Chapter 40
Homeostasis—internal environment is maintained within normal limits, cells maintain a constant
environment
Controlled by the nervous system (faster) and endocrine system (slower)
Conformers—needs less energy, maintain same composition as environment
Regulators—requires more energy, works to maintain body different than environment (us)
Set point—normal value for controlled variable
Sensor—monitors particular variable
Integrator—compares signals from the senor to set point
Effector—compensates for deviations between actual value and set point
Tissue—group of cells, tissues bind together to form organs, organs come together to form organ
systems
4 different tissues
1.
Muscle tissue (most abundant)
a.
Produces body movement, shortens and contracts
b.
Functional unit is sarcomere
2.
Nervous tissue
a.
Network of neurons, initiates and conducts electrical signals
b.
Functional unit is neuron (stimulates muscle, glands, other neurons)
3.
Epithelial tissue
a.
Sheets of packed cells, protects structures, asymmetrical, secretes, absorbs
b.
Classified by stratification or shape
4.
Connective tissue (most diverse)
a.
forms extracellular matrix
i.
Blood, bone, cartilage, ligaments, and tendons
3 types of muscle tissue
1.
Skeletal muscle
a.
Linked to bones, striated, multinucleated, voluntary control
2.
Smooth muscle
a.
Surrounds tubes, involuntary control, not striated, single nuclei
3.
Cardiac muscle
a.
Only in heart, involuntary control, striated, can have more than one nuclei
Organs—need more than one type of tissue
Intracellular fluid—cytoplasm inside the cell
Extracellular fluid—interstitial fluid outside the cell and plasma
Interstitial fluid—in-between cells, cytoplasm
Prevents homeostatic responses from overcompensating
Positive feedback loop—may accelerate a process, less common
Neurotransmitters—small signaling molecules that are synthesized and stored in neurons, alters the
activity of that cell
Hormones—chemical messengers produced by the endocrine system of animals, long distance
Osmotic homeostasis—regulating water within the body
**know glucose homeostasis**
Set point—how much glucose is circling in the body
Integrator—compares signals from sensor to set point (hypothalamus)
Sensors in blood vessels to detect blood sugar levels
Effector—pancreas in glucose regulation
Pancreas releases insulin when glucose levels are high
Insulin acts on tissue cells glucose goes into the cells and allows blood sugar to decrease
Insulin turns glucose into glycogen in the liver to store it because you have too much glucose in the
blood
Glucagon is released when blood sugar is low
Glucagon acts on the liver and produces glucose
Pancreas releases glucagon and insulin (hormones)
Chapter 41
Nervous system—coordinated circuits of cells that sense internal and environmental changes and
transmit signals that enable you to respond in an appropriate way
Central nervous system—brain and spinal cord
