Biol 1057 - Tissue organisation & Homeostasis Flashcards
Briefly outline cells tissues and organ systems
- Cells are composed of molecules and have
specialised functions. - A tissue is a group of cells, all working together.
- An organ contains various types of tissues.
- Many organs are found in an organ system.
Outline tissues more and the 4 types
- Connective Tissue: binds and supports body parts by being flexible and giving structural support
- Bone, ligaments, tendons, cartilage, blood and lymph. - Muscular Tissue: moves the body and its parts
o Skeletal (skeleton), smooth muscle (stomach, intestines),
cardiac (heart). - Nervous Tissue: forms a rapid communication network.
o Neurons, nerves (carry messages-sensory information) - Epithelial Tissue: covers body surfaces and lines body cavities.
o Skin, lungs, respiratory tract, intestines.
Outline 3 types of connective tissues
Outline fibrous connective tissues
Outline supportive connective tissues
➢ Bone and cartilage are the two main supportive connective tissues.
➢ Provide structure, shape, protection, and leverage for movement.
➢ Cartilage (lacks mineralisation) is more flexible than bone.
Outline fluid connective tissues
Outline components of connective tissues
➢ Protein Fibres:
* Include collagen and elastin.
* Provide support, elasticity, flexibility and strength.
➢ Specialised Cells:
* Not attached to one another.
➢ Ground Substance:
* Noncellular material that separates the cells.
* It varies in consistency.
* It may be solid (bone), semifluid (cartilage) or fluid (blood).
Outline muscular tissue and the 3 types
➢Specialised to contract (become shorter)
➢Composed of cells called muscle fibres
➢Containing actin and myosin filaments
* Role = slide past one another (contraction)
➢Function: Movement of tissues, organs and body parts
Outline skeletal muscle
➢Attached by tendons to the bones.
➢Contraction under voluntary control (fast response).
➢ When it contracts, body parts move.
➢Fibres are cylindrical in shape and long.
➢Arise during development when several cells fuse
together.
➢Have multiple nuclei.
➢Appears striated (striped) due to the arrangement of
actin and myosin filaments.
Outline smooth muscle
➢No striations.
➢Spindle-shaped cells with one nucleus.
➢ Mediates involuntary movements (slow response).
➢Found in internal organs (intestine, bladder) and blood vessels.
➢Facilitates movement of substances.
Outline cardiac muscle
➢ Found only in the heart walls.
➢ Mediates contraction of the heart to pump blood.
➢ Involuntary contractions.
➢ Has striations.
➢ Composed of short branched cells, containing one nucleus.
➢ Cells are connected by intercalated disks
* Allow communication between the cells.
* Co-ordinate contraction (heartbeat).
Outline what nervous tissue consists of and the main functions
Nervous tissue consists of:
* Nerve Cells (neurons)
* Glial Cells (cells that support and nourish neurons)
Primary functions in the body:
o Sensory input
* detection of stimuli such as scent, pain, touch etc.
o Integration of the information
* by the central nervous system, brain and spinal cord
o Motor output
* conduction of signals from the brain and spinal cord to organs to trigger a response such
as muscle contraction, secretion of substances by glands etc.
Outline the process of the function of nervous tissue
➢ Sensory input is detected
➢ Information is integrated and processed
by the central nervous system (brain
and spinal cord).
➢ It is transcribed into Motor output by
the peripheral nervous system.
➢ Triggering a specific co-ordinated
response to the original sensory input.
Outline neurons and glial cells
Neurons are specialised cells that have
* Dendrites – extensions that receive signals
from other neurons
* A cell body – contains nucleus and cytoplasm
* An axon – an extension that conducts the
signals
Neurons conduct signals along the bod
➢ Glial cells: specialised cells that support neurons and assist
their function.
➢ Examples of glial cells are microglia, astrocytes, and
oligodendrocytes
Briefly outline epithelial cells
➢ Consists of tightly packed cells that form a continuous layer and have no capillaries
➢ Cover surfaces and lines body cavities, having a protective function.
➢ May also be able to secrete, absorb, excrete or filter substances.
➢ Exposed on one side to the environment, connected to a basement membrane on
the other side.
➢ Named based on the number of cell layers and the shape of the cells.
➢ These features are related to the specialised function that the cells need to
perform.
Brief examples of epithelial tisssue
Outline classification of epithelial tissue
Comaprison of one layer to more than 1 layer
Examples of epithelial tissue
Birefly outline microvilli and cilia
- Microvilli increase the surface area
of the cell membrane inorder to
increase absorption - Cilia move to propel mucous and other
substances along epithelial surfaces.
Some cilia also act as sensors
Outline ciliated epithelium
➢ Cilia line the nasal cavities, larynx, trachea, and large bronchial tubes.
➢ Move in wave-like motions to sweep mucus with trapped dust and
bacteria from inhaled air.
