Ch 41-42 notes.pptx

(1)

(2)

Concept 41.1: An animal’s diet must

supply chemical energy, organic

molecules, and essential nutrients

• _{An animal’s diet provides:}

• _{Chemical energy, which is converted into ATP to}

power cellular processes

• Organic building blocks, such as organic carbon and organic nitrogen, to synthesize a variety of organic molecules

• _{Essential nutrients}_{, which are required by cells and}

must be obtained from dietary sources

(3)

Essential Nutrients

• _{There are four classes of essential nutrients:}

• _{Essential amino acids} • Essential fatty acids

• _Vitamins • Minerals

(4)

Figure 41.5

Mechanical

digestion _Chemical digestion (enzymatic hydrolysis)

Nutrient molecules enter body cells

Undigested material

Elimination Absorption

Digestion Ingestion

(5)

How does the structure fit its

function?

• _{How do the villi and microvilli of the intestine increase digestion and}

absorption?

• _{How does the epithelial lining of the intestine aid in the absorption of}

(6)

(7)

Study Tip!

• _{How do pieces of food you ingest become reduced to}

monosaccharides, amino acids, fatty acids, and glycerol?

• _{How are monomers able to enter cells?} • _{How do enzymes work?}

(8)

Fat digestion Nucleic acid digestion

Protein digestion Fat (triglycerides) DNA, RNA Nucleotides Pancreatic nucleases Pancreatic lipase

(9)

• _{The first portion of the small intestine is the}

duodenum, where chyme from the stomach mixes with digestive juices from the pancreas, liver,

gallbladder, and the small intestine itself

(10)

Pancreatic Secretions

• _The_pancreas_{produces proteases trypsin and}

chymotrypsin that are activated in the lumen of the duodenum

• _{Its solution is alkaline and neutralizes the acidic chyme}

(11)

Bile Production by the Liver

• _{In the small intestine,}_bile_{aids in digestion and}

absorption of fats

• _{Bile is made in the}_liver_{and stored in the}_gallbladder • _{Bile also destroys nonfunctional red blood cells}

(12)

Secretions of the Small Intestine

• _{The epithelial lining of the duodenum produces}

several digestive hormones

• _Secretin

• A hormone that regulates water homeostasis

• regulating secretions in the stomach, pancreas, and liver

• _{Cholecystokinin (CCK)}

• causes the release of digestive enzymes and bile from the pancreas and gallbladder

• acts as a hunger suppressant

• _{Most digestion occurs in the duodenum; the jejunum}

and ileum function mainly in absorption of nutrients and water

(13)

Absorption in the Small Intestine

• _{The small intestine has a huge surface area, due to}

villi and microvilli that are exposed to the intestinal lumen

• _{The enormous microvillar surface creates a brush}

border that greatly increases the rate of nutrient absorption

• _{Transport across the epithelial cells can be passive or}

active depending on the nutrient

(14)

Figure 41.13

Vein carrying blood to liver

Muscle layers Blood capillaries Villi Intestinal wall Epithelial cells Large circular folds Key Nutrient absorption

(15)

Absorption in the Large Intestine

• _The_colon_{of the}_{large intestine}_{is connected to the}

small intestine

• _The_cecum_{aids in the fermentation of plant material}

and connects where the small and large intestines meet

• _{The human cecum has an extension called the}

appendix, which plays a very minor role in immunity

(16)

• _{A major function of the colon is to recover water that}

has entered the alimentary canal

• _{The colon houses bacteria (e.g.,}_{Escherichia coli}_{) that}

live on unabsorbed organic material; some produce vitamins

• _Feces_{, including undigested material and bacteria,}

become more solid as they move through the colon

(17)

Concept 41.4: Evolutionary

adaptations of vertebrate digestive

systems correlate with diet

• _{Digestive systems of vertebrates are variations on a}

common plan

• _{However, there are intriguing adaptations, often}

related to diet

(18)

Dental Adaptations

• _{Dentition, an animal’s assortment of teeth, is one}

example of structural variation reflecting diet

• _{The success of mammals is due in part to their}

dentition, which is specialized for different diets

• _{Nonmammalian vertebrates have less specialized}

teeth, though exceptions exist

• For example, the teeth of poisonous snakes are modified as fangs for injecting venom

(19)

