Lecture 3 - Organs and Tissues Flashcards
What is a tissue?
A collection of cells of the same type that perform a common function
Name the major tissue types within the body
- Connective
- Muscular
- Nervous
- Epithelial
What does connective tissue do?
- Binds and supports parts of the body
- All have specialised cells, ground substance and protein fibers
- Ground substance is noncellular and ranges from solid to fluid
- The ground substance and protein fibers together make up the matrix of the tissue
What are the 3 main types of connective tissue?
- Fibrous
- Supportive
- Fluid
Types of fibrous connective tissue?
2 types - dense or loose, but both contain fibroblasts cells with a matrix of collagen and elastic fibres
Loose fibrous tissue is found supporting epithelium and many internal organs
Adipose tissue is a special loose fibrous tissue where fat is stored
Types of supportive connective tissue?
Cartilage - cells are in chambers called lacunae
Matrix is solid but flexible
3 types are distinguished by types of fibres
Types of fluid connective tissue?
Blood - contained in blood vessels
Lymph - contained in lymphatic vessels
What do adipose cells release?
Hormone, Leptin which down-regulates appetite
Supportive connective tissue - Cartilage - What are the 3 types that are distinguished by types of fibres? and where are they located?
- Hyaline Cartilage - fine collagen fibres
Located at the nose, ends of long bones and fetal skeleton - Elastic cartilage - more elastic fibres than cartilage fibres
Located at the outer ear - Fibrocartilage - strong collagen fibres
Located at disks between vertebrae
Properties of supportive connective tissue - bone?
- Cells are in chambers called lacunae
- Matrix is solid and rigid that is made of collagen and calcium salts
2 types are distinguished by types of fibres
Compact - made of repeating circular units called osteons which contain the hard matrix and living cells and blood vessels
Located in shafts of long bone
Spongy - an open, latticework with irregular spaces
Located at ends of long bones
Properties of fluid connective tissue - blood?
- Made of fluid matrix called plasma and cellular components that are called formed elements:
- 3 formed elements:
1. Red blood cells - cells that carry oxygen
2. White blood cells - cells that fight infection
3. Platelets - pieces of cells that clot blood
Fluid connective tissue - Lymph
- Matrix is a fluid called lymph
- White blood cells congregate in this tissue
Properties of muscle tissue?
- Allows for movement in the body
- Made of muscle fibres/ cells and protein fibres called actin and myosin
Different types of muscle tissue in humans?
There are 3 different types of muscle tissue in humans
- Skeletal
- Smooth
- Cardiac
Muscle tissue - skeletal
Appearance: Long, cylindrical cells, multiple nuclei striated fibres
Location: Attached to bone for movement
Nature: Voluntary movement
Muscle tissue - smooth
Appearance: spindle-shaped cell with one nucleus, lacks striations
Location: walls of hollow organs and vessels
Nature: Involuntary movement
Muscle tissue - Cardiac
Appearance: branched cells with a single nucleus, striations called darker striations called intercalated disks between cells
Location: heart
Nature: Involuntary movement
Properties of nervous tissue?
- Allows for communications between cells through sensory input, integration of data and motor output
Made of 2 major cells
A. neurons
B. Neuroglia
Properties of neurons (nervous tissue)?
- Made of dendrites, a cell body and an axon
- Dendrites carry information toward the cell body
- Axons carry information towards a cell body
Properties of neuroglia (nervous tissue)?
- A collection of cells that support and nourish neurons
- Outnumber neurons 9:1
- Examples are oligodendrocytes, astrocytes and microglia
Properties of epithelial tissue?
- A group of cells that forms a tight, continuous network
- Lines body cavities, covers body surfaces and found in glands
- Cells are anchored by a basement membrane on one side and free on the other side
- Named after the appearance of cell layers and the shape of the cells
- There is transitional epithelium that changes in appearance in response to tension
How do we name epithelial tissue?
