physiology for scope Flashcards
what are the placental hormones in pregnancy?
oestrogens
progesterone
human placental lactogen (hpl)
Human Chorionic gonadotrophin (hCG)
what are the maternal hormones of pregnancy?
oxytocin
prolactin
relaxin
what are the functions of oestrogen? what effects can it cause on the body?
- increase in protein synthesis to stimulate tissue growth
- stimulates uterine growth by increasing uterine blood flow
- causes development of mammary ducts in breasts
- increases water in extracellular matrix (causing softening of connective tissues)
body effects?
pelvic discomfort due to stretching of pelvic joints and ligaments
odema
Progesterone is produced by the _______ _______ in the first __ - __ weeks of pregnancy
corpus luteum
6-8 weeks
actions of progesterone in pregnancy are;
- stimulates secretion of glycogen from endometrial glands
- decreases excitability of myometrial cells (inhibiting uterus from contracting)
- relaxes smooth muscle in GI tract, urinary tract & of blood vessels
- suppresses maternal responses to fetal antigens
- promotes lobular and alveolar growth in breasts
- inhibits prolactin
- increases sensitivity of respiratory system to CO2
- increases body temp
function of human Gonadotropin hormone (hCG)?
maintain the corpus luteum (which secretes oestrogens and progesterone) until the placenta takes over. hCG levels peak around 7-11 weeks
human placental lactogen (hPL) what does it do?
- peaks around third trimester
- promotes fetal growth
- inhibits prolactin
- supports mammary growth
why is human Placental Lactogen described as an “insulin antagonist”
It gives the mother an alternative source of energy so that the fetus can preserve its glucose and amino acid stores. it causes a rise in free fatty acids as the energy source and limits cell glucose uptake (usually achieved with insulin) thus the blood glucose level may be higher to travel to the fetus for cell growth.
role of oxytocin in pregnancy?
(produced in hypothalamus and released from AP gland)
acts on myometrium (muscle layer of the uterus) during labour
oxytocin receptors increase throughout pregnancy. causing braxton hicks contractions more frequently in the latter stages of pregnancy
relaxin?
secreted by corpus luteum - breaks down collagen fibres by increasing water abundance in connective tissue which softens it (pelvic ligaments, areola, cervix).
what are the haematological changes in pregnancy?
an increase in blood volume causing haemodilution
explain why haemodilution occurs in pregnancy and what changes can this create for the woman?
in pregnancy, blood volume is increased by 30-40% to provide more oxygen and nourishment to the fetus.
The majority of this volume increase comes from an increase in plasma making the blood less concentrated in its other constituents such as red blood cells and plasma proteins.
This leads to lower viscosity of the blood which reduces peripheral resistance and lessens the cardiac workload. It also lowers osmotic pressure and can cause odema.
Haemodilution causes a lower concentration in ferritin making pregnancy a risk factor for iron deficiency anaemia.
what are the coagulation changes that occur in pregnancy?
In pregnancy the blood becomes hyper-coagulable due to an increase in fibrinogen and clotting factors however there is a decrease in platelets due to haemodilution.
What cardiac changes occur in pregnancy?
- Stroke volume increases due to plasma increase
- heart rate increases by about 10-15bpm
- cardiac output increases due to above by about 40-50%
- peripheral resistance reduces due to relaxed blood vessels (progesterone causing)
(this and the the increase in utero-placental circulation accommodates the increase in blood volume) - blood pressure remains stable or may drop slightly due to the decrease in peripheral resistance
why does pregnancy predispose women to an increased risk of developing urinary tract infections?
Due to the increase in blood volume, the kidneys have more fluid to filter and produce more urine. This means the kidneys have to filter the blood at a higher rate - increasing the Glomerular filtration rate (GFR). Because of this, it can cause the filter to become leaky, allowing protein and glucose molecules to be secreted into the urine. Protein and glucose in the urinary tract facilitate the growth of bacteria. Additionally due to the effects of progesterone in pregnancy relaxing the smooth muscle of the urinary tract can cause dilation of the renal pelvis causing urinary stasis.
Both of these factors (urinary stasis and protein and glucose in the urinary tract) increases the risk of developing a UTI.