40
• Homeostasis
• maintenance of stable
conditions in internal
environment
• Makes complex multicellular
animals possible
• Physiological systems are
controlled by nervous and
endocrine systems
• Regulation of internal
environment requires
information
• Types of information necessary for
physiological systems:
• Set point – reference point
• Desired temperature
• Feedback information –
what’s happening in system
• Too hot?
Too cold?
• Error signal – any difference
between set point and
feedback information
• There will be a response to
help get back to set point
http://web.lemoyne.edu/~hevern/psy340/graphics/negative.feedback.jpg
• Sensory information in regulatory systems includes:
• Negative feedback
•
•
•
Most common
Counteracts the influence that created the error signal
Examples are temperature control, blood pressure
• Positive feedback
• Not as common
• Amplifies a response, terminate rapidly
• Examples are responses that empty body cavities
• Feedforward information
• Change the set point for a short time
• Example is when your heart starts to beat fast when you are scared –
your body is getting ready for fight-and-flight response
www.mie.utoronto.ca/labs/lcdlab/biopic/fig
• Physiological systems are made up
of organs that serve specific
functions
• Organs are made up of
tissues, which are then
made up of cells
• 4 types of adult tissue
• Epithelial
• Connective
• Muscle
• Nervous
•Epithelial tissues
• Found:
• Skin, lining of intestines, line blood vessels and hollow organs
and tubules
• Functions:
•
•
Protection (skin, lining of organs)
•
Control filtration and transport (lining of kidney tubules, lining of blood
vessels)
Secretion and absorption (lining of glands - secrete hormones, lining of
intestines)
• Stratified squamous
epithelium on outer
surface of skin
(epidermis)
• Stratified because there
is much wear and tear
• Pseudostratified ciliated
columnar epithelium on
lining of trachea
• cilia helps move mucus
up and out of trachea
• Simple cuboidal epithelium lining kidney secretory
tubules
• Muscle tissues
• consist of elongated cells that generate force and cause movement
• Three types of muscle tissues:
• Skeletal
• Cardiac
• Smooth
*
http://www.nicerweb.com/doc/class/bio1151/Locked/media/ch40/40_05Muscle.jpg
• Connective Tissues
• Made up of cells and extracellular matrix
•
•
Main proteins in extracellular matrix are collagen and elastin
Lots of cells and little matrix = less rigid (i.e. blood); little cells
and more matrix = rigid (i.e bone)
• Types:
•
•
•
•
•
•
Blood
Adipose tissue
Loose connective tissue
Dense connective tissue
Cartilage
Bone
• Functions – structure and support
Loose (areolar)
connective tissue is found
just about everywhere in
the body, as it provides
support for structures
passing through it, such
as blood and lymph
vessels and nerves.
• Connective tissues:
• Cartilage
• provides structural support and is flexible
• Chondrocytes – cells that secrete the extracellular
matrix
Hyaline cartilage
www.personal.psu.edu/faculty/w/x/wxm15/On
line/Human%20Biology/tissues/Tissue_slide
• Bone
• provides support
• hardened by calcium phosphate deposition in matrix
www.personal.psu.edu/faculty/w/x/wxm15/Online/Human%20Biology/tissues/Tissue_slide
• Adipose tissue
• Forms and stores lipid droplets
• Serves as fuel reserve and as a cushion to protect
internal organs
• Layers of adipose tissue under skin help insulate
against heat loss
www.mhhe.com/biosci/ap/histology_mh
• Blood
• consists of cells in a very liquid extracellular matrix, the
blood plasma
• Plasma also contains many proteins
www.tigerpath.com/images/unit_08
• Nervous tissues
• 2 basic cell types:
• Neurons
• Encode information as
electrical impulses that
travel over axons to their
targets
• Chemical signals from
neuron stimulate
response in target cell,
via receptors
• Glia – provide support for
neurons
www.fbs.osaka-u.ac.jp/en/seminar/image
• Organs consist of multiple tissue types
• Example: Stomach wall is arranged in layers:
• Epithelial cells (inside)
• Connective tissue
• Smooth muscle
• Neurons throughout
• Connective tissue and epithelial (outside)
• Body temperature of some
http://patagonia.byu.edu/taxonomy/lizards/LiolaemusLarge.jpg
animals is coupled to
environmental temperature
• In winter, a fish will acclimatize
to colder water by expressing
different isozymes
• This allows its biochemical
reactions to happen at different
temperatures
• Isozymes that are optimized at
