Transcript Chapters 40-47

Chapters 41-47
Internal regulation
• Interstitial fluid: internal fluid
environment of vertebrates;
exchanges nutrients and wastes
• Homeostasis: “steady state” or
internal balance
• Negative feedback: change in a
physiological variable that is being
monitored triggers a response that
counteracts the initial fluctuation;
i.e., body temperature
• Positive feedback: physiological
control mechanism in which a
change in some variable triggers
mechanisms that amplify the
change; i.e., uterine contractions
at childbirth
Metabolism: sum of all energyrequiring biochemical reactions
• Catabolic processes of
cellular respiration
• Calorie; kilocalorie/C
• Endotherms: bodies
warmed by metabolic heat
• Ectotherms: bodies
warmed by environment
• Basal Metabolic Rate
(BMR): minimal rate
powering basic functions of
life (endotherms)
• Standard Metabolic Rate
(SMR): minimal rate
powering basic functions of
life (ectotherms)
Chapter 41
•
Animal
Nutrition
Nutritional requirements
• Essential nutrients: materials
that must be obtained in
preassembled form
• Essential amino acids: the 8
amino acids that must be obtained
in the diet
• Essential fatty acids:
unsaturated fatty acids
• Vitamins: organic coenzymes
• Minerals: inorganic cofactors
Food types/feeding mechanisms
•
•
•
•
•
Opportunistic
Herbivore: eat autotrophs
Carnivore: eat other animals
Omnivore: both
Feeding Adaptations
– Suspension-feeders: sift food from
water (baleen whale)
– Substrate-feeders: live in or on their
food (leaf miner) (earthworm:
deposit-feeder)
– Fluid-feeders: suck fluids from a host
(mosquito)
– Bulk-feeders: eat large pieces of food
(most animals)
Overview of food processing
Earthworm http://www.tvdsb.on.ca/westmin/science/snc2g1/wormdig.htm Bird http://people.eku.edu/ritchisong/birddigestion.html
Grasshopper http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb6pg17.htm
• 1-Ingestion: act of eating
• 2-Digestion: process of food break down
–
–
–
–
enzymatic hydrolysis
intracellular: breakdown within cells (sponges)
extracellular: breakdown outside cells (most animals)
alimentary canals (digestive tract)
• 3- Absorption: cells take up small molecules
• 4- Elimination: removal of undigested material
Mammalian digestion
• Peristalsis: rhythmic waves of contraction by smooth muscle
• Sphincters: ring-like valves that regulate passage of material
• Accessory glands: salivary glands; pancreas; liver; gall
bladder
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter43/animations.html#
Mammalian digestion
•
Oral cavity
– salivary amylase- carbs
– •bolus
•
Pharynx
– •epiglottis
•
•
Esophagus
Stomach: protein
– •gastric juice
•pepsin/pepsinogen (HCl)
– •acid chyme
– •pyloric sphincter
•
•
Small intestine •duodenum
Intestinal digestion:
–
–
–
–
a-carbohydrate
b-protein
c- nucleic acid
d-fat •bile
http://www.whfoods.com/genpage.php?tname=faq&dbid=16#digestion
Bile http://www.zerobio.com/cck_flash.htm
Mammalian digestion
Mammalian digestion
•
•
•
•
Villi / microvilli
Lacteal (lymphatic)
Chylomicrons (fats mixed with cholesterol)
Hepatic portal vessel: to liver
Mammalian digestion
• Hormonal Action:
• Gastrin food---> stomach
wall ---> gastric juice
• Enterogastrones
(duodenum)
– 1-Secretin
acidic chyme--->
pancreas to release
bicarbonate
– 2-Cholecystokinin (CCK)
amino/fatty acids--->
pancreas to release
enzymes and gall bladder
to release bile
•
•
•
•
•
Large intestine (colon)
Cecum
Appendix
Feces
Rectum/anus
Evolutionary adaptations
•
•
•
•
Dentition: an animal’s assortment of teeth
Digestive system length
Symbiosis
Ruminants
Chapter 42
• Circulation and
Gas Exchange
Circulation system evolution, I
