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Mammals

What is a mammal? Endothermic vertebrate

Amniotic egg

Four chambered heart

Synapomorphies of Mammalia Mammary glands

Hair

Three inner ear bones

Neocortex region of brain

Single lower jaw bone (mandible)

Differentiated teeth

Diphyodont dentition

Two occipital condyles

Anapsids, Synapsids and DiapsidsBased on number of temporal openings (fenestra)

Jaw muscle attachment

Anapsid: no temporal openings

Turtles

Synapsid: single temporal opening

Mammals

Diapsid: two temporal openings

Reptiles including birds

Temporal

fenestra

Orbit (eye socket)

Evolutionary History of Mammals

Mammals First appeared ~225 mya

Small nocturnal, insectivores

Cynodonts First appeared ~270 mya

Secondary palate

Therapsids First appeared ~290 mya

Limbs vertically oriented

Synapsids First appeared ~320 mya

Large herbivores and carnivores

Evolution of the Mammal SkullSynapsids Large temporal fenestra

Differentiated teeth on single dentary bone

Hinge between quadrate and articular

Therapsids Further differentiation of teeth

Canines and incisors

Larger dentary bone

Cynodonts Cusped teeth

Secondary palate

Hinge forms between dentary and squamosal

Quadrate and articular bones migrate to inner ear

Single lower jaw bone (dentary)

Mammal Dentition Differentiation of teeth led to success

in mammals

Size and arrangement of teeth associated with diet

Cusps

Four distinct tooth types

Incisors: cutting

Canines: tearing

Premolars: grinding

Molars: crushing, grinding

Diversification of Mammalian DentitionA. Hedgehog

B. Mole

C. Armadillo

D. Anteater

E. Giant Anteater

F. Marmoset

G. Peccary

H. Bear

I. Fruit-eating bat

J. Nectar-eating bat

K. Raccoon

L. Coyote

M. Mountain lion

N. Horse

O. Deer

P. Jackrabbit

Q. Woodrat

R. Porpoise

S. Right whale

T. Walrus

Digestive Tracts of Carnivores and Herbivores

Carnivores Herbivores

Large, expandable

stomachs Large cecum with symbiotic

bacteria break down plant

material

Modes of Locomotion

Plantigrade Most ambulatory (walking)

mammals

Walk on soles of hands and feet

Bears, primates, lagomorphs

Digitigrade Many cursorial (running)

mammals

Run on one or more toes

Canids, felines

Unguligrade Ungulates

Walk or run on hoofs (nails)

