Circulation

Chapter 38

General Function

1. Transports nutrients (from digestion), wastes (to respiratory and urinary), hormone (endocrine) and gases (to and from respiratory) throughout the body

2. Helps fight infection

3. Helps regulate body temperature and pH

Functional Connections

food, water intake oxygen intake

DIGESTIVESYSTEM

RESPIRATORYSYSTEM

eliminationof carbondioxide

nutrients,water,salts

oxygencarbondioxide

CIRCULATORYSYSTEM

URINARYSYSTEM

water,solutes

eliminationof foodresidues

rapid transportto and from allliving cells

elimination ofexcess water,salts, wastes

Figure 38.2Page 665 

Circulatory Systems

spaces orcavitiesin bodytissues

aorta heart

pump pump

Open System Closed System

Figure 38.3Page 666

•Arthropods and most mollusks •Vertebrates and anelids

Circulation of higher animals- Heart- pump to move fluids-usually one way with a valve

Closed circulatory system- one that has vessels (veins and arteries) to move the blood

Open circulatory system- lacking vessels-allowing the blood to move in large sinuses

Open circulatory systems:

Insect circulatory system (picture)

Closed circulatory systems: Earthworm Anterior end--10 hearts (aortic arches) (5 on each side)

Vertebrate Circulatory

Arteries- take blood away from the heart

Veins- take blood to the heart

Capillaries- connect arteries and veins (exchanges materials)

Fish

1 circuit , 2 chambered heart

Amphibians

2 circuits (to lungs and body), 3 chambered heart (blood mixes)

3. Reptiles- 3 chambered heart; 2 atria, 1 ventricle but the ventricle is partial divided allowing very little mixing of blood

Birds and mammals – 2 circuits (to lungs and body), 4 chambered heart (blood doesn’t mix)

Functions of Blood

• Transports oxygen and nutrients to cells

• Carries carbon dioxide and wastes away

from cells

• Helps stabilize internal pH

• Carries infection-fighting cells

• Helps equalize temperature

Components of Blood

Blood6-8%of body weight

Plasma portion (50-60% of total volume)• Water• Proteins• Ions, sugars, lipids, amino acids, hormones, vitamins, dissolved gases

Cellular portion (40-50% of total volume)• White blood cells (leukocytes) – involved in immune response Neutrophils-fast acting phagocytes, nonspecific Lymphocytes-B & T cells, specific Monocytes-call up immune response, slow, nonspecific Eosinophils-fast, secrete enzymes, nonspecific Basophils-fast, inflammatory response, nonspecific• Red blood cells (erythrocytes) – carry oxygen• Platelets – involved in clotting

Figure 38.5Page 668 

See figure 38.7, page 669 also

Erythrocytes (Red Cells)

• Most numerous cells in the blood

• Transport oxygen and carbon dioxide

• Colored red by oxygen-binding pigment

(hemoglobin)

• Have no nucleus when mature

• Develop from stem cells in bone marrow

• Good for about 120 days, ongoing

replacementBiconcave disc

Leukocytes (White Cells)

• Function in housekeeping and defense

• Cell typesBasophils

Eosinophils B lymphocytes

Neutrophils T lymphocytes

Macrophages NK cells

Dendritic cells Mast cells

Leukocytes (White Cells)

Platelets (thrombocytes)

• Membrane-bound cell fragments

• Derived from megakaryocytes, which

arise from stem cells

• Release substances that initiate blood

clotting

Blood Cell Development

• Stem cells in bone marrow are unspecialized cells that retain the capacity to divide

• Some daughter cells of stem cells differentiate to form blood cells

• Body must continually replace blood cells

natural killer cells

eosinophils

neutrophils

basophils

mast cells

B lymphocytes (mature in bone

marrow)

T lymphocytes (mature in

thymus)

dendritic cells mature macrophages

platelets

red blood cells (ertyrocytes)

forerunners of the white blood

cells (leukocytes)

monocytes (immature

phagocytes)

stem cells that multiply and

differentiate in bone marrow

megakaryocytes

?

committed cell(proerythroblast)

Fig. 38-5, p.661

Blood Disorders• Red blood cell disorders

– Anemia – to few red-blood cells, oxygen blood levels cannot be kept high enough

• Many different kinds, from many causes

– Polycythemias – too many red-blood cells, makes blood flow sluggish

• White blood cell disorders– Infectious mononucleosis – too many

monocytes and lymphocytes– Leukemias – cancer suppresses or impairs

white blood cell formation in bone marrow

Blood Type in Transfusions

• Require that donor and recipient have

same blood type

• If bloods of incompatible types are mixed,

recipient’s immune system will attack,

clump up and destroy donor cells

• This is an agglutination reaction

ABO Blood Type

• Type A red cells have one type of marker

at surface (can accept type A or O)