• Gastrovascular cavity (cnidarians, flatworms)
• Open circulatory •hemolymph (blood & interstitial fluid)
•sinuses (spaces surrounding organs)
• Closed circulatory: blood confined to vessels
• Cardiovascular system: •heart (atria/ventricles) •blood vessels
(arteries, arterioles, capillary beds, venules, veins) •blood
(circulatory fluid)
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html
Circulation system evolution, II
Earthworm http://yucky.discovery.com/noflash/worm/multi/heart.mov
• Fish: 2-chambered heart; single circuit of blood flow
• Amphibians: 3-chambered heart; 2 circuits of blood flowpulmocutaneous (lungs and skin); systemic (some mixing)
• Mammals: 4-chambered heart; double circulation; complete
separation between oxygen-rich and oxygen poor blood
Pulmonary/systemic
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12704
Double circulation
Heart anatomy
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12504
The mammalian heart
Cardiac cycle http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0028-swf_the_cardiac_cy.swf
• Cardiac cycle: sequence of
filling and pumping
• Systole- contraction
• Diastole- relaxation
• Cardiac output: volume of
blood per minute
• Heart rate- number of beats
per minute
• Stroke volume- amount of
blood pumped with each
contraction
• Pulse: rhythmic stretching of
arteries by heart contraction
Blood flow
http://www.sumanasinc.com/webcontent/animations/content/human_heart.html
The heartbeat
•
•
•
Sinoatrial (SA) node (“pacemaker”): sets rate and timing of cardiac
contraction by generating electrical signals
Atrioventricular (AV) node: relay point (0.1 second delay) spreading impulse
to walls of ventricles
Electrocardiogram (ECG or EKG)
Open heart surgery http://www.abc.net.au/science/lcs/swf/heart.swf
Blood vessel structural differences
Capillary fluid exchange http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0029-swf_fluid_exchange.swf
Away
Low
pressure
Toward heart
Thicker: more
pressure
Gas exchange,
osmosis, diffusion
The lymphatic system
•
•
•
•
Lymphatic system: system
of vessels and lymph nodes,
separate from the circulatory
system, that returns fluid and
protein to blood
Lymph: colorless fluid,
derived from interstitial fluid
Lymph nodes: filter lymph
and help attack viruses and
bacteria
Body defense / immunity
Blood
•
•
•
•
•
•
Plasma: liquid matrix of blood in which cells are suspended (90%
water)
Erythrocytes (RBCs): transport O2 via hemoglobin
Leukocytes (WBCs): defense and immunity
Platelets: clotting
Stem cells: pluripotent cells in the red marrow of bones
Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia;
thrombus (clot)
Cardiovascular disease
•
•
•
•
•
•
•
Cardiovascular disease (>50%
of all deaths)
Heart attack- death of cardiac
tissue due to coronary blockage
Stroke- death of nervous tissue
in brain due to arterial blockage
Atherosclerosis: arterial plaques
deposits
Arteriosclerosis: plaque
hardening by calcium deposits
Hypertension: high blood
pressure
Hypercholesterolemia:
LDL, HDL
Gas exchange
• CO2 <---> O2
• Aquatic: gills , ventilation, countercurrent exchange
• Terrestrial: •tracheal systems •lungs
Mammalian respiratory systems
• Larynx (upper part of
respiratory tract)
• Vocal cords (sound
production)
• Trachea (windpipe)
• Bronchi (tube to
lungs)
• Bronchioles
• Alveoli (air sacs)
• Diaphragm
(breathing
muscle)
How do we breathe?
•
•
•
•
•
•
•
Thoracic cavity
pleura
diaphragm
intercostal muscles
Role of pressure
inspiration
What happens with
pressure and the
volume of the chest
cavity?
• Expiration
• What happens with
pressure and the
volume of the chest
cavity?
Respiratory System
• Why do we need to
breathe?
