Circulation and Respiration Chapter 22

The Circulatory System Works with other organ systems Maintains volume, solute concentration and temperature of interstitial fluid Interstitial fluid and blood are body’s internal environment

Blood Circulation Blood flows through blood vessels Heart generates force to keep blood moving Closed system – Blood is confined to vessels and heart Open system – Blood mingles with fluid in tissues

aorta heart Fig. 22-1a, p.361 Open and Closed Systems

spaces or cavities in body tissues pump Fig. 22-1b, p.361 Open and Closed Systems

dorsal blood vessel two of five hearts ventral blood vessels gut cavity Fig. 22-1c, p.361 Open and Closed Systems

large-diameter blood vessels (rapid flow) large-diameter blood vessels (rapid flow) small-diameter blood vessels (leisurely flow in diffusion zone) pump Fig. 22-1d, p.361 Open and Closed Systems

Blood Flow and Gas Exchange Rate of blood flow varies with diameter of blood vessels Slowest flow in smallest vessels, the capillaries Gases are exchanged between blood and interstitial fluid across capillary walls

Vertebrate Circulatory Systems Fish – Two-chambered heart, one circuit Amphibians – Three-chambered heart, two partially separate circuits Birds and mammals – Four-chambered heart, two entirely separate circuits

capillary beds of gills heart rest of body a In fishes, a two-chambered heart (atrium, ventricle) pumps blood in one circuit. Blood picks up oxygen in gills, delivers it to rest of body. Oxygen-poor blood flows back to heart. Fig. 22-2a, p.362 Vertebrate Circulatory Systems

right atrium left atrium heart rest of body lungs b In amphibians, a heart pumps blood through two partially separate circuits. Blood flows to lungs, picks up oxygen, returns to heart. But it mixes with oxygen-poor blood still in the heart, flows to rest of body, returns to heart. Fig. 22-2b, p.362 Vertebrate Circulatory Systems

rest of body lungs right atrium left atrium right ventricleleft ventricle c In birds and mammals, the heart is fully partitioned into two halves. Blood circulates in two circuits: from the heart’s right half to lungs and back, then from the heart’s left half to oxygen-requiring tissues and back. Fig. 22-2c, p.362 Vertebrate Circulatory Systems

Double Circuits In birds and mammals Right half of heart – Pulmonary circuit – Heart to lungs and return Left half of heart – Systemic circuit – Heart to body tissues and return

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 Plasma – Water – Proteins – Dissolved materials Cells – Red blood cells – White blood cells – Platelets

ComponentsRelative Amounts Plasma Portion (50%–60% of total volume): 1. Water 3. Ions, sugars, lipids, amino acids, hormones, vitamins, dissolved gases 91%–92% of plasma volume 7%–8% 1%–2% Cellular Portion (40%–50% of total volume): 1. Red blood cells 2. White blood cells: Neutrophils Lymphocytes Monocytes (macrophages) Eosinophils Basophils 3. Platelets 4,800,000–5,400,000 per microliter 3,000–6,750 1,000–2, – –360 25–90 250,000–300,000 Fig. 22-3b, p Plasma proteins (albumin, globulins, fibrinogen, etc. Components of Blood

Blood Cell Development Stem cells in bone marrow produce blood cells and platelets Body continually replaces blood cells

red blood cell white blood cell platelets Fig. 22-3a, p.363 Blood Cell Development

Erythrocytes (Red Cells) Most numerous cells in blood Transport oxygen and carbon dioxide Colored red by oxygen-binding pigment (hemoglobin) Have no nucleus when mature

Leukocytes (White Cells) Function in housekeeping and defense Cell types BasophilsDendritic cells EosinophilsB cells NeutrophilsT cells Macrophages

Platelets Membrane-bound cell fragments Derived from megakaryocytes, which arise from stem cells Release substances that initiate blood clotting

Human Heart Is a Double Pump Partition separates heart into left and right sides Each pumps blood through a different circuit

Pulmonary Circuit Heart to lungs Oxygenates blood right pulmonary arteryleft pulmonary artery capillary bed of right lung pulmonary trunk capillary bed of left lung (to systemic circuit) pulmonary veins lungs (from systemic circuit) heart

