1. Chapter 5 A Question of Pressure

2. Pressure: Its different with solids liquids and gasses

3. Gravity The Major problem of circulation which is made worse because we walk up- right

4. Water Compresses Gas Gravity is Pressure on gas, it compresses it

5. Cardiovascular System Heart: A 4 chambered muscular bump Blood Vessels: Paths through which blood can flow Blood: Water, molecules, ions, and Cells Purpose: To distribute resources around the body

6. Heart (left side) Arteries Capillaries VeinsHeart (Right side) Lungs Capillaries (O 2 in) (CO 2 ) out O2O2 O2O2 O2O2 O2O2 OUT CO 2 IN CO 2

7. Heart: a pump that contracts and relaxes rhythmically Relaxed: Blood enters the heart Contraction: Pushes blood out of the heart Heart Cells have an intrinsic rhythm Atrial cells ~70 beats/min Ventrical cells~ 30 beats/min Left atria: The pace maker The Rhythm of the Heart

8. Heart: Pressurized water pump that delivers ions, molecules and heat around the body Very important in gas exchange : eg flow of CO 2 and O 2 around the body

9. Control of the Heart Without any input from the brain the heart will contract to the rhythm of the pacemaker The autonomic nervous system can alter the rate and strength of contraction –Parasympathetic: slower, weaker –Sympathetic: faster, stronger

10. Blood Pressure Eg. 120/60 For Blood to move, the pressure generated by the heart must exceed the back Pressure in the system. The difference between the “top” and “bottom” numbers is the pressure to do the work of moving the blood

11. Measuring Blood Pressure

12. Blood Flow

13. As a artery gets larger resistance goes down and flow goes up

14. The rule also applies to forks in the road Resistance is how open/closed an artery is

15. Local Volume control By opening and closing arteries the brain can change the volume of blood going to different places in the body –Acute stress –Temperature regulation –Digestion –Immune/Inflammatory reactions: volume can leave circulation (swelling, congestion)

16. General Volume Control The amount of Water in the body can change The concentrations of ions must be maintained “just right” Na + : The most important ion for volume control Low salt diets

17. A Balance

18. Kidney Kidney: Filters out water, ions and small molecules from circulation and returns the “right amount of each to circulation Generally all small molecules such as sugars and amino acids are returned (not Urea) Return of water and ions must be balances

19. Control of the Kidney Blood flow to the kidney: how much blood is filtered (autonomic nervous system) Antidiuretic hormone (ADH) from the pituitary: increases the recovery of water (low blood pressure high Na+ concentration Mineralocorticoids a steroid from the adrenal gland: increases the recovery of Na + ( low Na + concentration)

20. Problems with Blood Pressure Prehypertension: >140/90 –Volume –Resistance –Congestive heart failure Hyoptension: harder to define (athletes) gravity shock

21. Back to the Problem of Blood Distribution

22. The Sinuses Prevent Blood from Falling out of the Head

23. Returning Blood from the Feet: Push and Suck Push Suck The expanding chest when you breath The expanding heart when it relaxes Skeletal Muscles

24. Water Environments of the Body With out circulation the large water environments inside and outside cells starve and become stagnant

25. Control of circulation Heart: How often, how strong Arteries: How open Capillaries: exchange permeability Veins: Push and suck Kidney: General volume control

26. Metabolic Syndrome Diabetes Hypertension Athrosclerosis Blindness Kidney failure Impotance stroke