Figure 41.16

Carnivore

Herbivore Omnivore

Molars Premolars

Canines Incisors

(20)

Stomach and Intestinal Adaptations

• _{Many carnivores have large, expandable stomachs} • _{Herbivores and omnivores generally have longer}

alimentary canals than carnivores, reflecting the longer time needed to digest vegetation

(21)

Figure 41.17

Small

intestine Stomach

Cecum

Carnivore

Colon (large intestine)

Small intestine

(22)

Mutualistic Adaptations

• _{Many herbivores have fermentation chambers, where}

mutualistic microorganisms digest cellulose

• _{The most elaborate adaptations for an herbivorous}

diet have evolved in the animals called ruminants

(23)

Reticulum

Esophagus

Omasum Abomasum

Intestine Rumen

1 2

3 4

(24)

Concept 41.5: Feedback circuits regulate

digestion, energy storage, and appetite

• _{The intake of food and the use of nutrients vary}

with an animal’s diet and environment

(25)

Regulation of Digestion

• _{Each step in the digestive system is activated as}

needed

• _{The enteric division of the nervous system helps to}

regulate the digestive process

• _{The endocrine system also regulates digestion through}

the release and transport of hormones

(26)

Figure 41.19 Liver Gallbladder Food Stomach Duodenum of small intestine

Gastric juices

Pancreas

Bile

Chyme

1 2 3

Gastrin

CCK

Key

Stimulation Inhibition

HCO₃_{, enzymes}

(27)

Regulation of Energy Storage

• _{The body stores energy-rich molecules that are not}

needed right away for metabolism

• _{In humans, energy is stored first in the liver and muscle}

cells in the polymer glycogen

• _{Excess energy is stored in adipose tissue, the most}

space-efficient storage tissue

(28)

Glucose Homeostasis

• _{Oxidation of glucose generates ATP to fuel cellular}

processes

• _{The hormones insulin and glucagon regulate the}

breakdown of glycogen into glucose

• _{The liver is the site for glucose homeostasis}

• _{A carbohydrate-rich meal raises insulin levels, which}

triggers the synthesis of glycogen

• _{Low blood sugar causes glucagon to stimulate the}

breakdown of glycogen and release glucose

(29)

Figure 41.20 Transport of glucose into body cells and storage of glucose as glycogen Breakdown of glycogen and release of glucose into blood Homeostasis:

70–110 mg glucose/ 100 mL blood

Stimulus: Blood glucose

level drops below set point.

(30)

Regulation of Appetite and Consumption

• _{Overnourishment causes obesity, which results from}

excessive intake of food energy with the excess stored as fat

• _{Obesity contributes to diabetes (type 2), cancer of the}

colon and breasts, heart attacks, and strokes

• _{Researchers have discovered several of the}

(31)

Figure 41.21

Satiety center

Ghrelin

Insulin

Leptin

PYY





(32)

• _{Hormones regulate long-term and short-term appetite}

by affecting a “satiety center” in the brain

• _{Studies on mice revealed that the hormone}_leptin

plays an important role in regulating obesity

• _{Leptin is produced by adipose tissue and can help to}

suppress appetite

(33)

Obesity and Evolution

• _{A species of birds called petrels becomes obese as}

chicks; in order to consume enough protein from high-fat food, chicks need to consume more calories than they burn

(34)

• _{The problem of maintaining weight partly stems from}

our evolutionary past, when fat hoarding was a means of survival

• _{Individuals who were more likely to eat fatty food and}

(35)

Study Tip!

• _{How are the foods we eat reduced to molecules that can cross into}

(36)

Circulation and Gas Exchange

Chapter 42

(37)

Concept 42.1: Circulatory systems link exchange surfaces with cells throughout the body

• _{Diffusion time is proportional to the square of the}

distance

• _{Diffusion is only efficient over small distances} • _{In small and/or thin animals, cells can exchange}

materials directly with the surrounding medium

• _{In most animals, cells exchange materials with the}

environment via a fluid-filled circulatory system

(38)

General Properties of Circulatory Systems

• _{A circulatory system has}

• _{A circulatory fluid}

• A set of interconnecting vessels

• _{A muscular pump, the}_heart

• _{The circulatory system connects the fluid that surrounds}

cells with the organs that exchange gases, absorb nutrients, and dispose of wastes

