1. The Circulatory System: Heart and Vessels
BIOLOGY 12
The Circulatory System:
Heart and Vessels

2. Introduction The circulatory system is considered a closed
system because blood
remains in blood vessels
heart -- arteries – capillaries
veins – and back to heart
and only nutrients, gases,
and wastes are exchanged
at the capillaries.

3. Introduction Functions: 1. Transport O2 from lungs to tissues
2. Transport CO2 from tissues to lungs
3. Transport nutrients from small
intestine to tissues.
4. Transport water from digestive
tract to tissues and from tissues to
lungs, skin, and kidneys

4. Introduction 5. Transport wastes from tissues to kidneys.
6. Transport hormones from glands
to target tissues.
7. Transport body heat from interior
of body to periphery (skin) for
disposal.
8. Maintain a constant pH in the
tissues - blood is a buffer.

5. Introduction 9. Regulate fluid levels in the
tissues (along with lymphatic
system).
10. Seal punctures to body by
forming clots and sealing
wounds.
11. Fight infection; destruction of
foreign protein and dead cells.

6. Comparison of Blood Vessels

7. Blood Vessels A. ARTERIES and arterioles Three layers:
1) endothelial lining: squamous epithelium
2) muscularis: thick layer of smooth muscle and elastic connective tissue.
3) serosa: outer layer of elastic connective tissue.
Arteries are thick walled to withstand the pressure created by heart contraction and to assist the pumping of the blood.
Transport blood away from heart.

8. Blood Vessels B. Veins and venules
Same three layers but much thinner muscularis.
Contain one-way valves to prevent backflow.
Blood moves by contraction of surrounding skeletal muscle.
Little internal blood pressure.
Carry blood from body to heart

9. Blood Vessels C. Capillaries Connect arterioles to venules
Very thin, one cell layer thick squamous epithelium.
Very narrow - one rbc or less diameter.
Blood flow regulated by sphincters
Are the site of all metabolic exchange.

10. BLOOD is regulated by sphincters at the base of the arterioles
BLOOD is regulated by sphincters at the base of the arterioles. These sphincters are controlled by the medulla and regulate the direction of blood flow into capillary beds.
IMPORTANT for sending blood to the digestive system after eating. Temperature regulation: sending blood to the surface to get rid of heat when the body is overheated. When the body is cold blood is diverted to internal organs to maintain core body temperature.

11. HEART EXTERNAL ANATOMY
The heart can be described as a double pump made up of 4 chambers, approximately the size of two fists. It is located directly behind the sternum (breast bone)

12. HEART INTERNAL ANATOMY

13. HEART LAYERS HEART LAYER DESCRIPTION AND FUNCTION MYOCARDIUM
thick muscular layer of the heart
responsible for contracting and pushing blood
out of the chambers
ENDOCARDIUM
thin layer of squamous epithelium
responsible for protecting inner layers of chambers
PERICARDIUM
outer layer (sac) containing pericardial fluid
responsible for lubricating the heart

14. Right side
the right side receives CO2 or deoxygenated blood from the BODY and pumps it to the LUNGS to exchange the CO2 for O2
Left side
the left side receives O2 or oxygenated blood from the LUNGS and pumps it to the BODY

15. The Heart Note the valves:
A. Atrioventricular valves - prevent backflow between ventricle and atrium
B. Semilunar valves: between ventricles and leaving arteries - prevent backflow when ventricles re-fill.
Chordae tendenae prevent valve inversion.

16. The Heart Heart contracts in two phases:
1. Systole: ventricles contract, atria relax
2. Diastole: atria contract, ventricles relax
Lub-dub sound due to opening and closing of valves.

18. The Heart Control of Heartbeat
The heart will continue to beat even if all nerve connections to it are severed, but at an unchangable rate.
Nerves and hormones adjust the intrinsic heart beat.
The heart contains its own nervous tissue that initiates the heartbeat.

19. The Heartbeat
Between the vena cava and the right atrium is a patch on nerves (a ganglion) called the SA node
Sino-Atrial Node
This is the hearts natural pacemaker and receives a signal from the MEDULLA initiating a wave of stimulation that goes over both atria causing them to contract.

