homeostasis and body organization what is homeostasis? “constancy” or “steady state”...
TRANSCRIPT
Homeostasis and Body Organization
What is homeostasis?
“constancy” or “steady state” maintained within the organisms’ bodies.
Whereas the environment can be highly variable, organisms incorporateinternal control mechanisms to oppose the forces that would change theirinternal physiological equilibrium.
The organisms’ internal state can be described as being in dynamic equilibrium, because the body needs to be constantly adjusting to theChanges.
This regulation occurs in two basic ways:
Negative feedback – most important means of maintaining homeostasis,negative feedback creates a counter-effect to the outside environmental change
Positive feedback – a mechanism whereby the effects from the originalenvironmental changes are intensified.
Homeostasis and Body OrganizationPositive and Negative Feedbacks
Homeostasis and Body OrganizationPositive and Negative Feedbacks
Homeostasis and Body OrganizationPositive and Negative Feedbacks
It should be noted though that there are many systems involved in organisms’ Body, and that they all need to interact with each other to maintain homeostasis.
Different systems working independently could end up working against each other,but since the body has systems that move substances and signals from one part of the body to the next, all the different body parts remain “connected”.
This coordination is achieved via chemical (hormones) and/or electrical(nervous) communication between tissues that elicits appropriate responses.
Body Organization
The body is organized at different levels:
Tissues: includes structurally similar cells that act together to perform a particular function. (e.g. muscular, nervous, epithelial, etc.)
Organs: the next higher level of organization, tissues come together to form organs. (e.g. stomach, kidneys, liver, etc.)
Organ systems: the different organs that work together towards a particularfunction come together to create organ systems. (e.g. digestive systemwhich is composed of the stomach, small intestine, large intestine, andother organs.
You are responsible to read pages 526 – 533. Learn the basic structure and function of the major vertebrate organ systems outlined in table 26-2 on page 532.
Circulation
Why do we even need a circulatory system?
Simple diffusion is too slow to serve the needs of “larger” organisms.
Primary Functions?
1. Gas exchange
2. Distribution of nutrients
3. Waste removal
Other functions in vertebrates (and some invertebrates)?
4. Distribution of hormones
5. Regulation of body temperature
6. Protection of body from bacteria and viruses – circulation of antibodies and white blood cells.
Circulation
All circulatory systems have 3 major components:
1. A fluid “blood” that serves as a medium of transport
2. A system of channels (blood vessels) that transport the blood throughout the body.
3. A “heart” that acts as a pump and keeps the blood circulating.
Animals have one of two types of circulatory systems:1. Open2. Closed
Circulation
Note: Vertebrates (including humans) have a closed circulatory system
Circulation – the vertebrate heart
There is an increased level of complexity associated with vertebrate evolution. Thisincreased complexity has created more efficient circulatory systems that have allowedfor greater diversity of form and function in different environments.
This is not of coursethe only solution,squids for examplehave three hearts...
Circulation – the four chambered heart
The mammalian and avian hearts consist of two pumps in one.
One pump is responsible for pulmonary circulation – consisting of the rightatrium and ventricles, this pump is responsible for sending blood to the lungs.
The other pump is responsible for systemic circulation – consisting of the leftatrium and ventricles, this pump is responsible for sending oxygenatedblood to the body.
Circulation – the four chambered heart
Electric impulses coordinatethe sequence of contractions
Valves maintain directionality ofblood flow. The valves are “one-way”
Circulation – the four chambered heart
The atria and ventricles of the heart need to pump in a coordinated fashion. The alternating contraction and relaxation of the heart chambers is calledthe cardiac cycle.
The nervous system and hormones influence heart rate...
The contraction of the ventricles is called the systole and the relaxation is called the diastole
Circulation – the four chambered heartMeasuring blood pressure
Circulation – the four chambered heartElectrocardiograms
Circulation – structure and function of blood vessels
Arteries and Arterioles – Thick-walled vessels that carry blood away from heart
arterioles can control the distribution of bloodby muscular contractions – they are influencedby nerves, hormones, and chemicals produced innearby tissues.
Capillaries – Microscopic vessels that allow blood and body to exchange gas, nutrients, and waste
Veins and Venules – Carry blood back to the heart
Valves direct flow of blood in veins
Circulation – structure and function of blood vessels
Change in blood velocity as a functionof circulatory cross section allows for more efficient transport as well as gas, nutrient, and waste exchange...
Circulation – blood
Blood components:
Plasma – the “fluid” part of the blood, it is composed of 90% water alongwith proteins, hormones, nutrients, gases, salts, and wastes...
Specialized cells – these are cells suspended in the plasma and include red bloodcells, white blood cells, and platelets.
Red blood cells are primarily involved in transport of oxygen
White blood cells are primarily involved in the immune system
Platelets are primarily involved in blood clotting
Circulation – blood
Red blood cells contain a large,iron-containing protein calledhemoglobin.
Each hemoglobin can bind to fouroxygen molecules and is involvedin picking up oxygen in the lungsand transferring it to the body...
Circulation – the lymphatic system
A network of lymph capilaries and large vesselsthat empty into the circulatory system. Functioninclude:
1. Removal of excess fluids and dissolvedsubstances that leak from capillaries.
2. Transport of fats from the small intestineto the blood stream.
3. Defense of the body by exposing bacteriaand viruses to white blood cells.