• Type B red cells have a different type of

marker (can accept type B or O)

• Type AB cells have both markers (tolerate

any donor)

• Type O cells have neither marker (can

only accept type O donor)

Blood Type Compatibility

O A B AB

Blood type of donor

O

A

B

AB

Blood type of recipient

Figure 38.8Page 670 

Rh Blood Type

• Based on presence or absence of Rh marker on red cells– Rh+ has marker, Rh- doesn’t have marker

• Can cause problems during pregnancy – If mother is Rh negative,

– has previously carried Rh positive child,

– is carrying fetus that is Rh positive

– Mother’s antibodies can attack fetal cells

Vessels•Blood flows from heart into arteries (large vessels that lead away from the heart)

•Then into arterioles (smaller vessels that lead away from the heart)

•Then into capillaries (smallest diameter, with thin walls that allow for diffusion of materials into and out of blood)

•Then into venules (small vessels that lead back toward the heart)

•And finally into veins (large diameter vessels that return blood to heart)

Blood Vessels

• Arteries: main transporters of oxygenated blood, thick elastic walls to withstand high pressure

Figure 38.15 Page 676

Blood Vessels

• Arteries: main transporters of oxygenated blood

• Arterioles: diameter is adjusted to regulate blood flow

• Capillaries: diffusion occurs across thin walls

Figure 38.17 Page 668

Blood Vessels

Human Heart Is a Double Pump

• Partition separates heart into

left and right sides

• Each pumps blood through a

different circuit

Pulmonary Circuit

Short loop that

oxygenates

blood, pumps

blood to and

from lungs.

right pulmonary artery left pulmonary artery

capillarybed ofrightlung

pulmonarytrunk

capillary bedof left lung

(to systemic circuit)

pulmonary veins

lungs

(fromsystemiccircuit)

heart

Figure 38.10 Page 672

Systemic Circuit

Longer loop that

carries blood to

and from body

tissues

capillary beds of headand upper extremities

(to pulmonarycircuit)

aorta

(frompulmonarycircuit)

heart

capillary beds of otherorgans in thoracic cavity

capillary bed of liver

capillary beds of intestines

Figure 38.10 Page 672

Hepatic Portal System

• Carries blood from capillaries in

digestive organs to capillaries in the

liver

• Allows liver to detoxify substances from

digestive tract before they are carried to

the body

jugular veins

superior vena cava

pulmonary veins

hepatic portal vein

renal vein

inferior vena cava

iliac veins

femoral vein

carotid arteries

ascending aorta

pulmonary arteries

coronary arteries

renal artery

brachial artery

abdominal aorta

iliac arteries

femoral artery

Major Vessels

Figure 38.11 Page 673  

Figure 38.12

Page 674 

Location of the Heart

right lungleft lung

diaphragm

Pericardium – double sac of tough connectivetissue that protects and anchors the heart to nearby structures

rib cage

Figure 38.12 Page 674

Four Chambers• Each side has two chambers

– Upper atrium

– Lower ventricle

• Valves between atria and

ventricles (AV valves)

• Valves between each ventrical

and artery (semilunar)

• Contraction of the ventricles is

the driving force for blood

circulation.

Figure 38.12 Page 674

Heart Anatomy

superior vena cava

right semilunar valve

right pulmonary veins

right atrium

right AV valve

right ventricle

inferior vena cava

septum

myocardiumheart’sapex

arch of aorta

trunk of pulmonaryarteriesleft semilunar valve

left pulmonaryveinsleft atrium

left AV valve

left ventricle

endothelium and connective tissue

inner layer ofpericardium

Figure 38.12Page 674

Blood Path

• From body in vena cava

• To right atrium

• To right ventricle

• To lungs (in pulmonary artery – deoxygenated)

• To left atrium from lungs (in pulmonary vein – oxygenated)

• To left ventricle

• To body in aorta

Cardiac Muscle•Cardiac muscle is striated, like skeletal muscles.

•Sliding filament model like skeletal muscles.

•But cardiac muscle cells are branching, short and connected at their endings

•Lots of gap junctions are present allowing quick spread of action potentials.

•Also, 1% of cardiac muscles do not contract, they function in the cardiac conduction system (make the heart pump by rhythmic waves of excitation).

intercalateddisk

mitochondrion

Fig. 38-15a,b, p.667

one sarcomere

Intercalated disk, a region of adhering cell junctions at the abutting ends of cardiac cells.

c Gap junction. These communication junctions occur on the sides of cardiac muscle cells, where mechanical stress is not as great as at the ends. They connect the cytoplasm of adjoining cells. We removed one cell’s plasma membrane for clarity.