21. EKG
A branch from the S-A node goes to a second ganglion located in the wall between the right atrium and ventricle called the Atrio-ventricular node.
When the impulse reaches the AV node from the SA node, it is transmitted along nerves called Purkinji fibers to the base of both ventricles.

22. P wave stimulatation of the atria (depolarization) contraction of the R and L atria QRS wave stimulation of the ventricles through the septum (depolarization) contraction of the R and L ventricles T wave recovery (repolarization) Na+ K+ pump active transport and redistribution of ions across the membranes of nerve cells in heart muscle cells

23. The Heart
The impulse then moves up more fibers to tiny nerve branches called the Purkinje fibers that go into the ventricular muscle and cause it to contract from the bottom up.
This neural-electrical activity of the heart beat can be seen in an ECG (electrocardiogram)

24. The Heart
The rate can be adjusted by effects of both nerves from the autonomic nervous system and hormones.
These effects are both stimulatory and inhibitory depending upon the needs of the body.

25. Pattern of Blood Flow
We have a four chambered heart which is actually a double pump.
we have two circulatory systems:
1. Pulmonary: right side pumps blood to lungs.
2. Systemic: left side pumps blood to rest of the body.
This means that blood goes through the heart twice for every round through the body.

26. Vascular Pathways Arteries carry blood away from heart and veins carry blood back to heart. All arteries carry oxygen except and all veins carry CO2 except

27. Systemic Blood Vessels

28. 1. Pressure 2. Velocity 3. Surfacearea
Exchange occurs mostly by diffusion - slow!
Three aspects of capillary structure facilitate this passage:
1. Pressure
2. Velocity
3. Surfacearea

30. Fetal Circulation The fetus is, biologically, an endoparasite.
To survive, it needs numerous adaptations, most of which involve the circulatory system.
Further, these modifications can’t be too elaborate as they must be shut off at the baby’s first breath upon being born.

31. Fetal Circulation
We will look at five circulatory adaptations
1. Foramen Ovale: a hole in the septum between the right and left atrium.
Used to bypass the lungs
2. Ductus Arteriosis: a shunt that connects the pulmonary trunk to the dorsal aorta, another lung bypass

32. Fetal Circulation
3. Ductus Venosus: connects umbilical vein to posterior vena cava.
Allows blood to bypass fetal liver.
4. Umbilical blood vessels
A. umbilical arteries (2): carry blood from fetal iliac arteries to placenta.
B. Umbilical vein (1): placenta to vena cava

33. Fetal Circulation 5. Fetal Hemoglobin
Produced by expression of different gene than normal hemoglobin.
Has greater affinity for oxygen than adult hemoglobin - necessary for fetus to pull oxygen from maternal circulation.

34. The Blood An adult has between 4 and 6 l. of blood.
Blood is divided into two components:
1. The plasma - a straw colored liquid that makes up 60% of the blood volume.
2. The Cellular Component - made of red blood corpuscles, white blood cells, and the platelets.

35. Plasma Plasma is 90% water: the other 10% contains:
Blood Proteins (7% - 10%)
Albumin: helps maintain the correct osmotic balance in the tissues by controlling the thickness of the blood.
Fibrinogen: together with platelets, form blood clots to seal wounds.
Immunoglobins: form antibodies to attack foreign protein

36. Plasma . Water soluble elements (other 3%)
Together, these elements help control blood pH (about 7.4) and adjust osmotic balance in the tissues (with albumin).

37. Plasma These elements include:
Oxygen: necessary for cellular respiration oxidation of glucose
Carbon dioxide: transported in plasma as dissolved CO2 (small amount) or reacted with water as bicarbonate ion, HCO3-.

38. Plasma
Nutrients glucose, amino acids, fatty acids, and nucleotides (absorbed from digestive system).
Hormones from glands to target organs ADH for water balance in kidneys and Insulin for maintaining proper blood sugar levels
Vitamins niacin (vitamin B) is necessary for cellular respiration, A, K, D, C are necessary for many chemical reactions (cellular health
Salts (blood electrolytes) there are a host of inorganic ions such as sodium, potassium, calcium, etc.
Wastes from cell metabolism (breakdown of proteins and nucleic acids) - mostly urea, some creatinine and ammonium salts

39. Cellular Component Red Blood Corpuscles (erythrocytes).
In mammals, rbc’s lack a nucleus and most other cell components.
They do anaerobic respiration to generate the small amount of ATP they need to function.
Basically, an rbc is a bag of hemoglobin.

