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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