• Gas exchange
system
• Requirements of
respiratory
membranes:
– must be moist.
– Must be thin
– must be permeable to
gases.
• All organisms must
have a mechanism
with which to
transport gases.
(circulatory system)
• Movement of gases
happens by simple
diffusion.
Breathing
• Positive pressure breathing: pushes air into lungs
(frog)
• Negative pressure breathing: pulls air into lungs
(mammals)
• Inhalation: diaphragm contraction; Exhalation:
diaphragm relaxation
• Tidal volume: amount of air inhaled and exhaled with
each breath (500ml)
• Vital capacity: maximum tidal volume during forced
breathing (4L)
• Regulation: CO2 concentration in blood (medulla
oblongata)
Gas Exchange
• Where does it occur?
• What gases are
exchanged?
• Simple diffusion is
responsible.
• Erythrocytes
• RBCs
• Role of hemoglobin
• Structure of
hemoglobin
•
•
•
•
Oxyhemoglobin
4 oxygens at a time.
Effects of CO
Carbon dioxide is
largely transported as
a dissolved gas in the
plasma although
some is transported
by hemoglobin
Respiratory pigments: gas transport
• Oxygen transport– Hemocyanin: found in
hemolymph of arthropods and
mollusks (Cu)
– Hemoglobin: vertebrates (Fe)
• Carbon dioxide transport– Blood plasma (7%)
– Hemoglobin (23%)
– Bicarbonate ions (70%)
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html
Control of breathing
• Respiratory Center
– Medulla Oblongata
– Brainstem
• Peripheral
Chemoreceptors
• aorta and carotid
arteries
• increase in Carbon
dioxide increases
H+ ion
concentration.
• Central
chemoreceptors in
the brain are sensitive
to this.
• Increase CO2,
Increase breathing
rate.
• Hyperventilation
Other mechanisms of breathing
• Gills
• Structure
• Why do fish
suffocate on land?
• Countercurrent
flow
• Insects
- spiracles
– tracheae
– tracheoles
• Why can’t this work in
us?
• Snail and Frogs
– Have lungs, but very
little respiratory
surface area.
– Cutaneous
Breathing.
Chapter 43
• The Body’s
Defenses
Lines of Defense
Nonspecific Defense Mechanisms……
Phagocytic and Natural Killer Cells
• Neutrophils
60-70% WBCs; engulf and
destroy microbes at infected
tissue
• Monocytes
5% WBCs; develop into….
• Macrophages
enzymatically
destroy microbes
• Eosinophils
1.5% WBCs; destroy large
parasitic invaders (blood flukes)
• Natural killer (NK) cells
destroy virus-infected body
cells & abnormal cells
The Inflammatory Response
• 1- Tissue injury; release of chemical signals~
• histamine (basophils/mast cells): causes Step 2...
• prostaglandins: increases blood flow & vessel permeability
• 2/3- Dilation and increased permeability of capillary~
• chemokines: secreted by blood vessel endothelial cells
mediates phagocytotic migration of WBCs
• 4- Phagocytosis of pathogens~
• fever & pyrogens: leukocyte-released molecules increase body
temperature
Specific Immunity
• Lymphocyctes
•pluripotent stem cells...
