where is the site of sperm production?
In the seminiferous tubules in the testes.
where is the site of testosterone production?
In the interstitial cells in the testes.
what is the job of the prostate gland and seminal vesicles?
To secrete a fluid which maintains the mobility and viability of sperm.
In the ovaries, what are the ova surrounded by? and what does this do?
a follicle which protects the developing ovum and secretes hormones.
where are the ova released to? and what may this form?
the oviduct where fertilisation may occur with sperm to form a zygote.
what 2 hormones does the pituitary gland release in males and females?
males: FSH( follicle stimulating hormone) and ICSH( interstitial cell stimulating hormone)
females: FSH( follicle stimulating hormone) and LH( luteinising hormone)
how are the pituitary hormones released and what does this trigger?
they are stimulated by a releaser hormone in the hypothalamus- this triggers puberty
in males what does FSH and ICSH do?
FSH- promotes sperm production
ICSH- stimulates testosterone production
what 2 things does testosterone stimulate?
1) sperm production
2) activates the prostate gland and seminal vesicles
how long does the menstrual cycle last? and what is regarded as day 1?
approx 28 days and day 1 is regarded as menstruation
what are the 2 phases of the menstrual cycle called?
1) follicular phase
2) luteal phase
challenge
draw the menstrual cycle without looking at your notes
explain male and female fertility
males are continuously fertile and females are cyclically fertile so are only fertile for approx 1-2 days a month.
in the time that females are fertile, how many eggs do they produce?
ONLY 1
how can the fertile period be calculated?
1) rise in body temp approx 0.5 degrees the day after ovulation
2) the cervical mucus becomes thin and watery to allow sperm to swim through
what is involved in stimulating ovulation?
drugs are given to prevent negative feedback of oestrogen on FSH and LH.
this can cause super ovulation.
what is involved in artificial insemination? why is this useful?
semen samples are collected over a period of time and inserted into the female reproductive tract.
useful for low sperm count.
if the partner is sterile what can be used?
donor sperm
what is involved in intra-cytoplasmic sperm injection (ICSI) and what is this useful for?
the head of the sperm is drawn into a needle and injected directly into the egg.
useful for low sperm or if sperm are defective.
what is IVF (in-vitro fertilisation)?
the surgical removal of eggs after hormone stimulation (super ovulation), mixed with sperm, zygotes are incubated and implanted into uterus
what can be used conjunction with IVF and why is it used?
PGD (pre implantation genetic diagnosis)- used to identify single gene disorders and chromosomal abnormalities
what are the physical methods of contraception?
barrier methods, IUD and sterilisation
what are the chemical methods of contraception?
pills/ implants
what is the combination pill?
combination of synthetic hormones that mimic negative feedback preventing FSH/LH production
what is the morning after pill?
it prevents ovulation or implantation
what is the progesterone only pill/mini pill?
it causes thickening of the cervical mucus
what is antenatal screening?
it identifies the risk of a disorder so that tests can be carried out and prenatal diagnosis given
what are the 2 types of ultrasounds?
1) dating scan
2) anomaly scan
what is a dating scan ? and when can it be carried out?
they check for the baby due sate and it can be carried out at 8-14 weeks
what is an anomaly scan ? and when can it be carried out?
they detect for serious physical abnormalities and they can be done at 18-20 weeks
what can a dating scan be used in conjunction with?
with testing for chemical markers
what do blood and urine tests check for?
different chemical markers which vary during pregnancy
what is a positive and negative of carrying out blood and urine tests?
positive- an atypical chemical concentration can lead to diagnostic testing to determine the presence of a medical condition.
negative- if carried out at the wrong time it can result in false +ve’s.
what is diagnostic testing?
cells are taken from samples and can be cultured to produce a karyotype to help diagnose a range of conditions.
what is amniocentesis? and state one advantage and one disadvantage
cells are taken from the amniotic fluid to produce a karyotype.
advantage- it has a lower chance of miscarriage
disadvantage- only available later in pregnancy
what is CVS (chorionic villus sampling)? and state one advantage and disadvantage
cells are taken from the placenta to produce a karyotype.
advantage- can be done early on in pregnancy
disadvantage- has a lower chance of miscarriage
explain autosomal recessive
expressed rarely and can skip generations
explain autosomal dominant
expressed in every generation, every sufferer has an affected parent and when it fails to appear in a generation it dies out.
explain incomplete dominance
the fully expressed form occurs rarely, the partially expressed is expressed much more commonly, every fully expressed sufferer has 2 partially expressed parents.
explain sex-linked
written as XX, XY, more males are affected than females and it is passed from mother to son.
what kind of testing is involved in postnatal care? what is it?
phenylketonuria- causes the enzyme which converts phenylalanine to tyrosine to be non-functional.
what kind of mutation is phenylketonuria? and what is the treatment?
a substitution mutation and sufferers are placed on a restricted diet.
what is cardiac output?
the volume of blood pumped out of each ventricle per minute
how do you calculate cardiac output?