Systemic Circuit Starts at aorta Carries oxygenated blood to body tissues capillary beds of head and upper extremities (to pulmonary circuit) aorta (from pulmonary circuit) heart capillary beds of other organs in thoracic cavity capillary bed of liver capillary beds of intestines capillary beds of other abdominal organs and lower extremities

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

Four Chambers Each side has two chambers – Upper atrium – Lower ventricle Valves between atria and ventricles

Heart Anatomy superior vena cava right semilunar valve right pulmonary veins right atrium right AV valve right ventricle inferior vena cava septum myocardium heart’s apex arch of aorta trunk of pulmonary arteries left semilunar valve left pulmonary veins left atrium left AV valve left ventricle endothelium and connective tissue inner layer of pericardium Major Vessels

Cardiac Cycle Diastole (mid to late). Ventricles fill, atria contract. Diastole (early). Both chambers relax. Ventricular systole (atria are still in diastole). Ventricles eject.

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 SA node

Blood Vessels Arteries: carry blood away from heart Arterioles: diameter is adjusted to regulate blood flow Capillaries: diffusion occurs across thin walls

Blood Pressure Highest in arteries, lowest in veins Usually measured in the brachial artery Systolic pressure is peak pressure – Ventricular contraction Diastolic pressure is the lowest pressure – Ventricular relaxation

Measuring Blood Pressure

Resistance Adjusted at arterioles Vasodilation – Increases vessel diameter – Lowers blood pressure Vasoconstriction – Decreases vessel diameter – Increases blood pressure

lungs heart’s right half heart’s left half liver digestive tract kidneys skeletal muscle brain skin bone cardiac muscle all other regions 100% 6% 21% 20% 15% 13% 9% 5% 3% 8% Fig , p.367 Distribution

Capillary Beds Diffusion zone; site of exchange between blood and interstitial fluid Capillary wall is one cell thick Flow is slow; allows gases to diffuse across membranes of blood cells and across endothelium

Bulk Flow in Capillary Bed blood to venule inward-directed osmotic movement cells of tissue outward-directed bulk flow blood from arteriole

Net Bulk Flow Normally, ultrafiltration only slightly exceeds reabsorption Fluid enters interstitial fluid and returned to blood via the lymphatic system High blood pressure causes excessive ultrafiltration and results in edema

The Venous System Blood flows from capillaries to venules to veins Veins are large-diameter vessels with some smooth muscle in wall

Vein Function Valves in veins prevent blood from flowing backward

blood flow to heart valve open valve closed valve closed valve closed venous valve Fig , p.369 Vein Function

Hemostasis Processes that stop blood loss and repair vessels – Blood vessel spasm – 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

Hypertension Blood pressure above 140/90 Tends to be genetic May also be influenced by diet Contributes to atherosclerosis “Silent killer”, few outward signs

Atherosclerosis Arteries thicken, lose elasticity Fill up with cholesterol and lipids High LDL increases risk

wall of artery, cross- section unobstructed lumen of normal artery Fig a, p.370

atherosclerotic plaque blood clot sticking to plaque narrowed lumen Fig b, p.370

Atherosclerosis in arteries of heart Causes heart attacks Coronary Artery Disease

coronary artery aorta location of a shunt made of a section taken from one of the patient’s other blood vessels coronary artery blockage Fig , p.371 Coronary Artery Disease

Risk Factors SmokingGenetics High cholesterolHigh blood pressure ObesityDiabetes AgeGender

Respiration – Physiological process by which oxygen moves into an animal’s internal environment and carbon dioxide moves out Aerobic respiration – Cellular process, produces ATP – Oxygen is used – Carbon dioxide is produced

Respiratory System Works with the circulatory system to deliver oxygen and remove carbon dioxide Also helps regulate acid-base balance

Pressure Gradients Concentration gradients for gases Gases diffuse down their pressure gradients Gases enter and leave the body by diffusing down pressure gradients across respiratory membranes

Factors In Gas Exchange Surface-to-volume ratio – Small, flat animals Ventilation – Adaptations enhance exchange rate Respiratory pigments – Hemoglobin and myoglobin

Surface-to-Volume Ratio As animal size increases, surface-to-volume ratio decreases Small, flat animals can use the body surface as their respiratory surface Larger animals have special structures to increase respiratory surface, such as gills or lungs

