Lecture 12- Physiology and homeostasis Flashcards
Where do cells of multicellular organisms get their nutrients from?
Extracellular fluid that makes up the internal environment
What makes complex multicellular organisms possible?
Physiological systems that maintain a stable internal environment
How is it possible that animals can occupy habitats that would kill cells if exposed directly?
Stable internal environment protects cells from harsh environments or changes
What is homeostasis?
The maintenance of a stable conditions within a narrow range in the internal environment
What does homeostasis require to prevent cell damage or death?
Physiological regulation
By what systems are physiological systems controlled?
Nervous system
Endocrine system
What is required for regulation of the internal environment?
Information
What is a set point?
A reference point at which the system is set
‘The threshold sensitivity to the feedback stimulus’
What is feedback information?
Information relevant to the rate of a process that can be used by a control system to regulate that process at a particular level
What is an error signal?
A signal produced when the set point and feedback information do not match
What is feedforward information?
Information that can be used to alter the setpoint of a regulatory process. This suggests corrective action that needs to be taken.
What are effectors?
Any organ, cell, or organelle that alters the environment. These effect changes in the internal environment.
What are effectors controlled by?
Controlled systems
What do regulatory systems do?
Systems that obtain, process and integrate information then issue commands to control the system
Define regulatory system.
A system that uses feedback information to maintain a physiological function or parameter at an optimal level.
What do sensors do?
Provide feedback information that is compared to the internal set point
Define negative feedback.
Information relevant to the rate of a process that can be used by a control system to return the outcome of that process to an optimal level
What effect does negative feedback have on a physiological system?
Tends to return a variable of the internal environment to the set point from which it deviated.
What are the three types of sensory information in a regulatory system?
Negative feedback
Positive feedback
Feedforward information
What effect does positive feedback have on a physiological system?
It amplifies a response (increases deviation from a set point)
What affect does feedforward information have on a physiological system?
It anticipates internal changes and changes the set point
Give an example of regulatory systems that use positive feedback.
- Responses that empty body cavities- urination, defecation, sneezing, vomiting
- Sexual behavior which causes more stimulation
What are physiological systems made of?
Cells, tissues and organs.
What is a tissue? What are the 4 kinds of tissue?
An assemblage of cells
- Epithelial
- Connective
- Muscle
- Nervous
What is epithelial tissue?
Sheets of densely packed, tightly connected epithelial cells that cover inner and outer body surfaces and act as barriers and provide transport
Where is epithelial tissue found?
Skin
Lining surfaces of hollow organs in the body- such as the gut
What 5 roles do epithelial cells play in the body?
- Secretion of substances (hormones, milk, mucus, digestive enzymes, sweat)
- Movement of substances with cilia
- Receptor cells to provide information to the nervous system (smell and taste receptors)
- Create boundaries- inside and outside of the body, between body compartments, line blood vessels, ducts and tubules
- Control filtration and transport (molecules and ions that leave the blood, urine etc.)
What is muscle tissue?
Elongated cells that can contract to generate forces and cause movement
What tissue type is most abundant in the human body?
Muscle tissue
What are the three types of muscle tissue?
Skeletal
Cardiac
Smooth
What is skeletal muscles responsible for?
Locomotion, breathing, shivering
What type of control is skeletal muscle under?
Both conscious and unconscious control
What is cardiac muscle?
Makes up the heart, responsible for heart beat and pumping of blood.
What is smooth muscle responsible for?
Movement and generation of forces in many hollow internal organs such as the gut, bladder and blood vessels
What controls smooth and cardiac muscles?
These are unconscious- they are controlled by physiological regulatory systems.
What is connective tissue?
Dispersed populations of cells embedded in an extracellular matrix that they secrete. Composition and properties differ among connective tissue types
What does the extracellular matrix of connective tissue contain?
Protein fibers.
- Collagen
- Elastin
What percentage of total body protein does collagen make up?
25%
What properties of collagen make is a useful protein in the extracellular matrix of connective tissues?
Fibers are strong and resistant to stretch
This gives strength to the skin and connections between bones and muscles
What role does collagen play in organs?
The fibers provide a net-like framework for organs, giving them shape and structural strength
What are the properties of elastin?
It can be stretched several times its resting length and then recoil
Where is elastin commonly found?
In tissues that are regularly stretched such as walls of lungs and large arteries.
Name three types of connective tissues.
Cartilage, bone, adipose tissue
What is the structure of cartilage?
A network of collagen fibers is embedded in a flexible matrix consisting of a protein-carbohydrate complex along with a specific type of cell called a chondrocyte
What is the function of chondrocytes?
They secrete an extracellular matrix rich in collagen fibers and elastin fibers
What properties of cartilage makes it a good connective tissue?
It is resistant to compressive forces- lines the joints of vertebrates
It is flexible- it provides structural support for flexible structures (external ears, nose)
Describe the structure of bone.
Contains lots of collagen fibers
Hardened by deposition of the mineral calcium phosphate
What is adipose tissue?
A form of loose connective tissue that includes adipose cells, which form and store droplets of lipids
What is adipose tissue a source of? What are its other functions?
Stored energy
Cushion organs, barrier to heat loss.
What is blood?
A connective tissue that consists of cells dispersed in an extracellular matrix- blood plasma
What are the two types of cells found in nervous tissue?
Neurons, glial cells
What is the function of neurons?
Encode information as electrical impulses that travel along their axons
What is the function of glial cells?
Supporting functions for neurons
What is an organ system?
A group of organs that function together.
Organs consist of multiple tissues. Explain how the stomach is a good example.
The stomach wall is arranged in layers.
- Epithelial cells
- Connective tissue
- Smooth muscle
- Nervous tissue
