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 Diapsids Based on number of temporal openings (fenestra)
Orbit (eye socket)
Jaw muscle attachment
Anapsid: no temporal openings
Turtles
Synapsid: single temporal opening
Mammals
Diapsid: two temporal openings
Reptiles including birds
Temporal fenestra
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 Skull Synapsids
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 Dentition A.
Hedgehog
K.
Raccoon
B.
Mole
L.
Coyote
C.
Armadillo
M.
Mountain lion
D.
Anteater
N.
Horse
E.
Giant Anteater
O.
Deer
F.
Marmoset
P.
Jackrabbit
G.
Peccary
Q.
Woodrat
H.
Bear
R.
Porpoise
I.
Fruit-eating bat
S.
Right whale
J.
Nectar-eating bat
T.
Walrus
Digestive Tracts of Carnivores and Herbivores Carnivores
Large, expandable stomachs
Herbivores
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
Marsupials
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
Days after conception
Lactation versus Gestation Times 500
Gestation 400
Lactation
300 200 100 0 Grasshopper mouse
Marsupial mouse
Thomson's gazelle
Wallaroo
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
Monotremes
Short gestation period
External cloaca only Body temp ~ 35°C
Eutharians
Placenta Separate urinary, fecal and reproductive openings Body temp ~ 38°C
Marsupials
Lactation, hair
Live birth, nipples,
Eutherians Well-developed placenta, separate reproductive, urinary, and fecal openings
Major lineages of Mammals Monotremes
Lack a placenta
Leathery eggs similar to reptiles
Body temp ~ 32°C
Marsupials Rudimentary, yolk sac placenta Body temp ~ 35°C
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
Eutharians Well-developed placenta Body temp ~ 38°C
Hedgehogs, moles, true shrews
Canines, felines, bears, seals, weasels Pangolins Horses, tapirs, rhinos Camels, pigs, whales, dolphins, antelope Bats
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
Milk glands
Lack nipples
Egg laying Lack teeth as adults Reptile like gate Low metabolic rate
Gondwana
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
Marsupium (pouch) often present Scrotum anterior to penis
No baculum
Females have bifurcated reproductive tract
Body temp. ~35°C
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
Scrotum posterior to penis
One vagina with uterus
High metabolic rate
Baculum sometimes present
Female have single reproductive tract
Introduced to Australia
Body temp ~38°C
Large braincase (relative to body size)
Neocortex
Complex neocortex: higher functions including sensory perception, language, spatial reasoning, motor commands Corpus callosum: connects left and right hemispheres of brain
Corpus callosum
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 Fetal portion of placenta Maternal portion of placenta
Umbilical cord
Placental Mammals Placenta: 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
Early Cretaceous (~ 135 mya) • Marsupials and monotremes isolated in “Australia” • Marsupials isolated on “South America”
Late Jurassic (~ 180 mya) • Eutheria diverge from Marsupials in “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
Mesonephros
adult hagfish, embryonic fish, amphibians, reptiles, birds, mammals 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)
Renin-angiotensinaldosterone system (RAAS)
water reabsorption
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 Contract
Neither
Atrial Systole Atria
Valves
AV open Semilunar closed 0.4 sec
AV open Semilunar closed 0.1 sec
Time
Function Fill Heart Overfill Ventricle
Ventricular r Systole
Ventricle AV closed Semilunar open 0.3 sec 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
Arthropods
myogenic neurogenic
Vertebrates
myogenic and neurogenic
Control of Heart Rhythm
Sinoatrial node (pacemaker) Atrioventricular node
Mammalian Blood Composition
Plasma (55%)
Water Ions Plasma Proteins Nutrients Wastes Gases Hormones
Cellular Elements (45%)
Erythrocytes Leukocytes Platelets
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)
Radial Glia
Form tracks for new neurons formed in the neural tube
Oligodendrocytes
Creates tight junctions and forms the blood-brain barrier
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
Temporal Summation
two signals do not reach threshold level but occur close enough to set off action potential
Spatial Summation
doesn’t reach threshold
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)
White Matter
Cerebrospinal fluid
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
Thalamus
Includes the pineal gland and the choroid plexus 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
Integration
conduction of signals from sensory receptors PNS 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)
Far-sightedness (hyperopia)
eyeball too long / focal point in front of fovea eyeball too short / focal point behind fovea
Astigmatism (blurred vision)
misshapen lens or cornea
Hearing and Equilibrium
Hearing Organ
Outer Ear
Middle Ear
pinna and the auditory canal tympanic membrane 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