• B Cells (bone marrow)
• T Cells (thymus)
• Antigen: a foreign molecule
that elicits a response by
lymphocytes (virus, bacteria,
fungus, protozoa, parasitic
worms)
• Antibodies: antigen-binding
immunoglobulin, produced by
B cells
• Antigen receptors:
plasma membrane receptors
on b and T cells
Self/Nonself Recognition
•
•
•
Self-tolerance: capacity to distinguish self from non-self
Autoimmune diseases: failure of self-tolerance; multiple sclerosis, lupus,
rheumatoid arthritis, insulin-dependent diabetes mellitus
Major Histocompatability Complex (MHC): body cell surface antigens coded by a
family of genes
– Class I MHC molecules: found on all nucleated cells
– Class II MHC molecules: found on macrophages, B cells, and activated T cells
•
•
•
Antigen presentation: process by which an MHC molecule “presents’ an
intracellular protein to an antigen receptor on a nearby T cell
Cytotoxic T cells (TC): bind to protein fragments displayed on class I MHC
molecules
Helper T cells (TH): bind to proteins displayed by class II MHC molecules
Clonal selection
• Effector cells: short-lived cells that combat the antigen
• Memory cells: long-lived cells that bear receptors for the antigen
• Clonal selection: antigen-driven cloning of lymphocytes
Types of immune responses
• Humoral immunity (outside cell)
– B cell activation
– Production of antibodies
– Defend against bacteria, toxins, and viruses free in
the lymph and blood plasma
• Cell-mediated immunity (inside)
– T cell activation
– Binds to and/or lyses cells
– Defend against cells infected with bacteria, viruses,
fungi, protozoa, and parasites; nonself interaction
Helper T lymphocytes
• Function in both humoral & cell-mediated immunity
– Stimulated by antigen presenting cells (APCs)
– T cell surface protein CD4 enhances activation
– Cytokines secreted (stimulate other lymphocytes):
a) interleukin-2 (IL-2): activates B cells and cytotoxic T cells
b) interleukin-1 (IL-1): activates helper T cell to produce IL-2
Humoral response: B cells
• Stimulated by T-dependent
antigens (help from TH cells)
– Macrophage (APCs) with class II
MHC proteins
– Helper T cell (CD4 protein)
– Activated T cell secretes IL-2
(cytokines) that activate B cell
• B cell differentiates into
memory and plasma cells
(antibodies)
Antibody Structure & Function
• Epitope: region on antigen surface recognized by
antibodies
• 2 heavy chains and 2 light chains joined by disulfide
bridges
• Antigen-binding site (variable region)
5 classes of Immunoglobins
•
•
•
•
•
IgM: 1st to circulate; indicates
infection; too large to cross placenta
IgG: most abundant; crosses walls of
blood vessels and placenta; protects
against bacteria, viruses, & toxins;
activates complement
IgA: produced by cells in mucous
membranes; prevent attachment of
viruses/bacteria to epithelial surfaces;
also found in saliva, tears, and
perspiration
IgD: do not activate complement and
cannot cross placenta; found on
surfaces of B cells; probably help
differentiation of B cells into plasma and
memory cells
IgE: very large; small quantity;
releases histamines-allergic reaction
Antibody-mediated Antigen Disposal
1) Neutralization (opsonization): antibody binds to and blocks
antigen activity
2) Agglutination: antigen clumping
3) Precipitation: cross-linking of soluble antigens
4) Complement fixation: activation of 20 serum proteins, through
cascading action, lyse viruses and pathogenic cells
Cell-mediated: cytotoxic T cells
• Destroy cells infected by intracellular pathogens and cancer
cells
– Class I MHC molecules (nucleated body cells) expose foreign proteins
– Activity enhanced by CD8 surface protein present on most cytotoxic T
cells (similar to CD4 and class II MHC)
• TC cell releases perforin, a protein that forms pores in the target cell
membrane; cell lysis and pathogen exposure to circulating antibodies
Induction of Immune Responses
• Primary immune response: lymphocyte proliferation and
differentiation the 1st time the body is exposed to an antigen
• Plasma cells: antibody-producing effector B-cells
• Secondary immune response: immune response if the
individual is exposed to the same antigen at some later time~
Immunological memory
Immunity in Health & Disease
• Active immunity: long term/
– natural: conferred immunity by
recovering from disease
– artificial: immunization and vaccination;
produces a primary response
• Passive immunity: short term transfer
of immunity from one individual to
another
– natural: mother to fetus; breast milk
– artificial: rabies antibodies
• ABO blood groups (antigen presence)
• Rh factor (blood cell antigen); Rhmother vs. an Rh+ fetus (inherited from
father)
Abnormal immune function
• Allergies
– hypersensitive responses to environmental antigens (allergens); mast
cells release histamine causes dilation and blood vessel permeability,
epinephrine
– Antihistamines can relieve symptoms
anaphylactic shock: life threatening reaction to injected or ingested
allergens.
