Micro - ch.14 - The Innate Immune Response

nonspecific resistance

innate immunity body’s general defense against all kinds of pathogens (not specific ones)

skin

physical barrier to prevent pathogens

• contains keratin (tough protein) and produce acid secretions

Mucus membrane

contains mucus to trap microbes and cilia to move them out the body or destroys

• lines respiratory, digestive , urogenital tracts

lysozyme 

enzyme in tears and saliva breaks down bacterial cell walls

gastric juices

in the stomach; mixture of HCl and enzymes that damage microbes that get swallowed

normal flora/microbiota

bacteria that lives on or inside the body

• healthy microbe that train and support immune system

• competes with pathogens and aids digestion and vitamins 

sentinel cells

specialized immune system cells in tissue

• frequently exposed to external environment

• constant monitoring 

• watch dogs

Host defense peptids/ Anti-microbial peptids (AMPs)

small proteins made by body which fight bacteria, viruses, fungi, and parasites

Lactoferrin

iron-binding protein found in milk and body fluid → bacteria needs iron → this helps with immune system

transferrin

iron-binding protein in blood which carry iron to cells for RBCs formation

What are the components of blood?

plasma, erythrocytes, leukocytes

plasma

liquid part of blood

• 90% water and proteins, nutrients, hormones, and waste products 

Erythrocytes (RBCs)

filled with hemoglobin to carry oxygen throughout the body

• biconcave in shape

• Iron carries in hemoglobin and binds to oxygen until released into tissue 

Leukocytes (WBCs)

defend body against infection and harmful invaders

• neutrophils, eosinophils, basophils, lymphocytes

neutrophils

first responders, phagocytes 

basophils

release histamine for inflammation and allergies

eosinophils

fight parasites, involved in allergies

lymphocytes

B and T cells and Natural Killer (NK) cells

What are natural killer cells?

nonspecific killed of virus infected or cancerous cells

monocytes

becomes macrophages 

What do enzymes have to label them part of the body?

markers - MHC I proteins

What do NK cells do?

when a cell is missing a label, it releases toxic chemicals to punch holes in the membrane which is controlled cell depth

What is apoptosis?

when NK punch holes into membrane to control cell depth

leukocytes

increase WBC - elevated WBC count

Leukopenia

decrease WBC

What is a sign of infection?

increased WBC count - leukocytes

What happens in the first step of pahgocytosis?

a neutrophil or phagocyte attracted to site of infection by chemical signals (damaged cells or bacteria)

What is the second step of phagocytosis?

phagocyte attaches to pathogen

describe step 3 of phagocytosis

extension called pseudopods surround the microbe forming a vesicle (transport pouch) called phagosome

what happens in the 4th step of phagocytosis?

phagosomes fuses with lysosome - full of digestive enzymes - forming phagolysosomes

describe step 5 of phagocytosis

enzyme in the phagolysosomes break down microbes

What happens in the 6th step of phagocytosis?

waste material is released from cell (exocytosis)

What are phagocytes?

general term for any immune cell that perform phagocytosis - “eating” and destroying microbes and debris

What is inflammation?

body’s natural response to injury or infection

• helps isolate harmful agents

First step of inflammation

triggered by chemical signals like histamine vessel dilate to increase blood flow to injury/infection

Second step of inflammation

chemicals like kinin, prostaglandins, and immune cells move from the blood into the tissue → these increase vascular permeability and fight pathogens

What are the signs of inflammation?

redness, swelling, heat, pain

How are WBCs getting to the site of infection/injury?

Step 1: margination

step 2: diapedesis

Margination

WBC stick to the inner walls of small blood vessels (capillaries) near infection or injury site 

Diapedesis

WBC squeeze through gaps in the capillary walls to leave the blood stream enter tissue

Fever

the increase in body temperature by the brains hypothalamus in response to pyrogens - released by macrophages 

• higher temp boosts immune cells and can slow the growth of some microbes 

• - response to pyrogens 

Cytokines 

small proteins release by immune cells that act as messengers - sends signals between cells 

Interferons

type of cytokine released by virus-infected cells to help protect cells nearby healthy cells 

warning signs 

• healthy cells begin making antiviral proteins for protections one received 

• NK cells are activated 

Complement system

group of proteins in blood that can 

• tag pathogens for destruction

• create holes in bacterial membranes

• attract immune cells to infection site 

Cystolysis

bursting/breaking open of a cell usually by damage to its outer membrane