Specialised Cells, Tissues and Organs

Erythrocytes (Red blood Cells) - Animal

*Flattened biconcave shape* increase SA for Oxygen exchange *No* nuclei or other organelles (in mammals) to increase space for haemoglobin *Flexible* to fit through narrow capillaries 7.5 micrometer diameter, 2micrometer height

Muscle tissue

Adapted to *contract*

Epithelial tissue

Adapted to cover body surfaces, internal *and* external

Connective tissue

Adapted to hold tissue *together* or as a *transport medium*

Nervous tissue

Adapted to support the transmission of electrical impulses

Gaseous exchange system - Animal organ system

Brings air into the body O2 can be extracted for respiration CO2 can be expelled

Organs

Collection of *tissues* that are adapted to perform a particular function within an organism

Tissue

Collection of differentiated cells that have a specialised function/s Each tissue is *adapted* for a particular function within the organism There are *4* main types of tissue in animals: Nervous, epithelial, muscle, connective

Cartilage - Animal tissue

Connective tissue (outer ear, nose, at the end and between bones) Contains *collagen* and *elastin* fibres Firm, flexible connective tissue composed of *chondrocyte* cells embedded in *extracellular matrix* Prevent bone ends rubbing together and causing damage Fish have complete cartilage skeletons

Muscle - animal tissue

Contracts and relaxes in order to move bones Skeletal muscle fibres contain *myofibrils* that contain *contractile proteins* Each pink strip is a muscle fibre, each white strip is connective tissue

Guard Cells - Plant

Form stomata Control gasses entering/leaving the cell (CO2 enter for photosynthesis) Thick inner wall means a change in osmotic forces causes the stomata to open or close was water comes in or leaves When there is a low water supply, osmotic pressure's low so the stomata closes, conserving water

Organ systems

Large multicellular organisms have *coordinated* organ systems each organ system is composed of a number of *organs* working together to carry out a major bodily function

Ciliated Epithelium - Animal tissue

Made up of ciliated epithelial cells Cells have *hair-like* structures (cilia) on one surface that move in a *rhythmic* manner It lines the trachea, sweeping mucus away from the lungs Goblet cells also present, secreting mucus, trapping unwanted particles, preventing bacteria reaching the lungs

Squamous Epithelium - Animal tissue

Made up of squamous epithelial cells (sometimes known as *pavement* epithelium) Very *thin*, one cel thick, flat cells Present when rapid diffusion *essential* Forms lining of lungs to allow rapid diffusion of oxygen into blood

Sperm cells - Animal

Male *gametes* Delivers male genetic information to *ovum* (egg) Long flagellum for movement (40 micrometers) requires many *mitochondria* *Acrosome* contains digestive enzymes , released to digest protective layers of ovum, leading to fertilisation

Cardiovascular system - Animal organ system

Moves blood around the body to provide an effective transport system for the substances it carries

Neutrophils (type of white blood cell) - Animal

Plays important part in *immune system* *Multi-lobed nucleus* makes it easier to squeeze through small gaps to infection sites *Granular* cytoplasm contains many *lysosomes* containing enzymes used to attack infectious pathogens 10-14 micrometer diameter

Root hair cells - Plant

Present at surfaces of root near growing tips Long root hairs increase SA of the cell Maximises uptake of water and minerals from the soil

Palisade Cells - Plant

Present in *mesophyll* Contain *chloroplasts* to absorb light for *photosynthesis* Rectangular box shape lets cells be stacked tightly together in a continuous layer Thin cell walls reduce diffusion distance Large vacuole maintains *turgor* Chloroplasts can move about to absorb more light

Epidermis - Plant tissue

Single layer of closely packed cells covering plant surfaces Usually covered by waxy, waterproof cuticle to reduce water loss Stomata are present, controlled by guard cells, that control of gaseous exchange

Digestive system - Animal organ system

Takes in food Breaks down large insoluble molecules into small, soluble ones Absorbs nutrients into the blood retains water needed by the body and removes any undigested material from the body

Specialised cells

The cells within a multicellular organism are *differentiated* - specialised to carry out particular functions

Phloem - Plant tissue

Vascular tissue responsible for the transport of organic nutrients (particularly *sucrose*) from leaves and stems (made by photosynthesis) to all parts of the plant where it is needed Composed of sieve tube cells separated by perforated walls called *sieve* plates

Xylem - Plant tissue

Vascular tissue responsible for transport of water and minerals throughout plants Composed of *vessel elements* (elongated, dead cells) Walls strengthened by *lignin* which provides structural support for plants