• Autoimmune disease:
– The system turns against the body’s own molecules
– Examples: multiple sclerosis, lupus, rheumatoid arthritis, insulin-dependent
diabetes mellitus
• Immunodeficiency disease:
–
Immune components are lacking, and infections recur
• Ex: SCIDS (bubble-boy); A.I.D.S.
Chapter 44
• Regulating the
Internal Environment
Homeostasis:
regulation of internal environment
• Thermoregulation
internal temperature
• Osmoregulation
solute and water balance
• Excretion
nitrogen containing waste
Regulation of body temperature
• Thermoregulation
•
4 physical processes:
– Conduction: transfer of heat
between molecules of body and
environment
– Convection: transfer of heat as
water/air move across body
surface
– Radiation: transfer of heat
produced by organisms
– Evaporation: loss of heat from
liquid to gas
• Sources of body heat:
– Ectothermic: determined by
environment
– Endothermic: high metabolic rate
generates high body heat
Regulation during environmental
extremes
• Torpor: physiological state
of low activity; decrease in
metabolic rate
– 1- Hibernation: long term
or winter torpor (winter cold
and food scarcity); bears,
squirrels
– 2- Estivation: short term or
summer torpor (high
temperatures and water
scarcity); fish, amphibians,
reptiles
• Both often triggered by
length of daylight
Water balance and waste disposal
• Osmoregulation: management of the body’s
water content and solute composition
• Nitrogenous wastes: breakdown products of
proteins and nucleic acids; ammonia-very toxic
• Ammonia: most aquatic animals, many fish
• Urea: mammals, most amphibians, sharks, bony
fish (in liver; combo of NH3 and CO2)
• Uric acid: birds, insects, many reptiles, land
snails
Osmoregulators
• Osmoconformer: no active adjustment of internal
osmolarity (marine animals); isoosmotic to environment
• Osmoregulator: adjust internal osmolarity (freshwater,
marine, terrestrial)
• Freshwater fishes (hyperosmotic)- gains water, loses;
excretes large amounts of urine salt vs. marine fishes
(hypoosmotic)- loses water, gains salt; drinks large amount
of saltwater
hyperosmotic
Because I’m a marine fish, I’m
hypoosmotic (less solute in me than
the water) so I lose lots of water and
therefore need to excrete small
amounts of urine.
Because I’m a freshwater fish,
I’m hyperosmotic (more solute
in me than the water), so I take
in a lot of water and therefore
excrete a lot of water!
hypoosmotic
Excretory Systems
•
Production of urine by 2 steps:
– Filtration (nonselective)
– Reabsorption (secretion of solutes)
•
•
•
•
Protonephridia: flatworms (“flame-bulb” systems)
Metanephridia: annelids (ciliated funnel system)
Malpighian tubules: insects (tubes in digestive tract)
Kidneys: vertebrates
Excretory Parts
•
•
•
•
•
•
•
•
•
Renal artery/vein: kidney blood flow
Ureter: urine excretory duct
Urinary bladder: urine storage
Urethra: urine elimination tube
Renal cortex (outer region)
Renal medulla (inner region)
Nephron: functional unit of kidney
Cortical nephrons (cortex; 80%)
Juxtamedullary nephrons (medulla; 20%)
http://www.physiology.ubc.ca/undergrad_files/transport.swf
http://www.sumanasinc.com/webcontent/an
imations/content/kidney.html
Nephron Structure
• Afferent arteriole: supplies blood to nephron from
renal artery
