1 Cells, Tissues, Organs and Systems

2 9.1 Introduction to Cells What are cells? Cells are the building blocks of life. Most animals and plants are made up of thousands of cells. (Human body made up of billions of cells) A cell is the smallest unit of life. Basically, there a two types of cells: - Plant Cells - Animal Cells

3 9.1 Introduction to Cells What are cells? Cells are alive. They do everything that living things do to stay alive. Cells have different parts to do all these functions.

4 9.2 Animal Cells

5 A more magnified look of an animal cell:

6 9.3 Plant Cells

7 A more magnified look of a plant cell:

8 9.4 Functions of different parts of a cell Protoplasm A cell consists of a mass of living matter called protoplasm. It includes the cell surface membrane, the nucleus and the cytoplasm, where numerous reactions take place.

9 9.4 Functions of different parts of a cell Nucleus The nucleus consists of a small spherical mass of denser protoplasm, the nucleoplasm, surrounded by a membrane called the nuclear envelope. It is embedded within the cytoplasm of the cell and controls the normal cell activities. Within the cells, there are a network of long thread- like structures called the chromatin, spherical structures called the nucleoli and a nuclear envelope.

Functions of different parts of a cell Nucleus The chromatin threads contain hereditary materials, i.e. materials inherited from the parents. The nucleolus plays a part in building up of proteins. A nuclear envelope separates the nuclear content from the surrounding cytoplasm.

Functions of different parts of a cell Nucleus Responsible for cell production Without nucleus, a mammal have as short lifespan and are unable to reproduce. Needed for the continued life of the cell, as well as for the repair of worn-out parts.

Functions of different parts of a cell Cytoplasm The part of the protoplasm surrounding the nucleus is called the cytoplasm. It usually forms the larger part of the cell and is the place where most life processes occur.

Functions of different parts of a cell Cytoplasm Embedded in the cytoplasm are some important organelles: mitochondria. Chloroplast (for plants only) Vacuole. Centrioles Ribosome (even smaller than Centrioles).

Functions of different parts of a cell Cytoplasm - Mitochondria Small spherical or rod-shaped Involved in the release of energy from food substances during cell respiration.

Functions of different parts of a cell Cytoplasm – Chloroplast (Plants only) Sites where plants make their food. Combine together carbon dioxide and water, and using the energy from sunlight to make sugar (glucose).

Functions of different parts of a cell Cytoplasm - Vacuoles A vacuole is a fluid-filled space enclosed by a membrane. Animal cells may have many small vacuoles but they are usually not permanent. Vacuoles may contain water and food substances. A plant cell usually has a large central vacuole which contains a liquid called cell sap. Cell sap contains dissolved substances such as sugar, mineral salts and amino acids. This large vacuole is enclosed by a membrane called the tonoplast.

Functions of different parts of a cell Cytoplasm – Cell membrane The cytoplasm is surrounded externally by a cell membrane (also known as plasma membrane). It is a partially permeable membrane which controls substances entering or leaving the cell. Similar membranes may also surround large spaces or vacuoles within the cell.

Functions of different parts of a cell Cytoplasm – Cell wall In a plant cell, there is a cell wall which encloses the whole cell. This cell wall is made of cellulose. It protects the cell from injury.

Functions of different parts of a cell Cytoplasm – Ribosome Smallest organelles in the protoplasm Produces protein from a set of genetic instructions. Floats freely in the cytoplasm.

Similarities between a plant and animal cells Similarities between a plant and animal cell: Both plants and animals cells have the following structures: Nucleus Cell membrane Cytoplasm

Differences between a plant and animal cells Differences between a plant and animal cell: StructureAnimal CellsPlant Cells VacuoleUsually has many small vacuoles containing air, water or food particles Has one large vacuole in the centre of the cell. This contains cell sap, which is water and dissolved substances such as sugar and salt.

Differences between a plant and animal cells Differences between a plant and animal cell: StructureAnimal Cells Plant Cells ChloroplastDoes not contain chloroplasts Contains tiny disc-like structures called chloroplasts. These contain the green pigment chlorophyll which traps the sunlight and allows the plant to photosynthesize (make food).

Differences between a plant and animal cells Differences between a plant and animal cell: StructureAnimal Cells Plant Cells Cell wallDoes not have a cell wall Has a rigid cellulose cell wall. This supports the plant cell and gives it its shape.

