key words module 3

Alveoli

Tiny air sacs that serve as the primary gaseous exchange surface

Thin epithelial cell layer, collagen and elastic fibres

Breathing rate

Number of breaths per minute

Bronchi

Divisions of the trachea that lead into the lungs

Small tubes supported by incomplete rings of cartilage

Bronchioles

Small divisions of the bronchi

Smooth muscle to restrict airflow, no cartilage

Lined with a thin layer of epithelial cells

Cartilage

Strong, flexible connective tissue that supports the walls of trachea and bronchi preventing collapse

Ciliated epithelial cells

Cells with tiny hair like cilia found lining the trachea that waft mucus to the back of the throat

Countercurrent flow

Blood in the gill filaments and water moving over the gills flow in opposite directions, maintaining a steep oxygen concentration gradient

Elastic fibres

Fibres of elastin that allow alveoli to stretch as air is drawn in and recoil back to normal expelling air

Found in trachea, bronchi and bronchioles

Exchange surface

Materials are exchanged from one region to another

Expiration

Breathing out

Gill filaments

Main site of gas exchange in fish, found in large stacks known as gill plates, have gill lamellae which provide large surface area

Gill lamellae

Fine branches of gill filaments

Large surface area and good blood supply

Gill plates

Large stacks of gill filaments

Gills

Organs of gaseous exchange in fish

Goblet cells

Specialised cells that secrete mucus into the trachea lining

Mucus traps harmful substances preventing entry to the lungs

Inspiration

Breathing in

Internal intercostal muscles

Found between the ribs which are responsible for forced exhalation

Operculum

Flap that covers gills of bony fish, protects the gills and helps maintain a constant stream of water over them

Smooth muscle

Involuntary muscle found in trachea and bronchi

Constricts the lumen and reduces airflow to lungs

Spiracles

Small, external openings along the thorax and abdomen of insects through which air enters and leaves

Spiracle sphincters

Open and close the spiracles

Spirometer

Device used to measure patterns of breathing and determine different aspects of lung volume

Tidal volume

Volume of air that moves in and out of the lungs during a normal breath

Trachea

Primary airway, carries air

Tracheal fluid

Fluid found at the end of tracheoles

Tracheoles

Divisions of the trachea that run throughout the tissues of an insect

Ventilation

Movement of fresh air into the lungs and stale air out of the lungs via inspiration and expiration

Vital capacity

Largest volume of air that can be breathed in following the strongest possible exhalation

Affinity

Tendency of one substance to bind with another substance

Aorta

Artery that takes oxygenated blood away from the heart to the body

Arteriole

Blood vessel that connects arteries and capillaries

Large amounts of smooth muscle, some elastic fibres and some collagen

Artery

Blood vessel that carries blood away from the heart to tissues, under high pressure

Walls contain collagen, smooth muscle and elastic fibres

Atrial fibrillation

An arrhythmia involving rapid contraction of the atria preventing complete ventricular filling

Atrial systole

Atria contract pushing blood into the ventricles

AV valves pushed open fully

Atrioventricular node

Group of cells located between atria that slow down the wave of excitation and pass it between the ventricles, along the bundle of His

Atrioventricular valves

Valves between atria and ventricles

Prevent back flow of blood from ventricles into the atria

Bicuspid valve

Atrioventricular valves found between left atrium and ventricle

Blood

Transport medium, consists of plasma, RBC, WBC, and platelets

Bohr effect

Loss of affinity of haemoglobin for oxygen as partial pressure of CO2 increases

Bradycardia

Slow resting heart rate below 60bpm

Bundle of His

Collection of Purkyne fibres which run from the AVN down to the apex of the ventricles

Capillaries

Microscopic blood vessels connecting arterioles to venules

Carbonic anhydrase

Enzyme that catalyses the reversible reaction between water and co2 to produce carbonic acid

Cardiac cycle

Sequence of events involved in one complete contraction and relaxation of the heart

Cardiac output

Volume of blood pumped un the heart through the circulatory system in one minute

Calculated using the equation: cardiac output = heart rate x stroke volume

Chloride shift

Chloride ions move into erythrocytes in exchange for hydrogen carbonate ions which diffuse out

Close circulatory system

Blood pumped is contained within blood vessels, does not come into direct contact with the cells

Diastole

Heart muscle relaxes, atria and ventricles fill with blood

Double circulatory system

Blood flows through the heart twice in two circuits

Ectopic heartbeat

Additional heartbeats outside of normal heart rhythm

Electrocardiogram (ECG)

Measure the spread of electrical activity through the heat

Haemoglobin

Red pigment that binds reversibility with four oxygen molecules to form oxyhemoglobin