• _{Circulatory systems can be open or closed and vary in}

the number of circuits in the body

(39)

Figure 42.3

(a) An open circulatory system

Heart

Hemolymph in sinuses surrounding organs Pores Tubular heart Dorsal vessel (main heart) Auxiliary hearts Small branch vessels in each organ Ventral vessels Blood Interstitial fluid Heart

(40)

• _{In a}_{closed circulatory system}_,_blood_{is confined to}

vessels and is distinct from the interstitial fluid

• _{Closed systems are more efficient at transporting}

circulatory fluids to tissues and cells

• _{Annelids, cephalopods, and vertebrates have closed}

circulatory systems

(41)

Organization of Vertebrate Circulatory Systems

• _{Humans and other vertebrates have a closed circulatory}

system called the cardiovascular system

• _{The three main types of blood vessels are arteries,}

veins, and capillaries

• _{Blood flow is one way in these vessels}

(42)

Figure 42.4

(a) Single circulation (b) Double circulation

(43)

Double Circulation

• _{Amphibian, reptiles, and mammals have}_double

circulation

• _{Oxygen-poor and oxygen-rich blood are pumped}

separately from the right and left sides of the heart

(44)

Systemic circuit Lung capillaries Pulmonary circuit A V Left Right Systemic capillaries

Mammals and Birds

(45)

Concept 42.2: Coordinated cycles of heart

contraction drive double circulation in mammals

• _{The mammalian cardiovascular system meets the}

body’s continuous demand for O₂

(46)

Mammalian Circulation

• _{Blood begins its flow with the right ventricle pumping}

blood to the lungs

• _{In the lungs, the blood loads O}₂_{and unloads CO}₂

• _{Oxygen-rich blood from the lungs enters the heart at}

the left atrium and is pumped through the aorta to the body tissues by the left ventricle

• _{The aorta provides blood to the heart through the}

coronary arteries

(47)

• _{Blood returns to the heart through the superior vena}

cava (blood from head, neck, and forelimbs) and inferior vena cava (blood from trunk and hind limbs)

• _{The superior vena cava and inferior vena cava flow into}

the right atrium

(48)

Superior vena cava

Pulmonary artery

Capillaries of right lung

Pulmonary vein Aorta Inferior vena cava Right ventricle Capillaries of abdominal organs and hind limbs Right atrium Aorta Left ventricle Left atrium Pulmonary vein Pulmonary artery Capillaries of left lung Capillaries of

head and forelimbs

(49)

• _{The heart contracts and relaxes in a rhythmic cycle}

called the cardiac cycle

• _{The contraction, or pumping, phase is called}_systole • _{The relaxation, or filling, phase is called}_diastole

(50)

• _The_{heart rate}_{, also called the pulse, is the number of}

beats per minute

• _The_{stroke volume}_{is the amount of blood pumped in a}

single contraction

• _The_{cardiac output}_{is the volume of blood pumped into}

the systemic circulation per minute and depends on both the heart rate and stroke volume

(51)

• _{Four valves prevent backflow of blood in the heart}

• _The_{atrioventricular (AV) valves}_{separate each atrium}

and ventricle

• _The_{semilunar valves}_{control blood flow to the aorta}

and the pulmonary artery

(52)

• _{The “lub-dup” sound of a heart beat is caused by the}

recoil of blood against the AV valves (lub) then against the semilunar (dup) valves

• _{Backflow of blood through a defective valve causes a}

heart murmur

(53)

Maintaining the Heart’s Rhythmic Beat

• _{Some cardiac muscle cells are self-excitable, meaning}

they contract without any signal from the nervous system

• _The_{sinoatrial (SA) node}_{, or pacemaker, sets the rate}

and timing at which cardiac muscle cells contract

• _{Impulses that travel during the cardiac cycle can be}

recorded as an electrocardiogram (ECG or EKG)

(54)

Figure 42.9-4

SA node (pacemaker)

AV

node _Bundle

branches Heart apex

Purkinje fibers

ECG

(55)

• _{Impulses from the SA node travel to the}_{atrioventricular}

(AV) node

• _{At the AV node, the impulses are delayed and then}

travel to the Purkinje fibers that make the ventricles contract

(56)

