40 Basic Principles Flashcards
What is is called when evolutionary animals have similar features and what does it suggest?
Convergent evolution, which shows that it is likely the most efficient form.
What is an example of convergent evolution?
Penguins, Seals and Tuna are all aquatic animals that are fusiform (smooth and tapered at both ends)
What circulation do hydras have?
Their body consist of a two cell thick tube. The cells on the outside are obviously in direct contact with the outside so don’t need circulation.
The inside of the tube is hollow and filled with water, known as a gastrovascular cavity so that all cells are in contact with the outside and thus circulation isn’t needed per se.
Why are parasitic tapeworms so long?
This ensures they are thin so that each cell is close to the nutrient rich intestinal fluid.
What is the advantage of having exchange systems i.e. alveoli inside the body as opposed to on the surface?
- Reduces dehydration
- Allows streamlined skin
- Protects them from damage
What is the fluid between cell called?
Interstitial fluid.
What are the main mammalian organ systems?
Digestive, Circulatory, Respiratory, Immune/Lymphatic, Excretory, Endocrine, Reproductive, Nervous, Integumentary, Skeletal, Muscular
What is the integumentary system?
Skin and its derivatives (i.e. hair, claws and skin glands)
What organ system is the spleen in?
Immune/Lymphatic
Name an organ that is in multiple organ systems.
Pancreas (digestive and endocrine)
What are the main animation tissue types?
Epithelial, Connective, Muscle and Nervous.
What are the forms of epithelial tissue?
Cuboidal epithelium, simple columnar epithelium, simple squamous epithelium, stratified squamous epithelium and pseudo stratified columnar epithelium.
What is the structure of cuboidal epithelium?
A ring of dice-shpaed cells to form a tube or bag.
Where is cuboidal epithelium found?
Kidney tubules and the walls of the thyroid and salivary glands as these cells are specialised for excretion i.e. of salivary amylase.
What is the structure of simple columnar epithelium?
Large brick shaped cells form a grid of columns
Where is simple columnar epithelium found?
The lining of the intestines as these cells are optimum for secreting digestive juices and absorbing nutrients while also preventing leakage.
What is the structure of simple squamous epithelium?
A single layer of platelike cells that appear like scales.
Where is simple squamous epithelium found?
It is thin and leaky. Therefore it is found in the lining of capillaries and alveoli as it facilitates diffusion
What is the structure of stratified squamous epithelium?
Many layers of spumous i.e. disk shaped cells.
Where is stratified squamous epithelium found?
Surfaces that are often exposed to abrasion i.e. outer skin and mouth lining.
This is because it is able to regenerate quickly. This is because new cells form at the bottom to replace cells that are sloughed off at the top.
What is the structure of pseudo-stratified columnar epithelium?
A single layer of cells columnar but they are of different heights. Thus there is some overlap and the cells are more wedge shaped.
Where is pseudo-stratified columnar epithelium found?
In mucous membranes where it is covered by cilia that sweep the film of mucus along it.
Generally speaking, how are the cells of epithelium connected and what property does this yield?
They are often tightly packed and bonded by tight junctions. Therefore they are strong and act as a barrier against pathogens and water loss (except simple squamous)
What is the general structure of epithelium?
They are polar i.e. have different sides. The apical surface is the one that faces the lamina or outside and thus is the ‘active side’ whereas the ‘basal surface’ is not in contact with the fluid/air etc.
Below the basal surface is the basal lamina. This dense mat of extracellular matrix separates the epithelium from other tissues.
What are the forms of connective tissue?
Loose connective tissue, fibrous connective tissue, bone, adipose tissue, cartilage and blood (yep-blood)
What is the basic structure of connective tissue?
A web of fibres forming an extracellular matrix, consisting of a sparse population of cells.
The matrix includes fibroblast cells which secrete fibre proteins. Macrophages engulf foreign particles and cell debris.
What are the types of connective tissue fibres and what property do they provide?
Collagenous fibres provide strength and flexibility, reticular fibres join connective tissue to adjacent tissue and elastic fibres make tissue elastic.
(a combination of these fibres leads to mixed properties)
What is the most widespread connective tissue in vertebrates?
Loose connective tissue.
What is loose connective tissue?
Binds epithelia to underlying tissues and holds organs in place. It consists of a loose weave of all three fibres and tis found in the skin and throughout the body.
What is fibrous connective tissue?
Dense with collagenous fibres and thus used in tendons and ligaments.
How are bones joined to each other and muscle?
Tendons join bones to muscles and ligaments connect bones at joints.
What is the structure of bones?
Bone consists of repeating units called osteons. Each osteon has concentric layers of the min- eralized matrix, which are deposited around a central canal containing blood vessels and nerves.
How are bones formed?
Bone-forming cells called osteoblasts deposits a matrix of collagen. Calcium, magnesium and phosphates collect in this matrix to form a tough structure.
What is adipose tissue?
Specialised loose connective tissue that stores fats using adipose cells distributed through its matrix.
Why is adipose tissue important?
It pads and insulates the body and provides energy stores.
How are fats stored within an adipose cell?
In fat droplets that swell and shrivel depending on whether there is lots or little fat.
What is the structure of cartilage?
Collagenous fibres are embedded in a rubbery protein-carbohydrate complex called chondroitin sulfate.
How is cartilage formed?
Cells called chondrocytes secrete the collagen fibres and chondroitin sulfate to form the strong yet flexible structure.
Where is cartilage found?
Many vertebrate embryos have skeletons made of cartilage that later harden into bone. Cartilage remains in some places like the nose and as cushions between vertebrae.
Some animals like sharks have cartilage skeletons/
Why is blood considered connective tissue?
It has a liquid extracellular matrix-plasma that supports cells.
What is the technical term for red blood cell?
Erythrocyte
What are the types of muscle tissue?
Skeletal muscle, smooth muscle and cardiac muscle.
What is the structure of skeletal muscle?
Bundles of muscle fibres. The arrangement of sarcomeres along these fibres gives it a striated appearance.
The muscle fibres are actually long cells that formed from the fusion of many cells and thus have multiple nuclei.
How does smooth muscle differ visually from skeletal muscle?
It does not have striations.
What is skeletal muscle also known as?
Striated muscle.
What is the structure of smooth muscle?
Spindle shaped cells without a striated appearance.
Where is skeletal muscle found?
In voluntarily controlled regions i.e.on the skeleton.
Where is smooth muscle found?
The involuntarily controlled regions such as the walls of the digestive tract, bladder and arteries etc.