CO=HRxSV
what does the SAN (Sino-atrial node) do?
the heartbeat originates within itself, however, the SAN/ pacemaker sets the rate of cardiac contraction.
what are the cells called that set the rate of cardiac contraction?
auto-rhythmic
what are electrical currents recorded on?
an ECG (electro-cardio gram)
what is the role of the medulla with the heart?
regulated the rate of the SAN through antagonistic action of the autonomic nervous system (ANS)
what does the sympathetic system do and what does it release?
nerves release nor-adrenaline and increase HR.
what does the para-sympathetic system do and what does it release?
slowing parasympathetic nerves release acetylcholine and decrease HR.
when does blood pressure increase and decrease in the heart?
BP increases during ventricular systole and decreases during diastole.
how do you measure blood pressure?
with a sphygmomanometer
what are the steps involved when using a sphygmomanometer?
1) the cuff inflates and stops blood flow in the artery and then deflates gradually.
2) blood flow starts (detected as a pulse) - systolic pressure.
3) the blood flows freely (no pulse detected) - diastolic pressure.
what is the typical reading for blood pressure?
120/80 mmHg
what is hypertension?
chronic high blood pressure
why is hypertension a problem?
it is a major risk factor for many diseases including CVD.
what is the pathway of blood circulation?
heart to arteries to capillaries to veins to heart
what happens to the pressure of the blood flow as the blood moves away from the heart?
it decreases
what are the cells called that line the lumen of arteries/ veins?
ENDOTHELIUM cells
a) what is the structure of an artery?
b) what is the function of an artery?
a) an outer layer of connective tissue containing elastic fibres
thick middle layer with smooth muscle containing elastic fibres
narrow lumen
b) carries blood away from the heart
why do arteries contain elastic fibres?
to stretch and recoil to accommodate a surge of blood after each heartbeat
what is the job of the smooth muscle in arteries?
to vasocontract and vasodilate to control blood flow to where it is most needed e.g. muscles during excessive, digestive system during relaxation
what are capillaries and why?
exchange vessels- the site of exchange with tissue because they are only 1 cell thick
a) what is the structure of an vein?
b) what is the function of an vein?
a) an outer layer of connective tissue containing elastic fibres
thin muscular middle layer with smooth muscle
wide lumen which reduces resistance
b) carry blood back to the heart
why do veins have thinner walls than arteries?
arteries need thick walls as they carry blood at high pressure but veins carry blood at a low pressure so don’t need thick walls
what do veins have that arteries don’t and why?
valves to prevent back flow due to low pressure of blood
what happens during exchange of materials?
much of the plasma is forced out of the capillaries due to it arriving at a high pressure from arteries and passes into tissue fluid surrounding cells
how does tissue fluid differ to plasma?
tissue fluid contains no proteins
what diffuse into cells due to tissue fluid having a high concentration?
soluble food
oxygen
useful ions
what diffuses out the cells into the tissue fluid?
carbon dioxide
urea
how does tissue fluid return to the capillaries?
by osmosis
what happens to the tissue fluid that does not return to the blood? and what is the fluid now known as?
it is absorbed into thin walled lymphatic vessels.
the fluid is known as lymph.
what does the lymphatic to with lymph?
returns it to the circulatory system
what is atherosclerosis?
the accumulation of fatty material (mainly cholesterol, fibrous material and calcium) forming an atheroma BENEATH the endothelium
what does atherosclerosis cause?
the artery to thicken and lose elasticity, a reduction in the diameter of the lumen and blood flow resulting in increased blood pressure
what can atherosclerosis eventually lead to?
the development of various CVD’s such as heart attack, angina, stroke and PVD
what is blood clotting?
a protective device triggered by damage to the cells in order to prevent blood loss
what happens if an atheroma ruptures?
it may damage the endothelium causing the release of clotting factors.
what happens when clotting factors are released?
prothrombin (inactive) turns into thrombin (active)
what does thrombin do?
it turns fibrinogen (soluble) into fibrin (insoluble)
what do threads of fibrin do?
they form a meshwork which clots the blood, seals the wound and provides a scaffold for the formation of scar tissue.
what is thrombosis?