- Number of cells layers
Simple - 1 layer of cells
Stratified - More than 1 layer of cells
Pseudostratified - Appears to have layers but only has one layer - Shape of cell
Cuboidal - cube-shaped
Columnar - column-shaped
Squamous - flattened
The integumentary system
- Includes the skin and accessory organs such as hair, nails and glands
- The skin has two main regions called the epidermis and the dermis
- Under the skin there is a subcutaneous layer between the dermis and internal structures where fat is stored
- Is important for maintaining homeostasis
What are the functions of the integumentary system?
- Protects the body from physical trauma, invasion by pathogens and water loss
- Helps regulate body temperature
- Allows us to be aware of our surroundings through sensory receptors
- Synthesises chemicals such as Melanin and Vitamin D
Two regions of the skin?
- Epidermis
2. Dermis
Properties of the epidermis?
- The thin, outermost layer of the skin
- Made of epithelial tissue
- Cells in the uppermost cells are dead and become filled with keratin thus acting as a waterproof barrier
- Langerhans cells are a type of white blood cells that help fight pathogens
- Melanocytes produce melanin that lend to skin colour and protection for UV light
- Some cells convert cholesterol to Vitamin D
Properties of the dermis?
- The thick, inner layer of the skin
- Made of dense fibrous connective tissue
- Contains elastic and collagen fibres
- Contains blood vessels, many sensory receptors and glands
What are the accessory organs of the skin and why are they important?
- Includes hair, nails and glands
- Nails are derived from the epidermis that offer a protective covering
- Hair follicles are derived from the dermis but hair grows from epidermal cells
- Oil glands are associated with hair and produce sebum that lubricates hair and skin as well as retards bacterial growth
- Sweat glands are derived from the dermis and help to regulate body temperature
Moving from tissue to organs and organ systems
- An organ is 2 or more tissue types working towards a particular function
- An organ system s a combination of organs that work together to carry out a particular function
Integumentary system
- Protects body
- Receives sensory input
- Helps control temperature
- Synthesises vitamin D
Cardiovascular system
- Transports blood, nutrients, gases and wastes
- Defends against disease
- Helps control temperature, fluid and pH balance
Lymphatic and immune systems
- Help control fluid balance
- Absorb fats
- Defend against infectious disease
Digestive system
- Ingests food
- Digests food
- Absorbs nutrients
- Eliminates waste
Urinary system
- excretes metabolic wastes
- helps control fluid balance
- helps control pH balance
Skeletal system
- supports the body
- protects body parts
- helps move the body
- stores minerals
- produces blood cells
Muscular system
- maintains posture
- moves body and internal organs
- produces heat
Nervous system
- Receives sensory input
- Integrates and stores input
- Initiates motor output
- Helps coordinate organ systems
Endocrine system
- Produces hormones
- Helps coordinate organ systems
- Responds to stress
- Helps regulate fluid and pH balance
- Helps regulate metabolism
Reproductive system
- Produces gametes
- Transports gametes
- Produces sex hormones
- Nurtures and gives birth to offspring in females
Respiratory system
- Maintains breathing
- Exchanges gases at lungs and tissues
- Helps control pH balance
What about the body membranes that line the cavities?
- Mucous membranes - lining of the digestive, respiratory, urinary and reproductive systems
- Serous membranes - line lungs, heart, abdominal cavity and cover the internal organs; named after their location
Pleura - lungs
Peritoneum - abdominal cavity and organs
Pericardium - heart - Synovial membrane - lines the cavities of freely movable joints
- Meninges - Cover the brain and spinal cord
What is homeostasis?
- The ability to maintain a relatively constant internal environment in the body
- The nervous and endocrine systems are key in maintaining homeostasis
- Changes from the normal tolerance limits result in illness or even death
What are the mechanisms for maintaining homeostasis?
- Negative feedback
- Positive feedback
What is negative feedback?
The primary mechanism for maintaining homeostasis
Has 2 components
- Sensor
- Control center
- The output of the system dampens the original stimulus
What is positive feedback?
- A mechanism for increasing the change of the internal environment in one direction
- An example is the secretion of oxytocin during birth to continually increase uterine contractions
- Can be harmful such as when a fever is too high and continues to rise