Horses, pigs, camels

Lactation versus Gestation TimesMarsupials Dependency on yolk sac for

nutrition

Young born in very immature state

Short gestation period

Prolonged lactation period

Eutherians Placenta facilitates nutrient transfer

between embryo and mother

Young born in well developed state

Long gestation period

Short lactation period

0

100

200

300

400

500

Grasshopper

mouse

Marsupial

mouse

Thomson's

gazelle

Wallaroo

Days

aft

er

co

ncep

tio

n

Gestation

Lactation

Lactation

Lactation: secretion of milk from

mammary glands

Modified sweat glands

Prolactin: stimulates milk production

Oxytocin: stimulates milk delivery

Milk: nutritional liquid

comprised of fats, proteins,

and lactose

Nutrition for newborn

Transmits passive immunity

Supports growth of intestinal flora

Major Lineages of Mammals Monotremes

Lack a placenta Leathery eggs similar to reptiles True cloaca Body temp ~ 32°C

Marsupials Rudimentary, short lived placenta

Short gestation period

External cloaca only Body temp ~ 35°C

Eutharians Placenta Separate urinary, fecal and

reproductive openings Body temp ~ 38°C

Monotremes

Marsupials

Eutherians

Lactation, hair

Live birth, nipples,

Well-developed

placenta, separate

reproductive, urinary,

and fecal openings

Major lineages of

Mammals

Platypus, echidnas

Marsupials

Golden moles

Elephant shrews

Aardvarks

Elephants

Hyrax

Manatees

Armadillos, sloths, anteaters

Flying lemurs

Tree shrews

Apes, monkeys, humans

Rabbits and hares

Rodents

Hedgehogs, moles, true shrews

Canines, felines, bears, seals, weasels

Pangolins

Horses, tapirs, rhinos

Camels, pigs, whales, dolphins, antelope

Bats

Monotremes Lack a placenta

Leathery eggs similar to reptiles

Body temp ~ 32°C

Marsupials Rudimentary, yolk sac placenta

Body temp ~ 35°C

Eutharians Well-developed placenta

Body temp ~ 38°C

Mammal Reproductive Tracts

Monotremes Marsupials Eutherians

Monotremes Prototherians (“first wild beast”)

Single platypus species and four species of echidna All found in either Australia or Papua New Guinea

Gondwana

Milk glands Lack nipples

Egg laying

Lack teeth as adults

Reptile like gate

Low metabolic rate Body temp. ~32°C

Single vagina, two uteri

Cloaca Single opening similar to reptiles

Marsupials Limited to Australia and the Americas

Yolk sac placenta

High metabolic rate

Body temp. ~35°C

Marsupium (pouch) often present

Scrotum anterior to penis

No baculum

Females have bifurcated reproductive tract

Three vagina and two uteri

Male penis bifurcated at tip

Small braincase (relative to body size)

Minimal neocortex development

No corpus callosum

Eutherians Worldwide distribution

Introduced to Australia

Scrotum posterior to penis Baculum sometimes present

Female have single reproductive tract One vagina with uterus

High metabolic rate Body temp ~38°C

Large braincase (relative to body size) Complex neocortex: higher functions including

sensory perception, language, spatial reasoning, motor commands

Corpus callosum: connects left and right hemispheres of brain

Corpus callosum

Neocortex

Differences in the Placenta

Marsupials Rudimentary connection between yolk sac and

maternal tissue

Large yolk sac provides nutrients to developing

embryo

Allantois: avascular; storage of nitrogenous waste

Eutherians Umbilical cord connects fetus to uterus

Umbilical vein and artery

Efficient exchange of nutrients, gases and waste

Reduced yolk sac

Allantois connects fetal bladder to yolk sac, which

drains into umbilical cord

Marsupial Eutherian

Chorion

Amnion

Embryo

Allantois

Yolk Sac

Maternal portion of

placentaUmbilical

cord

Fetal portion

of placenta

Placental MammalsPlacenta: organ that connects

developing fetus to uterine wall

and facilitated transfer of gases,

nutrients and wastes.

Chorion: outermost membrane

that develops chorionic villi,

which facilitate exchange between

mother and fetus

Umbilical cord: vascularized

cord connecting fetus to placenta

Biogeography of Mammals

Early Jurassic

(~ 200 mya)

• Monotremes and marsupials

in southern Pangaea

Late Jurassic (~ 180 mya)

• Eutheria diverge from

Marsupials in “South

America”

Early Cretaceous (~ 135 mya)

• Marsupials and monotremes

isolated in “Australia”

• Marsupials isolated on “South

America”

Early Paleocene (~ 65 mya)

• Dinosaurs extinct

• Mammal radiation

• Separation of primates

• New world/old world

• Lemurs

• Eutheria northern

distribution

Primate Evolution

Ancestral primate (arboreal) (65 mya)

binocular vision

opposable thumb

Prosimians

lemurs, tarsiers pottos

Primate Evolution

Ancestral primate (arboreal)

(47 mya)

binocular vision

opposable thumb

“Ida” – Missing Link

No claws

Lack a tooth comb

Short limbs

Short face

Talus – corner of leg/foot

Primate Evolution

Anthropoids (50 mya)

Monkeys

Old World

External nares close together

Opposable thumbs

Calloused ischial tuberosities

Primate Evolution

Anthropoids (50 mya)

