Unit 12: Diseases and Infection
Learning Aim D: Understand how the human body responds to diseases and infections
Immune system:
Humans have an immune system, which is a sophisticated network of defence
processes that helps them resist disease-causing bacteria (pathogens). Nonspecific innate immunity and
specific acquired immunity are two defence mechanisms that act together to create disease immunity.
Nonspecific defence systems are geared toward combating all germs in the same way, whereas specific
immune responses are tuned to specialised invading species. Both systems operate together to prevent
germs from entering the body and proliferating. These immune systems also assist the body in
eliminating cancer-causing cells.
Non-specific immune system:
Most of the bacteria encountered in daily life are fighting
before they cause symptoms of the disease. Due to the great variety of these pathogens, including
viruses, bacteria, fungi, protozoa, and worms, organisms benefit from common defence mechanisms
that effectively distract all species of this complex microscopic horde. Can be obtained. Physical barriers
such as the epidermis, chemical barriers such as antibacterial chemicals that harm or destroy invaders,
and cells that target foreign or somatic cells with infections are all used by the innate immune system to
offer non-specific protection. Provide. The respiratory, gastrointestinal, and genitourinary systems' skin
and mucous membranes are the first lines of defence against germs and parasites.
Physical barriers:
A mechanical barrier that physically blocks germs from entering the body is
the first line of defence against illness. The skin is the most essential physical barrier. The epidermis and
dermis are the epidermis and dermis, respectively, of the body's skin. The top layer is the epidermis and
the middle layer is the dermis. There is a dermis between the epidermis and the hypodermis. The
epidermis is the thinnest layer of skin and the dermis is the thickest layer. Collagen and elastin are found
in the dermis, thickening the dermis and supporting the overall structure of the skin. The dermis and
subcutaneous tissue include all connective tissue, nerve endings, sweat glands, sebaceous glands, and
hair follicles. All layers of skeletal muscle, organs, muscles, tissues, and skin work together to protect
the body. The epidermis also serves a variety of other purposes, including hydration. New skin cells are
generated. protection. Skin colour.
Various types of cells can be found in the epidermis, including: Keratinocytes: Keratinocytes produce the
protein keratin, which is the main component of the epidermis. Melanocytes are cells that produce
melanin in the skin. Langerhans cells: Langerhans cells help keep objects away from the skin. Keratin-
producing cells make up the outer layer of human skin. This layer of cells is renewed on a regular basis
from below, forming a mechanical barrier to infection. Sebaceous glands also release oily compounds
