Lecture 24 Circulatory system pt. 2 Transport in plants

Arteries/ Arterioles pressure levels:

• Highest pressure (Closest to the heart)

• Large pulse pressure

Capillaries Pressure levels:

• Lower pressure than Arteries, but higher than veins.

• Slower flow

Veins Pressure levels:

• Lowest pressure (furthest from the heart.

Problem with low blood pressure and gravity:

It makes it harder for blood to flow up through the veins and back to the heart.

Adaptations to address blood pressure and gravity problems.

• Skeletal muscle contractions:

• one way veinous valves

Skeletal muscle contractions

Muscles contract and produce a pumping action which helps move blood up through the veins.

One way veinous valves

Prevent backflow of blood when muscles contract. The blood can only go one way in the veins.

Varicose veins

Injury or genetics can damage one way veinous valves which allows blood flow to pool up. Looks like swollen twisted veins.

Deep Vein Thrombosis

Inactivity and/or damaged valves in the veins that lead to blood clots.

Pulmonary Embolism (PE Blood Clot)

A clot that breaks loose (embolus) can travel to the lungs an decrease or block blood flow.

Plant Uptake and Transport

• H2O and minerals are transported through the roots then up against gravity to the rest of the plant.

• Carbohydrates and other macromolecules are transported from photosynthetic areas to the rest of the plant.

• Transport in Vascular plants is accomplished via vascular tissues.

xylem

A vascular tissue that transports water and minerals from the roots to the rest of the plant. (Dead tissue)

Water and mineral transport steps:

Water travels through the roots first, then enters the xylem.

How is water transported through root tissues through the xylem?

epidermis

Outer layer of cells that forms a boundary between the plant and the external environment.

Root hairs

Outgrowths that absorb water and nutrients (damage can cause transplant shock).

cortex

• Cellular layer between the epidermis and the endodermis.

• Conducts water and is used for storage.

Endodermis

A water tight inner layer of cells

Casparian Strip (Gatekeeper of the root)

• a waxy coating that surrounds the cells of the endodermis. It’s a water tight seal.

• Stops water from flowing between the endodermal cells (water must flow through the endodermal cells)

• Allows endodermal cells to regulate the flow of water and dissolved solutes into the interior of the root

Pericycle

A layer between the endodermis and the xylem (structural support, conducts water)

Xylem

Vascular tissue through which water is transported upward to the rest of the plant.

2 ways water can travel to the xylem

1. Between root cells (Apo plastic transport)

2. Through root cells (Symplastic Transport) Uses cell cell channels called plasmodesmata.

From the soil water can travel either way until it reaches the casparian strip.

• Because of the strip, water must travel symplastically through the cells of the endodermis.

How does water move up the Xylem?

The transpiration (tension/cohesion model)

The transpiration (tension/cohesion model)

• H2O enters into the xylem from the roots.

• H2O exits the xylem through openings in the leaves called stomata (by evaporation).

• H2O molecules form a continuous connected chain from the roots to the stomata.

• H2O molecules are bound to each other through hydrogen bonding (Cohesion)

• H2O molecules leaving by evaporation pull the chain of H2O molecules upward from the roots (tension)