unit2 Flashcards
what is a ovum
The ovaries contain immature ova in various stages of development. Each ovum is surrounded by a follicle that protects the developing ovum and secretes hormones.
what does FSH do
FSH stimulates the development of a follicle and the production of oestrogen by the follicle in the follicular phase.
what hormone triggers LH and what does LH trigger
Peak levels of oestrogen stimulate a surge in the secretion of LH. This surge in LH triggers ovulation.
how does the corpus lutes degeneraete
the lack of LH leads to degeneration of the corpus luteum with a subsequent drop in progesterone levels leading to menstruation.
how do ovulation drugs work
Ovulation is stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion.
what hormones do these ovulatry drugs mimic
Other ovulatory drugs mimic the action of FSH and LH. These drugs can cause super ovulation that can result in multiple births or be used to collect ova for in vitro fertilisation (IVF) programmes.
how does oral pill work
The oral contraceptive pill is a chemical method of contraception. It contains a combination of synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland.
what is PKu
In PKU a substitution mutation means that the enzyme which converts phenylalanine to tyrosine is non-functional.
what happens after each contraction of teh hEART
The elastic walls of the arteries stretch and recoil to accommodate the surge of blood after each contraction of the heart.
explain pressure filitTRTION
Pressure filtration causes plasma to pass through capillary walls into the tissue fluid surrounding the cells. Tissue fluid supplies cells with glucose, oxygen and other substances. Carbon dioxide and other metabolic wastes diffuse out of the cells and into the tissue fluid to be excreted. Much of the tissue fluid returns to the blood. Lymphatic vessels absorb excess tissue fluid and return it as lymph to the circulatory system.
WHAT happens during diastole
During diastole, blood returning to the atria flows into the ventricles. Atrial systole transfers the remainder of the blood through the atrio-ventricular (AV) valves to the ventricles
where does blood pressure increase
Blood pressure increases during ventricular systole and decreases during diastole.
how do LDL receptors work
Most cells have LDL receptors that take LDL into the cell where it releases cholesterol. Once a cell has sufficient cholesterol a negative feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas.
impact of diabetes on dA BODY
Small blood vessels damaged by elevated glucose levels may result in haemorrhage of blood vessels in the retina, renal failure or peripheral nerve dysfunction.
what happens during flight or fight response
During exercise and fight or flight responses, glucose concentrations in the blood are raised by adrenaline, released from the adrenal glands, stimulating glucagon secretion and inhibiting insulin secretion.