Monkeys

New World

Broad flat nasal septum

Nonopposable thumb

Prehensile tail

Primate Evolution

Hominoids (30 mya)

apes

Human Evolution Brain Size

Jaw Size

Bipedalism

Reduced Size difference in sexes

Family Structure

Human Evolution

Sahelanthropus

(6.5 million years ago)

Human Evolution

Laetoli Footprints

(3.5 million years ago)

Human Evolution

Australopithecus

(3.24 million years ago)

Primate Evolution

Homo genus

(2.4-1.6 mya)

Homo sapiens (200,000

years ago)

Primate Evolution

Neanderthals

(40,000 years old)

Human Evolution

Turkana Boy (Homo

ergaster)

(1.7 million years ago)

Between H. habilis and

H. erectus

Origin of Modern Humans

Out of Africa

(monogeneus)

all races of humans

evolved from an ancestor

in Africa

Multiregional

Each race evolved from

regional populations of

Homo erectus

Evolution of the Vertebrate Heart Two chambers (one atria and one ventricle)

along with a sinus venosus and a conus venosus)

Two chambers plus septa

lungfish

Vertebrate Excretory Systems

Pronephros

adult hagfish, embryonic fish, amphibians, reptiles, birds, mammals

Mesonephros

adult lamprey, fish, amphibians, embryonic reptiles, birds, mammals

Metanephros

adult reptiles, birds, mammals

The Human Excretory System

Kidneys

Ureters

Urinary Bladder

Urethra

Blood Filtrate to Urine

Bowman’s Capsule and the Glomerulus

(filters the blood)

Proximal tubule

reabsorbed (NaCl, Potassium, Water, Nutrients)

secretes ( ammonia)

regulates (pH)

Blood Filtrate to Urine

Loop of Henle

Descending loop

reabsorbed (water)

Ascending loop

reabsorbed (NaCl)

Blood Filtrate to Urine

Distal tubule

reabsorbed (NaCl, Water)

secrete (potassium)

regulate (pH)

Collecting duct

reabsorbed (NaCl, Water, Urea)

Control of the

Kidney

Antidiuretic hormone (ADH) water reabsorption

Renin-angiotensin-aldosterone system (RAAS) water reabsorption

Atrialnatiuretic Factor (ANF) inhibits the release of renin

Evolution of the Vertebrate Heart Three chambers (two atria and one ventricle)

amphibians, reptiles

Evolution of the Vertebrate Heart

Four chambers (two atria and

two ventricles)

Crocodilians, mammals, birds

Path of Blood Through The Heart

Anterior and Posterior

Vena Cava

Right Atria

Atrioventricular (AV) Valve

(tricuspid)

Right Ventricle

Semilunar Valve

Pulmonary Arteries

Lungs

Pulmonary Veins

Left Atria

Atrioventricular (AV) Valve

(bicuspid)

Left Ventricle

Semilunar Valve

Aorta

Body

Circulatory Schemes

Cardiac Cycle

Diastole Atrial

Systole

Ventricular

r Systole

Contract Neither

Atria Ventricle

Valves AV open

Semilunar

closed

AV open

Semilunar

closed

AV closed

Semilunar

open

Time 0.4 sec 0.1 sec 0.3 sec

Function Fill Heart Overfill

Ventricle

Pump

Blood

Cardiac Output

Volume of blood per minute from the left ventricle

Depends on two factors

Heart rate (pulse)

Stroke volume

Average Human

75 ml/beat

70 beats/min

5.25 L/min (your blood volume)

Cardiac Control

Annelids and Mollusks

myogenic

Arthropods

neurogenic

Vertebrates

myogenic and neurogenic

Control of Heart Rhythm

Sinoatrial node (pacemaker)

Atrioventricular node

Mammalian Blood Composition

Cellular Elements (45%)