• Efferent arteriole: blood from glomerulus
• Glomerulus: ball of capillaries
• Bowman’s capsule: surrounds glomerulus
• Proximal tubule: secretion & reabsorption
• Peritubular capillaries: from efferent arteriole;
surround proximal & distal tubules
• Loop of Henle: water & salt balance
• Distal tubule: secretion & reabsorption
• Collecting duct: carries filtrate to renal pelvis
http://www.lakemichigancollege.edu/liberal/bio/anat/urin.html
http://www.biologymad.com/resources/kidney.swf
http://www.getbodysmart.com/ap/urinarysystem/kidney/externalanatomy/tutorial.html
secretion and reabsorption
secretion and
reabsorption
reabsorbs water, salt,
some urea
•Loop of Henle: reabsorption of water and salt
Kidney regulation: hormones
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter20/animation__hormonal_communication.html
• Antidiuretic hormone (ADH) ~ secretion increases
permeability of distal tubules and collecting ducts to water
(H2O back to body); inhibited by alcohol and coffee
• Juxtaglomerular apparatus (JGA) ~ reduced salt intake-->enzyme renin initiates conversion of angiotension (plasma
protein) to angiotension II (peptide); increase blood
pressure and blood volume by constricting capillaries
• Angiotension II also stimulates adrenal glands to secrete
aldosterone; acts on distal tubules to reabsorb more sodium,
thereby increasing blood pressure (renin-angiotensionaldosterone system; RAAS)
• Atrial natriuretic factor (ANF) ~ walls of atria; inhibits
release of renin, salt reabsorption, and aldosterone release
http://www.health.bcu.ac.uk/physiology/renalsystem.htm#top
http://www.wisc-online.com/objects/AP2204/AP2204.swf
Chapter 45 Chemical Signals in
Animals
• The endocrine system
and the nervous
system are
structurally,
chemically, and
functionally related.
Regulatory systems
• Hormone: chemical signal secreted into body fluids
(blood) communicating regulatory messages
• Target cells: body cells that respond to hormones
• Endocrine system/glands: hormone secreting
system/glands (ductless); exocrine glands secrete
chemicals (sweat, mucus, enzymes) through ducts
• Neurosecretory cells: specialized nerve cells that
secrete hormones
• Feedback mechanisms: negative and positive
(feature that is also common in the nervous system)
Mode of Action: Chemical Signaling
• 1- Plasma membrane reception
• signal-transduction pathways (neurotransmitters, growth factors,
most hormones)
• 2- Cell nucleus reception
• steroid hormones, thyroid hormones, some local regulators
Signal Transduction Pathway
• Signaltransduction
pathways allow
for small
amounts of a
hormone to
have a large
effect.
Local regulators: cells adjacent to or near point
of secretion
• Growth factors: proteins for cell proliferation
• Nitric oxide (NO): (highly reactive& potentially
toxic) neurotransmitter; cell destruction
(bacteria, cancer cells); vessel dilation
• Prostaglandins: modified fatty acids secreted
by placenta (induce labor) and immune system
(fever, pain); also found in semen (contract
smooth muscle in uterus helping convey sperm
to egg.
Vertebrate Endocrine System Page 961
• Tropic hormones: a hormone that has another
endocrine gland as a target
• Hypothalamus:causes release of hormones produced
by posterior pituitary and regulates anterior pit.
