UNIT 2 Flashcards
Name the structure within the testes which produces the male gamete
Seminiferous tubules
Name the structure within the testes which produces testosterone
Interstitial cells
Describe the function of the prostate gland and seminal vesicles
Secrete fluids that maintain the mobility and viability of the sperm
Name the part of the brain which secretes a releaser hormone
Hypothalamus
Describe the role of the releaser hormone
Stimulates pituitary gland to produce hormones that trigger puberty
Name the part of the brain which secretes FSH, ICSH and LH
Pituitary gland
Describe the effect of FSH and ICSH on the testes
FSH acts on semeinferous tuboulues, it promotes sperm production,
and
ICSH acts on interstitial cells, its stimulates testosterone production.
Describe the effects of testosterone
Stimulates sperm production
and activates prostate gland and seminal vesicles.
Name the hormones which are inhibited by high levels of testosterone
FSH and ICSH.
Explain how levels of testosterone are controlled by negative feedback
As testosterone levels increase it inhibits secretion of FSH and ICSH
This causes the levels of FSH and ICSH to decrease reducing the volume of testosterone production.
As testosterone levels decrease, inhibitory effect is switched off and levels of FSH and ICSH increase
This causes an increase in testosterone level
Name the structure where ova mature
Follicle
Describe the role of the follicle
Protectsthe developing ovum and secretes hormones (oestrogen)
State the site of fertilisation in females
Oviduct
Describe the process of fertilisation
Fusion of gamete nuclei to form zygote, which divides into embryo.
State the length of the average menstrual cycle
28 days, first day of mesutration is regarded as day one.
Name the first phase of the menstrual cycle
Follicular Phase
Describe the effect of FSH on the ovary
Stimulates follicle development and oestrogen production.
Name the hormone produced by the follicle
Oestrogen.
Describe the effects of oestrogen
stimulates proliferation of the endometruim , preparing it for implantation.
it also affects the consistency of cervial mucus, becoming thin and watery
Explain why the consistency of cervical mucus changes during the follicular phase
to make it easily penetrable by sperm.
Describe what happens to the LH levels following peak levels of oestrogen
There is a surge in LH.causing ovulation
Name the event which occurs following a surge in LH
Ovulation
Describe the process of ovulation
Release of matureovum from a follicle, usually occurs in mid-point of the cycle.
Name the second phase of the menstrual cycle
Luteal phase.
Name the structure produced when the follicle degrades (breaks down)
The follicle develops into a Corpus luteum.
Name the hormone produced by the corpus luteum
Progesterone.
Describe the effects of progesterone
Progesterone promotes further development and vascularisation of the endometrium preparing it for implantation if fertilisation occurs.
Describe the negative feedback effect of the ovarian hormones on the pituitary gland
The ovarian hormones inhibit the secretion of FSH and LH by the pituitary, which prevents further follicles from developing.
Describe the effect of a lack of LH
Leads to corpus luteum degeneration and levels of progesterone to drop.
Describe how menstruation is triggered
Drop in progesterone levels leads menstruation.
State what happens to the corpus luteum and progesterone levels if fertilisation occurs
If fertilisation does occur, the corpus luteum does not degenerate and progesterone levels remain high
Compare fertility periods in males and females
Men have continuous fertility, women have cyclical fertility.
Explain why females have cyclical fertility
they are only fertile for few days during each menstrual cycle
Describe the physiological changes which indicate a woman is in her fertile period
body temperature rising by around 0.5°C after ovulation, and her cervical mucus becoming thin and watery
Give examples of causes of infertility in both males and females
Males: low sperm, abnormal sperm, low motility.
Females: failure to ovulate, blocked oviducts, implantation failure.
Describe the process of artificial insemination
- is the insertion of semen into the female reproductive tract.
- particularly useful when male has a low sperm count
- several samples of semen are collected overtime.
- if a male is sterile, a donor may be used
Describe how to stimulate ovulation
can be stimulated by Drugs that prevent oestrogen negative feedback or mimic FSH/LH. causing superovulation resulting in multiple births
Describe the process of IVF
-eggs are surgically removed from the ovaries after hormone stimulation.
- eggs are mixed with sperm in a culture dish and zygote is incubated until they make at least 8 cells.
then they are transferred to the uterus for implantation
Suggest when IVF should be used
when a couple fail to conceive
Describe the process of ICSI
- If mature sperm are defective or very low in number,
- the head of the sperm is drawn into a needle
- and injected directly into the egg to achieve fertilisation
Explain why PGD is available to some couples
PGD can be used with IVF to identify single gene disorders and chromosomal abnormalities.
Give examples of physical methods of contraception and describe how they prevent pregnancy
Barrier methods like condoms and diaphragms prevent fertilisation,
while IUDs prevent implantation of the blastocyst.
Sterilisation blocks the reproductive ducts to prevent sperm and ova from meeting
Describe how the oral contraceptive pill, progesterone only and morning after pill prevent pregnancy
Oral pill(contain oestrogen and progesterone), it mimics negative feedback to prevent ovulation, progesterone -only pill thickens mucus, morning-after prevents ovulation/implantation.