different temperatures can
catalyze the same metabolic
reaction more efficiently
http://www.scielo.br/img/revistas/bjb/v66n3/20f2.gif
• Thermal classification of animals can be based on source of heat
• Ectotherms – have external sources of heat
(relatively passive)
• Endotherms – regulate temperature by actively
producing heat metabolically or by actively losing
heat
• Heterotherms – can behave either as an ectotherm
or an endotherm, depending on situation
• Major differences between ectotherms and
endotherms:
• Resting metabolic rate
• Endotherms are higher than
ectotherms because they have to
maintain temp
• Total energy expenditure when
at rest
• Cells of endotherms are less
efficient at using energy than
ectotherms
• That’s why endotherms give off
more heat – heat is lost energy
• Response to changes in
environmental temperatures
• Cold – endotherm metabolic
rate increases, ectotherm
decreases
• Warm – endotherm decreases,
ectotherm increases
• Both endotherms and ectotherms may use behavioral
regulation to maintain body temperature
• Example: moving into sun, burrowing, seeking shade,
orienting body to sun
http://finebushpeople.co.za
• Blood flow to skin helps endotherms and ectotherms maintain body
temperature
• Increased blood flow to skin increases heat loss and
lowers body temperature
• flushed
• Constriction of blood vessels to skin results in less heat
loss
http://www.pg.com/science/skincare/Skin_tws_41/Skin_tws_41_02.jpg
• Fur on animals acts as insulation that
retains body heat
Jack rabbits (Lepus
sp.) shunt blood to
their ears to lose heat.
• When animals are active and
must lose excess heat, special
blood vessels carry heat to
hairless skin surfaces
http://openlearn.open.ac.uk/file.php/2815/S324_1_021i.jpg
•
Fish produce heat metabolically in muscles, but most heat is lost as blood travels over gills
• Cold fish
•
•
cold, oxygenated blood travels from gills to aorta and is distributed to organs and
muscles
Majority of fishes
• Hot fish
•
•
•
Countercurrent heat exchange
Cold, oxygenated blood travels to from smaller aorta to vessels under the skin, these
vessels are close to veins carrying warm blood from muscles to heart, heat disperses into
the cold blood
Larger, faster fish – tuna, sharks
• Endotherms respond to cold by
producing heat & reducing heat loss www.mykindasite.com/know/images/
• Mammals produce heat in two ways:
• Shivering – skeletal muscles contract and
release energy from ATP as heat
• Non-shivering
• occurs in adipose tissue called brown fat
• Protein thermogenin causes heat
release by uncoupling proton pumps
from ATP production, this makes
cellular respiration less successful
• High concentrations of mitochondria
• found in human infants and
hibernating animals (don’t need a lot
of energy but do need to maintain
temperature)
• Other adaptations to reducing
heat loss include:
• Increased thermal
Arctic fox (Alopex lagopus),
insulation with fur,
feathers, or fat
• Ability to decrease
blood flow to the skin
by constricting blood
vessels
• Use of countercurrent
heat exchange in blood
flow to appendages
• Rise in environmental
http://brooklyncameraclub.org/v-web/gallery/albums/album137
temperature results in increased
blood flow to skin to dissipate
heat
• If temperature exceeds upper
critical temperature,
overheating is possible.
• Evaporation of water through
sweating or panting increases
heat loss, but is an active
process that also generates
some heat
www.frontrange.ca/Magazine/Nepal/chitwan
• Regulatory system that
controls body temperature
depends on feedback and acts
as thermostat
• In vertebrates,
hypothalamus, is major
center of thermostat
• Temperature of
hypothalamus can be main
feedback to the thermostat
•
Cooling hypothalamus can cause body temperature to rise by:
• Constricting blood vessels to skin
• Increasing metabolic rate
•
•
•
Warming hypothalamus can lower body temperature by:
Dilating blood vessels to the skin
Sweating or panting
www.sur-la-toile.com
• Fever is rise in body temperature
caused by pyrogens
• Pyrogens cause rise in set point for
metabolic heat production
Aspirin inhibits prostaglandin
synthesis, lowers set point
and makes body more
comfortable. Moderate fevers
help body fight infections,
but extreme fevers can be
dangerous.
• Exogenous pyrogens come from
foreign substances – bacteria or
viruses
• Endogenous pyrogens are produced
by immune cells in response to
infection
http://web.lemoyne.edu/~hevern/psy340/graphics/Fever.jpg