Mod 3 Flashcards
(31 cards)
Importance of Specialized Exchange Surfaces in Multicellular Organisms
Larger organisms need specialized exchange surfaces due to decreased surface area to volume ratio.
Single-celled organisms have easier substance exchange due to shorter distances.
Multicellular organisms require efficient gas exchange for oxygen and carbon dioxide.
Efficient exchange surfaces have a large surface area and are often folded or thin.
Good blood supply and ventilation are essential to maintain steep concentration gradients.
Understanding Lung Anatomy and Function
The lungs are inflating structures in the chest cavity with a large surface area.
They are protected by the rib cage and a lubricating substance reduces friction during movement.
Intercostal muscles help raise and lower the rib cage for breathing.
The diaphragm separates the lungs from the abdominal area.
Gaseous exchange occurs in the alveoli, tiny air-filled sacs in the lungs.
Understanding the Structure of Airways
The trachea, bronchi, and bronchioles facilitate air movement to and from the lungs.
Cartilage rings keep the airways open, with incomplete rings in the trachea for food passage.
The trachea and bronchi have thick walls made of cartilage, glandular tissue, and smooth muscle.
Bronchi are narrower than the trachea, while bronchioles are even narrower and mostly lack cartilage.
Smaller bronchioles feature clusters of alveoli at their ends for gas exchange.
Key Components of the Respiratory System
Cartilage supports the trachea and bronchi, preventing lung collapse during exhalation.
Ciliated epithelium helps move mucus to the throat to prevent lung infection.
Goblet cells secrete mucus in the airways to trap bacteria and dust.
Smooth muscle controls airway diameter and regulates airflow to and from alveoli.
Elastic fibers stretch during inhalation and recoil during exhalation, aiding airflow control.
Understanding Ventilation: The Process of Breathing
Ventilation includes two stages: inspiration and expiration.
Inspiration involves contraction of external intercostal muscles and diaphragm.
This contraction increases thoracic volume and lowers internal pressure, drawing air in.
During expiration, internal intercostal muscles contract and diaphragm relaxes.
These actions decrease thoracic volume, increasing pressure and expelling air.
Understanding Spirometry and Lung Volumes
A spirometer measures lung volume by recording breathing patterns.
Vital capacity is the maximum air volume inhaled or exhaled in one breath.
Tidal volume refers to the air volume exchanged during normal resting breathing.
Breathing rate is calculated from the spirometer trace, counting peaks or troughs.
Residual volume is the air always present in the lungs, even after exhalation.
Understanding Fish Gas Exchange Mechanism
Fish have a low surface area to volume ratio for gas exchange.
They possess an impermeable membrane, preventing gas diffusion through skin.
Bony fish have four pairs of gills supported by arches.
Gill filaments with lamellae facilitate gas exchange through counter-current flow.
Fish cannot survive long out of water due to gill projections sticking together.
Understanding Fish Ventilation Mechanics
Fish ventilation requires a continuous unidirectional flow of water.
It starts with the fish opening its mouth to allow water into the buccal cavity.
The floor of the buccal cavity lowers to facilitate water intake.
When the mouth closes, the floor raises, increasing pressure to push water out.
The operculum serves as both a valve and pump to manage water flow over gills.
How Insects Breathe Without a Transport System
Insects lack a transport system for oxygen.
Oxygen is delivered directly to tissues via spiracles.
Spiracles are small openings connected to tubes called trachea and tracheoles.
Tracheoles contain fluid that helps gases dissolve for cell diffusion.
Spiracles can open and close to minimize water loss.
Understanding Circulatory Systems: Open vs Closed
Circulatory systems can be open or closed.
Open systems, like in insects, allow blood to flow freely.
Closed systems confine blood to vessels, seen in fish and mammals.
Closed systems can be single-chambered or double-chambered.
Double-chambered systems involve blood passing through the heart twice per circuit.
The Structure and Function of Blood Vessels
Arteries carry blood away from the heart and have thick walls to handle high pressure.
Arterioles branch from arteries and have thinner walls to direct blood into capillaries.
Capillaries are the smallest vessels, only one cell thick, facilitating fast metabolic exchanges.
Venules are larger than capillaries but smaller than veins, connecting them to the venous system.
Veins return blood to the heart, featuring wide lumens and valves to prevent backflow due to low pressure.
Understanding Tissue Fluid and Its Role in Metabolism
Tissue fluid supplies tissues with oxygen and nutrients while removing waste products.
Hydrostatic pressure from blood flow forces fluid out of capillaries into the tissue.
Only small substances can escape through capillary walls to form tissue fluid.
Osmotic pressure helps pull some fluid back into the capillaries.