Describe the role of antenatal screening
Identifies disorder risk for further testing and diagnosis.
Name the type of screening used for dating and anomaly scans
Ultrasound imaging.
Compare dating and anomaly scans
Dating scan: determine pregnancy stage and due date.
they take place between 8 and 14 weeks.
Anomaly scan: detect serious physical abnormalities in the fetus
they take place between 18 and 20 weeks
Explain why routine blood and urine tests are carried out throughout the pregnancy
To monitor the concentrations of marker chemicals
Explain how false positive results can occur
Measuring a chemical at the wrong time
Describe how to carry out CVS
Fetal cells can be obtained from a sample of cells taken from the placenta using a needle
Describe how to carry out amniocentesis
Fetal cells obtained from a sample of amniotic fluid taken and used to produce a karyotype
Compare the advantages and disadvantages of CVS to amniocentesis
CVS can be carried out earlier in pregnancy but has a higher risk of miscarriage compared to amniocentesis.
Name the diagram produced which shows the chromosome complement of a person
A karyotype.
Describe how karyotypes are produced
Cells from samples obtained from amniocentesis or CVS can be cultured to obtain sufficient cells to produce a karyotype
Explain why males are more likely to inherit a recessive sex-linked disorder
Males only have one X chromosome, so one recessive allele is enough.
Explain why predicted and observed ratios are often different
Fertilization is random
Describe how postnatal screening can diagnose PKU
Newborns tested for metabolic disorders like PKU.
Explain why individuals with PKU are placed on a restricted diet
Individuals with high levels of phenylalanine are placed on a restricted diet, which keeps the effect to a minimum
Describe the structure of arteries, capillaries and veins
Arteries: Outer connective tissue, middle smooth muscle, elastic to accommodate surges.
Veins: Outer connective tissue, thinner muscle, contain valves to prevent backflow.
Capillaries: Thin walls to allow exchange.
Explain how the structure of each blood vessel relates to their function
Arteries: Thick, elastic walls withstand high pressure. Smooth muscle controls flow.
Veins: Thinner walls, valves suited for lower pressure return to heart.
Capillaries: Thin walls enable gas, nutrient and waste exchange.
Compare vasoconstriction and vasodilation
Vasoconstriction: Smooth muscle contracts, reducing vessel diameter, decreasing flow.
Vasodilation: Smooth muscle relaxes, increasing vessel diameter, increasing flow.
Describe the formation of tissue fluid by pressure filtration
Narrowing arteries increase blood pressure, forcing plasma out of capillaries into tissue.
Explain why tissue fluid has less plasma proteins than blood plasma
Plasma proteins are too large to be filtered through capillary walls.
Describe the role of tissue fluid
Supplies cells with glucose, oxygen, absorbs waste.
Describe the role of lymphatic vessels
Absorb excess tissue fluid and return it to circulation as lymph.
Identify the chambers, blood vessels and valves within the heart
4 Chambers - left/right atria, left/right ventricles.
Blood vessels - pulmonary artery/vein, aorta, vena cava
Valves - AV, SL.
Describe the flow of blood through the heart and its associated blood vessels
Deoxygenated blood flows to right atrium, through tricuspid valve to right ventricle, then to lungs.
Oxygenated blood returns to left atrium, through mitral valve to left ventricle, then to body via aorta
Define cardiac output
Volume of blood pumped per minute by each ventricle.
Calculate cardiac output from stroke volume and heart rate
CO = HR x SV
Describe each stage of the cardiac cycle
1-Diastole - ventricles relax, AV valves open., SL closed
2- Atrial systole - atria contract.
3-Ventricular systole - ventricles contract, AV valves close, SL valves open.
Describe the pressure changes which occur during the cardiac cycle which causes the valves to open and close
Ventricular pressure drops below atrial, opening AV.
Ventricular rises above aortic/pulmonary, opening SL.
Calculate heart rate in beats per minute from the length of one cardiac cycle
HR (bpm) = 60 / Cardiac cycle length (s)
State the location of the SAN and describe its role
SAN in right atrium wall, sets heart contraction rate.
State the location of the AVN and describe its role
AVN in heart center, transmits impulses from SAN to ventricles.
Describe the flow of impulses across the heart
SAN to atria, then AVN to ventricles.
Name the test which detects impulses in the heart
Electrocardiogram (ECG).
Calculate heart rate from an ECG
HR (bpm) = 60 / Time between P waves (s)
Identify atrial systole, ventricular systole and diastole from an ECG
P QRS T:
P wave - atrial, QRS - ventricular, T wave - diastole.
Name the part of the brain and the branch of the nervous system which regulates the rate of the SAN
Medulla, autonomic nervous system.
Name the neurotransmitter which is released by the sympathetic nerves and describe its effect on heart rate
Noradrenaline, increases heart rate.
Name the neurotransmitter which is released by the parasympathetic nerves and describe its effect on heart rate
Acetylcholine, decreases heart rate.
Describe the changes to blood pressure during the cardiac cycle
Increases during ventricular systole, decreases during diastole.
Compare systolic and diastolic pressure
Systolic is higher pressure during contraction, diastolic is lower pressure during relaxation.