40. Cellular Component Rbc’s live about 120 days before wearing out.
You have about 75 trillion rbc’s and each one contains about 300 million molecules of hemoglobin!
Rbc’s can also transport some CO2 (small amount) as carbaminohemoglobin.

41. Cellular Component
Hemoglobin is made from an iron based pigment called Heme together with 4 globular proteins.
Hemoglobin binds to O2 in the lungs (cool temperature, low pressure) and release it in the tissue capillaries (warm, high pressure).
Hemoglobin + O2 ---> oxyhemoglobin
Hb + O2 ----> HbO2

42. Cellular Component White Blood Cells (leukocytes):
Overall function is body defense.
There is about one wbc for every 1000 rbc’s
Are true cells with all the cell organelles and can live a long time - some a life time.
Wbc’s can and do leave the blood stream where they patrol the tissues searching for foreign protein.

43. Cellular Component
Thrombocytes Platelets: cell fragments from formation of other blood cells.
Function in helping seal wounds and form clots.
All of the blood cells originate in bone marrow from stem cells (except lymphocytes)

44. Blood Cells
In summary the 3 main functions of blood are:
TRANSPORT ; nutrients, gases, vitamins, minerals, hormones and wastes
FIGHT INFECTION; our blood stream is patrolled by an army of white blood cells which provide us with our immunity
CLOTTING; if not for the chemicals involved in closing and repairing cuts we would bleed to death

45. 60% of blood is PLASMA
40% of blood consists of
FORMED ELEMENTS
Erythrocytes
Leukocytes
Thrombocytes

46. How does your body replace blood cells?
1. LOW OXYGEN TENSION
STIMULATES THE LIVER
2. Liver releases the protein GLOBULIN
Kidney releases REF
renal erythropoietin factor which combines with the globulins
5. INCREASE IN
RBC which
increases
bodies ability to
carry more OXYGEN
Erythropoietic stem cells in long and flat bones are stimulated to produce more RBC’S

47. What causes a decrease in carrying capacity of oxygen in our blood?
Loss of blood due to trauma
Lack of hemoglobin due to anemia
- pernicious lack of vitamin B12
- iron deficiency due to poor diet
High altitude due to less oxygen in the air

48. shape, size, nucleus present
Erythrocytes
Leukocytes
Thrombocytes
diagram
origin /life span
approximately 120 days then broken down in spleen
1 day to lifetime if they are memory cells
vary
number / kinds
only 1 type
Approximately 600 to 800 rbc to every 1 wbc
5 main w.b.c.
lymphocytes are the most common
fragments of megakaryocytes produced in bone marrow
shape, size, nucleus present
disc shaped much smaller than w.b.c. and have no nucleus
Vary in shapes can move using pseudopods and have a large nucleus
no nucleus small and contain a protein to aid in blood clotting
function
carry O2
fight infection
blood clotting

49. Cellular Component AGRANULOCYTES GRANULOCYTES
Mononucleocytes: single lobed nucleus
Do not contain visible granules (lysosomes)
GRANULOCYTES
Polymorphonucleocytes: nucleus takes on many different shapes.

50. Cellular Components
Contain visible granules: called Neutrophils (55% - 65%): major phagocytic cell - attacks pathogens
Eosinophils (2% - 3%): attack larger cells and parasites
Basophils: help in body repair by releasing histimine.

51. Neurtophils 60-70% of all wbc’s
Engulf and destroy microbes
Last only a few days because they self destruct
Stimulated by chemicals, this attraction is called chemotaxis
Monocytes 5% of all wbc’s
Develop into large “marcrophages” and can extend pseudopods and attach to the carbohydrate chains of microbes engulfing foreign invaders
Lymphocytes 20-30% of all wbc’s
These are the blood cells responsible for producing ANTIBODIES

52. 

