Physiology and Health Flashcards
What do the testes produce?
Sperm and testosterone
Where is sperm made?
In the seminiferous tubules
Where is testosterone made?
In the interstitial cells
What does the prostate gland and seminal vesicles do?
Secrete fluids which maintain the mobility and viability of sperm
Where are immature ova contained?
In the ovaries
What are ova surrounded by?
A follicle
What does the follicle do?
Protects the developing ovum and secrets hormones
What happens when an ova is mature?
It is released into the oviduct and then either discarded during menstruation or fertilised
What does the hypothalamus do?
Secretes a releaser hormone whose target is the pituitary gland
What does the pituitary gland release?
FSH
ICSH
LH
What does ICSH do?
Stimulates testosterone production
What does FSH do?
In females - stimulates follicle development
In males - stimulates sperm production
What does LH do?
Stimulates ovulation
Brings the development of the corpus luteum
What triggers puberty?
ICSH
FSH
LH
What does testosterone do?
Stimulates sperm production
Activates the prostate gland and seminal vesicles
How does negative feedback control testosterone levels?
Testosterone builds up in the bloodstream and reaches a level where it inhibits the secretion of FSH and ICSH
Testosterone decreases
Inhibition lowers
Pituitary gland is stimulated
A steady secretion of sperm is maintained
How long does the menstrual cycle last?
28 days
What is the first day of menstruation regarded as?
Day one of the cycle
What happens during the follicular phase of the menstrual cycle?
- FSH stimulates the development of a follicle
- Follicle produces oestrogen
- Oestrogen stimulates proliferation of the endometrium and thins the cervical mucus
- High levels of oestrogen cause a surge in LH
- Surge in LH = direct cause of ovulation
What happens during the luteal phase of the menstrual cycle?
- Follicle develops into corpus luteum
- Corpus luteum produces progesterone
- Progesterone stimulates further vascularisation of the endometrium
- High levels of ovarian hormones trigger negative feedback on pituitary
- LH levels drop
- Corpus luteum can’t be maintained
- Progesterone levels drop
- Endometrium can’t be maintained
- Menstruation occurs
What is a males fertility described as?
Continuous
What is a females fertility described as?
Cyclical (lasts 1-2 days)
How can a females fertile period be calculated?
Temperature (rises around 0.5°C day after ovulation)
Cervical mucus (becomes thin and watery to allow sperm to travel through)
How can ovulation be stimulated?
Drugs that mimic FSH and LH
Drugs that prevent negative feedback of oestrogen on FSH
What is a flaw of stimulating ovulation?
Super ovulation can occur
What is artificial insemination and when is it useful?
Semen samples are collected over a period of time and inserted into female reproductive tract
Useful for low sperm count
What is ICSI and when is it useful?
Sperm drawn into a needle and injected into egg
Useful if low or defective sperm
What is IVF?
Eggs are surgically removed and mixed with sperm
The zygotes are incubated and implanted into the uterus
What is PGD (pre-implantation genetic diagnosis)?
It is used during IVF to identify single gene disorders and chromosomal abnormalities
What is a barrier method?
A plastic or rubber barrier which blocks passage of sperm through the vagina
What is IUD and how does it work?
Birth control device
Inserted through the cervix and into the womb
Releases copper which thickens cervical mucus
What is male and female sterilisation?
Male - vasectomy
Cuts/seals the tube that carries the sperm
Female - cutting of the Fallopian tube
What does the morning after pill do?
Prevents ovulation
What does the combined pill do?
Prevents ovulation
Thickens the cervical mucus
What does the mini pill do?
Thickens cervical mucus
Can stop ovulation
What is antenatal screening benefitial for?
Identifying the risk of a disorder
When is a dating scan carried out and what does it determine?
Carried out between 8-14 weeks
Determines pregnancy stage and due date
When is an anomaly scan and what does it detect?
Carried out Between 18-20 weeks
It detects serious physical abnormalities
What do blood and urine tests check for?
Marker chemicals in the mother
What does diagnostic testing do?
Diagnoses a range of conditions
What is a karyotype?
Shows chromosomes arranged as homologous pairs
When is amniocentesis carried out and what does it consist of?
Carried out at 14-16 weeks
Sample of amniotic fluid taken
When is chorionic villus sampling (CVS) carried out and what does it consist of?
Carried out as early as 8 weeks
Sample of placental cells taken
Which has a lower chance of miscarriage - amniocentesis or CVS?
Amniocentesis
What are the traits of autosomal recessive?
Expressed rarely
Skips generations
What are the traits of autosomal dominant?
Expressed in every generation
Every sufferer has an affected parent
When it fails to appear in a generation it dies out
What are the traits of autosomal incomplete dominance?
Fully expressed form is rare
Partially expressed is more common
Fully expressed sufferer has two partially expressed parents
What are the traits of sex linked?
More common in males
Passed from mother to son
Y does not carry the gene
How is PKU tested for?
Heel prick test
What is PKU?
Substitution mutation which causes the enzyme which converts phenylaline to tyrosine to be non-functional
What happens to sufferers of PKU?
