David Sadava H. Craig Heller Gordon H. Orians
William K. Purves David M. Hillis
Biologia.blu
C – Il corpo umano
Human Body Organization
Human Body Organization - Physiology, homeostasis, and temperature regulation
• Why must humans regulate their internal
environments?
• Abnormal tissue: what is cancer?
• How do humans alter their heat exchange
with the environment?
Human Body Organization - Why must humans regulate their internal environments?
Physiological systems are made up of
organs that serve specific functions.
Organs are made up of tissues, which are
then made up of cells.
Four types of tissue:
• Epithelial
• Connective
• Muscle
• Nervous
Human Body Organization - Why must humans regulate their internal environments?
Epithelial tissues are sheets of tightly
connected epithelial cells. The tissues form
skin and line hollow organs.
Some epithelial cells can:
• secrete substances, like hormones;
• move substances with cilia;
• act as chemical receptors;
• create boundaries;
• control filtration and transport.
Human Body Organization - Why must humans regulate their internal environments?
Epithelial tissues
Human Body Organization - Why must humans regulate their internal environments?
Muscle tissues consist of elongated cells
that generate force and cause movement.
Three types of muscle tissues:
• skeletal - responsible for locomotion and
other body movements;
• cardiac - makes up the heart and is
responsible for the heartbeat and blood flow;
• smooth - involved in movement and
generation of forces in internal organs.
Human Body Organization - Why must humans regulate their internal environments?
Filaments in skeletal muscle cells
Human Body Organization - Why must humans regulate their internal environments?
Connective tissues are dispersed cells in
an extracellular matrix that they secrete.
The matrix contains protein fibers:
• collagen - strong and resistant to stretch,
supports skin and connections between
muscles and bones;
• elastin - can be stretched and then recoils;
found in tissues that stretch (e.g., lungs,
arteries).
Human Body Organization - Why must humans regulate their internal environments?
Connective tissues:
• cartilage provides structural support
and is flexible, it has chondrocytes cells that secrete the extracellular
matrix;
• bone provides support and is
hardened by calcium phosphate
deposition in the matrix.
Human Body Organization - Why must humans regulate their internal environments?
More connective tissues:
• adipose tissue includes adipose cells
that form and store lipids;
• blood consists of cells in a very liquid
extracellular matrix, the blood
plasma.
Human Body Organization - Why must humans regulate their internal environments?
Cartilage
Human Body Organization - Why must humans regulate their internal environments?
Nervous tissues contain two basic
cell types: neurons and glia.
Neurons encode information as
electrical impulses that travel over
axons to their targets.
Chemical signals from the neuron
stimulate a response in the target
cell, via receptors.
Glia provide support for neurons.
Human Body Organization - Why must humans regulate their internal environments?
Nervous tissue includes neurons and glia
Human Body Organization - Why must humans regulate their internal environments?
Organs consist of multiple tissues.
An organ system is a group of organs that
function together. Fore example, the
stomach wall is arranged in layers:
• epithelial cells
• connective tissue
• smooth muscle
• neurons
• connective tissue
Human Body Organization - Why must humans regulate their internal environments?
Tissues form organs
Fig 40.7 whole figure except stomach
Human Body Organization - Why must humans regulate their internal environments?
A stable internal environment of
extracellular fluid makes complex
multicellular humans possible.
Cells are specialized for maintaining parts of
the internal environment.
External functions: transport of nutrients and
waste and maintenance of ion
concentrations.
Internal functions: circulation, energy storage,
movement, and information processing.
Human Body Organization - Why must humans regulate their internal environments?
Homeostasis is the maintenance of
stable conditions in an internal
environment.
Physiological systems are controlled
by the nervous and endocrine
systems.
Regulation of the internal environment
requires information.
Human Body Organization - Abnormal tissue: what is cancer?
Changes in the control of cell division lie
at the heart of cancer.
In the human genome, some genes act
to stimulate cell division—oncogenes;
others act to suppress cell division—
tumor suppressor genes.
Human Body Organization - Abnormal tissue: what is cancer?
Oncogenes are normally turned off.
Products of oncogenes are involved in
pathways by which growth factors
stimulate division.
Some control apoptosis. Activation of
these genes by mutation prevents
apoptosis.
Human Body Organization - Abnormal tissue: what is cancer?
Oncogene proteins enhance cell division
Human Body Organization - Abnormal tissue: what is cancer?
About 10 percent of cancers are
inherited.
Noninherited cancers are usually a form
that occur later in life—sporadic form.
Inherited cancers show up earlier in life,
and as multiple tumors.
A tumor suppressor gene that normally
acts as a brake must be inactivated.
Human Body Organization - Abnormal tissue: what is cancer?
Full inactivation requires two mutations—
both alleles must be turned off.
People with inherited cancer are born
with one mutant allele, and need only
one more mutational event for
inactivation of the tumor suppressor
gene.
Human Body Organization - Abnormal tissue: what is cancer?
Oncosuppressor-gene proteins inhibit cell division
Human Body Organization - Abnormal tissue: what is cancer?
Two hit model for cancer development
Human Body Organization - Why must humans regulate their internal environments?
Maintaining internal stability
Human Body Organization - Why must humans regulate their internal environments?
Types of information necessary for
physiological systems:
• set point - a reference point;
• feedback information - what is
happening in the system;
• error signal - any difference between
the set point and feedback information.
Human Body Organization - Why must humans regulate their internal environments?
Effectors of systems effect changes in
the internal environment.
Effectors are controlled systems
because they are controlled by
regulatory systems.
Human Body Organization - Why must humans regulate their internal environments?
Regulatory systems:
• obtain, integrate, and process
information;
• tissue commands to controlled
systems;
• contain sensors to provide feedback
information that is compared to the
set point.
uman Body Organization - Why must humans regulate their internal environments?
Control, regulation, and feedback
Human Body Organization - Why must humans regulate their internal environments?
Sensory information in regulatory
systems includes:
• negative feedback
• positive feedback
• feedforward information
Human Body Organization - Why must humans regulate their internal environments?
Negative feedback causes effectors to
reverse the influence that creates an error
signal; and returns a variable to its set
point.
Positive feedback amplifies a response;
and increases deviation from a set point .
Feedforward information anticipates
internal changes; and changes the set
point.
Human Body Organization – How do humans alter their heat exchange with the environments?
Animals exchange heat with the environment
Human Body Organization – How do humans alter their heat exchange with the environments?
Radiation: heat transfer via infrared
radiation.
Conduction: heat transfer by direct
contact.
Convection: heat transfer through a
surrounding medium.
Evaporation: heat transfer through
evaporation of water from a surface.