CVA Final

Why is gas exchange necessary?

•Oxygen is needed to efficiently produce ATP

•O2 must get to cells from surrounding environment

•CO2 is given off as a byproduct of cell respiration

•CO2 must get from tissues to surrounding environment

•Both are exchanged by simple diffusion

•based on partial pressure of gases

simple diffusion

What is partial pressure determined by

stage 1 of breath

Bulk flow of medium across respiratory surface

stage 2 of breath

Diffusion of gases across respiratory surface

stage 3 of breath

Bulk flow in the circulatory system, transport of gases through organism

stage 4 of breath

Diffusion of gases out of circulatory system into tissues

External respiration

•…………….. between environment & blood

•Requires movement of air/water across respiratory organ

•Ventilation

Internal respiration

•…………………. between blood & tissues

•Requires pumping of blood through capillaries

•perfusion

both maximize efficiency of gas exchange

•Water flows in through mouth out over the gill

•Blood & water flow in opposite directions in the gills

Chondrichthyes ventilation

•Many rely on ram ventilation

•Continuous movement to keep water moving over gills

•Some use a spiracle or buccal pumping at rest

•Pushes water over the gills after drawing it in

operculum

•Branchial arch supports V-shaped gill filaments

•Opening of mouth creates a vacuum to draw water in

Mouth closes & operculum opens to force water

Gas bladder

•Form as outcroppings of the foregut

•Used as swim bladders in Actinopterygii

•Serve to store gas to aid in buoyancy in water column

Can serve as a temporary oxygen source if needed

Physostomous

•………….stay connected

•Gulping air opens a pneumatic duct

•Air moves into the gas bladder

Physoclistous

•………………are filled directly from the blood

•Regulation of blood flow to the bladder regulates its volume

Lungs

•Forms as a ventral outcropping of esophagus

•………….are highly vascularized to maximize gas exchange

•………are subdivided to maximize the surface area

•Subdivisions are called faveoli & are rich in capillaries

amphibian ventilation

•Most have gills in an aquatic larval stage

•Some adults retain gills exclusively

Others combine gills & lungs both

•Most transition from larval gills to adult lungs

•Cutaneous respiration is common in adults & larvae

•Some lack lungs or gills as adults

Buccal pump

•Air is drawn into mouth & then forced into lungs using throat musculature; **positive pressure**

•Oxygenated & deoxygenated air mix in some species but not all

buccal pump variations

two stroke and four stroke

aspiration pump (amniotes)

•Muscles & ribs expand space around lungs

•Results in **negative pressure** around lungs

•Draws air in from outside environment like a vacuum

•When muscles & ribs relax air is forces out again

•Buccal cavity is typically not involved

turtle ventilation

Whole body is encapsulated in shell

Plastron (sternum) & Carapace (ribs + vertebra)

Abdominal muscles & limb movements are responsible for the increase & decrease of lung volume

Snake ventilation

•One lung is often lost & the other subdivides

•Anterior portion of the lung contains many faveoli

•Posterior portion lacks faveoli & serves for air storage

lizard ventilation

Tidal ventilation & exchange in some

Unidirectional vent. w/ cross-current exchange in some

crocodilian ventilation

•Also rely on intercostal muscles & gastralia

•Liver serves as a piston & diaphragm pulls it posteriorly

When diaphragm relaxes it bounces back forcing air out

Cross-current exchange w/ unidirectional flow

bird ventilation

Respiratory system branches to form air sacs

•Sacs are avascular & do not function in gas exchange

Extend between viscera & into hollow bones

Bird ventilation steps

•Flows into posterior air sacs on 1st inhalation

•1st exhalation moves air into lungs

•Passes through unidirectional parabronchi

•Prevents oxygenated & deoxygenated air from mixing

•2nd inhalation drives air out of lungs & into anterior sacs

•2nd exhalation drives air from anterior sacs out of body

Muscles of ventilation in mammals & roles

•External intercostals & diaphragm draw air in

•Diaphragm pushes abdominal organs caudally

•Relaxation & recoil of the liver drives exhalation

•Internal intercostals & abdominal muscles also aid in increasing exhalation

pharynx

•Connects the oral & nasal cavit

•Leads to the larynx which separates the digestive & respiratory tracts

Epiglottis & false vocal cords

•………………………… close during swallowing

•Block entry into the trachea

•Opening into the trachea is the glottis

Bohr

………– reduces hemoglobin O2 affinity

Root

…………– reduces hemoglobin O2 carrying capacity

larynx

epiglottis and false vocal cords

left & right primary bronchi

Trachea Branches At The Carina

•Forms…………………

•Left bronchus leads to upper & lower secondary bronchi

•Right bronchus leads to upper, middle, & lower bronchi

secondary bronchi

•Lead to progressively smaller tubes (bronchioles)

