Higher Human Biology SQA

This subject is broken down into 26 topics in 4 modules:

  1. Human Cells 8 topics
  2. Physiology and Health 8 topics
  3. Neurobiology and Immunology 8 topics
  4. Apparatus and Techniques 2 topics
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  • 4
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  • 26
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  • 10,165
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  • 1+
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This page was last modified on 28 September 2024.

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Human Biology

Human Cells

Division and Differentiation in Human Cells

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Division and Differentiation in Human Cells

Cell Division and Specialisation

  • The life cycle of a cell is called the cell cycle, composed of interphase and mitosis.
  • Interphase includes subphases G1 (growth), S (DNA replication), and G2 (preparation for mitosis).
  • Mitosis is the process by which a single cell divides into two identical daughter cells, having the same number of chromosomes as the parent cell.
  • The phases of mitosis include prophase, metaphase, anaphase, telophase, and cytokinesis.

Cell Differentiation

  • Cell differentiation takes place in multicellular organisms allowing the development of specialised cell types.
  • Stem cells can differentiate into various cell types due to the presence of pluripotent genes.
  • During differentiation, cells undergo changes in shape, function, and metabolic activity controlled by the activation and deactivation of genes.

Stem Cells

  • Stem cells are undifferentiated cells with the potential to differentiate into different cell types.
  • Embryonic stem cells are pluripotent, capable of differentiating into nearly all cell types.
  • Adult stem cells, also known as somatic stem cells, have a lesser potential for differentiation but play a key role in growth, healing, and replacing cells lost through daily wear and tear.

Cellular Differentiation and Organism Development

  • Cellular differentiation initiates during the early stages of embryonic development.
  • The initial cell division leads to the formation of blastocyst, composed of an inner cell mass that becomes the embryo.
  • Cells of the embryo keep dividing and differentiating guided by various biological signals, resulting in formation of various organs and systems.
  • The development of functionally different cells, organs, and systems from the same zygote is a result of genetic signals and the local environment.

Tissues, Organs, and Systems

  • Differentiated cells with similar structure and function group together to form tissues.
  • Several tissues work together to form an organ, each contributing to the organ's specific function.
  • Organs work in a coordinated manner to form a system.
  • Examples include the circulatory, respiratory, and digestive systems.

Implications of Cell Differentiation

  • Understanding the process of cell differentiation can lead to advances in regenerative medicine and treatment of various diseases.
  • Manipulating the differentiation of stem cells in laboratories can potentially help in organ transplantation, treating neurodegenerative diseases, and heart disease. -The study of cell differentiation helps understand the process of development, ageing, and the basis of biological diversity.

Course material for Human Biology, module Human Cells, topic Division and Differentiation in Human Cells

Human Biology

Physiology and Health

The Structure and Function of the Heart

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The Structure and Function of the Heart

Structure of The Heart

  • The heart is divided into four chambers: two atria (single: atrium) at the top and two ventricles at the bottom.
  • The right atrium receives deoxygenated blood from the body through the vena cava and pumps it to the right ventricle.
  • The right ventricle pumps the deoxygenated blood to the lungs through the pulmonary artery for oxygenation.
  • The left atrium receives oxygenated blood from the lungs through the pulmonary vein and pumps it to the left ventricle.
  • The left ventricle pumps the oxygenated blood to the rest of the body through the aorta.

Function of The Heart

  • The function of the heart is to pump blood around the body to supply cells with oxygen and nutrients required for cellular respiration.
  • The heart contracts and relaxes in a process known as the cardiac cycle. This cycle includes diastole (relaxation of the heart) and systole (contraction of the heart).
  • The beating of the heart is regulated by the sinoatrial node (SA node), also known as the natural pacemaker. It sends out electrical signals to trigger the contraction of the heart muscle.

Blood Vessels

  • The heart is connected to the body tissues through three types of blood vessels: arteries, veins, and capillaries.
  • Arteries have thick, elastic walls to withstand the high blood pressure from the heart. They carry blood away from the heart.
  • Veins have thinner walls and valves to prevent backflow of blood. They carry blood to the heart.
  • Capillaries are the smallest blood vessels where exchange of oxygen, nutrients, and waste materials occur between the blood and the body tissues.

Blood Circulation

  • The heart is involved in a double circulatory system: the pulmonary circulation and the systemic circulation.
  • In the pulmonary circulation, deoxygenated blood is pumped from the heart to the lungs for oxygenation.
  • In the systemic circulation, oxygenated blood is pumped from the heart to the rest of the body to deliver oxygen and nutrients.
  • The heart is responsible for maintaining a constant blood pressure to ensure adequate blood flow to all parts of the body.

Health and The Heart

  • Coronary heart disease (CHD) is a major heart condition that involves the build-up of fatty deposits in the coronary arteries, which can decrease oxygen supply to the heart muscle and may lead to heart attack.
  • Regular physical activity, balanced diet, and avoiding harmful habits like smoking and excessive alcohol intake can contribute to heart health.

The Heart and Medical Technologies

  • An Electrocardiogram (ECG) is a medical test that measures the electrical activity of the heart. It can help identify heart abnormalities.
  • Pacemakers are small devices that can be implanted into the chest or abdomen to help regulate abnormal heart rhythms.
  • Heart transplants are surgery options for severe heart diseases, where the diseased heart is replaced with a healthy donor heart.

Course material for Human Biology, module Physiology and Health, topic The Structure and Function of the Heart

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