Animal Circulatory System

• a circulatory fluid

• a set of interconnecting vessels

• a muscular pump (heart)

What are the the three basic components of a circulatory system?

the circulatory system

connects the fluid that surrounds cells with organs that exchange gases, absorb nutrients, and dispose of wastes

True

(T/F) Circulatory can be open or closed and vary in the number of circults in the body.

• circulatory fluid (hemolymph) bathes organs directly

What is an open circulatory system?

• circulatory fluid (blood) confined to vessels and is distinct from interstitial fluid

What is a closed circulatory system?

• one-way through three main blood vessels

  • arteries

  • veins

  • capillaries

How does blood flow in closed circulatory systems?

• hearts pump to circulate blood through closed circulatory systems

  • blood enters through an atrium and is pumped out through a ventricle

What types of hearts do closed chambers have?

• blood leaving the heart passes through two capillary beds before returning

ex. bony fishes, rays, and sharks have single circulation with a two-chambered heart

What is single circulation?

• oxygen-poor and oxygen-rich blood are pumped separately

• oxygen-rich blood is delivered from the heart to the rest of the body through the systemic circuit

• blood travels separately between the heart and the respiratory surfact (pulmonary circuit)

What is double circulation?

• frogs and other amphibians haver a three-chambered heart

  • two atria and one ventricle

• amphibians

  • oxygen-poor blood flows through a pulmocutaneous circuit to pick up oxygen through lungs and skin

What is incomplete separation?

• mammals

  • pulmonary and systemic blood are completely separated

• mammals and birds have a four-chambered heart with two atria and two ventricles

What is complete separation?

• a vessel’s cavity is called the central lumen

• the epithelial layer that lines blood vessels is called the endothelium

• arteries and veins have an endothelium, smooth muscle, and connective tissue

What is the structure of blood vessels?

• only slightly wider than a red blood cell

• velocity of blood flow is the slowest in capillary beds

  • result of high resistance and large total cross-sectional area

• capillaries have thin walls

  • the endothelium plus its basal lamina to facilitate exchange of materials

• osmotic pressure (blue) remains constant

• blood pressure (red) highest at arterial end

What is the structure of capillaries?

• develop from a common source of stem cells (hematopoietic stem cells) in the red marrow of bones

How are blood cells developed?

• myeloid → cells that function in your circulatory system

• lymphoid → cells active in your immune system

  • lymphocytes → T cells, B cells, natural killer cells, and innate lymphoid cells

What are the two different stem cell lines?

• monocytes

• neutrophils

• basophils

• eosinophils

• lymphocytes

What are the different types of leukocytes?

• red blood cells transport O₂

  • most numerous blood cells

  • in mammals, lack nuclei and mitochondria (gives concave appearance)

• contains hemoglobin (Hb)

  • iron-containing protein that transports gases

What are erythrocytes?

partial pressure

the pressure exerted by a particular gas in a mixture of gases (or dissolved in liquid)

• gases undergo a net diffusion from a region of higher partial pressure to a region of lower partial pressure

respiratory medium

what animals use air and water as for a source of O₂

• in a given volume, there is less O₂ available in water than in air

• obtaining O_2, from water requires greater efficiency than air breathing

• animals require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium

• gas exchange across respiratory surfaces takes place by diffusion

• respiratory surfaces vary by animal and can include the skin, gills, tracheae, and lungs

What is the nature of respiratory surfaces?

negative pressure breathing → pulls air into lungs

• lung volume increases as rib muscles and diaphragm (smooth muscle) contracts

• tidal volume → the volume of air inhaled with each breath

• vital capacity → maximal tidal volume

How do mammals ventilate their lungs?

• gases diffuse from higher partial pressure to lower partial pressure

  • blood arriving in the lungs has a low partial pressure of O₂ and high partial pressure of CO₂ relative to air in the alveoli

• alveoli → O₂ diffuses into the blood, and CO₂ diffuses into the air

• tissue capillaries → partial pressure gradients favor diffusion of O₂ into the interstitial fluids and CO₂ into the blood

How are gases loaded and unloaded?

• hemoglobin proteins carry O₂ from the lungs to the body and CO₂ from the body to the lungs

  • oxyhemoglobin → oxygen bound to hemoglobin

  • deoxyhemoglobin → oxygen no longer attached

  • carbaminohemoglobin → CO₂ bound to hemoglobin

What is the erythrocyte gas exchange?