1. Veins returning blood
Veins have large radii and low resistance. Walls are thin, not elastic Most blood volume is in veins

2. Veins Valves prevent engorgement and backflow
Sympathetic NS constricts veins to increase venous return
Skeletal muscles also help return

4. Baroreceptor reflex
Baroreceptors detect fluctuations in blood pressure and send info to medulla Signals go to ANS
Baroreceptors

5. Response to low pressure

6. Problems with vessels Hemorrhage Why do aneurysms form?
Hypertension, inflammation,
arteriosclerosis, genetics…
Aneurysm

7. Blood pressure problems
Hypertension – Blood pressure over 140/90
Baroreceptors can adjust to higher BP
High BP puts stresses on vessels, elasticity (atherosclerosis, strokes) and stresses on heart (heart attacks), kidneys

8. Blood pressure problems
Treatments for hypertension:
Low salt diet, reduce stress, increase exercise
ACE inhibitors (reduce blood volume)
Alpha, beta blockers (reduce sympathetic effects)
Calcium blockers (reduce cardiac contractions)

9. Blood pressure problems
Circulatory shock – blood pressure drops too low to serve tissues.
From weak heart, blood loss, dilation from allergic response
Body compensates w/sympathetic signals, fluid shifts

10. Components of blood Plasma
Blood cells: erythrocytes leukocytes (WBC), and platelets
Hematocrit is the % of blood occupied by RBC.
(RBC)

11. What is plasma? Ions: mostly Na+ and Cl-.
Gasses, waste, nutrients, hormones
Plasma proteins:
Albumins establish an osmotic gradient, carry some hormones
Globulins (alpha, beta, gamma) transport molecules, serve as antibodies
Fibrinogen - blood clotting

12. RBCs RBCs have no nuclei, ribosomes, or organelles
Packed with hemoglobin
“Doughnut-like” shape

13. Hemoglobin Heme - contains iron and binds with one molecule of O2
Globin - 4 protein chains
Turns bright red when combined with oxygen
CO2, CO, H+ can also bind

14. RBCs replenished every second
Spleen removes old RBCs, RBCs last about 4 months
RBCs are produced in bone marrow from pluripotent stem cells (2 M/sec)

15. Kidney controls RBC production
Kidney is sensitive to anemia and releases erythropoietin

16. Blood doping Banned in competitive sports:
Erythropoietin (EPO) can be synthesized and injected to enhance endurance
An athlete’s own blood can be stored and reinjected to boost RBC’s
Hematocrit can detect

17. Causes of anemia? Anemia – O2 to tissues is low
Due to RBC, erythropoiesis, or hemoglobin
“Pernicious anemia” – lack of B12 results in low RBC production
Aplastic anemia – bone marrow production

18. How the body repairs itself
Initial response:
vascular spasm - reduces blood flow through the vessel
platelet plug - Aggregation of platelets. Platelets attach to areas with exposed collagen
These processes are stimulated by ADP

19. Platelets Platelets are cell fragments that are functional for 10 days
Reduce blood loss (maintain hemostasis)
Platelets and a RBC

21. Positive feedback at injury site
Initial stimulus is exposed collagen
Repair is contained to site of injury 3
Platelets
ADP
Inhibits platelet
aggregation
Inhibits platelet
aggregation
Prostacyclin
and nitric oxide
Prostacyclin
and nitric oxide 2 4 5
Vessel
wall
Normal endothelium
Plug
Normal endothelium 1
Injury site

22. How the body repairs itself
Stopping blood loss:
Fibrinogen (plasma protein) is converted into fibrin (thread-like protein). This conversion is catalyzed by thrombin
Fibrin threads trap RBCs, forming a clot

23. How the body repairs itself
Stopping blood loss:
Fibrinogen (plasma protein) is converted into fibrin (thread-like protein). This conversion is catalyzed by thrombin
Fibrin threads trap RBCs, forming a clot
Thrombin is formed from inactive prothrombin in plasma

24. The clotting cascade...!
Clotting cascade is a series of reactions activating enzymes in a series... final conversion is fibrinogen into fibrin

