mechanisms to maintain internal enviro Flashcards
define endotherms
Endotherms: organisms that can maintain a constant internal body temperature within a very narrow range of tolerance limits despite variations in the ambient temperature
define adaptation
Adaptation: characteristic that an organism posses that will increase its survival and reproductive chances
TRENDS AND PATTERNS
examples of BEHVIOURAL ADAPTATIONS
- Movement: move to shaded/exposed areas to decrease/increase heat exposure
- Migration: move to different habitats that are within their tolerance range
- Sunbaking: increasing surface area available for heat absorption
- Licking: enabling more heat to be evaporated through saliva
- Drinking water: to replenish fluids to maintain cells in a consistent isotonic state
- Nocturnal activity: remain inactive during the heat of the day to refrain from activity that increases metabolic body heat
examples of STRUCTURAL ADAPTATIONS
- Insulation: feathers, hair and fur trap a layer of air next to the skin which reduces amount of heat lost
- Surface area to volume ratio: more compact bodies reduce surface area available for heat exchange, allowing animals to retail heat more effectively
examples of PHYSIOLOGICAL ADAPTATIONS
- Vasoconstriction and vasodilation: allow animals to regulate blood flow to increase or decrease the amount of heat lost to surroundings
- Metabolic activity: can be increased to increase the production of heat energy internally, or decreased to cool the body temperature
- Muscle contraction: making small movements produces heat energy
- Sweating: allows sweats to evaporate from the skin, which has a cooling effect
INTERNAL COORDINATION SYSTEMS THAT MAINTAIN HOMEOSTASIS
- endocrine and nervous systems work together
define HORMONES
- Are chemical signalling molecules, transported by the bloodstream, used by the body to regulate physiology and behaviour
where are hormones produced are how are they transported?
○ Produces in the glands and transported around the body using the circulatory or lymph systems
what is the process that hormones cause cells to change their activity to maintain homeostasis
○ Binds to specific receptors on their surfaces, enacting changes in a process called signal transduction
EXAMPLES OF HORMONES
what hormone and its function is produced in the PINEAL GLAND
melatonin- affects reproductive development and daily physiologic cycles
EXAMPLES OF HORMONES
what 3 hormone and its function is produced in the PITUATARY GLAND
growth hormone- controls bone and muscle growth
antidireutic hormone- increases reabsorption of water in kidneys
gonadotrophins- controls development of ovaries and testes
EXAMPLES OF HORMONES
what hormone and its function is produced in the THYROID GLAND
thyroxin- controls rate of metabolism and rate that glucose is used up in respiration and promotes growth
EXAMPLES OF HORMONES
what hormone and its function is produced in the ADRENAL GLAND
adrenalin- prepares body for emergencies, increases heart rate, breathing rate, raises blood sugar levels so that more glucose is available for respiration, diverts blood from gut to limbs
EXAMPLES OF HORMONES
what hormone and its function is produced in the PANCREAS
insulin- converts excess glucose into glycogen in liver
glucagon- converts glycogen back into glucose in liver
EXAMPLES OF HORMONES
what hormone and its function is produced in the OVARIES
oestrogen- controls ovulation and secondary sexual characteristics
progesterone- prepares the uterine lining for receiving an embryo
EXAMPLES OF HORMONES
what hormone and its function is produced in the TESTES
testosterone- controls sperm production and secondary sexual characteristics
EXAMPLES OF HORMONES
what hormone and its function is produced in the THYMUS
thymosin- promotes production and maturation of WBCs
function of the endocrine system
Regulates activity of the body by controlling hormone secretion and the glands that
secrete them.
Hormonal glands can be stimulated by messages from the nervous system, by other hormones or by receptors located in the particular gland.
what do receptors do
detect stimuli in the form of changes outside of
tolerance limits.
NERVOUS SYSTEM
- what does it do
- CNS ?
- peripheral? + function
○ Provides the neural pathways by which messages travel in the body and acts as a control centre to coordinate activities that maintain homeostasis.
○ Central nervous system (CNS) → brain and spinal cord
○ Peripheral nervous system → all nerves throughout body that are not part of CNS
○ The peripheral nerves detect stimuli and carry information to and from the CNS by
transmitting messages in the form of electrochemical responses.
list 4 features of neuron structures
cell body: nucleus and organelles found in other cells
dendrites: Fine branching extensions of the cytoplasms that receive messages in the form of impulses from other axons and conduct these nerve impulses towards the cell body
axons: Long extensions of cytoplasm that conduct messages away from the cell body
myelin sheath: Fatty insulating substance that surrounds and protects some nerve fibres
- the fatty sheath increases the speed of the nerve impulses along the neuron
list and describe the 3 types of neurons
- motor neurons: transfer messages along the CNS to effectors (things that produce a response to specific stimulus such as muscles or glands. short dendrite with long axon)
- interneurons: the link between motor and sensory neurons on the CNS.
short dendrite with short axon - sensory neurons: carry impulses from the sensory cells in the PNS to the CNS.
long dendrite with short axon
how do neurons carry signals to and from the CNS
When a stimulus is detected by sensory receptors, sensory neurons (nerve cells) send signal from the sensory receptors to the CNS. CNS coordinates response and sends signal down through a interneuron to a motor neuron. Nerve cells that receive from CNS transfer the signal to the effector. The effectors produce a response to the stimulus.
- Electrochemical impulses involve change in electricial potential of the cell membrane of the axon. (action potential)
MECHANISMS IN PLANTS THAT ALLOW WATER BALANCE TO BE MAINTAINED
explain INTERNAL WATER CONTROL via GUARD CELLS AND STOMATA
• Plants control water movement out of leaves to keep stable internal environment
* When water level is high in plants -> guard cells on leaves absorb water and become turgid-> thin outerwalls stretch out and thick inner walls are pulled apart-> stomata open * Water diffuses out of plant until homeostasis returns
Low water level-> guard cells become flaccid-> stomata close to prevent water loss-> homeostasis returns -> maintains water balance
OTHER STRUCTURES
- Orientation: angling leaves away from the sun at different times of the day reduces the rate of the transpiration
- Smaller leaves: reduces SA to volume ratio -> less SA for transpiration
- Water storage: succulents survive in dry enviro asthey have fleshy stems and leaves that swell up and retain moisture when its available
- Regulating openining and closing of stomata: opening stomata at the cooler parts of day and night and closing it during the hotter parts reduces evaporation and therefore minimises water loss
waxy cuticle: ensures epidermal cells are waterproof, preventing loss of water by evaporation from surface cells