• _{The pacemaker is regulated by two portions of the}

nervous system: the sympathetic and parasympathetic divisions

• _{The sympathetic division speeds up the pacemaker} • _{The parasympathetic division slows down the}

pacemaker

• _{The pacemaker is also regulated by hormones and}

temperature

(57)

Changes in Blood Pressure During the

Cardiac Cycle

• _{Systolic pressure}_{is the pressure in the arteries during}

ventricular systole; it is the highest pressure in the arteries

• _{Diastolic pressure}_{is the pressure in the arteries during}

diastole; it is lower than systolic pressure

• _A_pulse_{is the rhythmic bulging of artery walls with each}

heartbeat

(58)

Regulation of Blood Pressure

• _{Blood pressure is determined by cardiac output and}

peripheral resistance due to constriction of arterioles

• _{Vasoconstriction}_{is the contraction of smooth muscle in}

arteriole walls; it increases blood pressure

• _Vasodilation_{is the relaxation of smooth muscles in the}

arterioles; it causes blood pressure to fall

(59)

Figure 42.17

Plasma 55%

Constituent Major functions Water Ions (blood electrolytes) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Solvent for carrying other substances Osmotic balance, pH buffering, and regulation of membrane permeability Plasma proteins Osmotic balance, pH buffering Albumin Fibrinogen Immunoglobulins (antibodies) Clotting Defense

Substances transported by blood Nutrients Waste products Respiratory gases Hormones Separated blood elements Basophils Neutrophils Monocytes Lymphocytes Eosinophils Platelets

Erythrocytes (red blood cells) 5–6 million

250,000–400,000 Blood clotting

Transport of O₂ and some CO₂ Defense and immunity

Functions Number per L

(mm3_{) of blood}

Cell type

Cellular elements 45%

(60)

Stem Cells and the Replacement of Cellular

Elements

• _{The cellular elements of blood wear out and are being}

replaced constantly

• _{Erythrocytes, leukocytes, and platelets all develop from}

a common source of stem cells in the red marrow of bones, especially ribs, vertebrae, sternum, and pelvis

• _{The hormone}_{erythropoietin (EPO)}_stimulates

erythrocyte production when O₂ delivery is low

(61)

Cardiovascular Disease

• _{Cardiovascular diseases are disorders of the heart and}

the blood vessels

• _{Cardiovascular diseases account for more than half the}

deaths in the United States

• _{Cholesterol, a steroid, helps maintain membrane fluidity}

(62)

• _{Low-density lipoprotein (LDL)}_{delivers cholesterol to}

cells for membrane production

• _{High-density lipoprotein (HDL)}_{scavenges cholesterol}

for return to the liver

• _{Risk for heart disease increases with a high LDL to HDL}

ratio

• _{Inflammation is also a factor in cardiovascular disease}

(63)

Atherosclerosis, Heart Attacks, and Stroke

• _{One type of cardiovascular disease,}_{atherosclerosis}_{, is}

caused by the buildup of plaque deposits within arteries

(64)

• _A_{heart attack,}_{or myocardial infarction,} _{is the death of}

cardiac muscle tissue resulting from blockage of one or more coronary arteries

• _{Coronary arteries supply oxygen-rich blood to the heart}

muscle

• _A_stroke_{is the death of nervous tissue in the brain,}

usually resulting from rupture or blockage of arteries in the head

• _{Angina pectoris is caused by partial blockage of the}

coronary arteries and results in chest pains

(65)

Concept 42.5: Gas exchange occurs across

specialized respiratory surfaces

• _{Gas exchange}_{supplies O}₂_{for cellular respiration and}

disposes of CO₂

(66)

Partial Pressure Gradients in Gas Exchange

• _{A gas diffuses from a region of higher partial pressure to}

a region of lower partial pressure

• _{Partial pressure}_{is the pressure exerted by a particular}

gas in a mixture of gases

• _{Gases diffuse down pressure gradients in the lungs and}

other organs as a result of differences in partial pressure

(67)

Respiratory Media

• _{Animals can use air or water as a source of O}₂_{, or}

respiratory medium

• _{In a given volume, there is less O}₂_{available in water}

than in air

• _{Obtaining O}₂_{from water requires greater efficiency than}

air breathing

(68)

Respiratory Surfaces

• _{Animals require large, moist respiratory surfaces for}

exchange of gases between their cells and the respiratory medium, either air or water