Differences between a plant and animal cells Differences between a plant and animal cell: StructureAnimal Cells Plant Cells CytoplasmMost of the cell is filled with cytoplasm Has a thin lining of cytoplasm

Level of Organisations Differences between cells, tissues, organs, etc: Many cells will make up a Tissue Many tissues working together will make an Organ Many organs working together will form an Organ system Many organ systems will form a Organism

Tissues of Plant What is a tissue? A tissue is a group of cells which have a common origin and a similar structure, which enables them to perform a particular function. Some examples of plant tissues: Epidermal tissue (also known as epidermis) Xylem tissue Phloem tissue Tissues in Plants: Photosynthetic tissue (also known as mesophyll) Palisade tissue

Functions of Tissues of Plant Cells Epidermal Tissue Also known as epidermis Transports water and dissolved mineral salts to the leaf. Xylem Tissue Protects the underlying cells of a leaf by preventing water loss and acts as a barrier to fungi and other invaders. Phloem transports the manufactured food away from the leaf to other part of the plants. Phloem Tissue

Functions of Tissues of Plant Cells Photosynthetic Tissue Also known as Mesophyll  Long cylindrical cells that occur at right angle to the epidermis. Palisade Mesophyll Tissue Carries out photosynthesis.  Contains numerous chloroplasts for photosynthesis.

Functions of Tissues of Plant Cells

Tissues of Animal Some examples of animal tissues: Epithelial tissues Muscle tissues Connective tissues Tissues in Animal: Nerve tissue Glandular tissue

Functions of Tissues of Animal Epithelial Tissue Also known as epithelium Functions include secretion, absorption, protections, trancellular transport, sense of touch. This is a sheet of cells which covers the internal and external surfaces of an organ. This tissue lines both the outside (skin) and the inside cavities of an animal.

Functions of Tissues of Animal Cells Muscle Tissue Divided into 3 main groups  Smooth muscle tissue  skeletal muscle tissue Smooth muscle controls slow, involuntary movements such as the contraction of the smooth muscle tissue in the walls of the stomach and intestines. Skeletal muscles function in pairs to bring about the co-ordinated movements of the limb, trunk, jaws, eyeballs, etc.

Functions of Tissues of Plant Cells Muscle Tissue Divided into 3 main groups  cardiac muscle tissue Cardiac muscle tissue plays the most important role in the contraction of the atria and ventricles of the heart. Refer to handouts !

Functions of Tissues of Animal Cells Connective Tissue Divided into 4 main groups  Dense connective tissue  Loose connective tissue Forms ligaments and tendons. It is densely packed and have great tensile strength. Holds organs in place.

Functions of Tissues of Animal Cells Connective Tissue  Reticular connective tissue  Adipose tissue This is a network of reticular fibers (fine collagen) that form a soft skeleton to support the lymphoid organs (lymph nodes, bone marrow and spleen). Used for cushioning, thermal insulation and energy storage.

Functions of Tissues of Animal Nerve Tissue Make up the nervous system that carry information within the body. Forms gland that produces substances to secrete hormones or sweat. Glandular Tissue

Organs of Plant What is an organ? An organ is a structure made up of different tissues working together for a specific function. Some examples of plant organs: Leaf  An organ of photosynthesis (contains photosynthetic tissues). Stem Organs in Plants:  Contains Xylem and phloem tissues and supporting tissues  Provide support and transport food to other parts of the plants.

Organs of Plant Some examples of plant organs: Roots  Contain xylem and phloem tissues.  These tissues take in the nutrients from the soil and transport them to other parts of the plant.  Roots serve to anchor the plants to the soil and absorb water and minerals. Organs in Plants:

Animal Organs Some examples of animal organs: Stomach  Consist of glandular tissues which secrete digestive juices to digest food  Muscle tissue which causes stomach to contract and relax and mix the food well with the digestive juices  Connective tissue which helps to connect the other tissues. Organs in Animals:

Animal Organs Some examples of animal organs: Heart  Circulates blood around the body  Consist of blood tissue  Muscle tissue which causes heart to contract and expand to circulate blood  Connective tissue which helps to connect the other tissues. Organs in Animals:

Organs systems of human body What is an organ system? An organ system consists of several organs working together to perform a special function, e.g.the digestive system. Respiratory system  Lungs, windpipe, nose and mouth.  Supplies the body with oxygen and remove carbon dioxide.  Allows animal to breathe in order to carry out respiration. Organ systems in Human:

Organs of Animal Digestive system Organs in Animals: Breaks down food into smaller and soluble substances that can be absorbed by the blood.

Organs of Animal Circulatory system Organs in Animal:  Made up of heart, capillaries, arteries and veins.  Allows animal to circulate blood around the body so that different parts of the body will receive food, oxygen,