Homeostasis within the Circulatory & respiratory Systems AP Biology: Big Idea #2 & #4 Chapter 42

Learning Goals  Identify how oxygen and carbon dioxide are transported and their effects on breathing rate.  Identify a dissociation curve and explain the role of partial pressure of oxygen and oxygen saturation in delivery of oxygen to the body.  Identify and explain how heart rate is controlled.  Identify changes in heart rate and connect to the function of the heart.

Moving Gasses  Diffusion moves substances from areas of HIGH to LOW pressure  Gasses dissolve in and out of solution based on partial pressure  Partial Pressure of O2 21% O2 X 760mmHG = 160mmHG

Partial Pressure Gradients drive the transport of gasses  Partial pressure of gasses varies throughout the circulatory system  Where is ppO 2 high? Low?  Where is ppCO 2 high? Low?

Role Of Pressure CO 2 : Greater at tissues; movement directed AWAY from tissues. Oxygen : Greatest in alveoli; movement directed toward tissues

Role of Transport Pigments  O 2 solubility is low, therefore plasma alone cannot carry enough  Hemoglobin can carry 4 oxygen atoms each  Note: Hemoglobin saturation (or carrying oxygen) does not change ppO2

Other functions of RBC Fig  Transport of CO2  Undergoes a reaction and becomes carbonic acid.  Equilibrium lungs back to CO 2.  Hemeoglobin acts as a buffer

Measures  pO 2: partial pressure of oxygen at a given atmospheric pressure.  Saturation of O 2 : amount of oxygen bound to hemoglobin  Concentration of O 2: dependent on saturation and pressure. Normal: >95% saturation 100 mm/mg pO2 20 ml/100mL blood

Oxygen Dissociation Curve Shows cooperative binding effect, more oxygen = easier binding High pressure = high saturation, O 2 bound to hemoglobin (Where ?) Low pressure = low saturation, O 2 released from hemoglobin (Where?)

What happens when the muscles need more oxygen?  Bohr Shift:  Saturation decreased at lower pH.  More O 2 falls off blood and enters body tissues.  What do you think the decrease in pH does to hemoglobin to cause this phenomenon?

The Bohr shift  Factors that affect binding:  pH (exercise)  temperature  Other binding proteins  Myoglobin  Fetal Hemoglobin

The High Altitude Problem  The concentration of oxygen in air is 20.9%. Pressure at sea level is 760 mmHg. 1)What is the pO 2 at sea level? 2)What changes at high altitude? 3)How does that affect physiology? 4)What changes does the body undergo when it spends weeks at high altitude?

Chemoreceptors detect CO2 levels as first indicator  High CO2 levels normally signal low O2 levels  Underwhat conditions is can receptors be “ tricked ” ?  Backup system: O2 receptors in the heart

How does blood gas affect breathing rate?

Respiratory System Case Study  What happens when a person is afflicted with carbon monoxide poisoning!!!

Discuss answers  This is a practice with multiple choice!!!  What do you need to know to answer the question?!?  Why are wrong answers wrong and why is the right answer right?!?!

Control of Circulatory System  Blood pressure  Heart Rate

Blood Pressure

What do the values tell us?

Review: Arteries and Veins  Artery: AwayVein: Towards

Review: Heart/Lung Circulation

Structure meets function Review: What is an intercalated disk? What is a gap junction? What signals muscles to contact? Cardiac muscles?

Nervous Control

Heart Rate and Pacemaker

EKG with Letters

Abnormal heart Rhythms  Describe and Draw each of the abnormal heart rhythms:  Atrial Fibrillation  Tachycardia  Bradycardia  Ventrilcular Fibrillation  Then, write a case study for a patient and have a partner determine which rhythm he/she would likely experience.