Week 1 - Cell Adaptions Flashcards
Definition: Physiology
Scientific study of the function of living things
Definition: Pathology
Scientific study of disease
Definition: Active
Requiring energy
Definition: Aerobic
With oxygen
Definition: Anaerobic
Without oxygen
Definition: Hypoxia
Lack of Oxygen
Definition: Ischaemia
Lack of Blood Supply
Definition: Reperfusion
Restoration of blood following period of ischaemia
Definition: Acute
Sudden onset or sudden severe
Definition: Chronic
Long duration
Definition: Cytology
Study of Cells (e.g., pap-smear)
Definition: Histology
Study of tissues (e.g., biopsy)
Definition: Well-Differentiated
Contains features that can be identified as different proteins are being expressed or silenced.
Definition: Undifferentiated
Not unique, cannot be differentiated. Stem cell with no protein being expressed
Most Common Stain: Haematoxylin and Eosin (H&E)
- Haematoxylin stains the nucleus dark blue purple
- Eosin stains the cytoplasm (proteins) pink
- E.g., Cancer would be predominantly dark blue and purple
Flow of Human Makeup
Cells —> Tissues —> Organs —> Organ System
Cellular Differentiation
- Characteristics that determine the cell type
- Structure and function are integrated
3 Types of Cells
- Labile
- Stable
- Permanent
Labile Cells
- Continuously dividing
- Epithelial e.g. Skin, GIT, reproductive, urinary tracts , lining of exocrine ducts
- Haemopoietic stem cells within bone marrow
Stable Cells
- Quiescent
- Not consistently dividing but divide when stimulated
- Epithelial e.g. Liver, kidney, lung, pancreas
- Smooth muscle cells, fibroblasts, endothelial cells
Permanent Cells
- Non-dividing in a full-developed adult
- Cardiac & skeletal myocytes, CNS neurons
- Skeletal Muscle – Population of stem cells within skeletal muscle
- `Original cells don’t divide however the stem cells do
Aging Cells
As we age, cells also age. They become shorter and eventually die
Different Processes of Cell Stress/injury
- Leads to Cell Death —-> Apoptosis or Necrosis
- Apoptosis - Cell death or suicide
- Necrosis - Extensive/explosive cell death, kills surrounding cells as well, causes inflammation, can be caused by sudden loss of blood supply
- Anoikis – Epithelial cells die by apoptosis because connections are lost to their neighbouring cells
Negatives with Necrosis
- Neighbouring cells induced to undergo necrosis and area of tissue becomes infarct
- Stimulation of acute inflammation
- Loss/reduced function of tissue —> scarring, calcification, and death
- Lost tissue cannot be replaced
- Infarct tissue could lead to death
Explain Apoptosis
• Programmed cell death, cell suicide
o Physiological & Pathological
- Active dismantling of the cell
- Condensation of cytoplasm & nucleus
- Break-up and sequ estration within apoptotic bodies
• Phagocytosis of apoptotic bodies
o Macrophages & neighbouring cells
- No inflammation or scarring
- Does not cause harm to neighbouring cells
- Immune system can trigger apoptosis
- Can be caused due to a lack of hormones
Physiological Apoptosis
- Embryonic Development
- Tissue Homeostasis
- Removal of Redundant Cells
- Crucial for Immune Function
- Immune mediated killing
Pathological Apoptosis
- Pathological Atrophy
- Transplant Rejection
- Autoimmune diseases
- Some infections (AIDS, hepatitis)
- Anti-Cancer treatments
Key Differences between Apoptosis and Necrosis
Apoptosis
- Occurs in physiology and pathology
- Active (requires energy)
- Single cell death
- No inflammation
Necrosis
- Is only pathological
- Passive (does not require energy)
- Kills neighbouring cells
- Causes inflammation
Tissue Requirements
Nerve innovation
Blood & lymphatic supply (delivery & removal) o Gases o Hormones o Growth Factors o Nutrients
Defence against invasions o Skin/epidermis o GIT o Urogenital o Respiratory
Cell Requirements
- Functional plasma membrane
- Ability to make RNA & proteins
- The ability to copy & repair DNA*
- Functional cytoskeletal proteins
- Energy (ATP)
- Antioxidant defences
- Ability to remove waste including proteins
- Ability to repair or destroy redundant & damaged organelles
- CHEMISTRY – Temperature, pH etc
Mitochondria
- Surrounded by double membrane
- Have cristae
- Generate energy
- Are full of oxidative enzymes (e.g., cytochrome oxidase)
- Induce cell death
- Prone to stress
Internal Sources of Stress in Mitochondria
More mutations occur in mitochondria as we age, hence prone to more stress
Lysosome
- Waste disposal organelle
- Membrane-bound digestive organelles
- Primary lysosome
- Secondary lysosomes Heterophagosomes autophagosomes
- Give rise to residual bodies (“lipofuscin”)
Cell Adaption Process
- In labile cells, these adaptations are reversible
- Permanent cells cannot reverse cell adaptation (atrophy cannot be reversed)
Autophagy
- Cell shrinkage
- Impaired autophagy cause ageing
Aging (Senescence) - Tissue Atrophy
- Atrophy only occurs at the level of tissue
- Reduced size of a tissue/organ due to loss of cells
- Reduction in size due to individual cells undergoing a combination of autophagy and apoptosis or just apoptosis in old cells
- Reduce functional reserve with age
Apoptosis
Decrease in cell number
Autophagy
Decrease in cell size, reversible
Physiological Atrophy
Accumulate over the course of our life
Pathological Atrophy
Damage to nerve e.g. Broken a bone
Senile Atrophy
Due to age e.g osteoporosis and reduction of muscle mass (Sarcopenia)
Difference between tissue atrophy and infarction
Tissue Atrophy - involves apoptosis, autophagy
Infarct - Ischaemic, haemorrhagic and necrosis
Depends on the health of cells and age
Hypertrophy
Increased size of cells.
Can happen physiologically (gym) and pathologically
Hyperplasia: Physiological and Pathological
Increased number of cells.
Physiological: pregnancy and breast tissue. Pathological: hormonal imbalance (goiter)
Metaplasia: Physiological and Pathological
o The change from one normal/well-differentiated cell type to another normal/well-differentiated cell type.
o Physiological: respiratory system with various epithelial cells. Irritation due to smoking, cell types change. Reversible process.
o Pathological: chronic gastric reflux. Changes to stratified squamous to simple glandular layer.
Connective Tissue: Cell Types
- Myocytes, skeletal, cardiac and smooth myocytes
- Myo- = muscle & -cytes = cells
In pathology,
o Skeletal - Permanent, non-dividing cell
o Cardiac - Permanent cells
o Smooth - Stable cells
o Fibroblasts, collagen and fat (adipocytes) - Stable cells
o Endothelium (lining of blood vessels), cartilage (chondrocytes) and bone (osteoblasts, osteocytes) - stable cells
Epithelium: Duties
Structure and function, secretion, absorption, mechanical and chemical stress, transport
Glandular Epithelium
Endocrine or Exocrine
Tissue Types other than CT and Epithelium
- Mesothelial, melanocytes, germ cells, lymphoid tissue and bone marrow