53. Blood Clotting damaged cells release THROMBOPLASTIN
(enzyme)
PROTHROMBIN activator
Released from platelets into blood
Calcium
PROTHROMBIN already present in plasma
THROMBIN also in plasma
Calcium
FIBRINOGEN a blood protein in plasma
FIBRIN threads trap red blood cells and they dry up (CLOT)

54. Capillary Exchange

55. Blood Pressure
Blood pressure is the pressure force exerted by blood against the walls of the arteries.
It goes up and down rhythmically with the contraction and relaxation of the ventricles.
It is measure in mm Hg with normal being around 120/80 (systole/diastole).

56. Blood Pressure
- Hypertension is abnormally high bp and can be caused by many factors:
occlusion of the arteries
- loss of elasticity in arteries (hardening of the arteries).
- smoking (contracts smooth muscle)
- Stress increases resistance by contracting surrounding muscles.
- Fat - increases km of blood vessels

57. Blood Pressure
Hypotension is lower than normal blood pressure and is often related to low heart volume outputs. Low blood pressure can also lead to kidney failure.

60. The Lymphatic System Immune System consists of
SPLEEN which is the largest gland in the immune system and acts as a filter for dead white blood cells and pathogens
LYMPH NODES are located in the in the neck, under arms, and groin area and also filter out pathogens and toxins
LYMPH VESSELS run parallel to veins and pick up any excess fluids and wbc’s
LYMPH FLUID is made up of excess water and white blood cells that leave the circulatory system

62. The Lymphatic System
The lymph vessels are similar to veins because they are made up of muscles and have valves. However they do not carry any blood only lymph fluid.
Recall in Biology 11 that blocked lymphatic vessels by the filarial worm leads to elephantiasis!

64. Inflammatory Reaction

65. IMMUNE SYSTEM
Skin is our first barrier against foreign invaders (pathogens)
Pathogens can only penetrate our circulatory system when this barrier is broken. We have several orifices where pathogens can enter our circulatory system
Oral cavity
Nasal cavity
Anal opening
Vaginal orifice
Urethras

67. Some ways we are protected besides our skin acting as a barrier are;
Mucous membranes
Sebaceous glands
Sweat glands
Anti-microbial proteins like lysozyme
Phagocytic cells

68. Antigen Antibody Reaction
Antigens will stimulate lymphocytes to produce chemical proteins called antibodies which are specific to each antigen and help the immune system by eliminating the foreign antigens. Antigen is short for “anti-body generator.”

69. Autoimmune Diseases
Sometimes the immune system loses tolerance for self and turns against certain molecules of the body, causing one of the many autoimmune diseases.
Lupus
Rheumatoid arthritis
Diabetes mellitus
Multiple sclerosis

70. Blood Types
There are actually about 25 or so blood typing differences in human blood.
Two are most critical: ABO and Rh
1. ABO system.
This is an example of a multiple allele gene system where there are three possible alleles in the human gene pool: IA, IB, and I.

71. Blood Types
If you receive blood containing an antigen foreign to you, your antibodies will attach to the antigen and cause all the rbc’s to clump together (termed agglutination) and you quickly die.
Therefore, it is critically important that blood transfusions be done correctly.

73. A B AB O Blood types A O B O A B AB O only O Antigens present
Antibodies present
Receive blood from
Blood typing test
A antigen B antigen Rh antigen
serum serum factor
Blood type A
all cells have the
A antigen
on outside
B antibodies are present in plasma
A O B
B antigen
A antibodies are present in plasma
B O AB
50% have A and 50% have B antigens
Plasma has NO antibodies present
A B
AB O O
All RBC’s lack any antigens on outside of RBC’s
Both A and B
Antibodies are present in plasma
only O

74. Blood Types 2. The Rh System:
This has two possible alleles: positive means you produce the Rh antigen on your rbc’s or negative - no antigen.
Negatives produce anti Rh antibodies and the same clumping problem exists.

75. Stimulus low blood pressure 90/65
Normalcy 120/80
Receptors are osmoreceptors that detect water levels in blood
Response is;
Less urine more water reabsorbed back into blood
Heart beats faster to keep blood pressure up
Arteries constrict to narrow the opening in blood vessels
Autonomic nervous system which includes MEDULLA and HYPOTHALMUS and PITUITARY GLAND
PITUITARY releases ADH
( antidiuretic hormone)
Effectors are;
KIDNEY (nephron tubules)
HEART
ARTERIES and ARTERIOLES