•Maximizes surface area for gas exchange as it branches

•Walls contain muscles but lack cartilage found in bronchi

•Branches eventually lead to small alveolar ducts

alveolar

•Alveoli are connected by …………pores to maintain pressure

alveolus 3 cell types

Type I, Type II and Macrophages

alveolus Type I

are simple squamous epithelium for gas exchange

alveolus Type II

produce surfactants to reduce surface tension

alveolus Macrophages

remove debris & pathogens

red blood cells transporting gas

•Hemoglobin binds oxygen as it passes from lungs

•Releases oxygen into surrounding tissues

•Also responsible for over 90% of CO2 transfer

•Remaining 10% dissolves in plasma

•20% of CO2 binds to globin groups

Carbonic anhydrase

•………………………. in membrane & cytoplasm converts most to carbonic acid (H2CO3) in RBCs by reacting with H2O

transport systems

cardiovascular and lymphatic systems

platelets

•Fragment off of growing megakaryocytes

•Grow in response to thrombopoietin from liver & kidneys

•Principally responsible for closing breaks in vessels

associated with our immune system

lymphocytes

infarct

an inappropriately formed clot that breaks off and blocks blood flow to a tissue is called ………..

arteries

blood is carried from the heart in thick elastic vessels called …………

Erythrocyte Growth

•Erythropoietin travels from kidneys to bone marrow

•Also affected by levels of vitamin B12, folic acid, & iron

•Deficiency in red blood cells or hemoglobin is anemia

•Erythrocytes survive 3-4 months

Erythrocytes Specific Antigens

•Cell surface proteins that form a personal signature

•A or B antigens are on the surface of RBC

•People with Type O Blood have no antigens

•Immune system recognizes its own antigens

•Also produces antibodies against foreign antigens

Rh antigens

•Individuals lacking …………… are Rh negative

•Develop anti-Rh antibodies if exposed to Rh+ blood

•Issues if Rh– woman is pregnant w/ Rh+ fetus

•May result in female immune system attacking fetus

O blood type

Can go to A, B, & AB but not back to O

A & B blood type

can go to AB but not back to A or B

Leukocytes

•Vary from 0.1 to 9% of total blood cells

•Produced in bone marrow & differentiate to 5 types

•Triggered by thymosins (lymphocytes) or cytokines

•Principle component of the immune response

types of Leukocytes

Monocyte, Eosinophil, Basophil, lymphocytes, and Neutrophil

Aorta

The Largest Artery Is The ……………..

•Has a tunica intima of simple squamous epithelium

•Surrounded by tunica media containing smooth muscle & large amounts of elastic tissue

•Surrunded by tunica externa of collagenous fibers

fish Aorta

•Gives rise to paired afferent branchial arteries that enter the gill arches

•Each gill contains capillaries where blood is oxygenated

•Capillaries only contain a tunica intima

Arterioles

Arteries Give Rise To ………….

•Tunica wall becomes less elastic as distance from the heart increases

•Arterioles have sphincters to shunt blood to/from tissues

•Allows the body to survive on a lower blood volume

capillaries

•Primary site of exchange in the circulatory system

•Materials are forced out due to hydrostatic pressure from BP

•Maximizes transfer of small materials (gases, nutrients)

•“Leaky” portion of vasculature

capillary types

continuous capillaries, fenestrated capillaries, and Sinusoidal capillaries

Continuous capillaries

•………………… possess tight junctions

•Limit flow of materials out of capillaries

•Common in fat, muscle, & nervous tissue

Fenestrated capillaries

•………………… have pores

•Permit movement of larger molecules out of capillaries

•Common in intestines, kidneys, & endocrine glands

Sinusoidal capillaries

•………………….. have large gaps between cells

•Allows cells to move in & out of blood, not always “round”

Vanules

Capillaries Coalesce To ………….

veins

•Venules coalesce to form ………..

•Possess valves to accommodate low pressure & prevent backflow of blood

•Tunica media is also rigid instead of elastic

cardinal veins or vena cava

Veins come together into ……………………… to return blood to the heart

Hepatic portal system

•…………………. routes blood through liver

•Includes nutrient dense blood from the digestive tract

•Permits absorption/modification of nutrients

•Also permits cleaning & modification of blood from spleen

All blood leaves the liver through hepatic veins

Pericardium

•2 layers of connective tissue in the thoracic cavity

Parietal pericardium

Visceral pericardium

Parietal pericardium

•…………………. is fibrous & doubles back on itself to form visceral pericardium

Visceral pericardium

•……………….fuses to the surface of the heart

•Space in between is fluid lubricated pericardial cavity

heart layers

epicardium, myocardium, and endocardium

left ventricle

has thickest walls

•Pumps blood out through aortic valve to the aorta

•First two branches form the left & right coronary arteries

•Blood then returns to the heart via cardiac veins

•Enters coronary sinus & dumps into the right atrium

right ventricle

Contraction of ventricle pumps snaps AV valve shut

•Forces the pulmonary valve open & blood passes through pulmonary arteries to the lungs

