Semester 2 exam Human Biology year 11 ATAR

Why are the walls of the atrium thinner than the ventricles?

Why are the walls of the atrium thinner than the ventricles?

Because blood is pumped out of the heart with lesser pressure from the atria compared to the ventricles and the ventricles work against gravity.

List functions of the blood

transportation (Oxygen, Carbon dioxide and hormones)
regulation (pH levels, water content, ion concertation and body temperature)
protection (protects disease-causing micro-organisms and blood clotting)

Structure of blood

Plasma (55%), Formed elements [Erythrocytes, leucocytes and thrombocytes] (45%)

Plasma function

transport the components of blood (cells, nutrients, wastes, hormones, proteins and, antibodies) throughout the body.

Plasma composition

•mixture of water (91%) with dissolved substances such as nutrients (glucose, amino acids, lipids), ions, hormones, gases and wastes (urea).

Erythrocytes function

to transport oxygen from the lungs to the cells throughout the body.

Erythrocytes structure

The cells are a biconcave shape and flattened in the middle on both sides. No nucleus (which increases their flexibility and, hence, their ability to move through blood vessels). Filled with haemoglobin

Leucocytes function

Fights infection by removing injured or dead cells and disease causing microorganisms, producing antibodies or forming memory cells.

Leucocytes

white blood cells that make up only 1% of the blood, but larger than red blood cells. Two types: macrophages and lymphocytes

Thrombocytes function and stucture

Small fragments of cells that blood clot.

In which ways oxygen can be transported?

In oxyhaemoglobin (97%) and dissolved in plasma (3%)

Why erythrocytes are well suited for transporting materials.

Haemoglobin: Can combine with oxygen, increasing carrying capacity
No nucleus: More room for haemoglobin
Biconcave disc: increases surface area for oxygen exchange

Formula for the synthesis of oxyhaemoglobin

Haemoglobin + oxygen-> oxyhaemoglobin

In which ways can carbon dioxide be transported?

In carbaminohaemoglobin (22%), Bicarbonate ions in plasma (70%) and dissolved in plasma (8%).

Formula for carbon dioxide transportations.

Carbon dioxide + Water <->Carbonic acid <-> Hydrogen ions + Bicarbonate ions

what are blood vessels?

Carry blood to the cells of the body or the lungs, and then bring it back to the heart again.
The movement of blood through the heart and blood vessels is called circulation. Three types: Artery, Capillary and Vein

Artery function

Takes blood away from heart

Artery structure

- Thick wall (high blood pressure/oxygenated blood)

- Elastic walls

- small lumen diameter

- Arteries can increase blood flow to an organ (vasodilation) and reduce blood flow to an organ (Vasoconstriction)

- Elastic walls stretch to accommodate extra blood when ventricles contract and recoil when ventricles relax. The recoil keeps blood moving and maintains pressure

Capillary function

Carries blood between cells to exchange materials between blood and cells it is the link between arteries and veins

Capillary structure

•Microscopic
•One layer of cells allows materials to easily pass out of blood into tissue fluid and from tissue fluid into blood. Smallest lumen diameter

Vein function

Takes blood towards the heart.

Vein structure

- Thin wall (low blood pressure/deoxygenated blood)
- Little smooth muscle meaning veins cannot change diameter
- Valves to prevent backflow
- Large lumen diameter
- Inelastic as blood pressure in veins is low and constant as most pressure is lost as it flows through tiny capillaries.
- Carries larger volume of blood

What is the heart?

A double pump that pushes blood to the cells of the body or to the lungs. Its located between the two lungs.

Pericardium

the membrane that encloses the heart, but also allows it to beat

Cardiac muscle

Makes up the wall of the heart.

Septum

Divides the right and left chambers of the heart

Superior vena cava and inferior vena cava

Major veins bringing deoxygenated blood from upper body (SVC) and lower body (IVC)

Pulmonary trunk

Divides into two pulmonary arteries that carry deoxygenated blood to the lungs

Pulmonary veins

Return oxygenated blood to heart

Aorta

Main artery that takes oxygenated blood to all parts of the body except lungs.

Process of blood pumping in the right part of the heart

1.The right atrium receives deoxygenated blood from the body and passes it to the right ventricle.
2.The right ventricle pumps deoxygenated blood to the lungs.