• Pituitary gland
• Pineal gland
• Thyroid gland
• Parathyroid glands
• Thymus
• Adrenal glands
• Pancreas
• Gonads (ovary, testis)
•Melatonin: biological rhythms
•Calcitonin: lowers blood calcium
•Thyroxine: metabolic processes
•(PTH): raises blood calcium
T cells
Islets of Langerhans (clusters of endocrine
cells that secrete hormones)
Alpha cells: glucagon:
raises
blood
glucose levels
Beta cells: insulin : lowers blood
glucose levels
Type I diabetes mellitus (insulin-dependent; autoimmune disorder, attack
mounted on pancreas cells)
Type II diabetes mellitus (non-insulin-dependent; reduced responsiveness in
insulin targets)
Adrenal medulla (catecholaminessynthesisized from AA tyrosine):
•epinephrine & norepinephrine: increase
basal metabolic rate (blood glucose and
pressure)
Adrenal cortex (corticosteroids):
•glucocorticoids (cortisol): raise blood
glucose •mineralocorticoids
(aldosterone): reabsorption of Na+ and
K+
The hypothalamus & pituitary
• Releasing and inhibiting hormones
• Anterior pituitary:
– Growth (GH)~bones
• √gigantism/dwarfism
• √acromegaly
– Prolactin (PRL)~mammary glands; milk production
– Follicle-stimulating (FSH) &
– Luteinizing (LH): ovaries/testes
– Thyroid-stimulating (TSH): thyroid
– Adrenocorticotropic (ACTH): adrenal cortex
– Melanocyte-stimulating (pigment cells)(MSH)
– Endorphins: natural ‘opiates’; brain pain receptors
The pituitary
• The posterior pituitary:
• Oxytocin:
uterine and mammary gland
cell contraction
• Antidiuretic (ADH):
retention of water by kidneys,
increase permiability of epithelium
to water, amplifies water
reabsorption (dark yellow, stinky
urine)
The pineal, thyroid, & parathyroid
The pancreas
The adrenal glands
The gonads
• Steroid hormones: precursor is cholesterol
• androgens (testosterone): sperm formation; male secondary sex
characteristics, gonadotropin
• Estrogens (estradiol):uterine lining growth; female secondary sex
characteristics; gonadotropin
• Progestins (progesterone)~uterine lining growth
Chapter 46 Animal Reproduction
•
•
•
•
•
Asexual (one parent)
fission (parent separation)
budding (corals)
gemmules (porifera)
fragmentation &
regeneration (inverts)
• Sexual (fusion of haploid
gametes)
•
•
•
•
gametes (sex cells)
zygote (fertilized egg)
ovum (unfertilized egg)
spermatozoon (male
gamete)
Reproductive cycles
• Parthenogenesis
unfertilized
egg development; haploid, sterile
adults (honeybees)
• Hermaphroditism
both male
& female reproductive systems;
sessile & burrowing organisms
(earthworms)
• Sequential
hermaphroditism reversal of
gender during lifetime
•protogynous (female 1st)
•protandrous (male 1st)
Mechanisms of sexual reproduction
• Fertilization
(union of
sperm and egg)
• external
• internal
• Pheromones
chemical signals that influence the
behavior of others (mate
attractants)
Mammalian reproduction
• The Human Male
•
•
•
•
Testes: male gonads
Leydig cells: hormone production
Scrotum:outside body temp.
Seminiferous tubules: where
sperm is made
• Epididymis: where it matures
• Vas deferens: (tubing) sperm
propulsion
• Penis/urethra (exit tube)
Add fluids
– Seminal vesicles: semen
– Prostate gland:anticoagulant;
nutrients
– Bulbourethral glands: acid
neutralizer
Spermatogenesis
• Puberty until death!
• Seminiferous tubules~ location
• Primordial germ cell (2N)~
differentiate into….
• Spermatogonium (2N)~ sperm
precursor
•
•
•
•
•
•
•
Repeated mitosis into….
Primary spermatocyte (2N)
1st meiotic division
Secondary spermatocyte (1N)
2nd meiotic division
Spermatids (1N)~Sertoli cells….
Sperm cells (1N)
The Human Female
•where fertilization happens
•female gonads
pituitary1) FSH: follicle
enlargement
3)LH: follicle ruptures,
releases egg
egg capsule: secrets
2)estrogen: begin build
up, LH
Secretes 4)progesterone:
•womb/lining
Continue build up of uterine
lining
Egg not fertilized,
progesterone decreases,
lining shed, FSH increases
•sperm receptacle
Oogenesis
•
•
•
•
•
•
•
•
•
•
As embryo until menopause...