Erythrocytes

Leukocytes

Platelets

Plasma (55%)

Water

Ions

Plasma Proteins

Nutrients

Wastes

Gases

Hormones

Blood Clotting

Injury triggers platelets to area

Changes prothrombin to thrombin which than converts fibrinogen to fibrin

Blood Pressure

Systolic Pressure

Diastolic Pressure

Cardiovascular Disease

Hypertension

Heart Attack

Stroke

Atherosclerosis

Arteriosclerosis

LDL’s

HDL’s

Cardiovascular “Surgeries”

Angiogram

Angioplasty

Stents

Cardiovascular “Surgeries”

Bypass Surgery

Cardiovascular Disease

Cardiovascular Disease

Ventilation Lungs

Found in amphibians, reptiles, mammals and birds

Pharynx

Larynx

Trachea

Bronchi

Bronchioles

Alveoli

Alveoli

Ventilating The Lungs

Positive Pressure

Breathing

pushes air down trachea

seen in frogs and other

amphibians

Negative Pressure

Breathing

suction created by

diaphragm

seen in mammals

Negative Pressure Breathing

Breathing Control

Occurs in Medulla oblongota and Pons

Monitors Carbon Dioxide (converts to carbonic acid) lowers pH and

causes increase in depth and rate of breathing

Oxygen

Transport

Hemocyanin - used by

arthropods and mollusks

Hemoglobin - used by verts

CO2Transport

Carbon Dioxide Transport

Carbon dioxide transported from tissue by erythrocyte

7% transported as Carbon Dioxide in blood

23% of Carbon Dioxide and most of the Hydrogen ions are attached to hemoglobin

70% transported as Bicarbonate in plasma

Deep-diving Mammals Stores large amounts of oxygen

in blood and muscles (twice as

much as us)

twice the volume of blood

huge spleen

myoglobin

Deep-diving Mammals Conservation techniques

exhale before diving (prevent bends

/ pressure)

decrease heartrate and oxygen

consumption

reduce blood supply to muscles

(anaerobic)

Overview of a Nervous System

Axons

Myelin Sheath - insulating layer

Node of Ranvier - gaps between Schwann Cells

Synaptic Terminals - neuron ending

Clusters of Neurons

Ganglion

Cluster of nerve cell bodies in the PNS

Nuclei

Cluster of cells in the brain

Supporting Cells

Glia (glue)

Astrocytes (structural support)

Creates tight junctions and forms the blood-brain barrier

Radial Glia

Form tracks for new neurons formed in the neural tube

Oligodendrocytes

Form myelin sheath in brain

Schwann Cells

Form myelin sheath in the PNS

Reflex

Sensory

neuron to

a motor

neuron

Neural Signals

Membrane Potential

Sodium-Potassium Pump

Threshold Potential

Resting State

Both sodium

and

potassium

activation

gates are

closed

Interior of

cell is

negative

Depolarization State

Sodium

activation

gates are

opened on

some

channels

Interior of

cell

becomes

more

positive

Rising Phase of Action Potential

Most sodium

activation gates

are opened

Potassium

activation gates

are still closed

Falling Phase of Action Potential Inactivation gates

on sodium channels are closing

Activation gates on potassium channels are opened

interior of cell becomes more negative

Undershoot

Both gates to sodium channels are closed

Potassium channels are closing

Membrane returns to its resting state

Propagation of the

Action Potential

Localized event

First action potential’s

depolarization sets off

second action

potential

Travels in one

direction due to

refractory period

Salatory Conduction Action Potential jumps from node to node

Speeds up signal from 5 m/sec to 150 m/sec

Communication Between Synapses

Electrical Synapses

gap junctions allow for direct transfer of action potential (used during escape

responses)

