living in the environment: regulation and control
TRANSCRIPT
Living in the environment: regulation and control
ProcessesHeat
GenerationHeat Input Heat Output
Homeostasis: the maintenance of relatively stable conditions in the internal environment of the body despite variations in the external environment.
Factors such as: – blood pressure, – body temperature, – respiration rate, – blood glucose levels– pH – Ions– O2 and CO2 levels– Nutritional needs– H2O levels
• are maintained within a range of normal values around a set point despite constantly changing external conditions.
• Homeostasis requires the body being able to :– detect external changes– Implement internal changes to compensate
The Stimulus - Response Model
The Stimulus - Response Model
Heat
Cools
The Stimulus Response Model
How can the body control the response?1. Disrupt the signal transduction pathway
2. Removal of the original stimulus3. Responding in a way that alters the original signal. Feedback
Negative feedback mechanisms
Negative Feedback
Negative Feedback Mechanism
Positive feedback• Works by adding to the stimulus and increasing
the effect of it.
Positive feedback
Mechanisms enabling Homeostasis
Negative feedback model
Modes of TransmissionHormonal system• Slow ( 30-178cm/sec)• Act by binding to
specific receptors on target cells after travelling through the blood stream.
• Can be more long term effect
Nervous system• Fast ( 1-120m/sec)• Act by sending electrical
impulses along neuron cells.
• Short term effect.
The Nervous System
The nervous system is a rapid response to stimuli. It is a more direct communication pathway than hormones .
• There are 2 main parts to the Nervous System:– The peripheral nervous system– The central nervous system
Nerve Structure
The nervous system is made up of neuron cells that send an electrical impulse along from one neuron to the next.
Action Potentials
NEURONS
Basic types of neurons
receptor effector
Neuronal structure
The Nerve impulse
Nerve impulse s are an electrical signal that travels along an axon. There is an electrical difference between the inside of the axon and its surroundings,.When the nerve is activated, there is a sudden change in the voltage across the wall of the axon, caused by the movement of ions in and out of the neuron. This triggers a wave of electrical activity that passes from the cell body along the length of the axon to the synapse.
The synapseThe Synapse
There are hundreds of different types of neurotransmitters, each of which control something different.
This makes the nervous system controllable, meaning some neurotransmitter initiate a response while others block a response.
Neurotransmitters
Receptors in the Skin
Types of sensory receptors
CNS
Reflex Response• Many responses are a reflex; not under conscious
control.
• Explain somatic nerves, autonomic nerves, parasympathetic and sympathetic.
HormonesHormones are signalling molecules or chemical messengers that control many functions in the bodies of organisms.
eg temperature, blood glucose levels, calcium uptake and many many more are controlled by hormones.
Endocrine glands
• Cells that produce hormones and are clustered into organs.
Blood sugar levels
Blood sugar levels
When the homeostatic control of Blood sugar is disrupted: Diabetes
• Type 1 Diabetes
• Type 2 Diabetes
The pituitary gland
Cushing's disease-Pituitary Gland
The pituitary gland secretes hormones regulating homeostasis, including tropic hormones that stimulate other endocrine glands. It is functionally connected to the hypothalamus by the median eminence via a small tube called the Pituitary Stalk. It is considered to be the "master gland".
THERMOREGULATION
Ectotherms Endotherms
Thermoregulation animation
countercurrent heat exchange
ThermoregulationFur, feathers and fat Counter-current heat exchange
WHEN ALL ELSE FAILS! Hibernate Diapause
A ind of dormancy shown by insects, where they pause a part of their lifecycle. (Flies in winter??)
When food is scare and the temperature is low. Some animals can’t maintain a stable internal temperature. So instead they hibernate! (Below: Dormice)
Osmoregulation
Maintaining water balanceWays that water can be lost• Panting in dogs, dingos & wolves• Sweating• Urine• Faeces
Ways to save or increase water supply
• Thirst response- experienced as the concentration of water in the blood is lowered
• Waterproof barriers like; hair, feathers, scales and skin protect against evaporative water loss.
• Reabsorption of water from the large intestine.
• Increase in concentration of urine by increasing reabsorption of water in
Kidneys.• Storage of water.
– (Desert frogs store water in a cocoon,– Camel’s store fat in their hump and
metabolise the fat to gain water
Aquatic animalsSaltwater • Marine saltwater animals tend
to have body fluids that are HYPOTONIC to their surroundings. So they lose water via osmosis to their surroundings.
• To gain more water they drink salt water and must spend a lot of energy removing salt from their body.
Freshwater
• Freshwater animals have lots of water in their surroundings but have body fluids that are HYPERTONIC to their surroundings. So they can gain too much water from their surroundings, causing their cells to burst.
External : Hi H2O LO Salts External : LO H2O Hi Salts
Internal : Hi H2O LO SaltsInternal : LO H2O Hi Salts