Animal Biology: Cell Development, Tissues, ECM & Junctions

Cell

smallest basic unit of life for an organism is responsible for structure, function, and processes.

Tissue

group of cells performing a similar function. Essential for an organism's survival. Ex: muscle, nerve, epithelial, connective

What is an organ?

A structure made up of different types of tissue working together to perform a specific function.

Give an example of an organ.

Lungs, heart, liver, etc.

What is an organ system?

A group of related organs working together to perform a specific function.

Give an example of an organ system.

Digestive system, circulatory system, nervous system, etc.

Cell signaling

communication between cells from target to response

Cell differentiation

Unspecialized cells become more specialized

Cell specialization

cells perfomr a specific function

Cell diversification

A single cell type, such as stem cells, forms a variety of specialized cells with distinct functions and structures. Ex: bone marrow cells, red blood cells.

Developmental stages

sequence of distinct phases through which an organism progresses as it grows and develops

What is embryonic development?

The early development of an organism from a fertilized egg.

What does embryonic development involve?

The formation of major body structures and organ systems.

Organogenesis

The formation and develoment of organs from embryonic tissues

What is morphogenesis?

The process by which tissues and organs acquire their characteristic shapes and structures.

What drives morphogenesis?

Coordinated changes in cell behavior.

Four basic types of tissue in the animal body

Epithelial, Nervous tissue, muscular, and connective (bone and tendon tissues)

Epithelial

Lines, body surfaces/cavities, internal organs. Functions in protection, absorption, secretion and sensation

Nervous tissue

coordinates, regulates, and controls body activities by transmitting electrochemical signals

Muscular

allows body movement and supports organs

Connective (bone and tendon tissue)

Provides structure, support, and protection throughout the body. Ex: bone, cartilage, fat, blood, lymphatic tissue.

Tissues are made of

several cell types

Each cell is connected to

the other cells or extracellular matrix, adjacent cells nearby

What type of tissue makes up the epithelium of the epidermis?

Epithelial tissue

What type of connective tissue is found in the dermis?

Loose connective tissue

What type of connective tissue is found in the dense layer of the dermis?

Dense connective tissue

What type of connective tissue is found in the hypodermis?

Fatty connective tissue

What is the extracellular matrix?

A network secreted by cells that surrounds and supports tissues.

What is an example of a tissue supported by the extracellular matrix?

Bones or wood.

What is one function of the extracellular matrix?

It provides a way to bind or connect cells.

What do junctions do in relation to cells?

They link cells together.

Extracellular matrix

network of proteins and polysaccharide filaments surrounding cells. Secreted by cells

Cancer cells at ECM

Mutations in cancer cells. Can compromise attachments to the ECM. Causing detachment and metastasis

Inappropriate attachment

negatively impacts cell divsion - marked for apoptosis

What is an example of a rigid extracellular matrix (ECM)?

Bones

What is an example of an elastic extracellular matrix (ECM)?

Tendons

What does the extracellular matrix (ECM) provide for cells?

An attachment point and platform

Connective tissue is always covered by an

epithelial tissue

Epithelial cells

connected to each other microtubule networks (provide support

Intercellular connections or junctions

Maintian the organization of the body and transmit signals between cells

Tight junctions

Seals neighboring cells together, preventing leakage of extracellular molecules between them.

Channel forming junctions (gap junctions)

Fomrs channels that allow molecules (ions) and metabolites to pass from cell to cell

Cell-matrix anchoring junctions

connects cells to basal lamina, providing support

Cell-cell anchoring junctions

Mechanically link cells to each other or to the extracellular matrix, providing structural stability to tissues.

Cadherins

Transmembrane proteins that mediate cell-cell anchoring junctions

Tissues maintain organization

1. Cell communication

2. selective cell - cell adhesion

3. cell memory

Three major processes contribute to development:

Cell diversification

Cell diversification and specialization

Cell movement

Cell diversification

cell replicates DNA then divides

Cell diversification and specialization

Form different cell types, perfom specific functions

All cells of an adult multicellualr organism have exactly the same

genome

The difference between them is

due to the different expressions of their genes

What determines the structure of the clone of cells that will develop from a fertilized egg?