Process of blood pumping in the left part of the heart

1.The left atrium receives oxygenated blood from the lungs and passes it to the left ventricle.
2.The left ventricle pumps oxygenated blood to the body.

What are the heart valves?

Tricuspid, mitral valves (Atrioventricular valves)
Aortic, Pulmonary valves (Semilunar valves)

Chordae tendineae

strong, fibrous connections between the valve and papillary muscles. Anchors the valve and prevents it from inverting

Ways the blood flow can change

1.changing the output of blood from the heart
2.changing the diameter of the blood vessels supplying the tissues.

Phases of the cardiac cycle

systole (contraction/pumping) and diastole (relaxation/filling)

What happens during diastole

Atria will fill with blood. Ventricles will also receive blood as the atrioventricular valves open.

What happens during Atrial systole

The contraction of the atria forces the remaining blood to flow into the ventricles. The atria will relax and refill.

What happens during ventricular systole

Ventricles contract and blood is forced into the arteries.

What is cardiac output

The volume of blood leaving one of the ventricles every minute

Stroke volume

volume of blood forced from ventricles (mL)

Heart rate

number of beats each minute (BPM)

Formula for cardiac output

Cardiac output (mL/minute) = stroke volume (mL) × heart rate (beats/minute)

What is the name and function of the blood vessels on the surface of the heart?

The coronary arteries provides oxygenated blood to the heart. Veins drain deoxygenated blood and take it back to the chambers

Why is the left ventricle's walls thicker than the right ventricles?

Because the left ventricle pumps blood for all the parts and tissues of the body and hence, need thicker walls for more work that needs to be done, whereas the right ventricle only pumps blood to the lungs which require less work.

what is a membrane?

the thin layer that forms the outer boundary of a living cell or of an internal cell compartment.

What is a microfilament?

moves materials around the cytoplasm or moves the whole cell.

describe how the membrane acts as a physical barrier

the membrane separates the cell cytoplasm from the extracellular fluid around the cell

what is vesicular transport?

Materials move into or out of the cell in vesicles; two major categories are endocytosis and exocytosis. It is an active process

what happens when you double the length of a side of a cell?

8 times the volume but only 4 times the surface area.

why is it bad when cells grow?

as a cell grows, its ability to exchange enough materials to support its increasing volume is diminished because the volume increases at a greater rate than the surface area

levels of organisation

cell, tissue, organ, system, organism

what is a tissue?

a group of similar cells and their intercellular substances functioning together to perform a specialised activity

function of connective tissues

holds together (binds) and supports the body. It is the most abundant tissue. the tissues cells are widely scattered and contains large amounts of non cellular material called matrix.

what do chemical processes in metabolism do

converts the food you eat into the energy and materials needed for all life processes

What is the role of ATP in cells?

A organic chemical that provides energy to drive many processes in living cells. e.g. muscle contraction, and chemical synthesis.

what is cell theory?

All living things are made up of cells, cells are the basic units of structure and function in living things, new cells are produced from existing cells

what are the three main parts of a cell?

cell membrane, nucleus, cytoplasm

What is the cell membrane?

The outer boundary of the cell that holds the cell together and controls what goes in and out

What is cytoplasm?

a thick fluid within the cell membrane that has all the structures suspended in it.

What is cytosol?

Fluid portion of cytoplasm

what is the cytoskeleton?

framework of protein fibres within the cytoplasm that gives cells shape and assists with cell movement

what is the nucleus and its function in the cell?

the largest organelle in the cell and is usually oval or spherical in shape. It controls the structure and function of the cell or it determines the type of protein the cell makes.

what are ribosomes?

small spherical organelles where amino acids are joined together to make proteins. ribosomes may be free in the cytoplasm, but most are attached the endoplasmic reticulum.

what is endoplasmic reticulum?

the network of channels formed by the parallel membranes is called the ER. it is thought that the membranes of the ER provide a surface for chemical reactions. It also has channels for storing/transporting.

What is the rough endoplasmic reticulum?

when ribosomes are attached to the outside of the endoplasmic reticulum.

what is the smooth endoplasmic reticulum?

when there are no ribosomes attached to the outside of the endoplasmic reticulum.