Ovaries
Primordial germ cells (2N)
Oogonium (2N)
Primary oocyte (2N)
Between birth & puberty;
prophase I of meiosis
Puberty; FSH; completes
meiosis I
Secondary oocyte (1N); polar
body
Meiosis II; stimulated by
fertilization
Ovum (1N); 2nd polar body
The female pattern
• Estrous cycles/estrus
(many mammals)
• Menstrual cycle (humans and
many other primates):
• Ovarian/Menstrual
cycles~ •follicular
phase~follicle growth
•ovulation~ oocyte release
•luteal phase~ hormone
release
Embryonic & fetal development
•
•
•
•
•
Gestation~ pregnancy
1st trimester:
organogenesis
fetus (week 8; all adult features)
HCG hormone
(menstruation override; pregnancy
test detection)
• Parturition~birth
• Labor~uterine contractions
• Lactation~prolactin &
oxytocin
Modern technologies
Chapter 47
Animal Development
A Body-Building Plan for
Animals
• It is difficult to imagine that each of us
began life as a single cell, a zygote
• A human embryo at about 6–8 weeks after
conception shows development of
distinctive features
LE 47-1
1 mm
Minutes
Seconds
LE 47-5
1
Binding of sperm to egg
2
3
4
Acrosomal reaction: plasma membrane
depolarization (fast block to polyspermy)
6
8
10
Increased intracellular calcium level
20
Cortical reaction begins (slow block to polyspermy)
30
40
50
1
Formation of fertilization envelope complete
2
Increased intracellular pH
3
4
5
Increased protein synthesis
10
20
30
40
60
90
Fusion of egg and sperm nuclei complete
Onset of DNA synthesis
First cell division
Cleavage
• Fertilization is followed by cleavage, a
period of rapid cell division without growth
• Cleavage partitions the cytoplasm of one
large cell into many smaller cells called
blastomeres
LE 47-7
Fertilized egg
Four-cell stage
Morula
Blastula
• The eggs and zygotes of many animals,
except mammals, have a definite polarity
• The polarity is defined by distribution of yolk,
with the vegetal pole having the most yolk
• The development of body axes in frogs is
influenced by the egg’s polarity
LE 47-8
Point of
sperm entry
Animal
hemisphere
Vegetal
hemisphere
Point of
sperm
entry
Anterior
Right
Ventral
Gray
crescent
Vegetal pole
Future
dorsal
side of
tadpole
First
cleavage
Dorsal
Left
Posterior
Body axes
Animal pole
Establishing the axes
• Cleavage planes usually follow a pattern
that is relative to the zygote’s animal and
vegetal poles
LE 47-9
Zygote
0.25 mm
2-cell
stage
forming
4-cell
stage
forming
Eight-cell stage (viewed
from the animal pole)
8-cell
stage
0.25 mm
Animal pole
Blastula
(cross
section)
Blastocoel
Vegetal pole
Blastula (at least 128 cells)
• Meroblastic cleavage, incomplete division
of the egg, occurs in species with yolk-rich
eggs, such as reptiles and birds
LE 47-10
Fertilized egg
Disk of
cytoplasm
Zygote
Four-cell stage
Blastoderm
Cutaway view of
the blastoderm
Blastocoel
BLASTODERM
YOLK MASS
Epiblast
Hypoblast
LE 47-17
Amnion
Allantois
Embryo
Amniotic
cavity
with
amniotic
fluid
Albumen
Shell
Yolk
(nutrients)
Chorion
Yolk sac
• Holoblastic cleavage, complete division of
the egg, occurs in species whose eggs
have little or moderate amounts of yolk,
such as sea urchins and frogs
Gastrulation
• Gastrulation rearranges the cells of a
blastula into a three-layered embryo,
called a gastrula, which has a primitive gut
LE 47-15
Eye
Neural tube
Notochord
Forebrain
Somite
Heart
Coelom
Archenteron
Endoderm
Mesoderm
Lateral fold
Blood
vessels
Ectoderm
Somites
Yolk stalk
YOLK
Yolk sac
Form extraembryonic
membranes
Early organogenesis
Neural tube
Late organogenesis
Developmental Adaptations of
Amniotes
• Embryos of birds, other reptiles, and
mammals develop in a fluid-filled sac in a
shell or the uterus
• Organisms with these adaptations are called
amniotes
• In these organisms, the three germ layers
also give rise to the four membranes that
surround the embryo