The Cardio-Respiratory System Ch 42 AP Biology

What’s the Current Exchange Rate? Multicellular, complex organisms require specialized structures to exchange with their environment internal transport systems circulate fluid connect the organs of exchange with the body cells More efficient with bulk transport

Open or Closed? Both open and closed circulatory systems have: A circulatory fluid (blood or hemolymph) A set of tubes (blood vessels) A muscular pump (the heart)

Come on in. We’re Open! Arthropods and moluscs have open systems Less costly from energy and pressure stance hemolymph general body fluid of blood and interstitial fluid Heart contracts; hemolymph out into sinuses Heart relaxes; hem. back in through ostia www1.istockphoto.com/file_thumbview_approve/7..

Sorry. We’re Closed. Vertebrates, squid, earthworms more efficient at transporting circulatory fluids to tissues and cells to meet metabolic demands Specialized blood vessels, chambered heart http://dcharmedone.files.wordpress.com/2007/12/closed.jpg

REPTILES (EXCEPT BIRDS) Lung and skin capillaries FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS Gill capillaries Lung and skin capillaries Lung capillaries Lung capillaries Gill circulation Pulmocutaneous circuit Right systemic aorta Pulmonary circuit Pulmonary circuit Artery Heart: Ventricle (V) Left systemic aorta A A A A A A Atrium (A) V V V V V Right Left Right Left Right Left Systemic circulation Systemic circuit Systemic circuit Vein Systemic capillaries Systemic capillaries Systemic capillaries Systemic capillaries Systemic circuits include all body tissues except lungs. Note that circulatory systems are depicted as if the animal is facing you: with the right side of the heart shown at the left and vice-versa.

Hearts Insects: system of tracheal tubes, gas exchange throughout the length of the tubes Amphibians: 3 chambered heart Reptiles: double circulation Pulmonary circuit + systemic circulation NO mixing of oxygenated and deox blood

The Human Heart: go with the flow Pulmonary Circuit Systemic Circuit www.williamsclass.com/.../CellsOrganization.htm

The Cardiac Cycle: a perfect marriage Cardiac Circulation System library.med.utah.edu/kw/ecg/mml/ecg_ccs.html

LE 42-8 Pacemaker generates wave of signals to contract. Signals are delayed at AV node. Signals pass to heart apex. Signals spread throughout ventricles. SA node (pacemaker) AV node Bundle branches Purkinje fibers Heart apex ECG

Cardiac Output the volume of blood pumped into the systemic circulation per minute Cardiac output can increase about fivefold during heavy exercise.

Structural Differences in vessels arteries veins Thicker walls elasticity (elastic recoil) helps maintain blood pressure even when the heart relaxes Pressure high during systole thinner-walled blood flows back to the heart mainly as a result of skeletal muscle action one-way valves allow blood to flow only toward the heart

LE 42-9 Artery Vein 100 µm Endothelium Valve Basement membrane Smooth muscle Smooth muscle Capillary Connective tissue Connective tissue Artery Vein Arteriole Venule

Effects on Blood Pressure 1. cardiac output and 2. peripheral resistance due to constriction of arterioles Contraction of smooth muscles increase peripheral resistance nervous and hormonal responses constrict blood vessels in response to stress

Taking a Blood Pressure LE 42-12_4 Taking a Blood Pressure Blood pressure reading: 120/70 Pressure in cuff above 120 Pressure in cuff below 120 Pressure in cuff below 70 Rubber cuff inflated with air 120 120 70 Sounds audible in stethoscope Sounds stop Artery Artery closed

Circulatory System meets Lymphatic System What is Lymph? How is the Circulatory System dependent on the Lymphatic System?

Blood. More than meets the eye. Blood is a suspension: lots of different stuff suspended in an aqueous solution. Formed Elements vs Plasma

What’s the source? Erythrocytes, leukocytes, and platelets develop from a common source, pluripotent stem cells in the red marrow of bones The average life span of a RBC is 120 days It cannot divide and self-renew RBCs are replaced by erythropoeisis Circulatory meets Endocrine meets Renal meets skeletal

Erythro-what?

a) Kidneys respond to a lower than normal oxygen concentration in the blood by releasing the hormone erythropoietin. b) Erythropoietin travels to the red bone marrow and stimulates an increase in the production of red blood cells (RBCs). c) The red bone marrow manufactures RBCs from stem cells that live inside the marrow. d) RBCs squeeze through blood vessel membranes to enter the circulation. e) The heart and lungs work to supply continuous movement and oxygenation of RBCs. f) Damaged or old RBCs are destroyed primarily by the spleen