What is the golgi body/apparatus?

the Golgi body (Golgi Apparatus) is a series of flattened membranes stacked one upon the other. ITS FUNCTION IS TO MODIFY PROTEINS AND TO PACKAGE THEM FOR SECRETION FROM THE CELL. proteins produced at the ribosomes pass through the channels of the endoplasmic reticulum to the Golgi body. At the edges of the membranes of the Golgi body, small sacs of liquid containing proteins are formed. these sacs are surrounded by a membrane and are called vesicles.

What are lysosomes?

small spheres, bound by a membrane , that are formed from the Golgi body. they contain digestive enzymes that are able to break down large molecules. lysosomes also digest worn out organelles in a similar way.

what is the mitochondria?

cellular respiration occurs in the mitochondria. the folding of the inner membrane produces a large surface area on which these chemical reactions can take place.

what are microtubes?

hollow rods that keep organelles in place or move them around the cell.

4 functions of the cell membrane

1. it acts as a physical barrier.
2. it regulates the passage of materials
3. it is sensitive to changes
4. it helps support the cell.

What is extracellular fluid?

fluid outside the cell that surrounds the cell

describe how the cell membrane regulates the passage of materials

the membrane controls the movement of materials in and out of the cell

what is the word for what the cell membrane lets in and out?

semi permeable

describe what it means by the cell membrane is sensitive to change

the cell membrane is the first part of the cell affected by any changes in the extracellular fluid

describe what it means by the membrane helps support the cell.

the internal part of the cell membrane is attached to the microfilaments of the cells cytoskeleton, giving support to the cell. there are connections between the membranes of adjacent cells, providing support to the whole tissue.

what is the name of the cell membrane model

fluid mosaic model

what is the main structure of the cell membrane composed of?

the main structure of the cell membrane is composed of phospholipid molecules, which are lipid molecules containing a phosphate group. they are arranged in two layers known as a phospholipid-bilayer.

the phosphate head is?

hydrophilic ( water loving)

the lipid tail is?

hydrophobic ( water hating)

what are the passive transport processes?

do not use ATP ( energy) examples are diffusion, osmosis, facilitated diffusion.

what are active transport processes?

Processes that uses the cells energy (Adenosine Triphosphate). Vesicular transport (Endocytosis and Exocytosis) and active diffusion.

what is diffusion?

diffusion is the tendency for particles to move from an area of a higher concentration to an area of lower concentration. the substance will diffuse along the concentration gradient until the concentration of the two areas becomes equal.

What is a concentration gradient?

difference in concentration

where will molecules move on the concentration gradient?

molecules will move along the concentration gradient from high to low.

what is simple diffusion?

when substances easily enter cells as they can diffuse through the lipid portions of the membrane. oxygen and carbon dioxide can also diffuse through the phospholipid bilayer.

what is a solute?

the substance being dissolved. for example, sugar or salt

what is a solvent?

the substance that dissolves the solute. for example water

which channel does water pass through in osmosis?

The semipermeable membrane

if salt is added to the water where will the water move?

the water will move from an area where a solute is in low concentration (High water conc) to an area where the solute is in high concentration (low water conc).

why does the water move to where there is more solute?

because where there is more solute that means there is less water particles so the water moves through the concentration gradient from a high to a low.

what are amino acids

molecules that form together to make proteins.

what is endocytosis?

process by which the cell takes in materials that are outside of the cell. Taking in liquids (Pinocytosis) or solids (Phagocytosis) into the cell. the cell membrane folds around the droplet of liquid or solid until it is fully enclosed. this forms a vesicle which fuses with the cell membrane which then pinches off and is suspended into the cells cytoplasm.

what is exocytosis?

a process by which the contents of a cell vesicle are released to the exterior through fusion of the vesicle membrane with the cell membrane.

what is a hypertonic solution?

The solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to lose water and shrink.

what is a hypotonic solution?

Solute concentration is less than that of inside the cell; cell gains water and may burst.

what is an isotonic solution?

Contains equal concentratinos of solutes on both sides.

what is facilitated transport

Molecules that may be too large to pass through the lipid bi-layer may require the use of channel proteins which provide a pathway across the cell membrane. which allows carrier mediated transport along with the concentration gradient.

what are the 2 types of carrier mediated transport

facilitated diffusion and active transport