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Physiological adaptations Homeostasis: The body's ability to maintain a relatively stable environment. Internal environment: Tissue fluid, interstitial fluid. External environment: Our surroundings. | Intracellular= Inside the cell Extracellular= Outside the cell Systems that help maintain homeostasis= Nervous, endocrine,<-- (control systems) cardiovascular, respiratory, skeletal, etc. |
Internal aspects of the body that need to be maintained at a steady state= Blood glucose levels, temperature, blood pressure, insulin, cholesterol, pH, ions/salts, red & white blood cells, water. | The human nervous system: Detects internal and external stimuli and transmits the information to produce a suitable response. Includes the CNS & PNS. Info is sent via a combination of electrical and chemical signals. |
The somatic nervous system: *Controls skeletal muscles (movement) *Instructions generally originate from the primary motor cortex of the brain. *Controls voluntary movements. | The automatic nervous system: *Controls involuntary functions, such as heart rate, respiration, stomach, endocrine glands, pupil dilation etc. *Can control skeletal muscles if rapid response is required. (Reflex arc). |
Sensory neuron: -Afferent neuron -Detect stimuli and transmit to the CNS. Inter neuron: -Connecting neuron -Transmits signal to motor neurons/ other parts of the CNS | Motor neuron= -Efferent neuron -Initiates the response. Reflex arc= -A simple stimulus- Response pathway that allows for an autonomic response in dangerous situations. |
Human endocrine system: ~Uses chemical substances called hormones to send messages all around the body. ~In response to a signal, hormones are released by specialised groups of cells called 'endocrine glands'. | ~Hormones travel through the bloodstream to all areas of the body but only act on 'target cells'. ~Target cells are cells. |
Nervous system: *Mode of transmission= Electrical and chemical *Speed= Fast *Travel to target= Direct via nerves *Energy expenditure= High *Duration of effect= Short | Endocrine system: *Mode of transmission= Chemical *Speed= Slow *Travel to target= Indirect via bloodstream *Energy expenditure= Low *Duration of effect= Long |
Afferent: Afferent or sensory neurons receive information from the outside (sensory receptors) and sends them to other neurons so the body can produce a response. | Efferent: Efferent neurons or motor neurons receive information from other neurons and send that information to effectors (muscles, glands), which produce a response. |
Stimulus response system: ~Model of how a stimulus cases a change in the state or activity of a cell or organism (response). ~The system results in a changing of the stimulus effect. ~Stimulus may be internal or external. | ~These systems work to maintain homeostasis. ~Controlled by the nervous and/ or endocrine systems. ~A stimulus respond system generally includes a 'negative feedback' stage, which reduces the effect of the stimulus. |
~Our body's core temperature= 37* ~Our bodies heat comes from= Internal reactions, metabolism. ~Our body can detect temperature changes via= Thermoreceptors (Hot & cold receptors); Skin, internal (Blood vessels). | The hypothalamus= ~Receives info from thermoreceptors ~Processes the information ~Initiates an appropriate response HOW WE LOOSE THAT HEAT= Radiation, conduction, convection, evaporation (Sweat, panting). |
Too cool down: ~Reduce the amount of heat generation. ~Increase the amount of heat loss. -->Behavioural: Remove clothing, spread out. --> Sweating: Evaporation increases. | Vasodilation: ~Blood flows to the skin. ~Increase heat loss through radiation. Metabolism: ~Reduce metabolism ~Reduce heat production. |
To warm up we can: ~Increase the amount of heat generated. ~Reduce the amount of heat lost. --> Behavioural: Put on clothes, huddle, shiver (movement of muscles generates heat). | Vasoconstriction: ~Reduce blood flow to skin. ~Reduce heat loss via radiation. Increase metabolism. |
Control centre= Hypothalamus ENDOTHERM: ~Mainly generates their own internal heat through metabolic reactions. ~Tend to have stable core body temperature. | ECTOTHERM: ~Mainly relies on external sources to maintain their body temperature. ~Tend to have fluctuating body temperatures. |
Endotherms (Disadvantage): ~Energy intensive ~Need to eat to provide fuel to warm our body. | Ectotherms (Disadvantage): ~Restricted range due to environmental changes ~Restricted to certain changes of the day/temperatures. |
Endotherms (EXAMPLES): ~Eat a lot of food ~Metabolic processes ~Rely on panting to increase evaporation due to fur ~Avoid overheating | Ectotherms (EXAMPLES): ~Rely on heat, positions that make maximise their exposure. ~Huddle to retain heat ~Vibrating muscles (Sluggish at night) |
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