body?
A lipid in cell membranes and used to make sex hormones.
165
Where is cholesterol synthesised, and what percentage occurs in the liver?
All cells synthesize it; 25% occurs in the liver.
166
How can diet influence cholesterol levels in the blood?
A diet high in saturated fats or cholesterol increases blood cholesterol.
167
What is the role of HDL in cholesterol transport?
It transports excess cholesterol to the liver for elimination.
168
What is the role of LDL in cholesterol transport?
It delivers cholesterol to body cells.
169
How do body cells regulate LDL uptake through feedback control?
When cells have enough cholesterol, they inhibit new LDL receptor production.
170
What happens when there is excess LDL in the blood?
It circulates and deposits cholesterol in arteries, forming atheromas.
171
What health condition can result from the accumulation of LDL in the arteries?
Atherosclerosis.
172
How does the HDL:LDL ratio affect cardiovascular health?
A higher ratio reduces blood cholesterol and risk of atherosclerosis.
173
What is the effect of regular physical activity on HDL levels?
It increases HDL levels.
174
How can dietary changes help control cholesterol levels?
By reducing total fat intake and replacing saturated fats with unsaturated fats.
175
What is the function of statins in controlling cholesterol?
They inhibit cholesterol synthesis in liver cells.
176
What happens to endothelial cells when blood glucose levels are chronically elevated?
Endothelial cells take in more glucose than normal, damaging the blood vessels.
177
How does this damage to endothelial cells contribute to atherosclerosis?
This damage can lead to the development of atherosclerosis.
178
Name three conditions that can result from atherosclerosis caused by chronic high blood glucose levels.
Conditions include cardiovascular disease, stroke, and peripheral vascular disease.
179
Which small blood vessels can be damaged due to high glucose levels?
The small blood vessels in the retina, kidneys, and peripheral nerves.
180
What health issues may arise from damage to small blood vessels caused by elevated glucose?
Potential effects are haemorrhage in the retina, renal failure, and peripheral nerve dysfunction.
181
Which organ contains receptors that detect changes in blood glucose levels?
Pancreatic receptors detect changes in blood glucose levels.
182
What hormone is secreted in response to high blood glucose levels, and what effect does it have?
Insulin is secreted; it lowers blood glucose levels.
183
What hormone is secreted in response to low blood glucose levels, and what effect does it have?
Glucagon is secreted; it raises blood glucose levels.
184
How does insulin lower blood glucose concentration?
Insulin activates the conversion of glucose to glycogen in the liver.
185
How does glucagon raise blood glucose concentration?
Glucagon activates the conversion of glycogen to glucose in the liver.
186
What role does adrenaline play in blood glucose regulation during stress or exercise?
Adrenaline raises blood glucose levels during exercise or fight-or-flight responses.
187
How does adrenaline affect insulin and glucagon secretion?
Adrenaline stimulates glucagon secretion and inhibits insulin secretion.
188
At what stage of life does type 1 diabetes typically develop?
Type 1 diabetes usually develops in childhood.
189
Why is a person with type 1 diabetes unable to regulate blood glucose levels properly?
A person with type 1 diabetes cannot produce insulin.
190
How is type 1 diabetes usually treated?
It is treated with regular doses of insulin.
191
What increases the risk of developing type 2 diabetes?
The risk is increased by being overweight.
192
How do insulin levels and insulin sensitivity differ between type 1 and type 2 diabetes?
In type 1, no insulin is produced. In type 2, insulin is produced but cells are less sensitive due to fewer receptors.
193
Why do people with type 2 diabetes have trouble converting glucose to glycogen?
The liver cannot convert glucose to glycogen effectively due to fewer insulin receptors.
194
In both types of diabetes, what happens to blood glucose levels after a meal?
Blood glucose levels rise rapidly after eating.
195
How does the body attempt to remove excess glucose in diabetes?
The kidneys remove excess glucose, causing glucose to appear in urine.
196
What simple test is often used to indicate diabetes?
Urine testing for glucose is used.
197
What is the glucose tolerance test, and what does it involve?
The glucose tolerance test involves measuring blood glucose after fasting, then after drinking glucose, over a few hours.
198
How do the results of a glucose tolerance test differ between a diabetic and non-diabetic person?
A diabetic’s glucose level starts higher, increases more, and takes longer to return to normal than in a non-diabetic.
199
What is obesity characterised by in terms of body composition?
Obesity is characterised by excess body fat relative to lean tissue.
200
Which two health conditions are major risks associated with obesity?
Major risks include cardiovascular disease and type 2 diabetes.
201
What is BMI and how is it calculated?
BMI is calculated as body mass ÷ height².
202
At what BMI value is a person considered obese?
A BMI over 30 indicates obesity.
203
Why might BMI give an inaccurate indication of obesity in some individuals?
BMI can wrongly classify muscular individuals as obese.
204
What dietary changes can help reduce obesity?
A healthy diet should limit fats and free sugars.
205
Why are fats and free sugars problematic in high-energy diets?
Fats have high calorific value, and free sugars require no energy to digest.
206
How does exercise help reduce obesity and the risk of cardiovascular disease?
Exercise increases energy use, preserves lean tissue, and helps maintain weight.
207
Name four ways exercise contributes to reducing CVD risk factors.
Exercise helps reduce CVD risks by controlling weight, reducing stress, lowering blood pressure, and improving blood lipid profiles.