Fig. 38-15c, p.667

Conduction and Contraction

• SA node in right atrium is pacemaker

• Electrical signals cause contraction of atria

• Signal flows to AV node and down septum to ventricles, causing the ventricals to contract.

• The nervous can only adjust the rate and strength of contractions.

SA node

Figure 38.14Page 675

AV node

•Systole – contraction

•Diastole - relaxation

Blood Pressure

• Highest in arteries,

lowest in veins

• Systolic pressure is

peak pressure

(ventricular

contraction)

• Diastolic pressure is

the lowest Greatest pressure drop Greatest pressure drop

is in arteriolesis in arteriolesFigure 38.18 Page 668

Controlling Blood Pressure• Cardiac output is adjusted by controls over rate and strength

of heartbeat (nervous system)

• Total resistance in vessels changes due to diameter changes

(vasoconstriction and vasodilation) which is controlled by the

nervous and endocrine system.

• Baroreceptor response is main short-term control of blood

pressure

– By triggering the sympathetic or parasympathetic nerves

that control the blood vessels and heart

• Kidneys are the main long-term control of blood pressure

– By regulating the volume and composition of the blood

Velocity of Flow Varies

• Volume of blood flowing through vessels always has to equal heart’s output

• Flow velocity is highest in large-diameter transport vessels

• Flow velocity is slowest in capillary beds; blood spreads out into many vessels with greater total cross-sectional area

Diffusion Zone

• Capillary beds are the site of exchange between blood and interstitial fluid

• Capillary is a single sheet of epithelial cells

• Flow is slow; allows gasses to diffuse across membranes of blood cells and across endothelium

Movement in and out Capillaries• Capillary beds are the site of exchange between

blood and interstitial fluid

• Capillary is a single sheet of epithelial cells (very thin walls), some clefts between them, flow is slow

• allows gasses to diffuse across membranes of blood cells and across endothelium

• Some proteins leave and enter by endo and exocytosis

• Some ions leave at the clefts between the cells

• Bulk flow (in response to fluid pressure) also occurs– Ultrafiltration out and reabsorption in

Bulk Flow in Capillary Bed

blood tovenule

inward-directedosmotic movement

cells oftissue

outward-directedbulk flow

blood from arteriole

Figure 38.21Page 670

Net Bulk Flow

• Normally, ultrafiltration only slightly exceeds reabsorption

• Fluid enters interstitial fluid and is eventually returned to blood by way of the lymphatic system

• High blood pressure causes excessive ultrafiltration and results in edema

The Venous System• Blood flows from capillaries into venules, then

on to veins

• Veins are large-diameter vessels with some smooth muscle in wall

• Valves in some veins prevent blood from flowing backward

Figure 38.17d Page 668

Bicarbonate Formation

CO2 + H2O H2CO3

carbonic acid

HCO3–

bicarbonate

+ H+

• Most carbon dioxide is transported as bicarbonate• Some binds to hemoglobin• Small amount dissolves in blood

Cardiovascular Disorder

Risk factors

• Smoking, Gender (maleness), Genetic factors, Old age, High cholesterol, Obesity, Lack of exercise, Diabetes mellitus

•Hypertension High Blood pressure (above 140/90)

Atherosclerosis• Arteries thicken, lose elasticity, and fill up with

cholesterol and lipidsArrhythmias• Irregular heartbeat

Hemostasis – stops bloodloss

• Blood vessel spasm (contracts, slows bloodflow), platelet plug formation, blood coagulation (clotting)

• Clotting mechanism– Prothrombin is converted to thrombin– Fibrinogen is converted to fibrin– Fibrin forms net that entangles cells

and platelets

Fig. 38-23, p.672

Lymphatic System

• Collects and returns fluid to the bloodstream

– The circulatory system is leaky

– Some fluid is forced out of the smallest vessels and

into the interstitial fluid

– Vessels of the lymphatic system pick up this fluid,

filter it, and return it to the circulatory system

• Defends against infection

Main Parts- See figure page 683

• Lymph nodes – organ acts as a filter for lymph, packed

with lymphocytes for immune response

• Lymph vessels – tubes that collect and deliver leaky

fluid back to vein in lower neck

• Lymph – the fluid

• Lymphoid organs – central to body’s defense

– Tonsils, Thymus, Spleen

Lymph Nodes• Located at intervals

along lymph vessels

• Act as a filter for lymph

• Contain lymphocytes

that can recognize a

foreign invader

Figure 38.27c Page 674

Lymphoid Organs

• Central to the

body’s defense

• Tonsils

• Spleen

• Thymus gland

Figure 38.27a Page 674