25. Vessel damage
Exposed collagen
Cascade is initiated when a platelet plug is present or from exposed collagen.
Platelet
aggregation
Hageman
factor
Activation of
next thrombin
PF3
Clotting
cascade
Activation
of thrombin
Formation of
fibrin meshwork
Damaged vessel
is sealed

26. Clots are temporary Fibroblasts form scar tissue for vessel repair.
The clot is dissolved slowly by the enzyme plasmin (breaks down fibrin). Plasmin is activated by the clotting cascade
Phagocytic WBC remove the products of clot breakdown

27. Ok, but what is pus?
Well, pus comes from infected wounds and consists of phagocytes, dead tissue and bacteria.

28. End of exam 3 material (estimated)

29. White blood cells There are five kinds of WBCs
WBCs defend against pathogens, cancer and clean up debris

30. Introduction to the WBCs
Granulocytes
Eosinophils - attack parasitic worms
Basophils - make and store histamine and heparin
Neutrophils - phagocytes, 1st to respond to infection
Monocytes - settle in tissue and become macrophages
Lymphocytes -
B and T cells of specific
immune response
Neutrophil
Eosinophil
Monocyte
Lymphocyte
Basophil

31. Production of WBCs Produced from pluripotent stem cells in bone marrow
Lymphocytes made in lymph tissue during adulthood
Two-thirds of the leukocytes in the blood are granulocytes, mainly neutrophils

32. Immune system Body must resist disease in order to function
Defends against pathogens, identifies and destroys abnormal cells.
The primary pathogens are bacteria and viruses.

33. Nonspecific immunity vs. Adaptive immunity
Nonspecific responses work immediately - 1st line of defense.
Neutrophils, macrophages, inflammation, MAC attack
Adaptive immunity specifically targets certain pathogens to which the body has been exposed
B and T lymphocytes, antibodies

34. Nonspecific response: inflammation
Redness and warmth
Blood flow due to vasodilation
Swelling
Increased capillary permeability
Pain
Nociceptors stimulated by fluid pressure
inflamed knee

35. Inflammation : the beginning
First response involves cells already in nearby tissue: macrophages and mast cells
Macrophages ‘eat’ bacteria
Triggered by infection, mast cells secrete histamine, causing vasodilation
Fibrin walls off infection
Guided by chemotaxins, neutrophils and monocytes go to the area
Mast cells in tissue

36. How do phagocytes know what to eat?
Bacteria get labeled for destruction by opsonins
Opsonins are made from complement cascade, helper T cells, antibodies
Bacteria acquire
opsonins, getting
labeled for macrophage
to engulf it

37. Phagocytes also send signals
They present antigens to helper T-cells to induce a specific response
They ‘wear what they eat’

38. plasma proteins
(including opsonins
and chemotaxins)
histamine
Phagocytes: stimulate histamine release, trigger clotting cascade, release pyrogen which causes fever, induce more WBC

39. Review

40. What do those plasma proteins do?
Some are clotting proteins..clotting cascade! Some are antibodies! (discussed later) Some are part of the complement system! (discussed now…)

41. Nonspecific response : Complement system
Complement = cascade of plasma proteins Cascade activated by molecules on surface of bacteria or antibodies Complement proteins are opsonins, chemotaxins or form MAC attack
MAC

42. Complement has the potential to be very damaging to host tissues
Bacterial wall has holes from membrane attack complex
Complement has the potential to be very damaging to host tissues

43. Nonspecific response: What about viral infections?
Infected cells release interferon
Cause neighboring cells to produce virus-fighting enzymes
Attracts natural killer cells
Host
Interferon
Nasty
virus

45. Adaptive immune response
Also fights viral and bacterial infections but uses B and T lymphocytes found in lymph
Pathogens have particular antigens, which induce a specific response from B and T cells.
Only cells with the antigen are attacked.

46. B cell response B lymphocytes respond to bacteria and toxins
An antigen stimulates some specific B cells to become plasma cells and produce antibodies
Contact with antigen can occur via macrophages

47. B cell response How antibodies work Once labeled, bacteria killed by:
antigen
bacteria
Once labeled, bacteria killed by:
MAC attack
Phagocytosis
Killer cells
binding site for this
specific antigen
Labels cell to be killed

49. Result of labeling