atrioventricular node (AV)

allows for signals to pass through connective tissue blocks

“Funny” leaky

………………. channels allow Na+ into the cells

SA Node

needs to be regulated

•Would self-stimulate 75-80 times/minute on own

•Regulated by vagus nerve & sympathetic nerves

•Also regulated by thyroid & adrenal glands

Lymphatic System

Prevents Edema

•Filters excess fluid (lymph) away from tissues

•Results from low internal pressure in blind lymph capillaries

•Fluid filters out of tissues & into capillaries

lymph nodes

•Lymphatic tissue wrapped in fibrous connective

•Composed of sinuses through which lymph flows

•Sinuses contain specialized white blood cells

lymph node functions

•Monitor for & filter harmful particles from lymph

•Macrophages destroy debris, damaged cells, & foreign substances

•Lymphocytes attack viruses, bacteria, & parasites

•Collectively remove \~99% of invaders & debris

•Serve as a major site of lymphocyte production

Thoracic

•………duct collects lymph from most of the body

Thymocytes

•……………….mature into T cells in the cortex

•Also houses epithelial cells, macrophages, dendritic cells

•Immature thymocytes are presented to epithelial cells with MHC molecules

•Those that don’t bind MHCs go through apoptosis (positive selection)

Spleen

•Acts as a lymph node for the blood

•Houses lymphocytes & macrophages

•Filters foreign matter from blood inside of the white pulp

•Also squeezes red blood cells through sinuses rupturing some

•Remnants are engulfed by macrophages in red pulp

Mechanical barriers

•………………….. are physical barriers

•Skin & mucus membranes prevent entrance to body

•Sweat & mucus wash away microorganism

Chemical barriers

•…………………… kill pathogens

•Enzymes & acids break down & destroy bacteria

•Lysozyme in tears & saliva tear apart bacterial cell walls

•Low pH in sweat & stomach acid kill pathogens

function of a fever

•Makes environment inhospitable for invaders; impairs protein function

•Endotherms generate extra body heat to raise temp

•Ectotherms seek out higher environmental temps; “behavioral fever”

MHC’s

•Specialized antigen presenting molecules in cells

•Class I MHCs are found in many cells

•Permit the presentation of antigens from viruses

•Stimulate the action of cytotoxic T cells & drive response

Cytotoxic T Cells

•Chemical cues in medulla of thymus shut down CD4

•CD8 presenting cells bind MHC class I molecules on cells infected by viruses

•Act like natural killer cells & stimulate apoptosis of infected cells by secreting granzymes & perforins

Helper T Cells

•Chemical cues in medulla of thymus shut down CD8

•CD4 presenting cells bind to MHC class II molecules on antigen presenting cells

•When an antigen is bound to the MHC the helper cells secretes cytokines

antibodies

•Are essentially free floating antigen receptors

•May bind to antigens on pathogens neutralizing them

•May mark pathogens for phagocytosis

•May target pathogens for destruction using a similar system to natural killer cells

Closing

Heart Sounds Are Valves ………….

cardiac conductions

Sinoatrial node, atrioventricular node, atrioventricular bundle, and Purkinje fibers

homology

anatomy due to descent

homoplasy

similar in appearence

analogy

similar function

symplesiomorphy

An ancestral character state (i.e., a plesiomorphy) shared by two or more lineages in a particular clade

synapomorphy

a characteristic present in an ancestral species and shared exclusively (in more or less modified form) by its evolutionary descendants

chordate characteristics

notochord, dorsal hollow nerve cord, pharyngeal slit, and postanal tail

**Agnatha**

•**…………..**use a muscular pharynx for feeding

•Forms a paraphyletic group

Superclass Cyclostomi

**…………………………** diverged early on

•Contains only two living classes of jawless fish

Chondrichthyes

•Possess cone shaped or pointed placoid scales

•Arise beneath the skin and then erupt but do not grow

•Similar structure to the teeth of these organisms

•Have a cartilaginous skeleton that contains calcium

•Represents a secondary loss of bone seen in ancestors

•Males possess pelvic claspers for copulation

•**gonopodium**

•Permits jaw to move independently of the skull

•Teeth are replaced serially though life (**polyphodont**)

•Most Chondrichthyes have open gills

•1st gill is a modified **spiracle** that runs to mouth

•Possess heterocercal tails and large buoyant livers

•Prevent sinking under their own body weight

Osteichthyes

•Bony fish have extensively ossified skeletons

For the most part

•Possess a swim bladder (modified from lungs)

•For the most part

•Possess a homocercal tail

•For the most part

•Covered in scales (usually overlapping)

•For the most part

•Gills are covered by a bony operculum (protection)

•For the most part

Actinopterygii

are ray finned fish

Sarcopterygii

are the lobe finned fish