Tissues, Organ Systems, and Homeostasis

1
Tissues, Organ Systems, and Homeostasis

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 33

2
Review/Recall

• Cells engage in metabolic activities and are the
  basic units of structure and function in living
  things.
• The cells of most animals interact at three
  levels of organization tissues, organs and organ
  systems (cell hierarchy)
• Four types of tissues are seen in most animals
  epithelial, connective, muscle and nervous tissues

3
Cell Hierarchy
Fig. 4.25, p. 73
4
Review/Recall

• The bodys internal environment consists of
  fluids outside of cells and the cells themselves.
• Stability in the internal environment is
  maintained by cells, tissues, organs and organ
  systems.
• Homeostasis is the stable environment maintained
  for normal operation of an organism.

5
Review/Recall

• Active and passive transport play key roles in
  maintaining homeostasis.
• Concentration
• Concentration gradient
• Diffusion and osmosis
• Facilitated diffusion
• Active transport

6
oligosaccharide groups
phospholipid
cholesteral
EXTRACELLULAR ENVIRONMENT
(cytoskeletal proteins beneath the plasma
membrane)
RECEPTOR PROTEIN
RECOGNITION PROTEIN
LIPID LAYER
ADHESION PROTEIN
(area of enlargement)
TRANSPORT PROTEINS
CYTOPLASM
Fig. 5.3, p. 81
7
Review/RecallCell-to-Cell Contacts

• Tight junctions
• Prevent leaks between cells
• Adhering junctions
• Cement cells together
• Gap junctions
• Help cells communicate
• Intercellular connections
• Connection of cytoplasm

8
free surface of a single epithelial cell
TIGHT JUNCTIONS
GAP JUNCTION
ADHERING JUNCTION
basement membrane
channel in a complex of proteins
intermediate filament
Fig. 33.3, p. 563
plaques
9
Organ Systems

• Integumentary
• Muscular
• Skeletal
• Nervous
• Endocrine
• Circulatory

• Lymphatic
• Respiratory
• Digestive
• Urinary
• Reproductive
• Immune

10
Organ Systems
Fig. 33.11a, p. 568
11
Organ Systems
Fig. 33.11b, p. 569
12
Homeostasis and Systems Control

• Our cells depend on extracellular fluid.
• Extracellular fluid
• Interstitial fluid
• Between cells
• Plasma
• Blood fluid (mostly water)
• Many parts of an organism work to maintain a
  stable fluid environment

13
Mechanisms of Homeostasis

• Sensory receptors
• Detect stimuli (changes in the environment)
• Integrators
• Direct impulses to the place where a response can
  be made
• Selects response
• Effectors
• Carry out response

14
Mechanisms of Homeostasis
STIMULUS (input into the system)
RECEPTOR (e.g., free nerve ending in the skin)
INTEGRATOR (such as the brain)
EFFECTOR (a muscle or a gland)
RESPONSE (systems output)
The response to the stimulus leads to change.
The change is fed back to the receptor. In
negative feedback, the response of the system
cancels or counteracts the effect of the original
stimulus.
Fig. 33.13, p. 570
15
Negative Feedback

• Situation in which a change in a certain
  direction provides information that causes a
  system to change less in that direction
• Tends to return conditions to the original state.
• Furnace with a thermostat
• Maintenance of body temperature

16
STIMULUS The husky is overactive on a hot, dry
day and its body surface temperature rises.
RECEPTORS in skin and elsewhere detect
the temperature change.
An INTEGRATOR (the hypothalamus, a brain
region) compares input from the receptors against
a set point.
Some EFFECTORS (pituitary gland and thyroid
gland) trigger widespread adjustments.
RESPONSE Temperature of circulating blood starts
decreasing
Many EFFECTORS carry out specific responses
Activity of the body in general slows
down (behavioral change).
The overall slowdown in activities results in
less metabolically generated heat.
Fig. 33.14, p. 571
17
Positive Feedback

• Situation in which a change in a certain
  direction provides information that causes a
  system to change more in that direction
• Childbirth
• Sexual intercourse

18
The Nervous System

• There are two vital command and control systems.
• Nervous system
• Endocrine system