Respiratory Surfaces In flat animals CO 2 O2O2

Fish Gills Usually internal Water is drawn in through mouth and passed over gills water flows in through mouth FISH GILL water flows over gills, then out

water flows into mouth FISH GILL water flows over gills, then out. mouth open lid closed mouth closed lid open gill arch gill filament direction of water flow respiratory surface direction of blood flow oxygen-poor blood from deep in body oxygenated blood back toward body abc de Fig , p.372

Countercurrent Flow Blood flows in the opposite direction of water flow over the filaments Enhances movement of oxygen from water to blood direction of water flow respiratory surface direction of blood flow oxygen-poor blood from deep in body oxygenated blood back toward body

Vertebrate Lungs Originated in some fishes as outpouching from gut wall Allow gas exchange in air and in oxygen- poor aquatic habitats salamander reptile

Avian Respiration Lungs are inelastic and connect to a series of air sacs Air is drawn continually though each lung air sacs air sacs lungs air sacs

Mammal Human; adapted to dry habitats Fig c, p.373 Mammals

Human Respiratory System pharynx (throat) larynx (voice box) trachea (windpipe) pleural membrane intercostal muscle diaphragm epiglottis Bronchiole Alveoli

NASAL CAVITY PHARYNX (THROAT) EPIGLOTTIS LARYNX (VOICE BOX) TRACHEA (WINDPIPE) LUNG (ONE OF A PAIR) BRONCHIAL TREE PLEURAL MEMBRANE ORAL CAVITY (MOUTH) INTERCOSTAL MUSCLES DIAPHRAGM Fig a, p.374

bronchiole alveolar duct alveoli alveolar sac (sectioned) Fig b, p.374

alveolar sac pulmonary capillary Fig c, p.374

Speech Production Vocal cords stretch across laryngeal opening; opening between them is glottis Position of cords is varied to create different sounds

vocal cords glottis (closed) epiglottis tongue’s base Fig a, p.375

Breathing Moves air into and out of lungs Occurs in a cyclic pattern called the respiratory cycle One respiratory cycle consists of inhalation and exhalation

Inhalation Diaphragm flattens External intercostal muscles contract Volume of thoracic cavity increases Lungs expand Air flows down pressure gradient into lungs

Normal (Passive) Exhalation Muscles of inhalation relax Thoracic cavity recoils Lung volume decreases Air flows down pressure gradient and out of lungs

INWARD BULK FLOW OF AIR OUTWARD BULK FLOW OF AIR b Inhalation. The diaphragm contracts, moves down. External intercostal muscles contract and lift rib cage upward and outward. The lung volume expands. Fig , p.376 c Exhalation. Diaphragm, external intercostal muscles return to resting positions. Rib cage moves down. Lungs recoil passively.

Active Exhalation Abdominal and internal intercostal muscles contract Contraction decreases thoracic cavity volume more than passive exhalation Greater volume of air flows out to equalize intrapulmonary pressure with atmospheric pressure

red blood cell air space inside alveolus pore for airflow between alveoli Cutaway View of Alveolus (see next slide)

Respiratory Membrane Area between an alveolus and a pulmonary capillary Oxygen and carbon dioxide diffuse across easily alveolar epithelium capillary endothelium fused basement membranes of both epithelial tissues

Oxygen Transport Most oxygen is bound to heme groups in hemoglobin in red blood cells Hemoglobin has higher affinity for oxygen when it is at high partial pressure (in pulmonary capillaries) Lower affinity for oxygen in tissues, where partial pressure is low

Bicarbonate Formation CO 2 + H 2 OH 2 CO 3 carbonic acid HCO 3 – bicarbonate + H + Most carbon dioxide is transported as bicarbonate Some binds to hemoglobin Small amount dissolves in plasma

alveolar sacs cells of body tissue DRY INHAILED AIR MOIST EXHAILED AIR pulmonary veins pulmonary arteries 4045 start of systematic veins 4045 less than 40more than 45 start of systemic capillaries Partial Pressure Gradients

Control of Breathing Nervous system controls rhythm and magnitude of breathing Breathing is adjusted as a result of changes in – Carbon dioxide levels – Oxygen levels – Blood acidity