Biology Exam 6

What are the major parts of the circulatory system?

heart, blood vessels, blood

Structure of the circulatory system

the heart: atriums on top, ventricles on the bottom

veins move blood to the heart

arteries move blood away from the heart

the right side is the pulmonary circulation, the left is systemic circulation

What is the process of the circulatory system?

• superior and inferior vena cava carry oxygen-poor blood returning from the body to the right atrium

• then goes to the right ventricle

• right ventricle sends blood through the pulmonary arteries to the lungs, where the blood picks up oxygen

• the now oxygen-rich blood flows through pulmonary veins back to the left atrium

• then goes to the left ventricle

• the aorta takes the blood out

• a series of one-way valves in the heart ensures the blood is moving in the correct direction

The Cardiac Cycle

hart undergoes a rhythm of relaxation (diastole) and contraction (systole)

1. the atria and ventricles are relaxed and blood enters the heart

2. the atria contract, forcing blood into the still-relaxed ventricles

3. atria relax, ventricles contract, forcing blood into the aorta and pulmonary arteries

What are the major types of blood vessels?

arteries: carry blood away from the heart | capillaries: site of exchange of materials b/t blood and body tissues | veins: carry blood toward the heart

Structures of blood vessels

• arteries move away from the heart, they branch into smaller arterioles (arterioles have thinner walls than arteries, allowing them to be closed to regulate blood flow in the body)

• arterioles keep branching and becoming smaller capillaries (smallest and most numerous of blood vessels; have thin walls and exchange stuff b/t blood and body cells)

• capillaries are organized into networks of capillary beds (blood moves slowly)

• capillaries then join to form venules (drain blood from cap. beds) and then join to form veins (both venules and veins carry blood to the heart)

• arteries can have high blood pressure, veins have low

Functions of blood

• transport of nutrients, wastes, and hormones

• regulation of body temperature, blood and osmotic pressures, and pH

• protection form disease-causing pathogens and excess loss of blood by clotting mechanisms

Blood structure

• blood consists of plasma and formed elements

• plasma makes up 50-60% of the blood and is mostly water in which a variety of ions and molecules are dissolved

• formed elements are the other 40-50% and includes red blood cells, white blood cells, platelets

Blood cells

• RBC (erythrocytes) contain hemoglobin, a protein that transports oxygen

• WBC (leukocytes) are involved in tissue maintenance and repair as well as providing defense against infection

• platelets are involved in blood clotting

• all blood cells are produced by red bone marrow

Cardiovascular Disorders

• CVD is the leading cause of death in Western countries

• atherosclerosis (artery blockage)

• hypertension (chronic high blood pressure)

• heart attack (lack of blood flow to the heart)

• stroke (lack of blood flow to the brain)

• certain arrhythmias (irregular heart beats)

• regular exercise, maintaining normal body weight, and not smoking lower the risk

Skeleton and muscle functions

• skeleton: protection for internal organs, supports body weight, stores mineral and lipids, produces blood cells, and allows for movement

• muscles: contract, causing movement of the skeleton as well as moving food and blood in the body

Skeletal System

• humans have endoskeleton consisting of 206 bones in the adult

• divided into axial skeleton and appendicular skeleton

Axial Skeleton

• includes skull, vertebral column, and thoracic cage

• skull protects brain and head organs

• vert. col. protects spinal cord and supports the body

• thor. cage protects heart/lungs and involved in breathing

Appendicular Skeleton

• consists of bones in pectoral/pelvic girdles and their attached limbs

• pectoral girdles and upper limbs are specialized for flexibility

• pelvic girdle and lower limbs are specialized for strength

Joints

joints are where bones meet

• fibrous joints are immovable, and are usually tightly connected bones (skull) (bone-against-bone)

• cartilaginous joints allow slight movement; bones joined by strips of cartilage (rib cage) (small space w/ cartilage)

• synovial joints can move freely, bones connected by ligaments (elbow) (space b/t bones)

Muscles

• skeletal muscles provide force needed to move the body

• muscles are bundles of cells attached to bones using tendons

• muscles work by contracting

• muscle pulls on the tendon which pulls on the bone, moving it

• muscles can only pull; they never push

• muscles must work in antagonistic pairs; one moves a bone in one direction and the other moves it in the other direction

Muscle Structure

• a skeletal muscle cell (muscle fiber) is made up of many myofibrils

• a myofibril consists of repeating sarcomeres (basic units of muscle contraction)

• each sarcomere is made of two proteins (myosin and actin) arranged as parallel filaments

• using ATP, the heads bend, pulling the actin with them

• the head then releases the actin and moves back to its original position

• this repeats, moving the actin filaments

Community Ecology

• ecology: study of how species interact with their environment

• each species lives in a habitat, characterized by physical and chemical features and the other species living in it

• a community is made of all populations of all species in a habitat

• each species in a community has its own niche (sum of all conditions, activities, and relationships it needs to survive and reproduce)

• most interactions b/t species are neutral (no effect on either species)

• a close, non-neutral association is symbiosis

Competition

• negative, negative

• two individuals try to use the same limited resource

• if resources are too limited, competition might force one of the species to extinction

• to avoid this, species may use different parts of the niche to reduce competition

Predation

• positive, negative

• involves a predator killing/eating its prey

• prey use many methods to avoid predation

• many prey species defend themselves mechanically (spines, thorns, etc.) or chemically (poisons, venomes)

• camouflage is making oneself “invisible”

• warning coloration is bright colors that warn the prey is noxious or dangerous in some way

• mimicry is making one’s self look like another usually harmful organism

Commensalism

• one species benefits but the relationship has no effect on the other

Mutualism

• both individuals benefits

Parasitism

• positive, negative

• parasite withdraws nutrients from the host’s tissues

• the host is usually not killed

• social parasites manipulate some aspect of a host’s behavior

Characteristics of Communities

• communities distinguished by their biodiversity (total # of species and relative abundance) and keystone species

• keystone species has a disproportionately large effect relative to its abundance

• removal of a keystone species can cause drastic changes, including extinction of other species

Threats to biodiversity

• humans cause extinction by:

  • habitat loss

  • overharvesting

  • exotic species

  • climate change

• most threatened or endangered species are affected by multiple causes

Habitat Loss

• reduction/loss of living space

• single greatest factor causing extinction because it affects all species in an area

• hardest factor to reverse

Overharvesting

• individuals are taken faster than mother nature can replace them

• population size reduces and reaches a point where recovery isn’t possible

Exotic Species

• nonnative species that migrate or are introduced to new ecosystems

• can alter habitats, outcompete and/or displace native species, or introduce a disease

Climate Change

• occurs naturally (slowly)

• accelerated by human actions

• can cause shifts in species distributions and changes to timing of natural events

Preserving Biodiversity

• extinction is a natural event

• trying to prevent human-caused extinction

1. change human behavior (reduce consumptions, sustainable harvest, ecotourism)

2. conservations preserves (save biodiversity hotspots- small areas that hold an unusually high number of species)

3. habitat restoration (remove dams, replant vegetation, protect keystone species, etc. to improve biodiversity)