They are placed on a restricted diet
Where does the left side of the heart pump blood to?
The body
Does the left side of the heart take in oxygenated or deoxygenated blood?
Oxygenated
Where does the right side of the heart pump blood to?
The lungs
Does the ride side of the heart take in oxygenated or deoxygenated blood?
Deoxygenated
What is cardiac output?
The volume of blood pumped through the ventricle per minute
What is the stroke volume?
Volume of blood expelled by each ventricle on contraction
What is the heart rate?
Number of beats that occur per minute
What happens during systole?
The cardiac muscle contracts and the heart pumps blood
What happens during diastole?
The cardiac muscle relaxes and the chambers fill with blood
What is the definition of the cardiac cycle?
One complete sequence of filling and pumping blood
What happens during atrial systole?
The remainder of blood is transferred through the AV valves to the ventricles
What happens during ventricular systole?
AV valves are closed
Blood is pumped out through the SL valves to the aorta and pulmonary artery
What is responsible for the sound of the heart?
The opening and closing of the AV and SL valves
What is used to hear the sound of a heart?
Stethoscope
What happens during the cardiac cycle?
- diastole - atrium fills with blood and flows into ventricle through AV valves
- SAN sends electrical impulse across atria to AVN
- atrial systole - blood forced from atria into ventricles
- ventricles fill and AV valves close
- AVN sends impulse down conducting fibres in centre and up ventricle walls
- ventricular systole - blood forced from ventricles into arteries through SL valves
- arteries fill with blood, SL valves close
- diastole
What does the SAN do?
Sets the rate of cardiac contraction by autorhythmic cells
Where is the SAN located?
The wall of the right atrium
Where is the AVN located?
At the base of atria
What is the job of the AVN?
Sends impulses down conducting fibres between ventricles causing ventricular systole
What does the SAN do to cause atrial systole?
Sends electrical impulses across atria to AVN
What can currents in the heart be detected by?
An electrocardiogram
What role does the medulla play in connection to the heart?
Regulates rate of SAN through antagonistic action of the autonomic nervous system
What do sympathetic nerves do?
Release nor-adrenaline to increase heart rate
What do parasympathetic nerves do?
Release acetylcholine to decrease heart rate
What happens at point P of a PQRST wave?
Atrial systole
What happens between QRS of a PQRST wave?
Ventricular systole
What happens at point T of a PQRST wave?
Recovery
What happens at point T-P of a PQRST wave?
Diastole
What happens to blood pressure during ventricular systole?
Increases
What happens to blood pressure during diastole?
Decreases
What is used to measure blood pressure?
Sphygmomanometer
What is a typical blood pressure reading?
120/80 mmHg
What is the systolic blood pressure?
The first reading - taken when the blood starts to flow again
What is the diastolic blood pressure?
The second reading - taken when the blood begins to flow freely again
What is hypertension?
Chronic high blood pressure
What is hypertension a major risk factor for?
Diseases including CVD
Where do arteries carry blood?
Away from the heart
Describe the structure of arteries. (4)
Connective tissue containing elastic fibres
Smooth muscle wall (thick) containing elastic fibres
Inner endothelium layer
Narrow lumen
What do elastic fibres do?
Allow arteries to stretch and recoil to accommodate surge of blood after each heartbeat
What does the smooth muscle do?
Contract and dilate to control blood flow to where it is most needed
What is vasoconstriction?
The contraction of arterioles
What is vasodilation?
The dilation of arterioles
Where do veins carry blood?
Back to the heart
Describe the structure of veins. (4)
Connective tissue containing elastic fibres
Smooth muscle wall (thin)
Inner endothelium lining
Wide lumen
Why do veins have low friction?
Due to their wide lumen
Why are veins thin walled?
Due to blood being carried back to heart at low pressure
What are capillaries job?
Exchange vessels
How thick is the wall of a capillary?
One cell thick
What is the order of blood flow?
Heart > arteries > capillaries > veins > heart
What happens to blood pressure as blood moves away from the heart?
Blood pressure decreases
What happens to the plasma in the capillaries after it arrives at high pressure from arteries?
Much of it is forced out
After leaving the capillaries, where does the plasma go?
Passes into tissue fluid
What is the difference between tissue fluid and blood plasma?
Tissue fluid contains no proteins
What does tissue fluid contain?
A high concentration of soluble food, oxygen and useful ions
During exchange of materials, by what movement do things in tissue fluid such as soluble food, oxygen and useful ions move into cells?
Diffusion
What substances diffuse out from cells into tissue fluid?
Carbon dioxide and urea
By what movement does the tissue fluid return to the capillaries during exchange of materials?
Osmosis
What happens to the tissue fluid that does not return to the blood?
It is absorbed into thin walled lymphatic vessels and then known as lymph.
The lymphatic system then returns lymph 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 do?
Thicken and lose it’s elasticity
The diameter of the lumen and blood flow decreases
This results in increased blood pressure
What can atherosclerosis lead to?
The development of various CVDs such as heart attack, angina, stroke and PVD
What is the purpose of blood clotting?
To prevent blood loss of damaged cells
What happens when an atheroma ruptures?