Excess tissue fluid is returned to circulation through the lymphatic system.
Understanding the Lymphatic System
The lymphatic system transports lymph fluid, which resembles tissue fluid.
Lymph fluid has lower oxygen and nutrient levels than tissue fluid.
Its primary role is to carry waste products away from tissues.
Lymph nodes filter out bacteria and foreign materials from lymph fluid.
Lymphocytes in the lymphatic system help destroy invaders, supporting immune defenses.
Understanding the Heart’s Myogenic Activity
The heart is termed myogenic for its ability to initiate contractions.
The sinoatrial node in the right atrium acts as the heart’s pacemaker.
Atria contract simultaneously due to electrical stimulation from the sinoatrial node.
The atrioventricular node transmits excitation to the ventricles after atrial contraction.
The bundle of His and Purkyne fibres facilitate ventricular contraction and emptying.
Understanding the Cardiac Cycle
The cardiac cycle consists of three stages: atrial systole, ventricular systole, and cardiac diastole.
During atrial systole, the atria contract, opening the atrio-ventricular valves to fill the ventricles with blood.
Ventricular systole occurs when the ventricles contract, closing the atrio-ventricular valves and opening the semilunar valves for blood ejection.
Cardiac diastole involves relaxation of the heart, lowering pressure and allowing blood to fill the chambers from arteries and veins.
The semilunar valves close during diastole to prevent backflow of blood into the ventricles.
Understanding Haemoglobin’s Role in Oxygen Transport
Haemoglobin is a globular protein made of two alpha and two beta chains with haem groups.
It carries oxygen in the blood by binding it to the Fe2+ in the haem group.
Each haemoglobin molecule can transport four oxygen molecules.
Oxygen affinity for haemoglobin increases with higher partial pressure of oxygen.
Oxygen is loaded in the lungs and released in respiring tissues as needed
Understanding Dissociation Curves in Hemoglobin Saturation
Dissociation curves show haemoglobin saturation changes with partial pressure.
High partial pressure results in high affinity and saturation for oxygen.
Lower partial pressure leads to reduced affinity and saturation.
The binding of the first oxygen molecule increases haemoglobin’s affinity.
Hemoglobin’s shape changes, facilitating the binding of additional oxygen molecules.
Understanding Fetal Hemoglobin and Its Oxygen Affinity
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.
This increased affinity is necessary for the fetus to survive in low oxygen conditions.
Oxygen saturation decreases as blood travels to the placenta.
The presence of carbon dioxide lowers hemoglobin’s affinity for oxygen.
This relationship is explained by the Bohr effect, facilitating oxygen release.
Structure and Function of Vascular Bundles in Plant Roots
Xylem and phloem are key components of the vascular bundle for transport and support.
Xylem vessels are arranged in an X shape at the center of the vascular bundle.
The X shape design helps plants withstand mechanical forces like pulling.
Endodermis surrounds the xylem, supplying it with water.
The pericycle is an inner layer of meristem cells within the vascular bundle.
Understanding Stem Vascular Bundles
Xylem is positioned inside the vascular bundle in non-woody plants.
Phloem is located on the outer side of the vascular bundle.
The cambium layer contains meristem cells.
Cambium cells are responsible for producing new xylem and phloem.
The arrangement provides support and flexibility to the stem.
Understanding Vascular Bundles in Leaves
Vascular bundles form the midrib and veins of a leaf.
They are crucial for the transport of nutrients and water.
Dicotyledonous leaves display a network of veins.
Veins extend outwards from the midrib.
These structures are essential for leaf support and function.
Key Features of Xylem Vessels
Xylem vessels transport water and minerals while providing structural support.
They are long cylinders made of dead tissue with open ends for continuous flow.
Pits in xylem vessels allow sideways movement of water between them.
Thickened with lignin, they maintain flexibility in plants.
Water in xylem vessels flows only upwards.
Key Features of Phloem Vessels
Phloem vessels are made of living cell tubes.
They transport nutrients to storage and growing parts of the plant.
Composed of sieve tube elements and companion cells.
Sieve tube elements transport sugars like sucrose in sap.
Companion cells produce ATP for active sucrose loading and communicate via plasmodesmata ( gaps between cell walls which allow communication and flow of substances such as minerals between the cells )
Understanding Transpiration in Plants
Transpiration involves water absorption through roots and release as vapour from leaves.
Carbon dioxide enters leaves while water and oxygen exit through stomata.
The transpiration stream supports photosynthesis, growth, and elongation in plants.
It also provides necessary minerals and helps regulate plant temperature through evaporation.
The process includes osmosis, evaporation from mesophyll cells, and diffusion of water vapour.
