BIOL 155 (L1)

Lecture 1

homeostasis

Maintain a stable internal environment by regulating variables around their set points.

mechanism for maintaining homeostasis & components

negative feedback; sensor → integrator → effector

sensor: detects change

integrator: compares change to set point and determines what needs to be done, sending the command to effector

effector: returns the change to set point

allostasis

anticipate future physiological demands by changing set point or behaviour before demand occurs.

behavioural allostasis

conscious performance of behaviours that anticipate future physiological demands (feed forward)

physiological allostasis

automatic physiological change in set point that anticipates future physiological demands (feed forward)

which ions are common in extracellular fluid?

Na+, Cl-, Ca2+

which ions are common in intracellular fluids (aka cytosol)?

K+, large anions

(SO1) name the 4 main types of tissue and give examples of where in the body each is likely to be found (or classify a tissue in an organ diagram based on these 4 types)

Epithelial tissue

• Covers exposed surfaces & provides physical protection

• Lines internal passages and chambers

• Forms secretory glands 

• Sensory reception

• Control permeability

• Where: skin, digestive tract, respiratory system, urinary & reproductive tract

Connective tissue

• Fills internal spaces

• Provides structural support

• Stores energy

• Where: dermis, bones, cartilage, forms tendons (attaching muscle to bone)

Muscle

• Contracts to produce movement

• Types:

  • Skeletal

    • Where: attached to bones via tendons, diaphragm, biceps

    • is under voluntary control

  • Cardiac

    • Where: exclusively in heart walls

  • Smooth muscle 

    • Where: walls of hollow visceral organs (e.g. stomach, intestines, bladder, uterus)

    • responsible for involuntary contractions that push materials through internal passageways 

Nervous

• Sends and receives information from electrical impulses 

• Where: brain, spinal cord, nerves, ganglia

(SO2) Describe or identify the shared features of epithelial tissue, including glands, such as cellular polarity, intercell junctions, and the basement membrane

•  Functions: provide physical protection, control permeability, provide sensation, produce specialized secretions

• Cellular polarity/polarization of epithelial cells:  apical surface & basolateral surface 

(SO3) Classify an example epithelial tissue based on key structural or physiological features (simple/stratified, squamous/cuboidal/columnar, leaky/tight)

• Leaky tight junctions - allow paracellular transport of water and solutes

• Tight tight junctions - do not allow paracellular transport

• Different types of epithelial tissue have different cellular and tissue structures specialized for different functions 

  • Simple epithelia: one layer

  • Stratified epithelia: multiple layers 

(SO4) Explain the basic definition of connective tissue and classify whether a tissue is a connective tissue or not based on a description. List the branches of connective tissue and examples, and functions of connective tissue.

• Connective tissue = presence of extracellular protein fibres and cells suspended within a ground substance (matrix), but can fulfill many functions

• Branches: 

  • Connective tissue proper

    • Loose 

      • Areolar tissue

      • Adipose tissue

      • Reticular tissue

    • Dense 

      • Dense regular

      • Dense irregular

      • Elastic

  • Fluid connective tissues

    • Blood

    • Lymph 

  • Supporting connective tissues

    • Cartilage

      • Hyaline cartilage

      • Elastic cartilage

      • Fibrocartilage

    • Bone 

• Functions: 

  • Establish a structural framework for the body

  • Transport fluids & dissolved materials

  • Protect delicate organs

  • Support, surround, and connect other types of tissue

  • Store energy 

  • Defend body from invasive microorganisms  

(SO5) Compare and contrast the structure and general functions of loose & dense connective tissue proper.

•  Connective tissue proper types → LOOSE & DENSE

  • Loose connective tissue

    • Lower density of extracellular fibers

    • Greater diversity of cell types 

      • Ex. areolar tissue 

  • Dense connective tissue

    • Higher density of extracellular fibres

    • Fewer diversity of cell types 

      • Ex. tendon 

• Connective tissue proper contains extracellular fibres (elastin fibres & collagen fibres)

  • Elastin fibers

    • Stretch & recoil

  • Collagen fibers

    • High tensile strength (strong but not stretchy)

(SO6) Describe the key features of tissue repair in proper connective tissue, and predict consequences for the organism if a component of the repair process is disrupted

• Epithelial & connective tissues illustrate different strategies for healing (repair & damage)

  • Tissue type: strategy for repair 

    • Epithelium: rapid proliferation

    • Connective: increased rates of secretion 

• General set of defence mechanisms are activated when a connective tissue is injured

  • Clot - forms out of blood tissue

  • Scar - forms when a dense web of collagen fibres is secreted at the injury site

what tissue type

epithelial

what tissue type

connective

what main tissue type AND specific type?

muscle tissue

skeletal muscle cross section

tissue type?

nervous tissue

What do muscle and nervous tissue contain and why? Provide specific examples.

• Contain highly specialized cells adapted for specific physiological roles

• Muscle tissue:  Contract + produce mechanical force

• Nervous tissue:  Send + receive information in form of electrochemical signals

Which tissue types are more diverse in their functions, specializations, and location?

Epithelial & connective tissues

What’s epithelium? What are the branches of epithelial tissue?

• Epithelium = sheet of connected epithelial cells to a basement membrane

• Epithelial tissue includes:

  • Epithalila 

  • Glands

    • Exocrine glands

    • Endocrine glands 

In what ways are the cells in an epithelium bound to each other? List the intercellular connections and basement membrane connections.

• Intercellular: 

  • Tight junctions

  • Adhesion belt

  • Gap junctions

  • Desmosomes 

• Basement membrane:

  • Basal lamina

  • Reticular lamina 

• A - T: Cilia on a ciliated epithelium are always found on the apical side of the cell

• B - T; A simple squamous epithelium will only have one layer of cells

• C - T: Simple cuboidal epithelium will contain cells that are approx. square-shaped

• D - T: Stratified epithelium are usually found in areas that experience more physical stress

• E - F: All cells in a stratified squamous epithelium are wider (lateral-lateral) than they are tall (apical-basal) 

List the different cell types can be found in loose connective tissues

• Wandering cells

  • move into/through tissue depending on physiological demands

• Fixed cells

  • remain permanently in the tissue 

• Mesenchymal cells

  • stem cells that can divide to replace damaged cells (fibroblasts)

• Fibroblasts

  • secrete the proteins of the extracellular matric 

• Fibrocytes

  • maintain the proteins of the extracellular matrix 

fix from iPad later

epithelial cells are ___________, but connective cells are _____________

connected by tight junctions

suspended in extracellular matrix