It damages the endothelium and causes the release of clotting factors
How is fibrin produced in thrombosis?
Prothrombin (inactive enzyme) is turned into thrombin (active enzyme), when clotting factors are released
Thrombin turns fibrinogen into insoluble fibrin
What is the job of fibrin in thrombosis?
Threads of fibrin from 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 thrombus/blood clot in a blood vessel usually caused by an atheroma rupturing the endothelium
What happens if a thrombus breaks loose?
It is known as an embolus which is carried along by blood until it blocks a narrow vessel
What can thrombosis in a coronary artery cause?
A myocardial infarction
What is a myocardial infarction?
A heart attack
What can thrombosis in a coronary artery leading to the brain cause?
A stroke
How does thrombosis cause health problems in terms of cells?
Cells are deprived of oxygen leading to the death of tissues
When is an embolus known as an embolism?
When it blocks a vessel
What are peripheral arteries?
Those other than aorta, coronary arteries or carotid arteries
What happens when peripheral arteries are affected by atherosclerosis?
Leads to PVD
Most commonly affecting the legs due to a limited supply of oxygen
What is deep vein thrombosis?
A formation of a thrombus in a deep vein, usually the calf
What happens if a thrombus breaks free in a vein?
It may travel through the heart and block the pulmonary artery - known as a pulmonary embolism
What are the two functions of cholesterol?
Precursor for synthesis of steroids
Basic component of cell membranes
Where is cholesterol synthesised?
By all cells
But 25% is produced in liver cells from saturated fats
How is cholesterol transported around the body?
Attached to lipoproteins
What do HDL do?
Transport excess cholesterol from body to liver cells for elimination
Which prevents a high level of cholesterol building up
What do LDL do?
Transports cholesterol from liver to body cells
What cells synthesise LDL receptors?
Most
What do LDL receptors do?
Take LDL into the cell where it releases cholesterol
What happens once a body cell has an adequate supply of cholesterol?
Negative feedback inhibits synthesis of new LDL receptors, therefore reduces amount of LDL cholesterol taken into cells - so it’s left circulating in blood where it may deposit cholesterol in the arteries forming atheroma
Does HDL contribute to atherosclerosis?
No as it isn’t taken into endothelial walls
Why is a higher ratio of HDL-LDL wanted?
Results 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
How can cholesterol be reduced?
Statins
What do statins do?
Reduce cholesterol levels by inhibiting an enzyme essential for cholesterol synthesis
What does chronic elevation of blood glucose level lead to?
The endothelium cells taking in more glucose than normal damaging the blood vessels and the development of atherosclerosis
What can happen to small blood vessels that are damaged by elevated glucose levels?
May result in haemorrhage of blood vessels in retina, reveal failure or peripheral nerve dysfunction
What happens when blood glucose levels are high?
Detection by pancreatic receptors
Increase in insulin production
Glucose is converted to glycogen which is stored in the liver
BG levels decrease
What happens when blood glucose levels are low?
Detection by pancreatic receptors Increase in glucagon production Glycogen is converted to glucose Returns to blood Increase in BG levels
What happens with blood glucose control during exercise or fight and flight?
The adrenal glands secrete adrenaline into the bloodstream which overrides normal homeostatic control and inhibits secretion of insulin and promotes secretion of glucagon
This provides the body with the additional energy needed
Describe type 1 diabetes - when it’s diagnosed, insulin production and treatment
Normally diagnosed in childhood
Unable to produce insulin
Treated with regular insulin injections
Describe type 2 diabetes - when it’s diagnosed, insulin production and treatment
Normally diagnosed later in life
Usually attributed to obesity or unhealthy lifestyle
Cells have a decreased number of insulin receptors - meaning they’re less sensitive to insulin
Treated with lifestyle modification
When may blood glucose concentration rise?
After a meal
What is an indicator of diabetes?
Glucose appearing in the urine due to the kidneys removing glucose after a meal
What happens during a glucose tolerance test?
It diagnoses diabetes
Blood glucose concentrations are measured after a period of fasting
A glucose solution is then consumed and changes in the patients blood glucose concentration is measured for at least 2 hours
In a diabetic, blood glucose concentration will start higher and increase to a much higher level than that of a non diabetic and takes longer to return to normal
What is obesity a major risk factor for?
CVD and type 2 diabetes
What is obesity characterised by?
Excess body fat in relation to lean tissue such as muscle
What is BMI?
The ideal body weight for each person
How is BMI calculated?
BMI = body mass/height^2
What number of BMI is considered obese?
Above 30
Why does BMI sometimes falsely classify obesity?
Can classify muscular individuals as obese as does not distinguish between body fat and muscle tissue
What is obesity caused by?
A high fat free sugar diet and a lack of exercise
How can you reduce high calorific value per gram?
Limit fats
What does limiting free sugars do?
Removes the issue of having no metabolic energy expended in their digestion
How can energy expenditure be increased and how can lean tissue be preserved?
By exercise
How does exercise help to reduce risk factors for CVD?
By keeping weight under control
Minimising stress
Reducing hypertension
Improving HDL blood lipid profiles
