Respiratoy System Flashcards
Why does the respiration system change
Increased need for o2 for increase in maternal metabolic rate and fetal/placenta
O2 increases by 16-20%
Increased demand for gas exchange
Accommodate new gaseous exchange system - placenta
What does the upper respiratory system do
AIDS in te passsage of air
Moistens the warm air before it reaches our lungs
What is in the upper respiratory tract
Nasal cavity- lined with ciliates epithelium
Pharynx- funnel shaped
Larynx- made up of pieces of cartilage connected y ligaments by ligaments and muscles
Changes to the upper tract
Increased blood flow to nasalpharyx
Increased secretion of mucus due to increased oestrogen
Result in nosebleeds ad stuffiness
What is in he lower tract
Trachea - connect larynx to lungs
Him- where bronchi enters lung
Bronchioles - structured by smooth muscle
Changes to lower tract
Increased progesterone relaxessmooooth ,iscle of bronchioles to reduce airway resistance - greater airflow
Changes to thorax
Diaphragm raises to 4cm to make room for growing uterus
Muscle and cartilage of thorax relax - rtranversdiameter increases
SU costal angle increases from 68 - 103 degree - more space for lungs
Mechanism o breathing
Voluntary control
Closed glottis
Open glottis
Voluntary control
Breath holding and hyperventilation
Closed glottis - valsava method
Breath holding - pushing through duration of contraction
High abdominal pressure induced by descent of the diaphragm which helps the mobilisation of the descending foetus by compressing the uterine fungus
Open glottis pushing
Slow exhalation through pursed lips involves a different muscle mechanism a,ed at reproducing expulsive reflexes but. Without the power .
- abdominal muscles contract Transverse and oblique muscle b compressing the uterus on both sides allowing descending foetus to progress
Peripheral chemoreceptor
On aortic arc
Monitor changes in pO2 and pCO2 in blood anrelay infor to respiratory cortex to increase respiration
Central chemoreceptors
Found under surface of medulla
Detect high levels of pCO2 and send messages to respiratory centre o increase rate of expiration
Central chemoreceptors
Found under surface of medulla
Detect high levels of pCO2 and send messages to respiratory centre o increase rate of resp
changes to chemoreceptor
Progesterone increases sensitive of chemoreceptors central) to pCO2
This stimulates over breathing to breathe off CO2 - have lower levels o aterilll co2 then non preg state
Increase progesterone means mild respiratory alkalosis which enables gradients for gas exchange across the placenta
