Chapter 40 Lecture 12 Physiology and Homeostasis Dr. Alan McElligott Heat Limits Performance

Physiology & Homeostasis Aims: To introduce the organisation of animal bodies To introduce homeostasis To be able to define cells, tissues, organs and organ systems. To be able to link the structure of the four tissues with function

Physiology & Homeostasis Aims: To introduce the organisation of animal bodies To introduce homeostasis To be able to define cells, tissues, organs and organ systems. To be able to link the structure of the four tissues with function These lecture aims form part of the knowledge required for learning outcome 1: Describe the structure, diversity and reproductions of selected plants and animal groups (LOC1).

Essential reading page Physiology & Homeostasis 40.1 Why Must Animals Regulate Their Internal Environments?

40.1 Why Must Animals Regulate Their Internal Environment? A stable internal environment of extracellular fluid makes complex multicellular animals possible. Cells are specialized for maintaining parts of the internal environment.

40.1 Why Must Animals Regulate Their Internal Environment? External functions: transport of nutrients and waste and maintenance of ion concentrations. Internal functions: circulation, energy storage, movement, and information processing.

40.1 Why Must Animals Regulate Their Internal Environment? 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.

Figure 40.1 Maintaining Internal Stability

40.1 Why Must Animals Regulate Their Internal Environment? 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

40.1 Why Must Animals Regulate Their Internal Environment? Effectors of systems effect changes in the internal environment. Effectors are controlled systems because they are controlled by regulatory systems.

40.1 Why Must Animals Regulate Their Internal Environment? Regulatory systems: Obtain, integrate, and process information Issue commands to controlled systems Contain sensors to provide feedback information that is compared to the set point

Figure 40.2 Control, Regulation, and Feedback

40.1 Why Must Animals Regulate Their Internal Environment? Sensory information in regulatory systems includes: Negative feedback Positive feedback Feedforward information

40.1 Why Must Animals Regulate Their Internal Environment? Negative feedback: Causes effectors to reverse the influence that creates an error signal Returns a variable to its set point Positive feedback: Amplifies a response Increases deviation from a set point Feedforward information anticipates internal changes and changes the set point.

40.1 Why Must Animals Regulate Their Internal Environment? Physiological systems are made up of organs that serve specific functions. Organs are made up of tissues, which are then made up of cells.

40.1 Why Must Animals Regulate Their Internal Environment? Four types of tissue: Epithelial Connective Muscle Nervous

40.1 Why Must Animals Regulate Their Internal Environment? Epithelial tissues are sheets of tightly connected epithelial cells. The tissues form skin and line hollow organs.

40.1 Why Must Animals Regulate Their Internal Environment? Some epithelial cells can: Secrete substances, like hormones Move substances with cilia Act as chemical receptors Create boundaries Control filtration and transport

Figure 40.3 Epithelial Tissue

40.1 Why Must Animals Regulate Their Internal Environment? Muscle tissues consist of elongated cells that generate force and cause movement. Three types of muscle tissues: Skeletal Cardiac Smooth

40.1 Why Must Animals Regulate Their Internal Environment? Skeletal: responsible for locomotion and other body movements (e.g., breathing, shivering). 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 (e.g., gut, blood vessels).

Figure 40.4 Filaments in Skeletal Muscle Cells

Muscle Cells Cardiac muscle Smooth muscle

40.1 Why Must Animals Regulate Their Internal Environment? Connective tissues are dispersed cells in an extracellular matrix that they secrete. The matrix contains protein fibres: 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)

40.1 Why Must Animals Regulate Their Internal Environments? Connective tissues: Cartilage provides structural support and is flexible: has chondrocytes; cells that secrete the extracellular matrix. Bone: provides support and is hardened by calcium phosphate deposition in the matrix.

Cartilage Bone

40.1 Why Must Animals 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. Adipose tissue (fat)

40.1 Why Must Animals 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.

Figure 40.6 Nervous Tissue Includes Neurons and Glia

40.1 Why Must Animals Regulate Their Internal Environments? Organs consist of multiple tissues. An organ system is a group of organs that function together.

40.1 Why Must Animals Regulate Their Internal Environments? Example: The stomach wall is arranged in layers: Epithelial cells Connective tissue Smooth muscle Neurons Connective tissue

Figure 40.7 Tissues Form Organs

Physiology & Homeostasis Check out 40.1 RECAP, page CHAPTER SUMMARY, page 871 Self Quiz page 871: Chapter 40, question 1 For Discussion page 872: Chapter 40, questions 1-2

Key terms: adipose tissue, axons, blood, blood plasma, cardiac, cartilage, cell, chemoreceptor, cilium (pl. cilia), collagen, connective, effector, endocrine, epithelial, feedback, Glial cell, homeostasis, loose connective tissue, matrix, metabolism, muscle, nerve, nervous, organ, organ system, reticular connective tissue, sensor, skeletal, smooth, tissue Physiology & Homeostasis