Chemical Synapses

uses neurotransmitters

Chemical Synapse

Chemical Synapses

Action potential triggers an influx of calcium

Synaptic vesicles fuse with presynaptic membrane

Neurotransmitter released into synaptic cleft

Neurotransmitters bind to receptors and open ion channels

on postsynaptic membrane which sets off new action

potential

Neurotransmitters are degraded by enzymes or removed by

a synaptic terminal

Neurotransmitters

Postsynaptic Potentials

Postsynaptic Potentials Subthreshold

doesn’t reach threshold

Temporal Summation

two signals do not reach threshold level but occur close

enough to set off action potential

Spatial Summation

two signals are set off at the same time setting off an action

potential

Spatial Summation with an inhibitor

doesn’t reach threshold

Vertebrate

Nervous

System

Central Nervous System

Ventricles (4)

Cerebrospinal fluid

White Matter

Made up of axons

Gray Matter

Made up of dendrites

Peripheral Nervous System

Peripheral Nervous System

Autonomic Nervous System regulates the internal environment (usually

involuntary)

Somatic Nervous System regulates the external environment (usually

voluntary)

Autonomic Nervous System

Autonomic Nervous System

Sympathetic Division

Flight or fight response

Parasympathetic Division

Rest or digest response

Brain

The Brainstem

The Medulla Oblongata and the Pons

controls breathing, heart rate,

digestion

The Cerebellum controls

coordination of movement and

balance

The Midbrain

The Midbrain receives, integrates, and

projects sensory information to the

forebrain

The Diencepholon

Forebrain

Epithalamus

Includes the pineal gland and the choroid

plexus

Thalamus

conducts information to specific areas of

cerebrum

Hypothalamus

produces hormones and regulates body

temperature, hunger, thirst, sexual response,

circadian rhythms

The Telencepholon

Cerebrum

with cortex and corpus

callosum

higher thinking

Cerebrum

Cerebrum

Cerebrum

Limbic System

Regulates

emotions

Association with

different situations

is done mostly in

the prefrontal lobe

Memory

Short Term

Done in the

frontal lobe

Long Term

Frontal lobes

interact with the

hippocampus and

the amygdala to

consolidate

Overview of a Nervous System

Sensory Input

conduction of signals from sensory receptors

PNS

Integration

environmental information is interpreted

CNS (brain and spinal cord)

Motor Output

conduction of signals to effector cells

PNS

Evolution of the Eye

Complex eyes have

developed many

times

Photoreceptors

Camera Type Eyes –

Evolved several times

Hagfish eye

Lamprey eye

Jawed vertebrate eyes

Single Lens Eye

Sclera (white)

Cornea (clear)

Choroid (pigmented)

Iris (color of eye)

Retina (rods and cones)

Pupil

Fovea (focal point)

Blind spot

Photoreceptors

Scars of Evolution

1. inside out retina that forces light to pass through the cell bodies and nerves before hitting the retina

2. blood vessels across the retina that cause shadows

3. nerve fibers that exit causing a blind spot

Focusing

Near vision

ciliary muscle

contracted

lens becomes more

spherical

Distance vision

ciliary muscle

relaxed

lens becomes flatter

Visual Problems

Near-sightedness (myopia)

eyeball too long / focal point in front of fovea

Far-sightedness (hyperopia)

eyeball too short / focal point behind fovea

Astigmatism (blurred vision)

misshapen lens or cornea

Hearing and Equilibrium

Hearing Organ Outer Ear

pinna and the auditory canal

tympanic membrane

Middle Ear

malleus, incus and stapes

oval window

Inner Ear

cochlea with the Organ of Corti

with a basilar membrane and hair cells

Eustachian Tube

Sound

Volume amplitude of sound wave

vibrates fluid in ear and bend hair cells which generates more action potentials

Pitch frequency of sound wave

Equilibrium

Utricle and Saccule

Semicircular Canals

used to detect body position and movement

Chemoreception

Taste Buds

sweet (tip), salty (behind), sour

(sides), bitter (back of tongue)

Chemoreception

Olfactory receptors cells

upper portion of nasal cavity