The genome of the fertilized egg

What is the process of tissue maintenance and renewal?

The ongoing process of replacing and repairing cells in tissues

Cell signaling

plays a key role during development

same signal

can lead to different results, different receptors/interaction with different proteins in the cell

What affects the same cell type differently?

Different signals from different regulators.

What results from different signals received by the same cell type?

Cell diversification and specialization.

What is cell diversification by sequential induction?

One cell population influences another, leading to a response.

What is the role of one cell population influencing another in development?

It leads to a response which influences another cell population.

What developmental processes are influenced by cell diversification?

Neural tube formation and gastrulation.

Morphogen gradient

signaling molecules involved in the development and patterning of tissues and organs

two daughter cells

Different from each other results from different regulators in chance cell, cell diversification as a result

What regulates the development of different tissues and organs in an organism?

Gradients across the body plan

What type of genes control body plan and organization of an embryo?

Hox genes

Are Hox genes conserved across all animals?

Yes, from fruit flies to humans

In humans hox genes

hair color, number and shape of vertebra

Master regulators

Transplantation of morphogen-producing tissues changes developmental patterning

the same master regulator genes are present in different vertebrates and control limb development

but the specifics differ

What is morphogenesis?

The process of an organism developing from cells to tissue and organs.

What drives cell movement during morphogenesis?

Signaling from neighboring cells and movement along a gradient.

What is an example of morphogenesis in vertebrates?

The development of lungs.

Sizing and timing

size of organisms regulated, dependent on the number of cells, the volume of the extracellular matrix

All of our cells have to come from some sort of precursor

stem cells

What is a stem cell?

A type of cell that has the ability to divide to produce a copy of itself.

What is self-renewal in stem cells?

The ability of a stem cell to divide and produce a copy of itself.

What is potency in stem cells?

The ability of a stem cell to generate a daughter cell capable of maturing into different cell types.

What are multipotent stem cells capable of?

Forming numerous cell types

What is a committed stem cell?

A stem cell that makes one or very few types of cells

What is a progenitor cell?

A cell that can divide many times to become a specific cell type

Potency of a stem cell

totipotent, pluripotent, multipotent, and unipotent

Totipotent

can produce all cell types, including placenta and ambilical cord

Pluripotent

capable of producing all cells of that embryo but not placenta, ambilical cords

What does multipotent mean?

It refers to cells that can generate cell types restricted specifically for the tissue in which they reside.

What is an example of a multipotent cell?

Adult stem cell

Unipotent

generate only 1 cell type

What type of potency do adult stem cells mostly exhibit?

Multipotent

Do adult stem cells have an unlimited number of generations for self-renewal?

No, they have a finite number of generations.

What is the transition stage that daughter cells of adult stem cells go through?

Progenitor or transition-amplifying cell stage.

Are progenitor cells capable of unlimited self-renewal?

No, they are not capable of unlimited self-renewal.

What type of stem cells are responsible for blood regeneration?

Hematopoietic stem cells (HSCs)

What is the nature of hematopoietic stem cells (HSCs)?

They are multipotent stem cells that generate blood cells throughout an individual's life.

Where can hematopoietic stem cells (HSCs) be found in humans?

In human bone marrow.

What can HSCs do in terms of cell division?

They can divide to produce more HSCs.

What type of progenitor cells do lymphoid progenitor cells form?

Cells of the adaptive immune system.

What do myeloid progenitor cells give rise to?

Other blood cell precursors.

Blood regerneration

paitent unable to produce healthy blood cells

Porcedures that utilize blood forming (hematopoietic) stem cells to treat diseases

Bone marrow transplantation and cord blood transplantaion

Bone marrow transplantation

replaces unhealthy or destroted bone marrow stem cells with healthy ones

Cord blood transplantation

uses blood-forming stem cells from the placenta and umbilical cord cord after a baby is born

Stem cells another example skin

The epidermis of the skin is renewed from stem cells in its basal layer