➢ Lines women fallopian tubes to sweep the ovum/egg from the ovary to
the uterus
Outline mucus membrane or mucosa
➢ Line the body tracts (systems) that have openings to the environment:
the respiratory, digestive, urinary, and reproductive tracts.
➢ Esophagus: stratified squamous epithelium
➢ Trachea: ciliated pseudostratified columnar epithelium stomach,
intestine: columnar epithelium
Briefly outline all the organ systems
Outline homeostasis
➢ Homeostasis is the maintenance of a relatively constant internal
environment.
➢ The body systems help maintain homeostasis by adjusting their
physiologicalresponses when conditions change.
➢ Internal environment is maintained close to an optimal point even
though the external environment may change dramatically.
o e.g. the external temperature may change but body temperature remains
near 37oC.
➢ If homeostasis is not maintained, the function of the organism is
adversely affected and illness occurs.
Outline negative feedback
➢ Negative feedback is the primary mechanism that is used to
keep a variable close to the optimum level and maintain
homeostasis.
➢ Has three components:
o A sensor that detects a change in the internal environment.
o A control centre that instructs a response to counteract the
change.
o An effector that gets activated to produce a physiological
response that brings conditions back to the optimumlevel.
Outline regulation of body temperature as negative feedback
➢ When body temperature rises above normal:
o The hypothalamus senses the change and causes
* Blood vessels to dilate
* More blood flow near surface of body = heat loss.
* Nervous system to activate the sweat glands to secrete.
* Evaporation of sweat.
➢ Lowers body temperature to normal value.
➢ When body temperature falls below normal:
o The hypothalamus senses the change and causes
* Blood vessels to constrict = conserves heat
* Nervous system activates skeletal muscles to induce
shivering.
➢ Increases body temperature to normal value.
Outline regulation of body temperature as negative feedback
➢ Baroreceptors are mechanoreceptors that respond to
changes in blood pressure of the blood.
➢ When blood pressure rises, baroreceptors signal the
regulatory centre in the brain, which responds by sending
out nerve signals to the arterial walls, causing their smooth
muscle to relax.
➢ The blood pressure then falls to normal.
➢ Once blood pressure is returned to normal, the
baroreceptors are no longer stimulated.
Outline regulation of blood pressure as negative feedback
➢ Baroreceptors are mechanoreceptors that respond to
changes in blood pressure of the blood.
➢ When blood pressure rises, baroreceptors signal the
regulatory centre in the brain, which responds by sending
out nerve signals to the arterial walls, causing their smooth
muscle to relax.
➢ The blood pressure then falls to normal.
➢ Once blood pressure is returned to normal, the
baroreceptors are no longer stimulated.
Diagram for low blood pressure
Outline regulation of blood glucose as negative feedback
WHEN BLOOD GLUCOSE DECREASE
- Detected by alpha cells in islets of Langerhands
- Alpha cells release glucagon and adrenal gland releases adrenaline
- Second messenger model occurs to activate enzymes to hydrolyse glycogen
- Glycogen is hydrolysed to glucose(Glycogenolysis) in liver and more glucose realeased back into blood or
WHEN BLOOD GLUCOSE INCREASES
- Detected by beta cells on islets of Langerhans
- Beta cells release insulin
- Liver cells become more permeable to glucose and enzymes activated to convert glucose to glycogen(Glycogenesis) in liver
- Glucose removed from blood and stores as glycogen in cells
Outline positive feedback
➢ Positive feedback is a mechanism by which the body responds to a change by
amplifying it.
➢ It brings about rapid change in the same direction as the stimulus.
➢ Positive feedback does not maintain homeostasis.
➢ Normal biological functions demonstrating positive feedback.
➢ Examples: childbirth, blood clotting.
➢ Positive feedback may also occur in disease.
➢ Example: fever that rises above 42oC.
Outline childbrith as an example of positive feedback
➢ Positive feedback is a mechanism by which the body responds to a change by
amplifying it.
➢ It brings about rapid change in the same direction as the stimulus.
➢ Positive feedback does not maintain homeostasis.
➢ Normal biological functions demonstrating positive feedback.
➢ Examples: childbirth, blood clotting.
➢ Positive feedback may also occur in disease.
➢ Example: fever that rises above 42oC.
Outline blood clotting as an example of positive feedback
➢ When an injury occurs, blood clots form
protecting against further blood loss.
➢ Blood clotting involves platelets and proteins.
➢ Prothrombin and fibrinogen are two inactive
blood proteins. They circulate constantly,
ready to be activated to form a clot if needed.
➢ Without blood clotting, excessive bleeding
may cause death even from a small cut.
Outline fever as an example of positive feedback
➢ Body temperature is normally controlled by negative
feedback mechanisms.
➢ If temperature rises above 42-43oC, the metabolic rate
increases, causing the body to produce heat faster, further
increasing body temperature (positive feedback).
➢ A positive feedback mechanism can be harmful, as when a
fever causes metabolic changes that push the fever higher.
➢ Death occurs at a body temperature of 45°C, because
cellular proteins denature at this temperature and
metabolism stops.