Globular protein with four polypeptide chains each with prosthetic haem group

Haemoglobinic acid

Product formed when haemoglobin accepts free hydrogen ions

Enables haemoglobin to act as a buffer, reducing changes in blood pH

Heart rate

Number of times the heart beats in one minute

Hydrostatic pressure

Pressure exerted on the walls of blood vessels by the blood

Inferior vena cava

Vein that returns deoxygenated blood to the heart from the lower body

Lymph

Modified tissue fluid that carries less oxygen and fewer nutrients than tissue fluid, contains fatty acids

Myogenic

Cardiac muscle tissue that initiates its own contraction, without outside stimulation from nervous impulses

Oncotic pressure

Movement of water into the blood by osmosis due to the tendency of plasma proteins to lower the water potential of blood

Open circulatory system

Transport medium is not contained within vessels, direct contact with the cells

Oxygen dissociation curve

Graph that describes relationship between partial pressure of oxygen and percentage saturation of haemoglobin in the blood

Plasma

Carries red blood cells, yellow liquid that contains proteins, nutrients, mineral ions, hormones, dissolves gases and waste

Pulmonary arteries

Carry deoxygenated blood away from the heart to the lungs

Pulmonary veins

Veins that carry oxygenated blood from lungs to heart

Purkyne tissue

Specialised cardiac muscle fibres which make up the bundle of His and conduct wave of excitation through the septum, from AVN down to the apex of the ventricles

Semilunar valves

Pair of valves found between ventricles and arteries. Prevent back-flow of blood from arteries into the ventricles

Septum

Wall of muscle which separates the left side of the heart from the right side of the heart

Single circulatory system

Blood pumped round the body once before returning to the heart

Sinoatrial node (SAN)

Group of cells in wall of right atrium that generate electrical activity causing atria to contract. Referred to as the hearts pacemaker

Stroke volume

Volume of blood pumped by left ventricle in a single contraction

Superior vena cava

Vein that returns deoxygenated blood to the heart from head and upper body

Tachycardia

Resting heart rate over 100bpm

Tissue fluid

Fluid surrounding cells with similar composition to plasma. Does not contain RBC or plasma proteins

Tricuspid valves

Atrioventricular valves found between right atrium and ventricle

Vein

Blood vessel that carries blood towards the heart under low pressure

Side lumen, smooth inner lining, large amounts of collagen, smooth muscle, little elastic fibre

Ventricular systole

Stage where ventricles contract pushing blood into the arteries

Semi-lunar valves pushed open fully

Venule

Blood vessel that connects capillaries to veins

Active loading

Process by which hydrogen ions are actively pumped out of companion cells using ATP, before diffusing down a concentration gradient, back into cells via co-transporter proteins, whilst carrying sucrose

Adhesion

Formation of hydrogen bonds between carbs in xylem wall and water molecules

Apoplast route

Water moved through intercellular spaces between cellulose molecules in the cell wall

Casparian strip

Waterproof strip surrounding endodermal cells that block the apoplast pathway, forcing water through symplast pathway

Cohesion

Hydrogen bonds between water molecules

Cohesion tension

Explains movement tog water from soil to the leaves

Companion cells

Active cells located adjacent to Sieve tube element. Retains nucleus and organelles

Dicotyledonous plants

Plants that have seeds that contain two cotyledons

Hydrophytes

Plants adapted to live well in water

Phloem

Transportation vessel for assimilates

Plasmodesmata

Small pores between adjacent sieve tube elements and companion cells that allow communication and the exchange of materials

Potometer

Apparatus used to measure water uptake from a cut shoot

Root hair cells

Specialised cells responsible for the uptake of water and minerals from the soil. Long hair like extensions to increase surface area

Sieve plates

Perforated end walls of sieve tube elements that allow plant assimilates to flow between cells unimpeded

Sieve tube elements

Main cells of the phloem containing few organelles

Sinks (plants)

Regions of a plant that remove assimilates

Sources (plants)

Regions of a plant that produce assimilates

Symplast route

A pathway that water and minerals move across the root

Water enters the cytoplasm through the plasma membrane and moves between adjacent cells via plasmodesmata

Translocation

Movement of organic compounds in the phloem, from sources to sink

Transpiration

Water loss from plant leaves and stems via diffusion and evaporation.

Rate is affected by light, temperature, humidity, air movement and soil-water availability

Transpiration stream

Flow of water from roots to leave in plants

Vascular bundle

Vascular system in herbaceous dicotyledonous plants consisting of xylem and phloem

Xerophytes

Plants that are adapted to live and reproduce in dry habitats where water availability is low