the formation of a blood clot (thrombus) in a blood vessel
what is thrombosis usually caused by?
an atheroma enlarging and rupturing the endothelium of the vessel.
what is a thrombus known as if it beaks lose? and what happens?
it is known as an embolus and it is carried along by blood until it blocks a narrow vessel
what can happen if the embolus blocks a narrow vessel?
it can reduce blood flow or cut toff completely
what can thrombosis in a coronary artery cause?
a myocardial infarction (heart attack)
how is a stroke caused?
by thrombosis in an artery leading to the brain
what are the peripheral arteries?
those other than the aorta, coronary arteries or carotid arteries.
what can people suffer if any peripheral arteries are affected by atherosclerosis?
they can experience pain in their leg muscles due to a limited supply of oxygen
a) what does DVT stand for?
b) what is DVT?
a) deep vein thrombosis
b) the formation of a thrombus in a deep vein usually the calf causing swelling which is painful
what may happen if a thrombus breaks free?
it may travel through the heart and block the pulmonary artery known as a pulmonary embolism
state the 2 functions of cholesterol?
1) precursor for steroid synthesis
2) basic component of cell membranes
where is cholesterol synthesised?
by all cells although 25% is produced in the liver cells from saturated fats
how is cholesterol transported through the body?
attached to lipoproteins
a) what does HDL stand for?
b) what does HDL do?
a) high density lipoproteins
b) transports excess cholesterol from the body cells to the liver for elimination preventing a high level of cholesterol from liver to body cells.
a) what des LDL stand for?
b) what does LDL do?
a) low density lipoproteins
b) transports cholesterol from the liver to the body cells.
explain negative feedback of cholesterol
once a body cell has an adequate supply of cholesterol negative feedback inhibits synthesis of new LDL receptors therefore reducing the amount of LDL-cholesterol taken into cells so is left circulating the blood where it may deposit cholesterol in the arteries forming atheroma’s.
why does HDL-cholesterol not contribute to atherosclerosis?
it isn’t taken into endothelial walls
what is a healthy ratio of cholesterol?
higher HDL-LDL
what does a higher HDL-LDL ratio result in?
lower blood cholesterol levels and a reduced chance of atherosclerosis and CVD.
what can increase HDL levels?
regular exercise and a low saturated fat diet
a) what drug is used to reduce cholesterol levels?
b) what does this drug do?
a) statins
b) inhibits an enzyme essential for cholesterol synthesis
what does chronic elevation of blood glucose levels lead to?
the endothelium cells taking in more glucose than normal damaging the blood vessels
what can happen if small blood vessels are damaged by elevated glucose levels?
may result in haemorrhage of blood vessels in retina, renal failure or peripheral nerve dysfunction
what detects a rise in blood glucose levels?
receptor cells in the pancreas which increase the secretion of insulin by the pancreas
what detects a drop in blood glucose levels?
receptor cells in the pancreas which increases the secretion of glucagon by the pancreas
a) what happens to the adrenal glands during fight or flight responses?
b) what does this do?
a) they secrete adrenaline into the bloodstream which overrides the normal homeostatic control
b) this inhibits the secretion of insulin and promotes the body with the additional energy supplies its needs
describe type 1 diabetes
normally diagnosed in childhood,
unable to produce insulin,
treated with regular insulin injections
describe type 2 diabetes
normally diagnosed later in life,
usually attributed to obesity or unhealthy lifestyle,
cells have a decreased number of insulin receptors meaning they are less sensitive to insulin,
treated with lifestyle modifications
what happens after a meal in both cases?
blood glucose concentrations will rise rapidly
what is an indicator of diabetes?
glucose in the urine which is removed by the kidneys
what is used to diagnose diabetes?
a glucose tolerance test
how does a glucose tolerance test work?
1) blood glucose concentrations are measured after a period of fasting
2) a glucose solution is then consumed and changes in their blood glucose concentration is measured for at least 2 hours
what will happen to blood glucose concentration in a diabetic?
it will start high and increase to a much higher level than that of a non-diabetic and takes longer to return to normal.
how is obesity characterised?
excess body fat in relation to lean tissue such as muscle
a) what is BMI?
b) how is it calculated?
a) the ideal body weight for each person
b) body mass over height squared
how can BMI wrongly characterise individuals?
it dosen’t distinguish between body fat and and muscle tissue
what does exercise do?
it increases energy expenditure and preserves lean tissue
how can exercise help to reduce risk factors for CVD?
keeping weight under control,
minimising stress,
reducing hypertension,
improving HDL blood lipid profiles