• _{Gas exchange across respiratory surfaces takes place by}

diffusion

• _{Respiratory surfaces vary by animal and can include the}

outer surface, skin, gills, tracheae, and lungs

(69)

Lungs

• _Lungs_{are an infolding of the body surface}

• _{The circulatory system (open or closed) transports gases}

between the lungs and the rest of the body

• _{The size and complexity of lungs correlate with an}

animal’s metabolic rate

(70)

Mammalian Respiratory Systems: A Closer Look

• A system of branching ducts conveys air to the lungs

• Air inhaled through the nostrils is warmed, humidified, and sampled for odors

• _{The pharynx directs air to the lungs and food to the}

stomach

• _{Swallowing tips the epiglottis over the glottis in the}

pharynx to prevent food from entering the trachea

(71)

Figure 42.25 Pharynx Larynx (Esophagus) Trachea Right lung Bronchus Bronchiole Diaphragm (Heart) Capillaries Left lung

Dense capillary bed enveloping alveoli (SEM)

(72)

• _{Air passes through the pharynx,}_larynx_{, trachea,}

bronchi, and bronchioles to the alveoli, where gas exchange occurs

• Exhaled air passes over the vocal cords in the larynx to create sounds

• _{Cilia and mucus line the epithelium of the air ducts and}

move particles up to the pharynx

• _{This “mucus escalator” cleans the respiratory system}

and allows particles to be swallowed into the esophagus

(73)

• _{Gas exchange takes place in}_alveoli_{, air sacs at the tips}

of bronchioles

• Oxygen diffuses through the moist film of the epithelium and into capillaries

• _{Carbon dioxide diffuses from the capillaries across the}

epithelium and into the air space

(74)

• _{Alveoli lack cilia and are susceptible to contamination} • Secretions called surfactants coat the surface of the

alveoli

• _{Preterm babies lack surfactant and are vulnerable to}

respiratory distress syndrome; treatment is provided by artificial surfactants

(75)

Concept 42.6: Breathing ventilates the lungs

• _{The process that ventilates the lungs is}_breathing_{, the}

alternate inhalation and exhalation of air

(76)

How a Mammal Breathes

• _{Mammals ventilate their lungs by}_{negative pressure}

breathing, which pulls air into the lungs

• _{Lung volume increases as the rib muscles and}

diaphragm contract

• _The_{tidal volume}_{is the volume of air inhaled with each}

breath

(77)

Figure 42.28

Rib cage expands.

Air

inhaled. Rib cage gets_smaller. Airexhaled.

1 2

Lung

(78)

• _{The maximum tidal volume is the}_{vital capacity}

• _{After exhalation, a}_{residual volume}_{of air remains in the}

lungs

(79)

Control of Breathing in Humans

• _{In humans, the main}_{breathing control centers}_{are in}

two regions of the brain, the medulla oblongata and the pons

• _{The medulla regulates the rate and depth of breathing}

in response to pH changes in the cerebrospinal fluid

• _{The medulla adjusts breathing rate and depth to match}

metabolic demands

• _{The pons regulates the tempo}

(80)

• _{Sensors in the aorta and carotid arteries monitor O}₂_and

CO₂ concentrations in the blood

• _{These sensors exert secondary control over breathing}

(81)

Homeostasis:

Blood pH of about 7.4

CO₂ level

decreases. Stimulus:

Rising level of CO₂ in tissues lowers blood pH. Response:

(82)

Concept 42.7: Adaptations for gas exchange

include pigments that bind and transport gases

• _{The metabolic demands of many organisms require that}

the blood transport large quantities of O₂ and CO₂

(83)

Coordination of Circulation and Gas Exchange

• _{Blood arriving in the lungs has a low partial pressure of}

O₂ and a high partial pressure of CO₂ relative to air in the alveoli

• _{In the alveoli, O}₂_{diffuses into the blood and CO}₂_diffuses

into the air

• _{In tissue capillaries, partial pressure gradients favor}

diffusion of O₂ into the interstitial fluids and CO₂ into the blood

(84)

Exhaled air Inhaled air

Pulmonary arteries

Systemic

veins Systemicarteries Pulmonary veins Alveolar capillaries Alveolar spaces Alveolar epithelial cells Inhaled air 160 120 80 40 0 Heart 8 1 2 3 4 6 7