Respiratory

Surface area Rate of diffusion proportional to surface area Protists: occurs over entire surface (cnid. Flats) Earthworms and amphibs: across moist skin Gills: warmer, saltier, less O2 Insects: tracheal tubes: branch out to do exchange with all body parts. Open circ. System NOT involved in transport: O2 CO2

Do fish drink water??? Animals require large, moist respiratory surfaces for adequate diffusion of gases between their cells and the respiratory medium, either air or water Gills are outfoldings of the body surface specialized for gas exchange Effectiveness of gas exchange in some gills, including those of fishes, is increased by ventilation and the countercurrent flow of blood and water

Countercurrent exchange LE 42-21 Oxygen-poor blood Lamella Oxygen-rich blood Gill arch Gill arch Blood vessel 15% 40% Water flow 70% 5% 30% Operculum 100% 60% 90% Water flow over lamellae showing % O2 O2 Blood flow through capillaries in lamellae showing % O2 Gill filaments Countercurrent exchange

Positive vs. Negative Pressure Positive Pressure Breathing- Negative Pressure Breathing- etc.usf.edu/.../16400/16428/sling-shot_16428.htm

Breathing Diaphragm: negative pressure Tidal volume: air in and out with reg breath Residual volume: air that remains in alveoli and tubes after you breath out. Us: air travels down 1 way street. Birds: better: air travels through… no dead ends

Lungs Lungs: only site of gas exchange: need circulatory system Breath: negative pressure breathing Partial pressure: gas diffuses from its own high partial press. To low (press. Just this 1 gas contributes to the press. Of air (a mix))

Control of Breathing Nervous System Cardio Vascular System Pons Medulla Cardio Vascular System Sensors in Aorta Respiratory System Concentration of CO2

LE 42-27 Inhaled air Exhaled air Alveolar spaces O2 CO2 O2 CO2 160 0.2 120 27 Alveolar spaces O2 CO2 O2 CO2 104 40 Alveolar epithelial cells O2 CO2 CO2 O2 Blood entering alveolar capillaries Blood leaving alveolar capillaries CO2 O2 Alveolar capillaries of lung 40 45 104 40 O2 CO2 O2 CO2 Pulmonary arteries Pulmonary veins Systemic veins Systemic arteries Heart Tissue capillaries CO2 O2 Blood leaving tissue capillaries Blood entering tissue capillaries 40 45 CO2 O2 100 40 O2 CO2 O2 CO2 Tissue cells < 40 > 45 O2 CO2

Heme group Iron atom O2 loaded in lungs O2 unloaded in tissues LE 42-28 Heme group Iron atom O2 loaded in lungs O2 unloaded in tissues Polypeptide chain

Hemoglobin binding of Oxygen hemoglobin must reversibly bind O2, loading O2 in the lungs and unloading it in other parts of the body Loading and unloading of O2 depend on cooperation between the subunits binding of O2 to one subunit induces the other subunits to bind O2 with more affinity A drop in pH lowers affinity of hemoglobin for O2 Bohr shift

Hemoglobin binding of CO2 Carbon from respiring cells diffuses into the blood plasma and then into erythrocytes and is ultimately released in the lungs CO2 reacts with water to form carbonic acid Lowers pH and induces release of O2 from Hgb Carbonic acid dissociates Hgb binds H+ to prevent acidifying blood Bicarbonate diffuses into plasma and is carried to lungs Carbonic acid is formed again in lungs Then converted back to CO2 and water and expelled

O2 saturation of hemoglobin (%) LE 42-29b 100 pH 7.4 80 Bohr shift: additional O2 released from hemoglobin at lower pH (higher CO2 concentration) O2 saturation of hemoglobin (%) 60 pH 7.2 40 20 20 40 60 80 100 P (mm Hg) O2 pH and hemoglobin dissociation

Carbon Monoxide Poisoning Red blood cells pick up CO quicker than they pick up oxygen. If there is a lot of CO in the air, the body may replace oxygen in blood with CO. This blocks oxygen from getting into the body, which can damage tissues and result in death.

Diving Reflex first line of defense against hypoxia http://www.mammalian.ca/template.php?content=about Diving Reflex first line of defense against hypoxia self-preservation technique triggered in extreme situations suddenly submerged water or caught in a freezing environment all of the major systems slow almost to a halt minimizing the need for oxygen www.ohusc.k12.in.us/.../Page347.htm