State the typical value of blood pressure for a young adult
120/80 mmHg.
Describe how a sphygmomanometer is used to measure blood pressure
Inflatable cuff stops flow, deflates to detect systolic and diastolic pressures.
State the term used to describe high blood pressure
Hypertension.
Describe the process of atherosclerosis
Accumulation of fatty material, including cholesterol, forming plaque under artery’s endothelium.
Describe the effects of an atheroma on an artery and blood pressure
- Artery thickens, loses elasticity,
- lumen narrows, restricting flow and increasing blood pressure.
Give examples of CVDs which can develop following atherosclerosis
- Angina
- heart attack
- stroke
- peripheral vascular disease.
State the term used to define the formation of a clot
Thrombosis
Describe the process of thrombosis
1- an atheroma ruptures damaging the endothelium.
2- clotting factors are released from the damaged area
3- the clotting factors activates a cascade of reactions
4-resulting in conversion of enzyme prothrombin to its active form thrombin.
5- thrombin cause molecules of plasma protein fibrinogen to form threads of fibrin
6- the fibrin threads form a meshwork
State the 3 functions of meshwork
1- it clots the blood
2- it seals the blood
3- it provides scaffold for the scar tissue
What is an Embolus
when a thrombus breaks loose and travels throughout the bloodstream till it blocks the blood vessel
Describe the effect of thrombosis in a coronary artery and in the brain
Coronary artery- heart attack, brain
Artery in the brain - stroke
Explain why cells die following the formation of a thrombus
because they are deprived of oxygen leading to sudden death
Describe peripheral vascular disease (PVD)
Narrowing of arteries, due to atherosclerosis other than heart/brain.
common in legs.
Explain why pain is often experienced in the leg in people with PVD
Limited oxygen supply
Describe deep vein thrombosis
Blood clot forming in deep vein, commonly in leg.
Explain how a pulmonary embolism can occur
DVT can break off and travel to lungs.
State the location of cholesterol synthesis in the body
25% in liver, rest in all cells.
Describe the role of cholesterol in the body
Cholesterol is a type of lipid found in the cell membrane.
It is also used to make the sex hormones — testosterone, oestrogen, and progesterone.
Explain how cholesterol levels in the blood can increase
High saturated fat/cholesterol diet increases blood levels.
Describe the role of HDL
Transports excess cholesterol to liver for elimination.
Describe the role of LDL
Transports cholesterol to cells.
Explain why LDL can sometimes deposit cholesterol in arteries
Negative feedback inhibits LDL receptor synthesis, reduces the amount of cholesterol that is absorbed into the cells
Explain why it is best to have a high HDL to LDL ratio
Higher HDL:LDL reduces blood cholesterol and atherosclerosis risk.
Describe the benefits of physical activity and a low fat diet in the control of cholesterol levels
Activity raises HDL, diet reduces total/saturated fat.
Explain how statins reduce blood cholesterol levels
by inhibiting the synthesis of cholesterol by liver cells
Explain blood vessels can be damaged from chronic elevation of blood glucose levels
Chronic high glucose causes endothelial cells to take in
more glucose, damaging blood vessels.
State the possible outcomes of blood vessels damaged by elevated glucose levels
Atherosclerosis, CVD, stroke, PVD, retinal haemorrhage, renal failure, nerve damage
Name the receptors which monitor blood glucose levels
Pancreatic receptors.
Name the hormone whose secretion increases when blood glucose levels decreases and describe its action
Insulin.
Insulin activates glucose to glycogen conversion in liver, decreasing blood glucose.
Name the hormone whose secretion increases when blood glucose levels increases and describe its action
Glucagon.
Glucagon activates glycogen to glucose conversion in liver, increasing blood glucose.
Name the organ which stores glucose as glycogen
The liver.
Name the hormone released from exercise or during a flight or fight response
Adrenaline.
Explain why individuals with Type 1 diabetes require insulin injections
Type 1 diabetics cannot produce insulin, so require injections.
Explain why the cells in individuals with Type 2 diabetes are less sensitive to insulin
Type 2 has insulin resistance due to decreased liver insulin receptors
Name the test used to indicate diabetes
Glucose tolerance test
Explain why glucose appears in the urine of diabetics
Kidneys remove excess blood glucose, which appears in urine
Describe how to carry out a glucose tolerance test to diagnose diabetes
Measure fasting blood glucose, then after drinking glucose solution.
Compare the results of a diabetic to a non-diabetic following a glucose tolerance test
Diabetic starts higher, increases more, takes longer to return to start.
Describe how obesity is characterised
Excess body fat relative to lean tissue.
Calculate BMI from an individual’s weight and height
BMI = weight (kg) / height^2 (m^2)
State the value of BMI deemed to indicate obesity
<30
Explain why BMI can wrongly classify individuals as obese
BMI misclassifies muscular people as obese.
Describe how an individual becomes obese
Linked to high fat diet and low exercise
Explain why obese individuals should have a low-fat diet and avoid free sugars
- Fats have high calories,
- free sugars require no digestion energy.
Explain the importance of exercise to health and wellbeing
Increases energy expenditure, reduces CVD risk factors.
